Programs & Examples On #Multidimensional array

Multidimensional-arrays can be described as multi-dimensional tables. Each index used in order to find a given element is called a dimension.

Iterate through 2 dimensional array

Simple idea: get the lenght of the longest row, iterate over each column printing the content of a row if it has elements. The below code might have some off-by-one errors as it was coded in a simple text editor.

  int longestRow = 0;
  for (int i = 0; i < array.length; i++) {
    if (array[i].length > longestRow) {
      longestRow = array[i].length;
    }
  }

  for (int j = 0; j < longestRow; j++) {
    for (int i = 0; i < array.length; i++) {
      if(array[i].length > j) {
        System.out.println(array[i][j]);
      }
    }
  }

Multi-dimensional associative arrays in JavaScript

Just use a regular JavaScript object, which would 'read' the same way as your associative arrays. You have to remember to initialize them first as well.

var obj = {};

obj['fred'] = {};
if('fred' in obj ){ } // can check for the presence of 'fred'
if(obj.fred) { } // also checks for presence of 'fred'
if(obj['fred']) { } // also checks for presence of 'fred'

// The following statements would all work
obj['fred']['apples'] = 1;
obj.fred.apples = 1;
obj['fred'].apples = 1;

// or build or initialize the structure outright
var obj = { fred: { apples: 1, oranges: 2 }, alice: { lemons: 1 } };

If you're looking over values, you might have something that looks like this:

var people = ['fred', 'alice'];
var fruit = ['apples', 'lemons'];

var grid = {};
for(var i = 0; i < people.length; i++){
    var name = people[i];
    if(name in grid == false){
        grid[name] = {}; // must initialize the sub-object, otherwise will get 'undefined' errors
    }

    for(var j = 0; j < fruit.length; j++){
        var fruitName = fruit[j];
        grid[name][fruitName] = 0;
    }
}

How do I declare a 2d array in C++ using new?

I don't know for sure if the following answer wasn't provided but I decided to add some local optimizations to the allocation of 2d array (e.g., a square matrix is done through only one allocation): int** mat = new int*[n]; mat[0] = new int [n * n];

However, deletion goes like this because of linearity of the allocation above: delete [] mat[0]; delete [] mat;

How do I iterate through each element in an n-dimensional matrix in MATLAB?

If you look deeper into the other uses of size you can see that you can actually get a vector of the size of each dimension. This link shows you the documentation:

www.mathworks.com/access/helpdesk/help/techdoc/ref/size.html

After getting the size vector, iterate over that vector. Something like this (pardon my syntax since I have not used Matlab since college):

d = size(m);
dims = ndims(m);
for dimNumber = 1:dims
   for i = 1:d[dimNumber]
      ...

Make this into actual Matlab-legal syntax, and I think it would do what you want.

Also, you should be able to do Linear Indexing as described here.

How to sort an array of associative arrays by value of a given key in PHP?

Was tested on 100 000 records: Time in seconds(calculated by funciton microtime). Only for unique values on sorting key positions.

Solution of function of @Josh Davis: Spended time: 1.5768740177155

Mine solution: Spended time: 0.094044923782349

Solution:

function SortByKeyValue($data, $sortKey, $sort_flags=SORT_ASC)
{
    if (empty($data) or empty($sortKey)) return $data;

    $ordered = array();
    foreach ($data as $key => $value)
        $ordered[$value[$sortKey]] = $value;

    ksort($ordered, $sort_flags);

    return array_values($ordered); *// array_values() added for identical result with multisort*
}

Get the size of a 2D array

In Java, 2D arrays are really arrays of arrays with possibly different lengths (there are no guarantees that in 2D arrays that the 2nd dimension arrays all be the same length)

You can get the length of any 2nd dimension array as z[n].length where 0 <= n < z.length.

If you're treating your 2D array as a matrix, you can simply get z.length and z[0].length, but note that you might be making an assumption that for each array in the 2nd dimension that the length is the same (for some programs this might be a reasonable assumption).

Matrix multiplication using arrays

static int b[][]={{21,21},{22,22}};

static int a[][] ={{1,1},{2,2}};

public static void mul(){
    int c[][] = new int[2][2];

    for(int i=0;i<b.length;i++){
        for(int j=0;j<b.length;j++){
            c[i][j] =0;
        }   
    }

    for(int i=0;i<a.length;i++){
        for(int j=0;j<b.length;j++){
            for(int k=0;k<b.length;k++){
            c[i][j]= c[i][j] +(a[i][k] * b[k][j]);
            }
        }
    }

    for(int i=0;i<c.length;i++){
        for(int j=0;j<c.length;j++){
            System.out.print(c[i][j]);
        }   
        System.out.println("\n");
    }
}

in_array() and multidimensional array

Shorter version, for multidimensional arrays created based on database result sets.

function in_array_r($array, $field, $find){
    foreach($array as $item){
        if($item[$field] == $find) return true;
    }
    return false;
}

$is_found = in_array_r($os_list, 'os_version', 'XP');

Will return if the $os_list array contains 'XP' in the os_version field.

PHP add elements to multidimensional array with array_push

I know the topic is old, but I just fell on it after a google search so... here is another solution:

$array_merged = array_merge($array_going_first, $array_going_second);

This one seems pretty clean to me, it works just fine!

push() a two-dimensional array

Iterating over two dimensions means you'll need to check over two dimensions.

assuming you're starting with:

var myArray = [
    [1,1,1,1,1],
    [1,1,1,1,1],
    [1,1,1,1,1]
]; //don't forget your semi-colons

You want to expand this two-dimensional array to become:

var myArray = [
    [1,1,1,1,1,0,0],
    [1,1,1,1,1,0,0],
    [1,1,1,1,1,0,0],
    [0,0,0,0,0,0,0],
    [0,0,0,0,0,0,0],
    [0,0,0,0,0,0,0],
];

Which means you need to understand what the difference is.

Start with the outer array:

var myArray = [
    [...],
    [...],
    [...]
];

If you want to make this array longer, you need to check that it's the correct length, and add more inner arrays to make up the difference:

var i,
    rows,
    myArray;
rows = 8;
myArray = [...]; //see first example above
for (i = 0; i < rows; i += 1) {
    //check if the index exists in the outer array
    if (!(i in myArray)) {
        //if it doesn't exist, we need another array to fill
        myArray.push([]);
    }
}

The next step requires iterating over every column in every array, we'll build on the original code:

var i,
    j,
    row,
    rows,
    cols,
    myArray;
rows = 8;
cols = 7; //adding columns in this time
myArray = [...]; //see first example above
for (i = 0; i < rows; i += 1) {
    //check if the index exists in the outer array (row)
    if (!(i in myArray)) {
        //if it doesn't exist, we need another array to fill
        myArray[i] = [];
    }
    row = myArray[i];
    for (j = 0; j < cols; j += 1) {
        //check if the index exists in the inner array (column)
        if (!(i in row)) {
            //if it doesn't exist, we need to fill it with `0`
            row[j] = 0;
        }
    }
}

how to create dynamic two dimensional array in java?

List<Integer>[] array;  
array = new List<Integer>[10]; 

this the second case in @TofuBeer's answer is incorrect. because can't create arrays with generics. u can use:

List<List<Integer>> array = new ArrayList<>();

Printing a 2D array in C

First you need to input the two numbers say num_rows and num_columns perhaps using argc and argv then do a for loop to print the dots.

int j=0;
int k=0;
for (k=0;k<num_columns;k++){
   for (j=0;j<num_rows;j++){
       printf(".");
   }
 printf("\n");
 }

you'd have to replace the dot with something else later.

How to insert values in two dimensional array programmatically?

Try to code below,

String[][] shades = new String[4][3];
for(int i = 0; i < 4; i++)
{
  for(int y = 0; y < 3; y++)
  {
    shades[i][y] = value;
  }
}

Calculate mean across dimension in a 2D array

If you do this a lot, NumPy is the way to go.

If for some reason you can't use NumPy:

>>> map(lambda x:sum(x)/float(len(x)), zip(*a))
[45.0, 10.5]

How to access the elements of a 2D array?

Look carefully how many brackets does your array have. I met an example when function returned answer with extra bracket, like that:

>>>approx
array([[[1192,  391]],
       [[1191,  409]],
       [[1209,  438]],
       [[1191,  409]]])

And this didn't work

>>> approx[1,1]
IndexError: index 1 is out of bounds for axis 1 with size 1

This could open the brackets:

>>> approx[:,0]
array([[1192,  391],
       [1191,  409],
       [1209,  438],
       [1191,  409]])

Now it is possible to use an ordinary element access notation:

>>> approx[:,0][1,1]
409

How to get every first element in 2 dimensional list

You can get it like

[ x[0] for x in a]

which will return a list of the first element of each list in a

2D array values C++

The proper way to initialize a multidimensional array in C or C++ is

int arr[2][5] = {{1,8,12,20,25}, {5,9,13,24,26}};

You can use this same trick to initialize even higher-dimensional arrays if you want.

Also, be careful in your initial code - you were trying to use 1-indexed offsets into the array to initialize it. This didn't compile, but if it did it would cause problems because C arrays are 0-indexed!

Iterating over a 2 dimensional python list

Use zip and itertools.chain. Something like:

>>> from itertools import chain
>>> l = chain.from_iterable(zip(*l))
<itertools.chain object at 0x104612610>
>>> list(l)
['0,0', '1,0', '2,0', '0,1', '1,1', '2,1']

what does numpy ndarray shape do?

yourarray.shape or np.shape() or np.ma.shape() returns the shape of your ndarray as a tuple; And you can get the (number of) dimensions of your array using yourarray.ndim or np.ndim(). (i.e. it gives the n of the ndarray since all arrays in NumPy are just n-dimensional arrays (shortly called as ndarrays))

For a 1D array, the shape would be (n,) where n is the number of elements in your array.

For a 2D array, the shape would be (n,m) where n is the number of rows and m is the number of columns in your array.

Please note that in 1D case, the shape would simply be (n, ) instead of what you said as either (1, n) or (n, 1) for row and column vectors respectively.

This is to follow the convention that:

For 1D array, return a shape tuple with only 1 element   (i.e. (n,))
For 2D array, return a shape tuple with only 2 elements (i.e. (n,m))
For 3D array, return a shape tuple with only 3 elements (i.e. (n,m,k))
For 4D array, return a shape tuple with only 4 elements (i.e. (n,m,k,j))

and so on.

Also, please see the example below to see how np.shape() or np.ma.shape() behaves with 1D arrays and scalars:

# sample array
In [10]: u = np.arange(10)

# get its shape
In [11]: np.shape(u)    # u.shape
Out[11]: (10,)

# get array dimension using `np.ndim`
In [12]: np.ndim(u)
Out[12]: 1

In [13]: np.shape(np.mean(u))
Out[13]: ()       # empty tuple (to indicate that a scalar is a 0D array).

# check using `numpy.ndim`
In [14]: np.ndim(np.mean(u))
Out[14]: 0

P.S.: So, the shape tuple is consistent with our understanding of dimensions of space, at least mathematically.

How do I 'foreach' through a two-dimensional array?

Multidimensional arrays aren't enumerable. Just iterate the good old-fashioned way:

for (int i = 0; i < table.GetLength(0); i++)
{
    Console.WriteLine(table[i, 0] + " " + table[i, 1]);
}

How do you add an array to another array in Ruby and not end up with a multi-dimensional result?

Just another way of doing it.

[somearray, anotherarray].flatten
=> ["some", "thing", "another", "thing"]

How to count the occurrence of certain item in an ndarray?

here I have something, through which you can count the number of occurrence of a particular number: according to your code

count_of_zero=list(y[y==0]).count(0)

print(count_of_zero)

// according to the match there will be boolean values and according to True value the number 0 will be return

PHP Multidimensional Array Searching (Find key by specific value)

I would do like below, where $products is the actual array given in the problem at the very beginning.

print_r(
  array_search("breville-variable-temperature-kettle-BKE820XL", 
  array_map(function($product){return $product["slug"];},$products))
);

2D arrays in Python

In Python one would usually use lists for this purpose. Lists can be nested arbitrarily, thus allowing the creation of a 2D array. Not every sublist needs to be the same size, so that solves your other problem. Have a look at the examples I linked to.

How to make a flat list out of list of lists?

Fastest solution I have found (for large list anyway):

import numpy as np
#turn list into an array and flatten()
np.array(l).flatten()

Done! You can of course turn it back into a list by executing list(l)

PHP combine two associative arrays into one array

array_merge() is more efficient but there are a couple of options:

$array1 = array("id1" => "value1");

$array2 = array("id2" => "value2", "id3" => "value3", "id4" => "value4");

$array3 = array_merge($array1, $array2/*, $arrayN, $arrayN*/);
$array4 = $array1 + $array2;

echo '<pre>';
var_dump($array3);
var_dump($array4);
echo '</pre>';


// Results:
    array(4) {
      ["id1"]=>
      string(6) "value1"
      ["id2"]=>
      string(6) "value2"
      ["id3"]=>
      string(6) "value3"
      ["id4"]=>
      string(6) "value4"
    }
    array(4) {
      ["id1"]=>
      string(6) "value1"
      ["id2"]=>
      string(6) "value2"
      ["id3"]=>
      string(6) "value3"
      ["id4"]=>
      string(6) "value4"
    }

How to Sort Multi-dimensional Array by Value?

Use array_multisort(), array_map()

array_multisort(array_map(function($element) {
      return $element['order'];
  }, $array), SORT_ASC, $array);

print_r($array);

DEMO

PHP multidimensional array search by value

No one else has used array_reduce yet, so thought I'd add this approach...

$find_by_uid = '100';
$is_in_array = array_reduce($userdb, function($carry, $user) use ($find_by_uid){
    return $carry ? $carry : $user['uid'] === $find_by_uid;
}); 
// Returns true

Gives you more fine control over the 'search' logic than array_search().

Note that I have used strict equality here but you could opt for different comparison logic. The $carry means the comparison needs to be true once, and the final result will be TRUE.

What is the purpose of meshgrid in Python / NumPy?

Actually the purpose of np.meshgrid is already mentioned in the documentation:

np.meshgrid

Return coordinate matrices from coordinate vectors.

Make N-D coordinate arrays for vectorized evaluations of N-D scalar/vector fields over N-D grids, given one-dimensional coordinate arrays x1, x2,..., xn.

So it's primary purpose is to create a coordinates matrices.

You probably just asked yourself:

Why do we need to create coordinate matrices?

The reason you need coordinate matrices with Python/NumPy is that there is no direct relation from coordinates to values, except when your coordinates start with zero and are purely positive integers. Then you can just use the indices of an array as the index. However when that's not the case you somehow need to store coordinates alongside your data. That's where grids come in.

Suppose your data is:

1  2  1
2  5  2
1  2  1

However, each value represents a 3 x 2 kilometer area (horizontal x vertical). Suppose your origin is the upper left corner and you want arrays that represent the distance you could use:

import numpy as np
h, v = np.meshgrid(np.arange(3)*3, np.arange(3)*2)

where v is:

array([[0, 0, 0],
       [2, 2, 2],
       [4, 4, 4]])

and h:

array([[0, 3, 6],
       [0, 3, 6],
       [0, 3, 6]])

So if you have two indices, let's say x and y (that's why the return value of meshgrid is usually xx or xs instead of x in this case I chose h for horizontally!) then you can get the x coordinate of the point, the y coordinate of the point and the value at that point by using:

h[x, y]    # horizontal coordinate
v[x, y]    # vertical coordinate
data[x, y]  # value

That makes it much easier to keep track of coordinates and (even more importantly) you can pass them to functions that need to know the coordinates.

A slightly longer explanation

However, np.meshgrid itself isn't often used directly, mostly one just uses one of similar objects np.mgrid or np.ogrid. Here np.mgrid represents the sparse=False and np.ogrid the sparse=True case (I refer to the sparse argument of np.meshgrid). Note that there is a significant difference between np.meshgrid and np.ogrid and np.mgrid: The first two returned values (if there are two or more) are reversed. Often this doesn't matter but you should give meaningful variable names depending on the context.

For example, in case of a 2D grid and matplotlib.pyplot.imshow it makes sense to name the first returned item of np.meshgrid x and the second one y while it's the other way around for np.mgrid and np.ogrid.

np.ogrid and sparse grids

>>> import numpy as np
>>> yy, xx = np.ogrid[-5:6, -5:6]
>>> xx
array([[-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5]])
>>> yy
array([[-5],
       [-4],
       [-3],
       [-2],
       [-1],
       [ 0],
       [ 1],
       [ 2],
       [ 3],
       [ 4],
       [ 5]])
       

As already said the output is reversed when compared to np.meshgrid, that's why I unpacked it as yy, xx instead of xx, yy:

>>> xx, yy = np.meshgrid(np.arange(-5, 6), np.arange(-5, 6), sparse=True)
>>> xx
array([[-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5]])
>>> yy
array([[-5],
       [-4],
       [-3],
       [-2],
       [-1],
       [ 0],
       [ 1],
       [ 2],
       [ 3],
       [ 4],
       [ 5]])

This already looks like coordinates, specifically the x and y lines for 2D plots.

Visualized:

yy, xx = np.ogrid[-5:6, -5:6]
plt.figure()
plt.title('ogrid (sparse meshgrid)')
plt.grid()
plt.xticks(xx.ravel())
plt.yticks(yy.ravel())
plt.scatter(xx, np.zeros_like(xx), color="blue", marker="*")
plt.scatter(np.zeros_like(yy), yy, color="red", marker="x")

enter image description here

np.mgrid and dense/fleshed out grids

>>> yy, xx = np.mgrid[-5:6, -5:6]
>>> xx
array([[-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5]])
>>> yy
array([[-5, -5, -5, -5, -5, -5, -5, -5, -5, -5, -5],
       [-4, -4, -4, -4, -4, -4, -4, -4, -4, -4, -4],
       [-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3],
       [-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2],
       [-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1],
       [ 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
       [ 1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1],
       [ 2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2],
       [ 3,  3,  3,  3,  3,  3,  3,  3,  3,  3,  3],
       [ 4,  4,  4,  4,  4,  4,  4,  4,  4,  4,  4],
       [ 5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5]])
       

The same applies here: The output is reversed compared to np.meshgrid:

>>> xx, yy = np.meshgrid(np.arange(-5, 6), np.arange(-5, 6))
>>> xx
array([[-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5],
       [-5, -4, -3, -2, -1,  0,  1,  2,  3,  4,  5]])
>>> yy
array([[-5, -5, -5, -5, -5, -5, -5, -5, -5, -5, -5],
       [-4, -4, -4, -4, -4, -4, -4, -4, -4, -4, -4],
       [-3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3],
       [-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2],
       [-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1],
       [ 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0],
       [ 1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1],
       [ 2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2],
       [ 3,  3,  3,  3,  3,  3,  3,  3,  3,  3,  3],
       [ 4,  4,  4,  4,  4,  4,  4,  4,  4,  4,  4],
       [ 5,  5,  5,  5,  5,  5,  5,  5,  5,  5,  5]])
       

Unlike ogrid these arrays contain all xx and yy coordinates in the -5 <= xx <= 5; -5 <= yy <= 5 grid.

yy, xx = np.mgrid[-5:6, -5:6]
plt.figure()
plt.title('mgrid (dense meshgrid)')
plt.grid()
plt.xticks(xx[0])
plt.yticks(yy[:, 0])
plt.scatter(xx, yy, color="red", marker="x")

enter image description here

Functionality

It's not only limited to 2D, these functions work for arbitrary dimensions (well, there is a maximum number of arguments given to function in Python and a maximum number of dimensions that NumPy allows):

>>> x1, x2, x3, x4 = np.ogrid[:3, 1:4, 2:5, 3:6]
>>> for i, x in enumerate([x1, x2, x3, x4]):
...     print('x{}'.format(i+1))
...     print(repr(x))
x1
array([[[[0]]],


       [[[1]]],


       [[[2]]]])
x2
array([[[[1]],

        [[2]],

        [[3]]]])
x3
array([[[[2],
         [3],
         [4]]]])
x4
array([[[[3, 4, 5]]]])

>>> # equivalent meshgrid output, note how the first two arguments are reversed and the unpacking
>>> x2, x1, x3, x4 = np.meshgrid(np.arange(1,4), np.arange(3), np.arange(2, 5), np.arange(3, 6), sparse=True)
>>> for i, x in enumerate([x1, x2, x3, x4]):
...     print('x{}'.format(i+1))
...     print(repr(x))
# Identical output so it's omitted here.

Even if these also work for 1D there are two (much more common) 1D grid creation functions:

Besides the start and stop argument it also supports the step argument (even complex steps that represent the number of steps):

>>> x1, x2 = np.mgrid[1:10:2, 1:10:4j]
>>> x1  # The dimension with the explicit step width of 2
array([[1., 1., 1., 1.],
       [3., 3., 3., 3.],
       [5., 5., 5., 5.],
       [7., 7., 7., 7.],
       [9., 9., 9., 9.]])
>>> x2  # The dimension with the "number of steps"
array([[ 1.,  4.,  7., 10.],
       [ 1.,  4.,  7., 10.],
       [ 1.,  4.,  7., 10.],
       [ 1.,  4.,  7., 10.],
       [ 1.,  4.,  7., 10.]])
       

Applications

You specifically asked about the purpose and in fact, these grids are extremely useful if you need a coordinate system.

For example if you have a NumPy function that calculates the distance in two dimensions:

def distance_2d(x_point, y_point, x, y):
    return np.hypot(x-x_point, y-y_point)
    

And you want to know the distance of each point:

>>> ys, xs = np.ogrid[-5:5, -5:5]
>>> distances = distance_2d(1, 2, xs, ys)  # distance to point (1, 2)
>>> distances
array([[9.21954446, 8.60232527, 8.06225775, 7.61577311, 7.28010989,
        7.07106781, 7.        , 7.07106781, 7.28010989, 7.61577311],
       [8.48528137, 7.81024968, 7.21110255, 6.70820393, 6.32455532,
        6.08276253, 6.        , 6.08276253, 6.32455532, 6.70820393],
       [7.81024968, 7.07106781, 6.40312424, 5.83095189, 5.38516481,
        5.09901951, 5.        , 5.09901951, 5.38516481, 5.83095189],
       [7.21110255, 6.40312424, 5.65685425, 5.        , 4.47213595,
        4.12310563, 4.        , 4.12310563, 4.47213595, 5.        ],
       [6.70820393, 5.83095189, 5.        , 4.24264069, 3.60555128,
        3.16227766, 3.        , 3.16227766, 3.60555128, 4.24264069],
       [6.32455532, 5.38516481, 4.47213595, 3.60555128, 2.82842712,
        2.23606798, 2.        , 2.23606798, 2.82842712, 3.60555128],
       [6.08276253, 5.09901951, 4.12310563, 3.16227766, 2.23606798,
        1.41421356, 1.        , 1.41421356, 2.23606798, 3.16227766],
       [6.        , 5.        , 4.        , 3.        , 2.        ,
        1.        , 0.        , 1.        , 2.        , 3.        ],
       [6.08276253, 5.09901951, 4.12310563, 3.16227766, 2.23606798,
        1.41421356, 1.        , 1.41421356, 2.23606798, 3.16227766],
       [6.32455532, 5.38516481, 4.47213595, 3.60555128, 2.82842712,
        2.23606798, 2.        , 2.23606798, 2.82842712, 3.60555128]])
        

The output would be identical if one passed in a dense grid instead of an open grid. NumPys broadcasting makes it possible!

Let's visualize the result:

plt.figure()
plt.title('distance to point (1, 2)')
plt.imshow(distances, origin='lower', interpolation="none")
plt.xticks(np.arange(xs.shape[1]), xs.ravel())  # need to set the ticks manually
plt.yticks(np.arange(ys.shape[0]), ys.ravel())
plt.colorbar()

enter image description here

And this is also when NumPys mgrid and ogrid become very convenient because it allows you to easily change the resolution of your grids:

ys, xs = np.ogrid[-5:5:200j, -5:5:200j]
# otherwise same code as above

enter image description here

However, since imshow doesn't support x and y inputs one has to change the ticks by hand. It would be really convenient if it would accept the x and y coordinates, right?

It's easy to write functions with NumPy that deal naturally with grids. Furthermore, there are several functions in NumPy, SciPy, matplotlib that expect you to pass in the grid.

I like images so let's explore matplotlib.pyplot.contour:

ys, xs = np.mgrid[-5:5:200j, -5:5:200j]
density = np.sin(ys)-np.cos(xs)
plt.figure()
plt.contour(xs, ys, density)

enter image description here

Note how the coordinates are already correctly set! That wouldn't be the case if you just passed in the density.

Or to give another fun example using astropy models (this time I don't care much about the coordinates, I just use them to create some grid):

from astropy.modeling import models
z = np.zeros((100, 100))
y, x = np.mgrid[0:100, 0:100]
for _ in range(10):
    g2d = models.Gaussian2D(amplitude=100, 
                           x_mean=np.random.randint(0, 100), 
                           y_mean=np.random.randint(0, 100), 
                           x_stddev=3, 
                           y_stddev=3)
    z += g2d(x, y)
    a2d = models.AiryDisk2D(amplitude=70, 
                            x_0=np.random.randint(0, 100), 
                            y_0=np.random.randint(0, 100), 
                            radius=5)
    z += a2d(x, y)
    

enter image description here

Although that's just "for the looks" several functions related to functional models and fitting (for example scipy.interpolate.interp2d, scipy.interpolate.griddata even show examples using np.mgrid) in Scipy, etc. require grids. Most of these work with open grids and dense grids, however some only work with one of them.

For loop in multidimensional javascript array

var cubes = [["string", "string"], ["string", "string"]];

for(var i = 0; i < cubes.length; i++) {
    for(var j = 0; j < cubes[i].length; j++) {
        console.log(cubes[i][j]);
    }
}

Matrix Transpose in Python

a=[]
def showmatrix (a,m,n):
    for i in range (m):
        for j in range (n):
            k=int(input("enter the number")
            a.append(k)      
print (a[i][j]),

print('\t')


def showtranspose(a,m,n):
    for j in range(n):
        for i in range(m):
            print(a[i][j]),
        print('\t')

a=((89,45,50),(130,120,40),(69,79,57),(78,4,8))
print("given matrix of order 4x3 is :")
showmatrix(a,4,3)


print("Transpose matrix is:")
showtranspose(a,4,3)

Difference between numpy.array shape (R, 1) and (R,)

1. The meaning of shapes in NumPy

You write, "I know literally it's list of numbers and list of lists where all list contains only a number" but that's a bit of an unhelpful way to think about it.

The best way to think about NumPy arrays is that they consist of two parts, a data buffer which is just a block of raw elements, and a view which describes how to interpret the data buffer.

For example, if we create an array of 12 integers:

>>> a = numpy.arange(12)
>>> a
array([ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11])

Then a consists of a data buffer, arranged something like this:

+-----------------------------------------------------------+
¦  0 ¦  1 ¦  2 ¦  3 ¦  4 ¦  5 ¦  6 ¦  7 ¦  8 ¦  9 ¦ 10 ¦ 11 ¦
+-----------------------------------------------------------+

and a view which describes how to interpret the data:

>>> a.flags
  C_CONTIGUOUS : True
  F_CONTIGUOUS : True
  OWNDATA : True
  WRITEABLE : True
  ALIGNED : True
  UPDATEIFCOPY : False
>>> a.dtype
dtype('int64')
>>> a.itemsize
8
>>> a.strides
(8,)
>>> a.shape
(12,)

Here the shape (12,) means the array is indexed by a single index which runs from 0 to 11. Conceptually, if we label this single index i, the array a looks like this:

i= 0    1    2    3    4    5    6    7    8    9   10   11
+-----------------------------------------------------------+
¦  0 ¦  1 ¦  2 ¦  3 ¦  4 ¦  5 ¦  6 ¦  7 ¦  8 ¦  9 ¦ 10 ¦ 11 ¦
+-----------------------------------------------------------+

If we reshape an array, this doesn't change the data buffer. Instead, it creates a new view that describes a different way to interpret the data. So after:

>>> b = a.reshape((3, 4))

the array b has the same data buffer as a, but now it is indexed by two indices which run from 0 to 2 and 0 to 3 respectively. If we label the two indices i and j, the array b looks like this:

i= 0    0    0    0    1    1    1    1    2    2    2    2
j= 0    1    2    3    0    1    2    3    0    1    2    3
+-----------------------------------------------------------+
¦  0 ¦  1 ¦  2 ¦  3 ¦  4 ¦  5 ¦  6 ¦  7 ¦  8 ¦  9 ¦ 10 ¦ 11 ¦
+-----------------------------------------------------------+

which means that:

>>> b[2,1]
9

You can see that the second index changes quickly and the first index changes slowly. If you prefer this to be the other way round, you can specify the order parameter:

>>> c = a.reshape((3, 4), order='F')

which results in an array indexed like this:

i= 0    1    2    0    1    2    0    1    2    0    1    2
j= 0    0    0    1    1    1    2    2    2    3    3    3
+-----------------------------------------------------------+
¦  0 ¦  1 ¦  2 ¦  3 ¦  4 ¦  5 ¦  6 ¦  7 ¦  8 ¦  9 ¦ 10 ¦ 11 ¦
+-----------------------------------------------------------+

which means that:

>>> c[2,1]
5

It should now be clear what it means for an array to have a shape with one or more dimensions of size 1. After:

>>> d = a.reshape((12, 1))

the array d is indexed by two indices, the first of which runs from 0 to 11, and the second index is always 0:

i= 0    1    2    3    4    5    6    7    8    9   10   11
j= 0    0    0    0    0    0    0    0    0    0    0    0
+-----------------------------------------------------------+
¦  0 ¦  1 ¦  2 ¦  3 ¦  4 ¦  5 ¦  6 ¦  7 ¦  8 ¦  9 ¦ 10 ¦ 11 ¦
+-----------------------------------------------------------+

and so:

>>> d[10,0]
10

A dimension of length 1 is "free" (in some sense), so there's nothing stopping you from going to town:

>>> e = a.reshape((1, 2, 1, 6, 1))

giving an array indexed like this:

i= 0    0    0    0    0    0    0    0    0    0    0    0
j= 0    0    0    0    0    0    1    1    1    1    1    1
k= 0    0    0    0    0    0    0    0    0    0    0    0
l= 0    1    2    3    4    5    0    1    2    3    4    5
m= 0    0    0    0    0    0    0    0    0    0    0    0
+-----------------------------------------------------------+
¦  0 ¦  1 ¦  2 ¦  3 ¦  4 ¦  5 ¦  6 ¦  7 ¦  8 ¦  9 ¦ 10 ¦ 11 ¦
+-----------------------------------------------------------+

and so:

>>> e[0,1,0,0,0]
6

See the NumPy internals documentation for more details about how arrays are implemented.

2. What to do?

Since numpy.reshape just creates a new view, you shouldn't be scared about using it whenever necessary. It's the right tool to use when you want to index an array in a different way.

However, in a long computation it's usually possible to arrange to construct arrays with the "right" shape in the first place, and so minimize the number of reshapes and transposes. But without seeing the actual context that led to the need for a reshape, it's hard to say what should be changed.

The example in your question is:

numpy.dot(M[:,0], numpy.ones((1, R)))

but this is not realistic. First, this expression:

M[:,0].sum()

computes the result more simply. Second, is there really something special about column 0? Perhaps what you actually need is:

M.sum(axis=0)

Multi-dimensional arrays in Bash

Expanding on Paul's answer - here's my version of working with associative sub-arrays in bash:

declare -A SUB_1=(["name1key"]="name1val" ["name2key"]="name2val")
declare -A SUB_2=(["name3key"]="name3val" ["name4key"]="name4val")
STRING_1="string1val"
STRING_2="string2val"
MAIN_ARRAY=(
  "${SUB_1[*]}"
  "${SUB_2[*]}"
  "${STRING_1}"
  "${STRING_2}"
)
echo "COUNT: " ${#MAIN_ARRAY[@]}
for key in ${!MAIN_ARRAY[@]}; do
    IFS=' ' read -a val <<< ${MAIN_ARRAY[$key]}
    echo "VALUE: " ${val[@]}
    if [[ ${#val[@]} -gt 1 ]]; then
        for subkey in ${!val[@]}; do
            subval=${val[$subkey]}
            echo "SUBVALUE: " ${subval}
        done
    fi
done

It works with mixed values in the main array - strings/arrays/assoc. arrays

The key here is to wrap the subarrays in single quotes and use * instead of @ when storing a subarray inside the main array so it would get stored as a single, space separated string: "${SUB_1[*]}"

Then it makes it easy to parse an array out of that when looping through values with IFS=' ' read -a val <<< ${MAIN_ARRAY[$key]}

The code above outputs:

COUNT:  4
VALUE:  name1val name2val
SUBVALUE:  name1val
SUBVALUE:  name2val
VALUE:  name4val name3val
SUBVALUE:  name4val
SUBVALUE:  name3val
VALUE:  string1val
VALUE:  string2val

php multidimensional array get values

For people who searched for php multidimensional array get values and actually want to solve problem comes from getting one column value from a 2 dimensinal array (like me!), here's a much elegant way than using foreach, which is array_column

For example, if I only want to get hotel_name from the below array, and form to another array:

$hotels = [
    [
        'hotel_name' => 'Hotel A',
        'info' => 'Hotel A Info',
    ],
    [
        'hotel_name' => 'Hotel B',
        'info' => 'Hotel B Info',
    ]
];

I can do this using array_column:

$hotel_name = array_column($hotels, 'hotel_name');

print_r($hotel_name); // Which will give me ['Hotel A', 'Hotel B']

For the actual answer for this question, it can also be beautified by array_column and call_user_func_array('array_merge', $twoDimensionalArray);

Let's make the data in PHP:

$hotels = [
    [
        'hotel_name' => 'Hotel A',
        'info' => 'Hotel A Info',
        'rooms' => [
            [
                'room_name' => 'Luxury Room',
                'bed' => 2,
                'boards' => [
                    'board_id' => 1,
                    'price' => 200
                ]
            ],
            [
                'room_name' => 'Non Luxy Room',
                'bed' => 4,
                'boards' => [
                    'board_id' => 2,
                    'price' => 150
                ]
            ],
        ]
    ],
    [
        'hotel_name' => 'Hotel B',
        'info' => 'Hotel B Info',
        'rooms' => [
            [
                'room_name' => 'Luxury Room',
                'bed' => 2,
                'boards' => [
                    'board_id' => 3,
                    'price' => 900
                ]
            ],
            [
                'room_name' => 'Non Luxy Room',
                'bed' => 4,
                'boards' => [
                    'board_id' => 4,
                    'price' => 300
                ]
            ],
        ]
    ]
];

And here's the calculation:

$rooms = array_column($hotels, 'rooms');
$rooms = call_user_func_array('array_merge', $rooms);
$boards = array_column($rooms, 'boards');

foreach($boards as $board){
    $board_id = $board['board_id'];
    $price = $board['price'];
    echo "Board ID is: ".$board_id." and price is: ".$price . "<br/>";
}

Which will give you the following result:

Board ID is: 1 and price is: 200
Board ID is: 2 and price is: 150
Board ID is: 3 and price is: 900
Board ID is: 4 and price is: 300

Java Comparator class to sort arrays

[...] How should Java Comparator class be declared to sort the arrays by their first elements in decreasing order [...]

Here's a complete example using Java 8:

import java.util.*;

public class Test {

    public static void main(String args[]) {

        int[][] twoDim = { {1, 2}, {3, 7}, {8, 9}, {4, 2}, {5, 3} };

        Arrays.sort(twoDim, Comparator.comparingInt(a -> a[0])
                                      .reversed());

        System.out.println(Arrays.deepToString(twoDim));
    }
}

Output:

[[8, 9], [5, 3], [4, 2], [3, 7], [1, 2]]

For Java 7 you can do:

Arrays.sort(twoDim, new Comparator<int[]>() {
    @Override
    public int compare(int[] o1, int[] o2) {
        return Integer.compare(o2[0], o1[0]);
    }
});

If you unfortunate enough to work on Java 6 or older, you'd do:

Arrays.sort(twoDim, new Comparator<int[]>() {
    @Override
    public int compare(int[] o1, int[] o2) {
        return ((Integer) o2[0]).compareTo(o1[0]);
    }
});

How does numpy.newaxis work and when to use it?

newaxis object in the selection tuple serves to expand the dimensions of the resulting selection by one unit-length dimension.

It is not just conversion of row matrix to column matrix.

Consider the example below:

In [1]:x1 = np.arange(1,10).reshape(3,3)
       print(x1)
Out[1]: array([[1, 2, 3],
               [4, 5, 6],
               [7, 8, 9]])

Now lets add new dimension to our data,

In [2]:x1_new = x1[:,np.newaxis]
       print(x1_new)
Out[2]:array([[[1, 2, 3]],

              [[4, 5, 6]],

              [[7, 8, 9]]])

You can see that newaxis added the extra dimension here, x1 had dimension (3,3) and X1_new has dimension (3,1,3).

How our new dimension enables us to different operations:

In [3]:x2 = np.arange(11,20).reshape(3,3)
       print(x2)
Out[3]:array([[11, 12, 13],
              [14, 15, 16],
              [17, 18, 19]]) 

Adding x1_new and x2, we get:

In [4]:x1_new+x2
Out[4]:array([[[12, 14, 16],
               [15, 17, 19],
               [18, 20, 22]],

              [[15, 17, 19],
               [18, 20, 22],
               [21, 23, 25]],

              [[18, 20, 22],
               [21, 23, 25],
               [24, 26, 28]]])

Thus, newaxis is not just conversion of row to column matrix. It increases the dimension of matrix, thus enabling us to do more operations on it.

How to create an 2D ArrayList in java?

I want to create a 2D array that each cell is an ArrayList!

If you want to create a 2D array of ArrayList.Then you can do this :

ArrayList[][] table = new ArrayList[10][10];
table[0][0] = new ArrayList(); // add another ArrayList object to [0,0]
table[0][0].add(); // add object to that ArrayList

How to sort an array of objects with jquery or javascript

var array = [[1, "grape", 42], [2, "fruit", 9]];

array.sort(function(a, b)
{
    // a and b will here be two objects from the array
    // thus a[1] and b[1] will equal the names

    // if they are equal, return 0 (no sorting)
    if (a[1] == b[1]) { return 0; }
    if (a[1] > b[1])
    {
        // if a should come after b, return 1
        return 1;
    }
    else
    {
        // if b should come after a, return -1
        return -1;
    }
});

The sort function takes an additional argument, a function that takes two arguments. This function should return -1, 0 or 1 depending on which of the two arguments should come first in the sorting. More info.

I also fixed a syntax error in your multidimensional array.

Initialising a multidimensional array in Java

You can also use the following construct:

String[][] myStringArray = new String [][] { { "X0", "Y0"},
                                             { "X1", "Y1"},
                                             { "X2", "Y2"},
                                             { "X3", "Y3"},
                                             { "X4", "Y4"} };

Which comes first in a 2D array, rows or columns?

All depends on your visualization of the array. Rows and Columns are properties of visualization (probably in your imagination) of the array, not the array itself.

It's exactly the same as asking is number "5" red or green?

I could draw it red, I could draw it greed right? Color is not an integral property of a number. In the same way representing 2D array as a grid of rows and columns is not necessary for existence of this array.

2D array has just first dimention and second dimention, everything related to visualizing those is purely your flavour.

When I have char array char[80][25], I may like to print it on console rotated so that I have 25 rows of 80 characters that fits the screen without scroll.

I'll try to provide viable example when representing 2D array as rows and columns doesn't make sense at all: Let's say I need an array of 1 000 000 000 integers. My machine has 8GB of RAM, so I have enough memory for this, but if you try executing var a = new int[1000000000], you'll most likely get OutOfMemory exception. That's because of memory fragmentation - there is no consecutive block of memory of this size. Instead you you can create 2D array 10 000 x 100 000 with your values. Logically it is 1D array, so you'd like to draw and imagine it as a single sequence of values, but due to technical implementation it is 2D.

Submitting a multidimensional array via POST with php

I made a function which handles arrays as well as single GET or POST values

function subVal($varName, $default=NULL,$isArray=FALSE ){ // $isArray toggles between (multi)array or single mode

    $retVal = "";
    $retArray = array();

    if($isArray) {
        if(isset($_POST[$varName])) {
            foreach ( $_POST[$varName] as $var ) {  // multidimensional POST array elements
                $retArray[]=$var;
            }
        }
        $retVal=$retArray;
    }

    elseif (isset($_POST[$varName]) )  {  // simple POST array element
        $retVal = $_POST[$varName];
    }

    else {
        if (isset($_GET[$varName]) ) {
            $retVal = $_GET[$varName];    // simple GET array element
        }
        else {
            $retVal = $default;
        }
    }

    return $retVal;

}

Examples:

$curr_topdiameter = subVal("topdiameter","",TRUE)[3];
$user_name = subVal("user_name","");

How do you extract a column from a multi-dimensional array?

Despite using zip(*iterable) to transpose a nested list, you can also use the following if the nested lists vary in length:

map(None, *[(1,2,3,), (4,5,), (6,)])

results in:

[(1, 4, 6), (2, 5, None), (3, None, None)]

The first column is thus:

map(None, *[(1,2,3,), (4,5,), (6,)])[0]
#>(1, 4, 6)

Printing 2D array in matrix format

I wrote extension method

public static string ToMatrixString<T>(this T[,] matrix, string delimiter = "\t")
{
    var s = new StringBuilder();

    for (var i = 0; i < matrix.GetLength(0); i++)
    {
        for (var j = 0; j < matrix.GetLength(1); j++)
        {
            s.Append(matrix[i, j]).Append(delimiter);
        }

        s.AppendLine();
    }

    return s.ToString();
}

To use just call the method

results.ToMatrixString();

2D character array initialization in C

C strings are enclosed in double quotes:

const char *options[2][100];

options[0][0] = "test1";
options[1][0] = "test2";

Re-reading your question and comments though I'm guessing that what you really want to do is this:

const char *options[2] = { "test1", "test2" };

Convert a numpy.ndarray to string(or bytes) and convert it back to numpy.ndarray

Imagine you have a numpy array of text like in a messenger

 >>> stex[40]
 array(['Know the famous thing ...

and you want to get statistics from the corpus (text col=11) you first must get the values from dataframe (df5) and then join all records together in one single corpus:

 >>> stex = (df5.ix[0:,[11]]).values
 >>> a_str = ','.join(str(x) for x in stex)
 >>> a_str = a_str.split()
 >>> fd2 = nltk.FreqDist(a_str)
 >>> fd2.most_common(50)

Selecting specific rows and columns from NumPy array

Fancy indexing requires you to provide all indices for each dimension. You are providing 3 indices for the first one, and only 2 for the second one, hence the error. You want to do something like this:

>>> a[[[0, 0], [1, 1], [3, 3]], [[0,2], [0,2], [0, 2]]]
array([[ 0,  2],
       [ 4,  6],
       [12, 14]])

That is of course a pain to write, so you can let broadcasting help you:

>>> a[[[0], [1], [3]], [0, 2]]
array([[ 0,  2],
       [ 4,  6],
       [12, 14]])

This is much simpler to do if you index with arrays, not lists:

>>> row_idx = np.array([0, 1, 3])
>>> col_idx = np.array([0, 2])
>>> a[row_idx[:, None], col_idx]
array([[ 0,  2],
       [ 4,  6],
       [12, 14]])

Loop over array dimension in plpgsql

Since PostgreSQL 9.1 there is the convenient FOREACH:

DO
$do$
DECLARE
   m   varchar[];
   arr varchar[] := array[['key1','val1'],['key2','val2']];
BEGIN
   FOREACH m SLICE 1 IN ARRAY arr
   LOOP
      RAISE NOTICE 'another_func(%,%)',m[1], m[2];
   END LOOP;
END
$do$

Solution for older versions:

DO
$do$
DECLARE
   arr varchar[] := '{{key1,val1},{key2,val2}}';
BEGIN
   FOR i IN array_lower(arr, 1) .. array_upper(arr, 1)
   LOOP
      RAISE NOTICE 'another_func(%,%)',arr[i][1], arr[i][2];
   END LOOP;
END
$do$

Also, there is no difference between varchar[] and varchar[][] for the PostgreSQL type system. I explain in more detail here.

The DO statement requires at least PostgreSQL 9.0, and LANGUAGE plpgsql is the default (so you can omit the declaration).

Map a 2D array onto a 1D array

As other have said C maps in row order

   #include <stdio.h>

   int main(int argc, char **argv) {
   int i, j, k;
   int arr[5][3];
   int *arr2 = (int*)arr;

       for (k=0; k<15; k++) {
          arr2[k] = k;
          printf("arr[%d] = %2d\n", k, arr2[k]);
       }

       for (i=0; i<5; i++) {
         for (j=0; j< 3; j++) {
            printf("arr2[%d][%d] = %2d\n", i, j ,arr[i][j]);
         }
       } 
    } 

Output:

arr[0] =  0
arr[1] =  1
arr[2] =  2
arr[3] =  3
arr[4] =  4
arr[5] =  5
arr[6] =  6
arr[7] =  7
arr[8] =  8
arr[9] =  9
arr[10] = 10
arr[11] = 11
arr[12] = 12
arr[13] = 13
arr[14] = 14
arr2[0][0] =  0
arr2[0][1] =  1
arr2[0][2] =  2
arr2[1][0] =  3
arr2[1][1] =  4
arr2[1][2] =  5
arr2[2][0] =  6
arr2[2][1] =  7
arr2[2][2] =  8
arr2[3][0] =  9
arr2[3][1] = 10
arr2[3][2] = 11
arr2[4][0] = 12
arr2[4][1] = 13
arr2[4][2] = 14

VBA Excel 2-Dimensional Arrays

Here's A generic VBA Array To Range function that writes an array to the sheet in a single 'hit' to the sheet. This is much faster than writing the data into the sheet one cell at a time in loops for the rows and columns... However, there's some housekeeping to do, as you must specify the size of the target range correctly.

This 'housekeeping' looks like a lot of work and it's probably rather slow: but this is 'last mile' code to write to the sheet, and everything is faster than writing to the worksheet. Or at least, so much faster that it's effectively instantaneous, compared with a read or write to the worksheet, even in VBA, and you should do everything you possibly can in code before you hit the sheet.

A major component of this is error-trapping that I used to see turning up everywhere . I hate repetitive coding: I've coded it all here, and - hopefully - you'll never have to write it again.

A VBA 'Array to Range' function

Public Sub ArrayToRange(rngTarget As Excel.Range, InputArray As Variant)
' Write an array to an Excel range in a single 'hit' to the sheet
' InputArray must be a 2-Dimensional structure of the form Variant(Rows, Columns)

' The target range is resized automatically to the dimensions of the array, with
' the top left cell used as the start point.

' This subroutine saves repetitive coding for a common VBA and Excel task.

' If you think you won't need the code that works around common errors (long strings
' and objects in the array, etc) then feel free to comment them out.

On Error Resume Next

'
' Author: Nigel Heffernan
' HTTP://Excellerando.blogspot.com
'
' This code is in te public domain: take care to mark it clearly, and segregate
' it from proprietary code if you intend to assert intellectual property rights
' or impose commercial confidentiality restrictions on that proprietary code

Dim rngOutput As Excel.Range

Dim iRowCount   As Long
Dim iColCount   As Long
Dim iRow        As Long
Dim iCol        As Long
Dim arrTemp     As Variant
Dim iDimensions As Integer

Dim iRowOffset  As Long
Dim iColOffset  As Long
Dim iStart      As Long


Application.EnableEvents = False
If rngTarget.Cells.Count > 1 Then
    rngTarget.ClearContents
End If
Application.EnableEvents = True

If IsEmpty(InputArray) Then
    Exit Sub
End If


If TypeName(InputArray) = "Range" Then
    InputArray = InputArray.Value
End If

' Is it actually an array? IsArray is sadly broken so...
If Not InStr(TypeName(InputArray), "(") Then
    rngTarget.Cells(1, 1).Value2 = InputArray
    Exit Sub
End If


iDimensions = ArrayDimensions(InputArray)

If iDimensions < 1 Then

    rngTarget.Value = CStr(InputArray)

ElseIf iDimensions = 1 Then

    iRowCount = UBound(InputArray) - LBound(InputArray)
    iStart = LBound(InputArray)
    iColCount = 1

    If iRowCount > (655354 - rngTarget.Row) Then
        iRowCount = 655354 + iStart - rngTarget.Row
        ReDim Preserve InputArray(iStart To iRowCount)
    End If

    iRowCount = UBound(InputArray) - LBound(InputArray)
    iColCount = 1

    ' It's a vector. Yes, I asked for a 2-Dimensional array. But I'm feeling generous.
    ' By convention, a vector is presented in Excel as an arry of 1 to n rows and 1 column.
    ReDim arrTemp(LBound(InputArray, 1) To UBound(InputArray, 1), 1 To 1)
    For iRow = LBound(InputArray, 1) To UBound(InputArray, 1)
        arrTemp(iRow, 1) = InputArray(iRow)
    Next

    With rngTarget.Worksheet
        Set rngOutput = .Range(rngTarget.Cells(1, 1), rngTarget.Cells(iRowCount + 1, iColCount))
        rngOutput.Value2 = arrTemp
        Set rngTarget = rngOutput
    End With

    Erase arrTemp

ElseIf iDimensions = 2 Then

    iRowCount = UBound(InputArray, 1) - LBound(InputArray, 1)
    iColCount = UBound(InputArray, 2) - LBound(InputArray, 2)

    iStart = LBound(InputArray, 1)

    If iRowCount > (65534 - rngTarget.Row) Then
        iRowCount = 65534 - rngTarget.Row
        InputArray = ArrayTranspose(InputArray)
        ReDim Preserve InputArray(LBound(InputArray, 1) To UBound(InputArray, 1), iStart To iRowCount)
        InputArray = ArrayTranspose(InputArray)
    End If


    iStart = LBound(InputArray, 2)
    If iColCount > (254 - rngTarget.Column) Then
        ReDim Preserve InputArray(LBound(InputArray, 1) To UBound(InputArray, 1), iStart To iColCount)
    End If



    With rngTarget.Worksheet

        Set rngOutput = .Range(rngTarget.Cells(1, 1), rngTarget.Cells(iRowCount + 1, iColCount + 1))

        Err.Clear
        Application.EnableEvents = False
        rngOutput.Value2 = InputArray
        Application.EnableEvents = True

        If Err.Number <> 0 Then
            For iRow = LBound(InputArray, 1) To UBound(InputArray, 1)
                For iCol = LBound(InputArray, 2) To UBound(InputArray, 2)
                    If IsNumeric(InputArray(iRow, iCol)) Then
                        ' no action
                    Else
                        InputArray(iRow, iCol) = "" & InputArray(iRow, iCol)
                        InputArray(iRow, iCol) = Trim(InputArray(iRow, iCol))
                    End If
                Next iCol
            Next iRow
            Err.Clear
            rngOutput.Formula = InputArray
        End If 'err<>0

        If Err <> 0 Then
            For iRow = LBound(InputArray, 1) To UBound(InputArray, 1)
                For iCol = LBound(InputArray, 2) To UBound(InputArray, 2)
                    If IsNumeric(InputArray(iRow, iCol)) Then
                        ' no action
                    Else
                        If Left(InputArray(iRow, iCol), 1) = "=" Then
                            InputArray(iRow, iCol) = "'" & InputArray(iRow, iCol)
                        End If
                        If Left(InputArray(iRow, iCol), 1) = "+" Then
                            InputArray(iRow, iCol) = "'" & InputArray(iRow, iCol)
                        End If
                        If Left(InputArray(iRow, iCol), 1) = "*" Then
                            InputArray(iRow, iCol) = "'" & InputArray(iRow, iCol)
                        End If
                    End If
                Next iCol
            Next iRow
            Err.Clear
            rngOutput.Value2 = InputArray
        End If 'err<>0

        If Err <> 0 Then
            For iRow = LBound(InputArray, 1) To UBound(InputArray, 1)
                For iCol = LBound(InputArray, 2) To UBound(InputArray, 2)

                    If IsObject(InputArray(iRow, iCol)) Then
                        InputArray(iRow, iCol) = "[OBJECT] " & TypeName(InputArray(iRow, iCol))
                    ElseIf IsArray(InputArray(iRow, iCol)) Then
                        InputArray(iRow, iCol) = Split(InputArray(iRow, iCol), ",")
                    ElseIf IsNumeric(InputArray(iRow, iCol)) Then
                        ' no action
                    Else
                        InputArray(iRow, iCol) = "" & InputArray(iRow, iCol)
                        If Len(InputArray(iRow, iCol)) > 255 Then
                            ' Block-write operations fail on strings exceeding 255 chars. You *have*
                            ' to go back and check, and write this masterpiece one cell at a time...
                            InputArray(iRow, iCol) = Left(Trim(InputArray(iRow, iCol)), 255)
                        End If
                    End If
                Next iCol
            Next iRow
            Err.Clear
            rngOutput.Text = InputArray
        End If 'err<>0

        If Err <> 0 Then
            Application.ScreenUpdating = False
            Application.Calculation = xlCalculationManual
            iRowOffset = LBound(InputArray, 1) - 1
            iColOffset = LBound(InputArray, 2) - 1
            For iRow = 1 To iRowCount
                If iRow Mod 100 = 0 Then
                    Application.StatusBar = "Filling range... " & CInt(100# * iRow / iRowCount) & "%"
                End If
                For iCol = 1 To iColCount
                    rngOutput.Cells(iRow, iCol) = InputArray(iRow + iRowOffset, iCol + iColOffset)
                Next iCol
            Next iRow
            Application.StatusBar = False
            Application.ScreenUpdating = True


        End If 'err<>0


        Set rngTarget = rngOutput   ' resizes the range This is useful, *most* of the time

    End With

End If

End Sub

You will need the source for ArrayDimensions:

This API declaration is required in the module header:

Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
                   (Destination As Any, _
                    Source As Any, _
                    ByVal Length As Long)

...And here's the function itself:

Private Function ArrayDimensions(arr As Variant) As Integer
  '-----------------------------------------------------------------
  ' will return:
  ' -1 if not an array
  ' 0  if an un-dimmed array
  ' 1  or more indicating the number of dimensions of a dimmed array
  '-----------------------------------------------------------------


  ' Retrieved from Chris Rae's VBA Code Archive - http://chrisrae.com/vba
  ' Code written by Chris Rae, 25/5/00

  ' Originally published by R. B. Smissaert.
  ' Additional credits to Bob Phillips, Rick Rothstein, and Thomas Eyde on VB2TheMax

  Dim ptr As Long
  Dim vType As Integer

  Const VT_BYREF = &H4000&

  'get the real VarType of the argument
  'this is similar to VarType(), but returns also the VT_BYREF bit
  CopyMemory vType, arr, 2

  'exit if not an array
  If (vType And vbArray) = 0 Then
    ArrayDimensions = -1
    Exit Function
  End If

  'get the address of the SAFEARRAY descriptor
  'this is stored in the second half of the
  'Variant parameter that has received the array
  CopyMemory ptr, ByVal VarPtr(arr) + 8, 4

  'see whether the routine was passed a Variant
  'that contains an array, rather than directly an array
  'in the former case ptr already points to the SA structure.
  'Thanks to Monte Hansen for this fix

  If (vType And VT_BYREF) Then
    ' ptr is a pointer to a pointer
    CopyMemory ptr, ByVal ptr, 4
  End If

  'get the address of the SAFEARRAY structure
  'this is stored in the descriptor

  'get the first word of the SAFEARRAY structure
  'which holds the number of dimensions
  '...but first check that saAddr is non-zero, otherwise
  'this routine bombs when the array is uninitialized

  If ptr Then
    CopyMemory ArrayDimensions, ByVal ptr, 2
  End If

End Function

Also: I would advise you to keep that declaration private. If you must make it a public Sub in another module, insert the Option Private Module statement in the module header. You really don't want your users calling any function with CopyMemoryoperations and pointer arithmetic.

Typescript - multidimensional array initialization

You only need [] to instantiate an array - this is true regardless of its type. The fact that the array is of an array type is immaterial.

The same thing applies at the first level in your loop. It is merely an array and [] is a new empty array - job done.

As for the second level, if Thing is a class then new Thing() will be just fine. Otherwise, depending on the type, you may need a factory function or other expression to create one.

class Something {
    private things: Thing[][];

    constructor() {
        this.things = [];

        for(var i: number = 0; i < 10; i++) {
            this.things[i] = [];
            for(var j: number = 0; j< 10; j++) {
                this.things[i][j] = new Thing();
            }
        }
    }
}

How to insert a new key value pair in array in php?

To add:

$arr["key"] = "value";

Then simply return $arr

Can't return directly like this way return $arr["key"] = "value";

Create two-dimensional arrays and access sub-arrays in Ruby

Here is the simple version

 #one
 a = [[0]*10]*10

 #two
row, col = 10, 10
a = [[0]*row]*col

JavaScript push to array

It's not an array.

var json = {"cool":"34.33","alsocool":"45454"};
json.coolness = 34.33;

or

var json = {"cool":"34.33","alsocool":"45454"};
json['coolness'] = 34.33;

you could do it as an array, but it would be a different syntax (and this is almost certainly not what you want)

var json = [{"cool":"34.33"},{"alsocool":"45454"}];
json.push({"coolness":"34.33"});

Note that this variable name is highly misleading, as there is no JSON here. I would name it something else.

How can I declare a two dimensional string array?

You just declared a jagged array. Such kind of arrays can have different sizes for all dimensions. For example:

string[][] jaggedStrings =  {
new string[] {"x","y","z"},
new string[] {"x","y"},
new string[] {"x"}
};

In your case you need regular array. See answers above. More about jagged arrays

How do I copy a 2 Dimensional array in Java?

You can give below code a try,

public void multiArrayCopy(int[][] source,int[][] destination){
destination=source.clone();}

Hope it works.

How to sum all column values in multi-dimensional array?

example array here

Code here:

        $temp_arr = [];
        foreach ($a as $k => $v) {
            if(!is_null($v)) {
                $sum = isset($temp_arr[$v[0]]) ? ((int)$v[5] + $sum) : (int)$v[5];
                $temp_arr[$v[0]] = $sum;
            }
        }
        return $temp_arr;

Result:

{SEQ_OK: 1328,SEQ_ERROR: 561}

Convert a 1D array to a 2D array in numpy

Change 1D array into 2D array without using Numpy.

l = [i for i in range(1,21)]
part = 3
new = []
start, end = 0, part


while end <= len(l):
    temp = []
    for i in range(start, end):
        temp.append(l[i])
    new.append(temp)
    start += part
    end += part
print("new values:  ", new)


# for uneven cases
temp = []
while start < len(l):
    temp.append(l[start])
    start += 1
    new.append(temp)
print("new values for uneven cases:   ", new)

Arrays.fill with multidimensional array in Java

Arrays.fill works with single dimensional array, so to fill two dimensional array we can do below

for (int i = 0, len = arr.length; i < len; i++)
    Arrays.fill(arr[i], 0);

How do you rotate a two dimensional array?

Here is my attempt for matrix 90 deg rotation which is a 2 step solution in C. First transpose the matrix in place and then swap the cols.

#define ROWS        5
#define COLS        5

void print_matrix_b(int B[][COLS], int rows, int cols) 
{
    for (int i = 0; i <= rows; i++) {
        for (int j = 0; j <=cols; j++) {
            printf("%d ", B[i][j]);
        }
        printf("\n");
    }
}

void swap_columns(int B[][COLS], int l, int r, int rows)
{
    int tmp;
    for (int i = 0; i <= rows; i++) {
        tmp = B[i][l];
        B[i][l] = B[i][r];
        B[i][r] = tmp;
    }
}


void matrix_2d_rotation(int B[][COLS], int rows, int cols)
{
    int tmp;
    // Transpose the matrix first
    for (int i = 0; i <= rows; i++) {
        for (int j = i; j <=cols; j++) {
            tmp = B[i][j];
            B[i][j] = B[j][i];
            B[j][i] = tmp;
        }
    }
    // Swap the first and last col and continue until
    // the middle.
    for (int i = 0; i < (cols / 2); i++)
        swap_columns(B, i, cols - i, rows);
}



int _tmain(int argc, _TCHAR* argv[])
{
    int B[ROWS][COLS] = { 
                  {1, 2, 3, 4, 5}, 
                      {6, 7, 8, 9, 10},
                          {11, 12, 13, 14, 15},
                          {16, 17, 18, 19, 20},
                          {21, 22, 23, 24, 25}
                        };

    matrix_2d_rotation(B, ROWS - 1, COLS - 1);

    print_matrix_b(B, ROWS - 1, COLS -1);
    return 0;
}

PHP: Get key from array?

Here is a generic solution that you can add to your Array library. All you need to do is supply the associated value and the target array!

PHP Manual: array_search() (similiar to .indexOf() in other languages)

public function getKey(string $value, array $target)
{
    $key = array_search($value, $target);

    if ($key === null) {
        throw new InvalidArgumentException("Invalid arguments provided. Check inputs. Must be a (1) a string and (2) an array.");
    }

    if ($key === false) {
        throw new DomainException("The search value does not exists in the target array.");
    }

    return $key;
}

How to print the array?

There is no .length property in C. The .length property can only be applied to arrays in object oriented programming (OOP) languages. The .length property is inherited from the object class; the class all other classes & objects inherit from in an OOP language. Also, one would use .length-1 to return the number of the last index in an array; using just the .length will return the total length of the array.

I would suggest something like this:

int index;
int jdex;
for( index = 0; index < (sizeof( my_array ) / sizeof( my_array[0] )); index++){
   for( jdex = 0; jdex < (sizeof( my_array ) / sizeof( my_array[0] )); jdex++){
        printf( "%d", my_array[index][jdex] );
        printf( "\n" );
   }
}

The line (sizeof( my_array ) / sizeof( my_array[0] )) will give you the size of the array in question. The sizeof property will return the length in bytes, so one must divide the total size of the array in bytes by how many bytes make up each element, each element takes up 4 bytes because each element is of type int, respectively. The array is of total size 16 bytes and each element is of 4 bytes so 16/4 yields 4 the total number of elements in your array because indexing starts at 0 and not 1.

Initialize 2D array

How about something like this:

for (int row = 0; row < 3; row ++)
    for (int col = 0; col < 3; col++)
        table[row][col] = (char) ('1' + row * 3 + col);

The following complete Java program:

class Test {
    public static void main(String[] args) {
        char[][] table = new char[3][3];
        for (int row = 0; row < 3; row ++)
            for (int col = 0; col < 3; col++)
                table[row][col] = (char) ('1' + row * 3 + col);

        for (int row = 0; row < 3; row ++)
            for (int col = 0; col < 3; col++)
                System.out.println (table[row][col]);
    }
}

outputs:

1
2
3
4
5
6
7
8
9

This works because the digits in Unicode are consecutive starting at \u0030 (which is what you get from '0').

The expression '1' + row * 3 + col (where you vary row and col between 0 and 2 inclusive) simply gives you a character from 1 to 9.

Obviously, this won't give you the character 10 (since that's two characters) if you go further but it works just fine for the 3x3 case. You would have to change the method of generating the array contents at that point such as with something like:

String[][] table = new String[5][5];
for (int row = 0; row < 5; row ++)
    for (int col = 0; col < 5; col++)
        table[row][col] = String.format("%d", row * 5 + col + 1);

Java ArrayList of Arrays?

As already answered, you can create an ArrayList of String Arrays as @Péter Török written;

    //Declaration of an ArrayList of String Arrays
    ArrayList<String[]> listOfArrayList = new ArrayList<String[]>();

When assigning different String Arrays to this ArrayList, each String Array's length will be different.

In the following example, 4 different Array of String added, their lengths are varying.

String Array #1: len: 3
String Array #2: len: 1
String Array #3: len: 4
String Array #4: len: 2

The Demonstration code is as below;

import java.util.ArrayList;

public class TestMultiArray {

    public static void main(String[] args) {
        //Declaration of an ArrayList of String Arrays
        ArrayList<String[]> listOfArrayList = new ArrayList<String[]>();

        //Assignment of 4 different String Arrays with different lengths
        listOfArrayList.add( new String[]{"line1: test String 1","line1: test String 2","line1: test String 3"}  );
        listOfArrayList.add( new String[]{"line2: test String 1"}  );
        listOfArrayList.add( new String[]{"line3: test String 1","line3: test String 2","line3: test String 3", "line3: test String 4"}  );
        listOfArrayList.add( new String[]{"line4: test String 1","line4: test String 2"}  );

        // Printing out the ArrayList Contents of String Arrays
        // '$' is used to indicate the String elements of String Arrays
        for( int i = 0; i < listOfArrayList.size(); i++ ) {
            for( int j = 0; j < listOfArrayList.get(i).length; j++ )
                System.out.printf(" $ " + listOfArrayList.get(i)[j]);

            System.out.println();
        }

    }
}

And the output is as follows;

 $ line1: test String 1 $ line1: test String 2 $ line1: test String 3
 $ line2: test String 1
 $ line3: test String 1 $ line3: test String 2 $ line3: test String 3 $ line3: test String 4
 $ line4: test String 1 $ line4: test String 2

Also notify that you can initialize a new Array of Sting as below;

new String[]{ str1, str2, str3,... }; // Assuming str's are String objects

So this is same with;

String[] newStringArray = { str1, str2, str3 }; // Assuming str's are String objects

I've written this demonstration just to show that no theArrayList object, all the elements are references to different instantiations of String Arrays, thus the length of each String Arrays are not have to be the same, neither it is important.

One last note: It will be best practice to use the ArrayList within a List interface, instead of which that you've used in your question.

It will be better to use the List interface as below;

    //Declaration of an ArrayList of String Arrays
    List<String[]> listOfArrayList = new ArrayList<String[]>();

How to create multidimensional array

So here's my solution.

A simple example for a 3x3 Array. You can keep chaining this to go deeper

Array(3).fill().map(a => Array(3))

Or the following function will generate any level deep you like

f = arr => {
    let str = 'return ', l = arr.length;
    arr.forEach((v, i) => {
        str += i < l-1 ? `Array(${v}).fill().map(a => ` : `Array(${v}` + ')'.repeat(l);
    });
    return Function(str)();
}
f([4,5,6]) // Generates a 4x5x6 Array

http://www.binaryoverdose.com/2017/02/07/Generating-Multidimensional-Arrays-in-JavaScript/

Passing a 2D array to a C++ function

Single dimensional array decays to a pointer pointer pointing to the first element in the array. While a 2D array decays to a pointer pointing to first row. So, the function prototype should be -

void myFunction(double (*myArray) [10]);

I would prefer std::vector over raw arrays.

How to pass 2D array (matrix) in a function in C?

2D array:

int sum(int array[][COLS], int rows)
{

}

3D array:

int sum(int array[][B][C], int A)
{

}

4D array:

int sum(int array[][B][C][D], int A)
{

}

and nD array:

int sum(int ar[][B][C][D][E][F].....[N], int A)
{

}

Multidimensional Array [][] vs [,]

double[][] is an array of arrays and double[,] is a matrix. If you want to initialize an array of array, you will need to do this:

double[][] ServicePoint = new double[10][]
for(var i=0;i<ServicePoint.Length;i++)
    ServicePoint[i] = new double[9];

Take in account that using arrays of arrays will let you have arrays of different lengths:

ServicePoint[0] = new double[10];
ServicePoint[1] = new double[3];
ServicePoint[2] = new double[5];
//and so on...

How can I create a two dimensional array in JavaScript?

 var items = [
      ["January 01", 42.5],
      ["February 01",  44.3],
      ["March 01",  28.7],
      ["April 01",  44.3],
      ["May 01",  22.9],
      ["June 01",  54.4],
      ["July 01",  69.3],
      ["August 01",  19.1],
      ["September 01",  82.5],
      ["October 01",  53.2],
      ["November 01",  75.9],
      ["December 01",  58.7]

    ];
  alert(items[1][0]); // February 01
  alert(items[5][1]); // 54.4

Syntax for creating a two-dimensional array in Java

Try:

int[][] multD = new int[5][10];

Note that in your code only the first line of the 2D array is initialized to 0. Line 2 to 5 don't even exist. If you try to print them you'll get null for everyone of them.

What is the difference between ndarray and array in numpy?

Just a few lines of example code to show the difference between numpy.array and numpy.ndarray

Warm up step: Construct a list

a = [1,2,3]

Check the type

print(type(a))

You will get

<class 'list'>

Construct an array (from a list) using np.array

a = np.array(a)

Or, you can skip the warm up step, directly have

a = np.array([1,2,3])

Check the type

print(type(a))

You will get

<class 'numpy.ndarray'>

which tells you the type of the numpy array is numpy.ndarray

You can also check the type by

isinstance(a, (np.ndarray))

and you will get

True

Either of the following two lines will give you an error message

np.ndarray(a)                # should be np.array(a)
isinstance(a, (np.array))    # should be isinstance(a, (np.ndarray))

How to "flatten" a multi-dimensional array to simple one in PHP?

// $array = your multidimensional array

$flat_array = array();

foreach(new RecursiveIteratorIterator(new RecursiveArrayIterator($array)) as $k=>$v){

$flat_array[$k] = $v;

}

Also documented: http://www.phpro.org/examples/Flatten-Array.html

PHP foreach loop through multidimensional array

<?php
$first = reset($arr_nav); // Get the first element
$last  = end($arr_nav);   // Get the last element
// Ensure that we have a first element and that it's an array
if(is_array($first)) { 
   $first['class'] = 'first';
}
// Ensure we have a last element and that it differs from the first
if(is_array($last) && $last !== $first) {
   $last['class'] = 'last';
}

Now you could just echo the class inside you html-generator. Would probably need some kind of check to ensure that the class is set, or provide a default empty class to the array.

Get first element in PHP stdObject

Update PHP 7.4

Curly brace access syntax is deprecated since PHP 7.4

Update 2019

Moving on to the best practices of OOPS, @MrTrick's answer must be marked as correct, although my answer provides a hacked solution its not the best method.

Simply iterate its using {}

Example:

$videos{0}->id

This way your object is not destroyed and you can easily iterate through object.

For PHP 5.6 and below use this

$videos{0}['id']

Both array() and the stdClass objects can be accessed using the current() key() next() prev() reset() end() functions.

So, if your object looks like

object(stdClass)#19 (3) {
  [0]=>
  object(stdClass)#20 (22) {
    ["id"]=>
    string(1) "123"
  etc...

Then you can just do;

$id = reset($obj)->id; //Gets the 'id' attr of the first entry in the object

If you need the key for some reason, you can do;

reset($obj); //Ensure that we're at the first element
$key = key($obj);

Hope that works for you. :-) No errors, even in super-strict mode, on PHP 5.4


2022 Update:
After PHP 7.4, using current(), end(), etc functions on objects is deprecated.

In newer versions of PHP, use the ArrayIterator class:

$objIterator = new ArrayIterator($obj);

$id = $objIterator->current()->id; // Gets the 'id' attr of the first entry in the object

$key = $objIterator->key(); // and gets the key

How to create a Multidimensional ArrayList in Java?

Once I required 2-D arrayList and I created using List and ArrayList and the code is as follows:

import java.util.*;

public class ArrayListMatrix {

    public static void main(String args[]){

        List<ArrayList<Integer>> a = new ArrayList<>();

        ArrayList<Integer> a1 = new ArrayList<Integer>();
        ArrayList<Integer> a2 = new ArrayList<Integer>();
        ArrayList<Integer> a3 = new ArrayList<Integer>();


        a1.add(1);
        a1.add(2);
        a1.add(3);

        a2.add(4);
        a2.add(5);
        a2.add(6);

        a3.add(7);
        a3.add(8);
        a3.add(9);

        a.add(a1);
        a.add(a2);
        a.add(a3);


        for(ArrayList obj:a){

            ArrayList<Integer> temp = obj;

            for(Integer job : temp){
                System.out.print(job+" ");
            }
            System.out.println();
        }
    }
}

Output:

1 2 3

4 5 6

7 8 9

Source : https://www.codepuran.com/java/2d-matrix-arraylist-collection-class-java/

How to re-index all subarray elements of a multidimensional array?

PHP native function exists for this. See http://php.net/manual/en/function.reset.php

Simply do this: mixed reset ( array &$array )

PHP - Merging two arrays into one array (also Remove Duplicates)

The best solution above faces a problem when using the same associative keys, array_merge() will merge array elements together when they have the same NON-NUMBER key, so it is not suitable for the following case

$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2=array("c"=>"red","d"=>"black","e"=>"green");

If you are able output your value to the keys of your arrays instead (e.g ->pluck('name', 'id')->toArray() in Eloquent), you can use the following merge method instead

array_keys(array_merge($a1, $a2))

Basically what the code does is it utilized the behavior of array_merge() to get rid of duplicated keys and return you a new array with keys as array elements, hope it helps

How to initialize a two-dimensional array in Python?

Another way is to use a dictionary to hold a two-dimensional array.

twoD = {}
twoD[0,0] = 0
print(twoD[0,0]) # ===> prints 0

This just can hold any 1D, 2D values and to initialize this to 0 or any other int value, use collections.

import collections
twoD = collections.defaultdict(int)
print(twoD[0,0]) # ==> prints 0
twoD[1,1] = 1
print(twoD[1,1]) # ==> prints 1

How to use a variable of one method in another method?

You can't. Variables defined inside a method are local to that method.

If you want to share variables between methods, then you'll need to specify them as member variables of the class. Alternatively, you can pass them from one method to another as arguments (this isn't always applicable).


Looks like you're using instance methods instead of static ones.

If you don't want to create an object, you should declare all your methods static, so something like

private static void methodName(Argument args...)

If you want a variable to be accessible by all these methods, you should initialise it outside the methods and to limit its scope, declare it private.

private static int[][] array = new int[3][5];

Global variables are usually looked down upon (especially for situations like your one) because in a large-scale program they can wreak havoc, so making it private will prevent some problems at the least.

Also, I'll say the usual: You should try to keep your code a bit tidy. Use descriptive class, method and variable names and keep your code neat (with proper indentation, linebreaks etc.) and consistent.

Here's a final (shortened) example of what your code should be like:

public class Test3 {
    //Use this array in your methods
    private static int[][] scores = new int[3][5];

    /* Rather than just "Scores" name it so people know what
     * to expect
     */
    private static void createScores() {
        //Code...
    }
    //Other methods...

    /* Since you're now using static methods, you don't 
     * have to initialise an object and call its methods.
     */
    public static void main(String[] args){
        createScores();
        MD();   //Don't know what these do
        sumD(); //so I'll leave them.
    }
}

Ideally, since you're using an array, you would create the array in the main method and pass it as an argument across each method, but explaining how that works is probably a whole new question on its own so I'll leave it at that.

Two dimensional array in python

In my case I had to do this:

for index, user in enumerate(users):
    table_body.append([])
    table_body[index].append(user.user.id)
    table_body[index].append(user.user.username)

Output:

[[1, 'john'], [2, 'bill']]

How to sort 2 dimensional array by column value?

It's this simple:

var a = [[12, 'AAA'], [58, 'BBB'], [28, 'CCC'],[18, 'DDD']];

a.sort(sortFunction);

function sortFunction(a, b) {
    if (a[0] === b[0]) {
        return 0;
    }
    else {
        return (a[0] < b[0]) ? -1 : 1;
    }
}

I invite you to read the documentation.

If you want to sort by the second column, you can do this:

a.sort(compareSecondColumn);

function compareSecondColumn(a, b) {
    if (a[1] === b[1]) {
        return 0;
    }
    else {
        return (a[1] < b[1]) ? -1 : 1;
    }
}

How do you get the width and height of a multi-dimensional array?

Some of the other posts are confused about which dimension is which. Here's an NUNIT test that shows how 2D arrays work in C#

[Test]
public void ArraysAreRowMajor()
{
    var myArray = new int[2,3]
        {
            {1, 2, 3},
            {4, 5, 6}
        };

    int rows = myArray.GetLength(0);
    int columns = myArray.GetLength(1);
    Assert.AreEqual(2,rows);
    Assert.AreEqual(3,columns);
    Assert.AreEqual(1,myArray[0,0]);
    Assert.AreEqual(2,myArray[0,1]);
    Assert.AreEqual(3,myArray[0,2]);
    Assert.AreEqual(4,myArray[1,0]);
    Assert.AreEqual(5,myArray[1,1]);
    Assert.AreEqual(6,myArray[1,2]);
}

Fastest way to zero out a 2d array in C?

How was your 2D array declared?

If it something like:

int arr[20][30];

You can zero it by doing:

memset(arr, sizeof(int)*20*30);

Create 3D array using Python

You should use a list comprehension:

>>> import pprint
>>> n = 3
>>> distance = [[[0 for k in xrange(n)] for j in xrange(n)] for i in xrange(n)]
>>> pprint.pprint(distance)
[[[0, 0, 0], [0, 0, 0], [0, 0, 0]],
 [[0, 0, 0], [0, 0, 0], [0, 0, 0]],
 [[0, 0, 0], [0, 0, 0], [0, 0, 0]]]
>>> distance[0][1]
[0, 0, 0]
>>> distance[0][1][2]
0

You could have produced a data structure with a statement that looked like the one you tried, but it would have had side effects since the inner lists are copy-by-reference:

>>> distance=[[[0]*n]*n]*n
>>> pprint.pprint(distance)
[[[0, 0, 0], [0, 0, 0], [0, 0, 0]],
 [[0, 0, 0], [0, 0, 0], [0, 0, 0]],
 [[0, 0, 0], [0, 0, 0], [0, 0, 0]]]
>>> distance[0][0][0] = 1
>>> pprint.pprint(distance)
[[[1, 0, 0], [1, 0, 0], [1, 0, 0]],
 [[1, 0, 0], [1, 0, 0], [1, 0, 0]],
 [[1, 0, 0], [1, 0, 0], [1, 0, 0]]]

Using numpy to build an array of all combinations of two arrays

Here's yet another way, using pure NumPy, no recursion, no list comprehension, and no explicit for loops. It's about 20% slower than the original answer, and it's based on np.meshgrid.

def cartesian(*arrays):
    mesh = np.meshgrid(*arrays)  # standard numpy meshgrid
    dim = len(mesh)  # number of dimensions
    elements = mesh[0].size  # number of elements, any index will do
    flat = np.concatenate(mesh).ravel()  # flatten the whole meshgrid
    reshape = np.reshape(flat, (dim, elements)).T  # reshape and transpose
    return reshape

For example,

x = np.arange(3)
a = cartesian(x, x, x, x, x)
print(a)

gives

[[0 0 0 0 0]
 [0 0 0 0 1]
 [0 0 0 0 2]
 ..., 
 [2 2 2 2 0]
 [2 2 2 2 1]
 [2 2 2 2 2]]

Excel VBA - How to Redim a 2D array?

This isn't exactly intuitive, but you cannot Redim(VB6 Ref) an array if you dimmed it with dimensions. Exact quote from linked page is:

The ReDim statement is used to size or resize a dynamic array that has already been formally declared using a Private, Public, or Dim statement with empty parentheses (without dimension subscripts).

In other words, instead of dim invoices(10,0)

You should use

Dim invoices()
Redim invoices(10,0)

Then when you ReDim, you'll need to use Redim Preserve (10,row)

Warning: When Redimensioning multi-dimensional arrays, if you want to preserve your values, you can only increase the last dimension. I.E. Redim Preserve (11,row) or even (11,0) would fail.

How do I use arrays in C++?

Arrays on the type level

An array type is denoted as T[n] where T is the element type and n is a positive size, the number of elements in the array. The array type is a product type of the element type and the size. If one or both of those ingredients differ, you get a distinct type:

#include <type_traits>

static_assert(!std::is_same<int[8], float[8]>::value, "distinct element type");
static_assert(!std::is_same<int[8],   int[9]>::value, "distinct size");

Note that the size is part of the type, that is, array types of different size are incompatible types that have absolutely nothing to do with each other. sizeof(T[n]) is equivalent to n * sizeof(T).

Array-to-pointer decay

The only "connection" between T[n] and T[m] is that both types can implicitly be converted to T*, and the result of this conversion is a pointer to the first element of the array. That is, anywhere a T* is required, you can provide a T[n], and the compiler will silently provide that pointer:

                  +---+---+---+---+---+---+---+---+
the_actual_array: |   |   |   |   |   |   |   |   |   int[8]
                  +---+---+---+---+---+---+---+---+
                    ^
                    |
                    |
                    |
                    |  pointer_to_the_first_element   int*

This conversion is known as "array-to-pointer decay", and it is a major source of confusion. The size of the array is lost in this process, since it is no longer part of the type (T*). Pro: Forgetting the size of an array on the type level allows a pointer to point to the first element of an array of any size. Con: Given a pointer to the first (or any other) element of an array, there is no way to detect how large that array is or where exactly the pointer points to relative to the bounds of the array. Pointers are extremely stupid.

Arrays are not pointers

The compiler will silently generate a pointer to the first element of an array whenever it is deemed useful, that is, whenever an operation would fail on an array but succeed on a pointer. This conversion from array to pointer is trivial, since the resulting pointer value is simply the address of the array. Note that the pointer is not stored as part of the array itself (or anywhere else in memory). An array is not a pointer.

static_assert(!std::is_same<int[8], int*>::value, "an array is not a pointer");

One important context in which an array does not decay into a pointer to its first element is when the & operator is applied to it. In that case, the & operator yields a pointer to the entire array, not just a pointer to its first element. Although in that case the values (the addresses) are the same, a pointer to the first element of an array and a pointer to the entire array are completely distinct types:

static_assert(!std::is_same<int*, int(*)[8]>::value, "distinct element type");

The following ASCII art explains this distinction:

      +-----------------------------------+
      | +---+---+---+---+---+---+---+---+ |
+---> | |   |   |   |   |   |   |   |   | | int[8]
|     | +---+---+---+---+---+---+---+---+ |
|     +---^-------------------------------+
|         |
|         |
|         |
|         |  pointer_to_the_first_element   int*
|
|  pointer_to_the_entire_array              int(*)[8]

Note how the pointer to the first element only points to a single integer (depicted as a small box), whereas the pointer to the entire array points to an array of 8 integers (depicted as a large box).

The same situation arises in classes and is maybe more obvious. A pointer to an object and a pointer to its first data member have the same value (the same address), yet they are completely distinct types.

If you are unfamiliar with the C declarator syntax, the parenthesis in the type int(*)[8] are essential:

  • int(*)[8] is a pointer to an array of 8 integers.
  • int*[8] is an array of 8 pointers, each element of type int*.

Accessing elements

C++ provides two syntactic variations to access individual elements of an array. Neither of them is superior to the other, and you should familiarize yourself with both.

Pointer arithmetic

Given a pointer p to the first element of an array, the expression p+i yields a pointer to the i-th element of the array. By dereferencing that pointer afterwards, one can access individual elements:

std::cout << *(x+3) << ", " << *(x+7) << std::endl;

If x denotes an array, then array-to-pointer decay will kick in, because adding an array and an integer is meaningless (there is no plus operation on arrays), but adding a pointer and an integer makes sense:

   +---+---+---+---+---+---+---+---+
x: |   |   |   |   |   |   |   |   |   int[8]
   +---+---+---+---+---+---+---+---+
     ^           ^               ^
     |           |               |
     |           |               |
     |           |               |
x+0  |      x+3  |          x+7  |     int*

(Note that the implicitly generated pointer has no name, so I wrote x+0 in order to identify it.)

If, on the other hand, x denotes a pointer to the first (or any other) element of an array, then array-to-pointer decay is not necessary, because the pointer on which i is going to be added already exists:

   +---+---+---+---+---+---+---+---+
   |   |   |   |   |   |   |   |   |   int[8]
   +---+---+---+---+---+---+---+---+
     ^           ^               ^
     |           |               |
     |           |               |
   +-|-+         |               |
x: | | |    x+3  |          x+7  |     int*
   +---+

Note that in the depicted case, x is a pointer variable (discernible by the small box next to x), but it could just as well be the result of a function returning a pointer (or any other expression of type T*).

Indexing operator

Since the syntax *(x+i) is a bit clumsy, C++ provides the alternative syntax x[i]:

std::cout << x[3] << ", " << x[7] << std::endl;

Due to the fact that addition is commutative, the following code does exactly the same:

std::cout << 3[x] << ", " << 7[x] << std::endl;

The definition of the indexing operator leads to the following interesting equivalence:

&x[i]  ==  &*(x+i)  ==  x+i

However, &x[0] is generally not equivalent to x. The former is a pointer, the latter an array. Only when the context triggers array-to-pointer decay can x and &x[0] be used interchangeably. For example:

T* p = &array[0];  // rewritten as &*(array+0), decay happens due to the addition
T* q = array;      // decay happens due to the assignment

On the first line, the compiler detects an assignment from a pointer to a pointer, which trivially succeeds. On the second line, it detects an assignment from an array to a pointer. Since this is meaningless (but pointer to pointer assignment makes sense), array-to-pointer decay kicks in as usual.

Ranges

An array of type T[n] has n elements, indexed from 0 to n-1; there is no element n. And yet, to support half-open ranges (where the beginning is inclusive and the end is exclusive), C++ allows the computation of a pointer to the (non-existent) n-th element, but it is illegal to dereference that pointer:

   +---+---+---+---+---+---+---+---+....
x: |   |   |   |   |   |   |   |   |   .   int[8]
   +---+---+---+---+---+---+---+---+....
     ^                               ^
     |                               |
     |                               |
     |                               |
x+0  |                          x+8  |     int*

For example, if you want to sort an array, both of the following would work equally well:

std::sort(x + 0, x + n);
std::sort(&x[0], &x[0] + n);

Note that it is illegal to provide &x[n] as the second argument since this is equivalent to &*(x+n), and the sub-expression *(x+n) technically invokes undefined behavior in C++ (but not in C99).

Also note that you could simply provide x as the first argument. That is a little too terse for my taste, and it also makes template argument deduction a bit harder for the compiler, because in that case the first argument is an array but the second argument is a pointer. (Again, array-to-pointer decay kicks in.)

How to Flatten a Multidimensional Array?

I needed to represent PHP multidimensional array in HTML input format.

$test = [
    'a' => [
        'b' => [
            'c' => ['a', 'b']
        ]
    ],
    'b' => 'c',
    'c' => [
        'd' => 'e'
    ]
];

$flatten = function ($input, $parent = []) use (&$flatten) {
    $return = [];

    foreach ($input as $k => $v) {
        if (is_array($v)) {
            $return = array_merge($return, $flatten($v, array_merge($parent, [$k])));
        } else {
            if ($parent) {
                $key = implode('][', $parent) . '][' . $k . ']';

                if (substr_count($key, ']') != substr_count($key, '[')) {
                    $key = preg_replace('/\]/', '', $key, 1);
                }
            } else {
                $key = $k;
            }           

            $return[$key] = $v;
        }
    }

    return $return;
};

die(var_dump( $flatten($test) ));

array(4) {
  ["a[b][c][0]"]=>
  string(1) "a"
  ["a[b][c][1]"]=>
  string(1) "b"
  ["b"]=>
  string(1) "c"
  ["c[d]"]=>
  string(1) "e"
}

ReDim Preserve to a Multi-Dimensional Array in Visual Basic 6

Function Redim2d(ByRef Mtx As Variant, ByVal QtyColumnToAdd As Integer)
    ReDim Preserve Mtx(LBound(Mtx, 1) To UBound(Mtx, 1), LBound(Mtx, 2) To UBound(Mtx, 2) + QtyColumnToAdd)
End Function

'Main Code
sub Main ()
    Call Redim2d(MtxR8Strat, 1)  'Add one column
end sub

'OR
sub main2()
    QtyColumnToAdd = 1 'Add one column
    ReDim Preserve Mtx(LBound(Mtx, 1) To UBound(Mtx, 1), LBound(Mtx, 2) To UBound(Mtx, 2) + QtyColumnToAdd)
end sub

Check if a specific value exists at a specific key in any subarray of a multidimensional array

TMTOWTDI. Here are several solutions in order of complexity.

(Short primer on complexity follows):O(n) or "big o" means worst case scenario where n means the number of elements in the array, and o(n) or "little o" means best case scenario. Long discrete math story short, you only really have to worry about the worst case scenario, and make sure it's not n ^ 2 or n!. It's more a measure of change in computing time as n increases than it is overall computing time. Wikipedia has a good article about computational aka time complexity.

If experience has taught me anything, it's that spending too much time optimizing your programs' little-o is a distinct waste of time better spent doing something - anything - better.

Solution 0: O(n) / o(1) complexity:

This solution has a best case scenario of 1 comparison - 1 iteration thru the loop, but only provided the matching value is in position 0 of the array. The worst case scenario is it's not in the array, and thus has to iterate over every element of the array.

foreach ($my_array as $sub_array) {
    if (@$sub_array['id'] === 152) {
        return true;
    }
}
return false;

Solution 1: O(n) / o(n) complexity:

This solution must loop thru the entire array no matter where the matching value is, so it's always going to be n iterations thru the array.

return 0 < count(
    array_filter(
        $my_array,
        function ($a) {
            return array_key_exists('id', $a) && $a['id'] == 152;
        }
    )
);

Solution 2: O(n log n) / o(n log n) complexity:

A hash insertion is where the log n comes from; n hash insertions = n * log n. There's a hash lookup at the end which is another log n but it's not included because that's just how discrete math works.

$existence_hash = [];
foreach ($my_array as $sub_array) {
    $existence_hash[$sub_array['id']] = true;
}
return @$existence_hash['152'];

Rotating a two-dimensional array in Python

There are three parts to this:

  1. original[::-1] reverses the original array. This notation is Python list slicing. This gives you a "sublist" of the original list described by [start:end:step], start is the first element, end is the last element to be used in the sublist. step says take every step'th element from first to last. Omitted start and end means the slice will be the entire list, and the negative step means that you'll get the elements in reverse. So, for example, if original was [x,y,z], the result would be [z,y,x]
  2. The * when preceding a list/tuple in the argument list of a function call means "expand" the list/tuple so that each of its elements becomes a separate argument to the function, rather than the list/tuple itself. So that if, say, args = [1,2,3], then zip(args) is the same as zip([1,2,3]), but zip(*args) is the same as zip(1,2,3).
  3. zip is a function that takes n arguments each of which is of length m and produces a list of length m, the elements of are of length n and contain the corresponding elements of each of the original lists. E.g., zip([1,2],[a,b],[x,y]) is [[1,a,x],[2,b,y]]. See also Python documentation.

What are the differences between a multidimensional array and an array of arrays in C#?

Array of arrays (jagged arrays) are faster than multi-dimensional arrays and can be used more effectively. Multidimensional arrays have nicer syntax.

If you write some simple code using jagged and multidimensional arrays and then inspect the compiled assembly with an IL disassembler you will see that the storage and retrieval from jagged (or single dimensional) arrays are simple IL instructions while the same operations for multidimensional arrays are method invocations which are always slower.

Consider the following methods:

static void SetElementAt(int[][] array, int i, int j, int value)
{
    array[i][j] = value;
}

static void SetElementAt(int[,] array, int i, int j, int value)
{
    array[i, j] = value;
}

Their IL will be the following:

.method private hidebysig static void  SetElementAt(int32[][] 'array',
                                                    int32 i,
                                                    int32 j,
                                                    int32 'value') cil managed
{
  // Code size       7 (0x7)
  .maxstack  8
  IL_0000:  ldarg.0
  IL_0001:  ldarg.1
  IL_0002:  ldelem.ref
  IL_0003:  ldarg.2
  IL_0004:  ldarg.3
  IL_0005:  stelem.i4
  IL_0006:  ret
} // end of method Program::SetElementAt

.method private hidebysig static void  SetElementAt(int32[0...,0...] 'array',
                                                    int32 i,
                                                    int32 j,
                                                    int32 'value') cil managed
{
  // Code size       10 (0xa)
  .maxstack  8
  IL_0000:  ldarg.0
  IL_0001:  ldarg.1
  IL_0002:  ldarg.2
  IL_0003:  ldarg.3
  IL_0004:  call       instance void int32[0...,0...]::Set(int32,
                                                           int32,
                                                           int32)
  IL_0009:  ret
} // end of method Program::SetElementAt

When using jagged arrays you can easily perform such operations as row swap and row resize. Maybe in some cases usage of multidimensional arrays will be more safe, but even Microsoft FxCop tells that jagged arrays should be used instead of multidimensional when you use it to analyse your projects.

Getting the array length of a 2D array in Java

Consider

public static void main(String[] args) {

    int[][] foo = new int[][] {
        new int[] { 1, 2, 3 },
        new int[] { 1, 2, 3, 4},
    };

    System.out.println(foo.length); //2
    System.out.println(foo[0].length); //3
    System.out.println(foo[1].length); //4
}

Column lengths differ per row. If you're backing some data by a fixed size 2D array, then provide getters to the fixed values in a wrapper class.

len() of a numpy array in python

You can transpose the array if you want to get the length of the other dimension.

len(np.array([[2,3,1,0], [2,3,1,0], [3,2,1,1]]).T)

Return a 2d array from a function

I would suggest you Matrix library as an open source tool for c++, its usage is like arrays in c++. Here you can see documention.

Matrix funcionName(){

    Matrix<int> arr(2, 2);

    arr[0][0] = 5;
    arr[0][1] = 10;
    arr[1][0] = 0;
    arr[1][1] = 44;

    return arr;
}

Convert unsigned int to signed int C

I know it's an old question, but it's a good one, so how about this?

unsigned short int x = 65529U;
short int y = *(short int*)&x;

printf("%d\n", y);

The total number of locks exceeds the lock table size

First, you can use sql command show global variables like 'innodb_buffer%'; to check the buffer size.

Solution is find your my.cnf file and add,

_x000D_
_x000D_
[mysqld]_x000D_
innodb_buffer_pool_size=1G # depends on your data and machine
_x000D_
_x000D_
_x000D_

DO NOT forget to add [mysqld], otherwise, it won't work.

In my case, ubuntu 16.04, my.cnf is located under the folder /etc/mysql/.

SeekBar and media player in android

To create a 'connection' between SeekBar and MediaPlayer you need first to get your current recording max duration and set it to your seek bar.

mSeekBar.setMax(mFileDuration/1000); // where mFileDuration is mMediaPlayer.getDuration();

After you initialise your MediaPlayer and for example press play button, you should create handler and post runnable so you can update your SeekBar (in the UI thread itself) with the current position of your MediaPlayer like this :

private Handler mHandler = new Handler();
//Make sure you update Seekbar on UI thread
MainActivity.this.runOnUiThread(new Runnable() {

    @Override
    public void run() {
        if(mMediaPlayer != null){
            int mCurrentPosition = mMediaPlayer.getCurrentPosition() / 1000;
            mSeekBar.setProgress(mCurrentPosition);
        }
        mHandler.postDelayed(this, 1000);
    }
});

and update that value every second.

If you need to update the MediaPlayer's position while user drag your SeekBar you should add OnSeekBarChangeListener to your SeekBar and do it there :

        mSeekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {

        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {

        }

            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {                
                if(mMediaPlayer != null && fromUser){
                    mMediaPlayer.seekTo(progress * 1000);
                }
            }
    });

And that should do the trick! : )

EDIT: One thing which I've noticed in your code, don't do :

public MainActivity() {
    mFileName = Environment.getExternalStorageDirectory().getAbsolutePath();
    mFileName += "/audiorecordtest.3gp";
}

make all initialisations in your onCreate(); , do not create constructors of your Activity.

Stylesheet not loaded because of MIME-type

I had this problem with a site I knew worked online when I moved it to localhost and PhpStorm.

This worked fine online:

    <link rel="stylesheet" href="/css/additional.css">

But for localhost I needed to get rid of the slash:

    <link rel="stylesheet" href="css/additional.css">

So I am reinforcing a few answers provided here already - it is likely to be a path or spelling mistake rather than any complicated server setup problem. The error in the console is a red herring; the network tab needs to be checked for the 404 first.

Among the answers provided here are a few solutions that are not correct. The addition of type="text/html" or changing href to src is not the answer.

If you want to have all of the attributes so it validates on the pickiest of validators and your IDE then the media value should be provided and the rel should be stylesheet, e.g.:

    <link rel="stylesheet" href="css/additional.css" type="text/css" media="all">

Is a URL allowed to contain a space?

Urls should not have spaces in them. If you need to address one that does, use its encoded value of %20

How do I change the color of radio buttons?

Try this css with transition:

enter image description here

Demo

$DarkBrown: #292321;

$Orange: #CC3300;

div {
  margin:0 0 0.75em 0;
}

input[type="radio"] {
    display:none;
}
input[type="radio"] + label {
    color: $DarkBrown;
    font-family:Arial, sans-serif;
    font-size:14px;
}
input[type="radio"] + label span {
    display:inline-block;
    width:19px;
    height:19px;
    margin:-1px 4px 0 0;
    vertical-align:middle;
    cursor:pointer;
    -moz-border-radius:  50%;
    border-radius:  50%;
}

input[type="radio"] + label span {
     background-color:$DarkBrown;
}

input[type="radio"]:checked + label span{
     background-color:$Orange;
}

input[type="radio"] + label span,
input[type="radio"]:checked + label span {
  -webkit-transition:background-color 0.4s linear;
  -o-transition:background-color 0.4s linear;
  -moz-transition:background-color 0.4s linear;
  transition:background-color 0.4s linear;
}

Html :

<div>
  <input type="radio" id="radio01" name="radio" />
  <label for="radio01"><span></span>Radio Button 1</label>
</div>

<div>
 <input type="radio" id="radio02" name="radio" />
 <label for="radio02"><span></span>Radio Button 2</label>
</div>

How do I get the find command to print out the file size with the file name?

a simple solution is to use the -ls option in find:

find . -name \*.ear -ls

That gives you each entry in the normal "ls -l" format. Or, to get the specific output you seem to be looking for, this:

find . -name \*.ear -printf "%p\t%k KB\n"

Which will give you the filename followed by the size in KB.

JavaScript get window X/Y position for scroll

The method jQuery (v1.10) uses to find this is:

var doc = document.documentElement;
var left = (window.pageXOffset || doc.scrollLeft) - (doc.clientLeft || 0);
var top = (window.pageYOffset || doc.scrollTop)  - (doc.clientTop || 0);

That is:

  • It tests for window.pageXOffset first and uses that if it exists.
  • Otherwise, it uses document.documentElement.scrollLeft.
  • It then subtracts document.documentElement.clientLeft if it exists.

The subtraction of document.documentElement.clientLeft / Top only appears to be required to correct for situations where you have applied a border (not padding or margin, but actual border) to the root element, and at that, possibly only in certain browsers.

How to select rows in a DataFrame between two values, in Python Pandas?

If you're dealing with multiple values and multiple inputs you could also set up an apply function like this. In this case filtering a dataframe for GPS locations that fall withing certain ranges.

def filter_values(lat,lon):
    if abs(lat - 33.77) < .01 and abs(lon - -118.16) < .01:
        return True
    elif abs(lat - 37.79) < .01 and abs(lon - -122.39) < .01:
        return True
    else:
        return False


df = df[df.apply(lambda x: filter_values(x['lat'],x['lon']),axis=1)]

How do I change a single value in a data.frame?

To change a cell value using a column name, one can use

iris$Sepal.Length[3]=999

For loop for HTMLCollection elements

On Edge

if(!NodeList.prototype.forEach) {
  NodeList.prototype.forEach = function(fn, scope) {
    for(var i = 0, len = this.length; i < len; ++i) {
      fn.call(scope, this[i], i, this);
    }
  }
}

How do I use namespaces with TypeScript external modules?

The proper way to organize your code is to use separate directories in place of namespaces. Each class will be in it's own file, in it's respective namespace folder. index.ts will only re-export each file; no actual code should be in the index.ts file. Organizing your code like this makes it far easier to navigate, and is self-documenting based on directory structure.

// index.ts
import * as greeter from './greeter';
import * as somethingElse from './somethingElse';

export {greeter, somethingElse};

// greeter/index.ts
export * from './greetings.js';
...

// greeter/greetings.ts
export const helloWorld = "Hello World";

You would then use it as such:

import { greeter } from 'your-package'; //Import it like normal, be it from an NPM module or from a directory.
// You can also use the following syntax, if you prefer:
import * as package from 'your-package';

console.log(greeter.helloWorld);

Run Stored Procedure in SQL Developer?

Using SQL Developer Version 4.0.2.15 Build 15.21 the following works:

SET SERVEROUTPUT ON
var InParam1 varchar2(100)
var InParam2 varchar2(100)
var InParam3 varchar2(100)
var OutParam1 varchar2(100)

BEGIN
    /* Assign values to IN parameters */
    :InParam1 := 'one';
    :InParam2 := 'two';
    :InParam3 := 'three';

    /* Call procedure within package, identifying schema if necessary */
    schema.package.procedure(:InParam1, :InParam2, :InParam3, :OutParam1);
    dbms_output.enable;
    dbms_output.put_line('OutParam1: ' || :OutParam1);
END;
/

"id cannot be resolved or is not a field" error?

In main.xml (or wherever your item is defined) make sure that the ID for the R item is defined with @+id/... Here is an example with a button:

<Button android:text="B1" android:id="@+id/button_one"
        android:layout_gravity="center_horizontal|center"
        android:layout_height="fill_parent" android:layout_width="wrap_content" />

Each of these is important because:

  • @ must precede the string
  • + indicates it will create if not existing (whatever your item is)

Update an outdated branch against master in a Git repo

Update the master branch, which you need to do regardless.

Then, one of:

  1. Rebase the old branch against the master branch. Solve the merge conflicts during rebase, and the result will be an up-to-date branch that merges cleanly against master.

  2. Merge your branch into master, and resolve the merge conflicts.

  3. Merge master into your branch, and resolve the merge conflicts. Then, merging from your branch into master should be clean.

None of these is better than the other, they just have different trade-off patterns.

I would use the rebase approach, which gives cleaner overall results to later readers, in my opinion, but that is nothing aside from personal taste.

To rebase and keep the branch you would:

git checkout <branch> && git rebase <target>

In your case, check out the old branch, then

git rebase master 

to get it rebuilt against master.

Web scraping with Java

Your best bet is to use Selenium Web Driver since it

  1. Provides visual feedback to the coder (see your scraping in action, see where it stops)

  2. Accurate and Consistent as it directly controls the browser you use.

  3. Slow. Doesn't hit web pages like HtmlUnit does but sometimes you don't want to hit too fast.

    Htmlunit is fast but is horrible at handling Javascript and AJAX.

JS jQuery - check if value is in array

You are comparing a jQuery object (jQuery('input:first')) to strings (the elements of the array).
Change the code in order to compare the input's value (wich is a string) to the array elements:

if (jQuery.inArray(jQuery("input:first").val(), ar) != -1)

The inArray method returns -1 if the element wasn't found in the array, so as your bonus answer to how to determine if an element is not in an array, use this :

if(jQuery.inArray(el,arr) == -1){
    // the element is not in the array
};

Hex to ascii string conversion

Few characters like alphabets i-o couldn't be converted into respective ASCII chars . like in string '6631653064316f30723161' corresponds to fedora . but it gives fedra

Just modify hex_to_int() function a little and it will work for all characters. modified function is

int hex_to_int(char c)
{
    if (c >= 97)
        c = c - 32;
    int first = c / 16 - 3;
    int second = c % 16;
    int result = first * 10 + second;
    if (result > 9) result--;
    return result;
}

Now try it will work for all characters.

Maven error :Perhaps you are running on a JRE rather than a JDK?

I had the same error and I was missing the User variable: JAVA_HOME and the value for the SDK - "C:\Program Files\Java\jdk-9.0.1" in my case

Ruby - test for array

You probably want to use kind_of().

>> s = "something"
=> "something"
>> s.kind_of?(Array)
=> false
>> s = ["something", "else"]
=> ["something", "else"]
>> s.kind_of?(Array)
=> true

Angular 2 optional route parameter

It's recommended to use a query parameter when the information is optional.

Route Parameters or Query Parameters?

There is no hard-and-fast rule. In general,

prefer a route parameter when

  • the value is required.
  • the value is necessary to distinguish one route path from another.

prefer a query parameter when

  • the value is optional.
  • the value is complex and/or multi-variate.

from https://angular.io/guide/router#optional-route-parameters

You just need to take out the parameter from the route path.

@RouteConfig([
{
    path: '/user/',
    component: User,
    as: 'User'
}])

Simple prime number generator in Python

python 3 (generate prime number)

import math

i = 2
while True:
    for x in range(2, int(math.sqrt(i) + 1)):
        if i%x==0:
            break
    else:
        print(i)
    i += 1

Escape text for HTML

Also, you can use this if you don't want to use the System.Web assembly:

var encoded = System.Security.SecurityElement.Escape(unencoded)

Per this article, the difference between System.Security.SecurityElement.Escape() and System.Web.HttpUtility.HtmlEncode() is that the former also encodes apostrophe (') characters.

Call-time pass-by-reference has been removed

Only call time pass-by-reference is removed. So change:

call_user_func($func, &$this, &$client ...

To this:

call_user_func($func, $this, $client ...

&$this should never be needed after PHP4 anyway period.

If you absolutely need $client to be passed by reference, update the function ($func) signature instead (function func(&$client) {)

good example of Javadoc

The page How to Write Doc Coments for the Javadoc Tool contains a good number of good examples. One section is called Examples of Doc Comments and contains quite a few usages.

Also, the Javadoc FAQ contains some more examples to illustrate the answers.

Push git commits & tags simultaneously

Git GUI

Git GUI has a PUSH button - pardon the pun, and the dialog box it opens has a checkbox for tags.

I pushed a branch from the command line, without tags, and then tried again pushing the branch using the --follow-tags option descibed above. The option is described as following annotated tags. My tags were simple tags.

I'd fixed something, tagged the commit with the fix in, (so colleagues can cherry pick the fix,) then changed the software version number and tagged the release I created (so colleagues can clone that release).

Git returned saying everything was up-to-date. It did not send the tags! Perhaps because the tags weren't annotated. Perhaps because there was nothing new on the branch.

When I did a similar push with Git GUI, the tags were sent.

Tags sent with Git GUI

For the time being, I am going to be pushing my changes to my remotes with Git GUI and not with the command line and --follow-tags.

Can I pass variable to select statement as column name in SQL Server

You can't use variable names to bind columns or other system objects, you need dynamic sql

DECLARE @value varchar(10)  
SET @value = 'intStep'  
DECLARE @sqlText nvarchar(1000); 

SET @sqlText = N'SELECT ' + @value + ' FROM dbo.tblBatchDetail'
Exec (@sqlText)

C# Ignore certificate errors?

Allowing all certificates is very powerful but it could also be dangerous. If you would like to only allow valid certificates plus some certain certificates it could be done like this.

.Net core:

using (var httpClientHandler = new HttpClientHandler())
{
    httpClientHandler.ServerCertificateCustomValidationCallback = (message, cert, chain, sslPolicyErrors) => {
        if (sslPolicyErrors == SslPolicyErrors.None)
        {
            return true;   //Is valid
        }

        if (cert.GetCertHashString() == "99E92D8447AEF30483B1D7527812C9B7B3A915A7")
        {
            return true;
        }
        return false;
    };
    using (var httpClient = new HttpClient(httpClientHandler))
    {
        var httpResponse = httpClient.GetAsync("https://example.com").Result;
    }
}

.Net framework:

System.Net.ServicePointManager.ServerCertificateValidationCallback += delegate (
    object sender,
    X509Certificate cert,
    X509Chain chain,
    SslPolicyErrors sslPolicyErrors)
{
    if (sslPolicyErrors == SslPolicyErrors.None)
    {
        return true;   //Is valid
    }

    if (cert.GetCertHashString() == "99E92D8447AEF30483B1D7527812C9B7B3A915A7")
    {
        return true;
    }

    return false;
};

Update:

How to get cert.GetCertHashString() value in Chrome:

Click on Secure or Not Secure in the address bar.

enter image description here

enter image description here

Then click on Certificate -> Details -> Thumbprint and copy the value. Remember to do cert.GetCertHashString().ToLower().

enter image description here

What is the `data-target` attribute in Bootstrap 3?

The toggle tells Bootstrap what to do and the target tells Bootstrap which element is going to open. So whenever a link like that is clicked, a modal with an id of “basicModal” will appear.

How to match all occurrences of a regex

if you have a regexp with groups:

str="A 54mpl3 string w1th 7 numbers scatter3r ar0und"
re=/(\d+)[m-t]/

you can use String's scan method to find matching groups:

str.scan re
#> [["54"], ["1"], ["3"]]

To find the matching pattern:

str.to_enum(:scan,re).map {$&}
#> ["54m", "1t", "3r"]

jQuery onclick toggle class name

It can even be made dependent to another attribute changes. like this:

$('.classA').toggleClass('classB', $('input').prop('disabled'));

In this case, classB are added each time the input is disabled

In Java, how do I check if a string contains a substring (ignoring case)?

You can use the toLowerCase() method:

public boolean contains( String haystack, String needle ) {
  haystack = haystack == null ? "" : haystack;
  needle = needle == null ? "" : needle;

  // Works, but is not the best.
  //return haystack.toLowerCase().indexOf( needle.toLowerCase() ) > -1

  return haystack.toLowerCase().contains( needle.toLowerCase() )
}

Then call it using:

if( contains( str1, str2 ) ) {
  System.out.println( "Found " + str2 + " within " + str1 + "." );
}

Notice that by creating your own method, you can reuse it. Then, when someone points out that you should use contains instead of indexOf, you have only a single line of code to change.

Pass array to where in Codeigniter Active Record

From the Active Record docs:

$this->db->where_in();

Generates a WHERE field IN ('item', 'item') SQL query joined with AND if appropriate

$names = array('Frank', 'Todd', 'James');
$this->db->where_in('username', $names);
// Produces: WHERE username IN ('Frank', 'Todd', 'James')

Why doesn't calling a Python string method do anything unless you assign its output?

Example for String Methods

Given a list of filenames, we want to rename all the files with extension hpp to the extension h. To do this, we would like to generate a new list called newfilenames, consisting of the new filenames. Fill in the blanks in the code using any of the methods you’ve learned thus far, like a for loop or a list comprehension.

filenames = ["program.c", "stdio.hpp", "sample.hpp", "a.out", "math.hpp", "hpp.out"]
# Generate newfilenames as a list containing the new filenames
# using as many lines of code as your chosen method requires.
newfilenames = []
for i in filenames:
    if i.endswith(".hpp"):
        x = i.replace("hpp", "h")
        newfilenames.append(x)
    else:
        newfilenames.append(i)


print(newfilenames)
# Should be ["program.c", "stdio.h", "sample.h", "a.out", "math.h", "hpp.out"]

Several ports (8005, 8080, 8009) required by Tomcat Server at localhost are already in use

All of above do not work for me.

What I found was click the Details button. enter image description here

Then following the Multiple contexts with the same path error running web service in Eclipse using Tomcat

Removed the duplicated line then I got an another error.

The server cannot be started because one or more of the ports are invalid. Open the server editor and correct the invalid ports.

Following Can't start tomcatv9.0 in Eclipse

Then it works.

How do I get the IP address into a batch-file variable?

The following was all done in cygwin on a Windows XP box.

This will get your IP address. Note that there are backquotes around the hostname command, not single quotes.

ping -n 1 `hostname` | grep "Reply from " | cut -f 3 -d " " | cut -f 1 -d ":"

This will get your subnet.

ping -n 1 `hostname` | grep "Reply from " | cut -f 3 -d " " | cut -f "1 2 3" -d "."

The following will list all hosts on your local network (put it into a script called "netmap"). I had taken the subnet line above and put it into an executable called "getsubnet", which I then called from the following script.

MINADDR=0
MAXADDR=255
SUBNET=`getsubnet`

hostcnt=0

echo Pinging all addresses in ${SUBNET}.${MINADDR}-${MAXADDR}

for i in `seq $MINADDR $MAXADDR`; do
addr=${SUBNET}.$i
ping -n 1 -w 0 $addr > /dev/null

if [ $? -ne 1 ]    
then    
echo $addr UP    
hostcnt=$((hostcnt+1))    
fi

done

echo Found $hostcnt hosts on subnet ${SUBNET}.${MINADDR}-${MAXADDR}

Adding Lombok plugin to IntelliJ project

If after installing the lombok intellij plugin and enabling annotation processing, if your getter and setters are still not recognised in intellij, do check if the plugin version is compatible with the intellij version you use.

It is listed under the Downloads section:

Removing double quotes from variables in batch file creates problems with CMD environment

This sounds like a simple bug where you are using %~ somewhere where you shouldn't be. The use if %~ doesn't fundamentally change the way batch files work, it just removes quotes from the string in that single situation.

Spring Security exclude url patterns in security annotation configurartion

Found the solution in Spring security examples posted in Github.

WebSecurityConfigurerAdapter has a overloaded configure message that takes WebSecurity as argument which accepts ant matchers on requests to be ignored.

@Override
public void configure(WebSecurity web) throws Exception {
    web.ignoring().antMatchers("/authFailure");
}

See Spring Security Samples for more details

Setting an image for a UIButton in code

Swift 3 version (butt_img must be an Image Set into Assets.xcassets or Images.xcassets folder in Xcode):

btnTwo.setBackgroundImage(UIImage(named: "butt_img"), for: .normal)
btnTwo.setTitle("My title", for: .normal)

Anyway, if you want the image to be scaled to fill the button's size, you may add a UIImageView over it and assign it your image:

let img = UIImageView()
img.frame = btnTwo.frame
img.contentMode = .scaleAspectFill
img.clipsToBounds = true
img.image = UIImage(named: "butt_img")
btnTwo.addSubview(img)

Converting an int or String to a char array on Arduino

Just as a reference, here is an example of how to convert between String and char[] with a dynamic length -

// Define 
String str = "This is my string"; 

// Length (with one extra character for the null terminator)
int str_len = str.length() + 1; 

// Prepare the character array (the buffer) 
char char_array[str_len];

// Copy it over 
str.toCharArray(char_array, str_len);

Yes, this is painfully obtuse for something as simple as a type conversion, but sadly it's the easiest way.

Why am I getting this error: No mapping specified for the following EntitySet/AssociationSet - Entity1?

I had set everything correctly (cardinalities and dependent properties) but could not figure out why I keep receiving error. Finally figured out that, EF generated a column in dependent table on its own (table_tablecolumn) and it does not have any relation to the table, so no mapping was specified. I had to delete the column in EDMX file and rebuild the solution which fixed the issue. I am using DB approach.

fs.writeFile in a promise, asynchronous-synchronous stuff

As of 2019...

...the correct answer is to use async/await with the native fs promises module included in node. Upgrade to Node.js 10 or 11 (already supported by major cloud providers) and do this:

const fs = require('fs').promises;

// This must run inside a function marked `async`:
const file = await fs.readFile('filename.txt', 'utf8');
await fs.writeFile('filename.txt', 'test');

Do not use third-party packages and do not write your own wrappers, that's not necessary anymore.

No longer experimental

Before Node 11.14.0, you would still get a warning that this feature is experimental, but it works just fine and it's the way to go in the future. Since 11.14.0, the feature is no longer experimental and is production-ready.

What if I prefer import instead of require?

It works, too - but only in Node.js versions where this feature is not marked as experimental.

import { promises as fs } from 'fs';

(async () => {
    await fs.writeFile('./test.txt', 'test', 'utf8');
})();

1114 (HY000): The table is full

Another possible reason is the partition being full - this is just what happened to me now.

Is it necessary to use # for creating temp tables in SQL server?

Yes. You need to prefix the table name with "#" (hash) to create temporary tables.

If you do NOT need the table later, go ahead & create it. Temporary Tables are very much like normal tables. However, it gets created in tempdb. Also, it is only accessible via the current session i.e. For EG: if another user tries to access the temp table created by you, he'll not be able to do so.

"##" (double-hash creates "Global" temp table that can be accessed by other sessions as well.

Refer the below link for the Basics of Temporary Tables: http://www.codeproject.com/Articles/42553/Quick-Overview-Temporary-Tables-in-SQL-Server-2005

If the content of your table is less than 5000 rows & does NOT contain data types such as nvarchar(MAX), varbinary(MAX), consider using Table Variables.

They are the fastest as they are just like any other variables which are stored in the RAM. They are stored in tempdb as well, not in RAM.

DECLARE @ItemBack1 TABLE
(
 column1 int,
 column2 int,
 someInt int,
 someVarChar nvarchar(50)
);

INSERT INTO @ItemBack1
SELECT column1, 
       column2, 
       someInt, 
       someVarChar 
  FROM table2
 WHERE table2.ID = 7;

More Info on Table Variables: http://odetocode.com/articles/365.aspx

CodeIgniter - how to catch DB errors?

In Codeigniter 3.0 (CI3), all you have to do is $this->db->error()

If you need to get the last error that has occured, the error() method will return an array containing its code and message

http://www.codeigniter.com/user_guide/database/queries.html#handling-errors

Selected value for JSP drop down using JSTL

I tried the accepted answer, it did not work.

However the simple way to do it is below:-

<option value="1" <c:if test="${item.quantity == 1}"> <c:out value= "selected=selected"/</c:if>>1</option>
<option value="2" <c:if test="${item.quantity == 2}"> <c:out value= "selected=selected"/</c:if>>2</option>
<option value="3" <c:if test="${item.quantity == 3}"> <c:out value= "selected=selected"/</c:if>>3</option>

Enjoy!!

How to convert a string with Unicode encoding to a string of letters

For Java 9+, you can use the new replaceAll method of Matcher class.

private static final Pattern UNICODE_PATTERN = Pattern.compile("\\\\u([0-9A-Fa-f]{4})");

public static String unescapeUnicode(String unescaped) {
    return UNICODE_PATTERN.matcher(unescaped).replaceAll(r -> String.valueOf((char) Integer.parseInt(r.group(1), 16)));
}

public static void main(String[] args) {
    String originalMessage = "\\u0048\\u0065\\u006C\\u006C\\u006F World";
    String unescapedMessage = unescapeUnicode(originalMessage);
    System.out.println(unescapedMessage);
}

I believe the main advantage of this approach over unescapeJava by StringEscapeUtils (besides not using an extra library) is that you can convert only the unicode characters (if you wish), since the latter converts all escaped Java characters (like \n or \t). If you prefer to convert all escaped characters the library is really the best option.

Show hide fragment in android

final Fragment fragment1 = new fragment1();
final Fragment fragment2 = new fragment2();
final FragmentManager fm = getSupportFragmentManager();
Fragment active = fragment1;

In onCreate, after setContentView, i hid two fragments and committed them to the fragment manager, but i didn't hide the first fragment that will serve as home.

fm.beginTransaction().add(R.id.main_container, fragment2, "2").hide(fragment2).commit();
fm.beginTransaction().add(R.id.main_container,fragment1, "1").commit();
 @Override
    public void onClick(View v) {
        Fragment another = fragment1;
         if(active==fragment1){
          another = fragment2;
         }
            fm.beginTransaction().hide(active).show(another).commit();
            active = another;
}

Ref : https://medium.com/@oluwabukunmi.aluko/bottom-navigation-view-with-fragments-a074bfd08711

Join between tables in two different databases?

Yes, assuming the account has appropriate permissions you can use:

SELECT <...>
FROM A.table1 t1 JOIN B.table2 t2 ON t2.column2 = t1.column1;

You just need to prefix the table reference with the name of the database it resides in.

SQL Server Text type vs. varchar data type

If you're using SQL Server 2005 or later, use varchar(MAX). The text datatype is deprecated and should not be used for new development work. From the docs:

Important

ntext , text, and image data types will be removed in a future version of Microsoft SQL Server. Avoid using these data types in new development work, and plan to modify applications that currently use them. Use nvarchar(max), varchar(max), and varbinary(max) instead.

Difference between JE/JNE and JZ/JNZ

  je : Jump if equal:

  399  3fb:   64 48 33 0c 25 28 00    xor    %fs:0x28,%rcx
  400  402:   00 00
  401  404:   74 05                   je     40b <sims_get_counter+0x51>

How can I get a Bootstrap column to span multiple rows?

I believe the part regarding how to span rows has been answered thoroughly (i.e. by nesting rows), but I also ran into the issue of my nested rows not filling their container. While flexbox and negative margins are an option, a much easier solution is to use the predefined h-50 class on the row containing boxes 2, 3, 4, and 5.

Note: I am using Bootstrap-4, I just wanted to share because I ran into the same problem and found this to be a more elegant solution :)

Quickly create a large file on a Linux system

I don't know a whole lot about Linux, but here's the C Code I wrote to fake huge files on DC Share many years ago.

#include < stdio.h >
#include < stdlib.h >

int main() {
    int i;
    FILE *fp;

    fp=fopen("bigfakefile.txt","w");

    for(i=0;i<(1024*1024);i++) {
        fseek(fp,(1024*1024),SEEK_CUR);
        fprintf(fp,"C");
    }
}

Purge or recreate a Ruby on Rails database

Just issue the sequence of the steps: drop the database, then re-create it again, migrate data, and if you have seeds, sow the database:

rake db:drop db:create db:migrate db:seed

Since the default environment for rake is development, in case if you see the exception in spec tests, you should re-create db for the test environment as follows:

RAILS_ENV=test rake db:drop db:create db:migrate

In most cases the test database is being sowed during the test procedures, so db:seed task action isn't required to be passed. Otherwise, you shall to prepare the database:

rake db:test:prepare

or

RAILS_ENV=test rake db:seed

Additionally, to use the recreate task you can add into Rakefile the following code:

namespace :db do
   task :recreate => [ :drop, :create, :migrate ] do
      if ENV[ 'RAILS_ENV' ] !~ /test|cucumber/
         Rake::Task[ 'db:seed' ].invoke
      end
   end
end

Then issue:

rake db:recreate

Rails - passing parameters in link_to

Try this

link_to "+ Service", my_services_new_path(:account_id => acct.id)

it will pass the account_id as you want.

For more details on link_to use this http://api.rubyonrails.org/classes/ActionView/Helpers/UrlHelper.html#method-i-link_to

file_get_contents behind a proxy?

There's a similar post here: http://techpad.co.uk/content.php?sid=137 which explains how to do it.

function file_get_contents_proxy($url,$proxy){

    // Create context stream
    $context_array = array('http'=>array('proxy'=>$proxy,'request_fulluri'=>true));
    $context = stream_context_create($context_array);

    // Use context stream with file_get_contents
    $data = file_get_contents($url,false,$context);

    // Return data via proxy
    return $data;

}

Is it possible in Java to access private fields via reflection

Yes it is possible.

You need to use the getDeclaredField method (instead of the getField method), with the name of your private field:

Field privateField = Test.class.getDeclaredField("str");

Additionally, you need to set this Field to be accessible, if you want to access a private field:

privateField.setAccessible(true);

Once that's done, you can use the get method on the Field instance, to access the value of the str field.

ListView with OnItemClickListener

if list item view contains button or checkbox or imagebutton, the onitemclicklistener and onitemlongclicklistener not working due to it has own onclick listener.

set focusable as false

holder.button.setFocusable(false);

PHP executable not found. Install PHP 7 and add it to your PATH or set the php.executablePath setting

This one also works

  1. Remove the "php.executablePath" line from the VS code settings.

  2. Then add the xampp php path to the System variables

enter image description here

enter image description here

After that restart the Visual Studio Code

How do I find the CPU and RAM usage using PowerShell?

I have combined all the above answers into a script that polls the counters and writes the measurements in the terminal:

$totalRam = (Get-CimInstance Win32_PhysicalMemory | Measure-Object -Property capacity -Sum).Sum
while($true) {
    $date = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
    $cpuTime = (Get-Counter '\Processor(_Total)\% Processor Time').CounterSamples.CookedValue
    $availMem = (Get-Counter '\Memory\Available MBytes').CounterSamples.CookedValue
    $date + ' > CPU: ' + $cpuTime.ToString("#,0.000") + '%, Avail. Mem.: ' + $availMem.ToString("N0") + 'MB (' + (104857600 * $availMem / $totalRam).ToString("#,0.0") + '%)'
    Start-Sleep -s 2
}

This produces the following output:

2020-02-01 10:56:55 > CPU: 0.797%, Avail. Mem.: 2,118MB (51.7%)
2020-02-01 10:56:59 > CPU: 0.447%, Avail. Mem.: 2,118MB (51.7%)
2020-02-01 10:57:03 > CPU: 0.089%, Avail. Mem.: 2,118MB (51.7%)
2020-02-01 10:57:07 > CPU: 0.000%, Avail. Mem.: 2,118MB (51.7%)

You can hit Ctrl+C to abort the loop.

So, you can connect to any Windows machine with this command:

Enter-PSSession -ComputerName MyServerName -Credential MyUserName

...paste it in, and run it, to get a "live" measurement. If connecting to the machine doesn't work directly, take a look here.

Passing two command parameters using a WPF binding

This task can also be solved with a different approach. Instead of programming a converter and enlarging the code in the XAML, you can also aggregate the various parameters in the ViewModel. As a result, the ViewModel then has one more property that contains all parameters.

An example of my current application, which also let me deal with the topic. A generic RelayCommand is required: https://stackoverflow.com/a/22286816/7678085

The ViewModelBase is extended here by a command SaveAndClose. The generic type is a named tuple that represents the various parameters.

public ICommand SaveAndCloseCommand => saveAndCloseCommand ??= new RelayCommand<(IBaseModel Item, Window Window)>
    (execute =>
    {
        execute.Item.Save();
        execute.Window?.Close(); // if NULL it isn't closed.
    },
    canExecute =>
    {
        return canExecute.Item?.IsItemValide ?? false;
    });
private ICommand saveAndCloseCommand;

Then it contains a property according to the generic type:

public (IBaseModel Item, Window Window) SaveAndCloseParameter 
{ 
    get => saveAndCloseParameter ; 
    set 
    {
        SetProperty(ref saveAndCloseParameter, value);
    }
}
private (IBaseModel Item, Window Window) saveAndCloseParameter;

The XAML code of the view then looks like this: (Pay attention to the classic click event)

<Button 
    Command="{Binding SaveAndCloseCommand}" 
    CommandParameter="{Binding SaveAndCloseParameter}" 
    Click="ButtonApply_Click" 
    Content="Apply"
    Height="25" Width="100" />
<Button 
    Command="{Binding SaveAndCloseCommand}" 
    CommandParameter="{Binding SaveAndCloseParameter}" 
    Click="ButtonSave_Click" 
    Content="Save"
    Height="25" Width="100" />

and in the code behind of the view, then evaluating the click events, which then set the parameter property.

private void ButtonApply_Click(object sender, RoutedEventArgs e)
{
    computerViewModel.SaveAndCloseParameter = (computerViewModel.Computer, null);
}

private void ButtonSave_Click(object sender, RoutedEventArgs e)
{
    computerViewModel.SaveAndCloseParameter = (computerViewModel.Computer, this);
}

Personally, I think that using the click events is not a break with the MVVM pattern. The program flow control is still located in the area of ??the ViewModel.

Insert NULL value into INT column

If column is not NOT NULL (nullable).

You just put NULL instead of value in INSERT statement.

Plugin is too old, please update to a more recent version, or set ANDROID_DAILY_OVERRIDE environment variable to

Replace your class path with something ambiguous like this. Its a solution and it works but it may not be a good solution.

classpath 'com.android.tools.build:gradle:+'

The best way is replacing the + with the latest version of gradle

Two dimensional array in python

You try to append to second element in array, but it does not exist. Create it.

arr = [[]]

arr[0].append("aa1")
arr[0].append("aa2")
arr.append([])
arr[1].append("bb1")
arr[1].append("bb2")
arr[1].append("bb3")

Gradle failed to resolve library in Android Studio

i had the same problem, i added the following lines in build.gradle

allprojects {
    repositories {
        jcenter()
        maven { url "https://jitpack.io" }

        maven {
            url 'http://dl.bintray.com/dev-fingerlinks/maven'
        }
        mavenCentral()
    }
}

How to install a gem or update RubyGems if it fails with a permissions error

You don't have write permissions into the /Library/Ruby/Gems/1.8 directory.

means exactly that, you don't have permission to write there.

That is the version of Ruby installed by Apple, for their own use. While it's OK to make minor modifications to that if you know what you're doing, because you are not sure about the permissions problem, I'd say it's not a good idea to continue along that track.

Instead, I'll strongly suggest you look into using either rbenv or RVM to manage a separate Ruby, installed into a sandbox in your home directory, that you can modify/fold/spindle/change without worrying about messing up the system Ruby.

Between the two, I use rbenv, though I used RVM a lot in the past. rbenv takes a more "hands-off" approach to managing your Ruby installation. RVM has a lot of features and is very powerful, but, as a result is more intrusive. In either case, READ the installation documentation for them a couple times before starting to install whichever you pick.

How to read a file line-by-line into a list?

Here's one more option by using list comprehensions on files;

lines = [line.rstrip() for line in open('file.txt')]

This should be more efficient way as the most of the work is done inside the Python interpreter.

Remote Linux server to remote linux server dir copy. How?

I think you can try with:

rsync -azvu -e ssh user@host1:/directory/ user@host2:/directory2/

(and I assume you are on host0 and you want to copy from host1 to host2 directly)

If the above does not work, you could try:

ssh user@host1 "/usr/bin/rsync -azvu -e ssh /directory/ user@host2:/directory2/"

in the this, it would work, if you already have setup passwordless SSH login from host1 to host2

DateTime format to SQL format using C#

   DateTime date1 = new DateTime();

    date1 = Convert.ToDateTime(TextBox1.Text);
    Label1.Text = (date1.ToLongTimeString()); //11:00 AM
    Label2.Text = date1.ToLongDateString(); //Friday, November 1, 2019;
    Label3.Text = date1.ToString();
    Label4.Text = date1.ToShortDateString();
    Label5.Text = date1.ToShortTimeString();

Oracle comparing timestamp with date

to_date format worked for me. Please consider the date formats: MON-, MM, ., -.

t.start_date >= to_date('14.11.2016 04:01:39', 'DD.MM.YYYY HH24:MI:SS')
t.start_date <=to_date('14.11.2016 04:10:07', 'DD.MM.YYYY HH24:MI:SS')

Is there a short cut for going back to the beginning of a file by vi editor?

In command mode: : + 1 will take you to first line

Jenkins: Failed to connect to repository

I faced a similar issue when I tried to connect jenkins in my Windows server with my private GIT repo. Following is the error returned in the source code management section of Jenkins job

Failed to connect to repository : Command "git.exe ls-remote -h ssh://git@my_server/repo.git HEAD" returned status code 128: stdout: stderr: Load key "C:\Windows\TEMP\ssh4813927591749610777.key": invalid format git@my_server: Permission denied (publickey). fatal: Could not read from remote repository.

Please make sure you have the correct access rights and the repository exists.

This error is thrown because jenkins is not able to pick the private ssh key from its user directory. I solved this in the following manner

Step 1

In the jenkins job, fill up the following info under Source Code Management

Repositories

Repository URL: ssh://git@my_server/repo.git
Credentials: -none-

Step 2

In my setup jenkins is running under local system account, so the user directory is C:\Windows\System32\config\systemprofile (This is the important thing in this setup that is not very obvious).

Now create ssh private and public keys using ssh-keygen -t rsa -C "key label" via git bash shell. The ssh private and public keys go under .ssh directory of your logged in user directory. Just copy the .ssh folder and paste it under C:\Windows\System32\config\systemprofile

Step 3

Add your public key to your GIT server account. Run the jenkins job and now you should be able to connect to the GIT account via ssh from jenkins.

How can I make a thumbnail <img> show a full size image when clicked?

The

<a href="image2.gif" ><img src="image1.gif"/></a>

technique has always worked for me. I used it to good effect in my Super Bowl diary, but I see that the scripts I used are broken. Once I get them fixed I will edit in the URL.

How do I escape reserved words used as column names? MySQL/Create Table

You should use back tick character (`) eg:

create table if not exists misc_info (
id INTEGER PRIMARY KEY AUTO_INCREMENT NOT NULL,
`key` TEXT UNIQUE NOT NULL,
value TEXT NOT NULL)ENGINE=INNODB;

How do I access the HTTP request header fields via JavaScript?

This can be accessed through Javascript because it's a property of the loaded document, not of its parent.

Here's a quick example:

<script type="text/javascript">
document.write(document.referrer);
</script>

The same thing in PHP would be:

<?php echo $_SERVER["HTTP_REFERER"]; ?>

Chrome & Safari Error::Not allowed to load local resource: file:///D:/CSS/Style.css

The solution is already answered here above (long ago).

But the implicit question "why does it work in FF and IE but not in Chrome and Safari" is found in the error text "Not allowed to load local resource": Chrome and Safari seem to use a more strict implementation of sandboxing (for security reasons) than the other two (at this time 2011).

This applies for local access. In a (normal) server environment (apache ...) the file would simply not have been found.

Using Server.MapPath in external C# Classes in ASP.NET

Can't you just add a reference to System.Web and then you can use Server.MapPath ?

Edit: Nowadays I'd recommend using the HostingEnvironment.MapPath Method:

It's a static method in System.Web assembly that Maps a virtual path to a physical path on the server. It doesn't require a reference to HttpContext.

C# Copy a file to another location with a different name

File.Copy(@"C:\oldFile.txt", @"C:\newFile.txt", true);

Please do not forget to overwrite the previous file! Make sure you add the third param., by adding the third param, you allow the file to be overwritten. Else you could use a try catch for the exception.

Regards, G

How to create a Date in SQL Server given the Day, Month and Year as Integers

In SQL Server 2012+, you can use DATEFROMPARTS():

DECLARE @Year int = 2016, @Month int = 10, @Day int = 25;
SELECT DATEFROMPARTS (@Year, @Month, @Day);

In earlier versions, one method is to create and convert a string.

There are a few string date formats which SQL Server reliably interprets regardless of the date, language, or internationalization settings.

A six- or eight-digit string is always interpreted as ymd. The month and day must always be two digits.

https://docs.microsoft.com/en-us/sql/t-sql/data-types/datetime-transact-sql

So a string in the format 'yyyymmdd' will always be properly interpreted.

(ISO 8601-- YYYY-MM-DDThh:mm:ss-- also works, but you have to specify time and therefore it's more complicated than you need.)

While you can simply CAST this string as a date, you must use CONVERT in order to specify a style, and you must specify a style in order to be deterministic (if that matters to you).

The "yyyymmdd" format is style 112, so your conversion looks like this:

DECLARE @Year int = 2016, @Month int = 10, @Day int = 25;
SELECT CONVERT(date,CONVERT(varchar(50),(@Year*10000 + @Month*100 + @Day)),112);

And it results in:

2016-10-25

Technically, the ISO/112/yyyymmdd format works even with other styles specified. For example, using that text format with style 104 (German, dd.mm.yyyy):

DECLARE @Year int = 2016, @Month int = 10, @Day int = 25;
SELECT CONVERT(date,CONVERT(varchar(50),(@Year*10000 + @Month*100 + @Day)),104);

Also still results in:

2016-10-25

Other formats are not as robust. For example this:

SELECT CASE WHEN CONVERT(date,'01-02-1900',110) = CONVERT(date,'01-02-1900',105) THEN 1 ELSE 0 END;

Results in:

0

As a side note, with this method, beware that nonsense inputs can yield valid but incorrect dates:

DECLARE @Year int = 2016, @Month int = 0, @Day int = 1025;
SELECT CONVERT(date,CONVERT(varchar(50),(@Year*10000 + @Month*100 + @Day)),112);

Also yields:

2016-10-25

DATEFROMPARTS protects you from invalid inputs. This:

DECLARE @Year int = 2016, @Month int = 10, @Day int = 32;
SELECT DATEFROMPARTS (@Year, @Month, @Day);

Yields:

Msg 289, Level 16, State 1, Line 2 Cannot construct data type date, some of the arguments have values which are not valid.

Also beware that this method does not work for dates prior to 1000-01-01. For example:

DECLARE @Year int = 900, @Month int = 1, @Day int = 1;
SELECT CONVERT(date,CONVERT(varchar(50),(@Year*10000 + @Month*100 + @Day)),112);

Yields:

Msg 241, Level 16, State 1, Line 2 Conversion failed when converting date and/or time from character string.

That's because the resulting string, '9000101', is not in the 'yyyymmdd' format. To ensure proper formatting, you'd have to pad it with leading zeroes, at the sacrifice of some small amount of performance. For example:

DECLARE @Year int = 900, @Month int = 1, @Day int = 1;
SELECT CONVERT(date,RIGHT('000' + CONVERT(varchar(50),(@Year*10000 + @Month*100 + @Day)),8),112);

Results in:

0900-01-01

There are other methods aside from string conversion. Several are provided in answers to "Create a date with T-SQL". A notable example involves creating the date by adding years, months, and days to the "zero date".

(This answer was inspired by Gordon Linoff's answer, which I expanded on and provided additional documentation and notes.)

Send HTTP GET request with header

You do it exactly as you showed with this line:

get.setHeader("Content-Type", "application/x-zip");

So your header is fine and the problem is some other input to the web service. You'll want to debug that on the server side.

Data was not saved: object references an unsaved transient instance - save the transient instance before flushing

It is because of CASCADE TYPE

if you put

@OneToOne(cascade=CascadeType.ALL)

You can just save your object like this

user.setCountry(country);
session.save(user)

but if you put

 @OneToOne(cascade={    
            CascadeType.PERSIST,
            CascadeType.REFRESH,
            ...
})

You need to save your object like this

user.setCountry(country);
session.save(country)
session.save(user)

HTML input file selection event not firing upon selecting the same file

Do whatever you want to do after the file loads successfully.just after the completion of your file processing set the value of file control to blank string.so the .change() will always be called even the file name changes or not. like for example you can do this thing and worked for me like charm

   $('#myFile').change(function () {
       LoadFile("myFile");//function to do processing of file.
       $('#myFile').val('');// set the value to empty of myfile control.
    });

C# Get/Set Syntax Usage

By the way, in C# 3.5 you can instantiate your object's properties like so:

Person TOM=new Person 
{ 
   title = "My title", ID = 1 
};

But again, properties must be public.

How can I convert JSON to a HashMap using Gson?

Try this, it will worked. I used it for Hashtable.

public static Hashtable<Integer, KioskStatusResource> parseModifued(String json) {
    JsonObject object = (JsonObject) new com.google.gson.JsonParser().parse(json);
    Set<Map.Entry<String, JsonElement>> set = object.entrySet();
    Iterator<Map.Entry<String, JsonElement>> iterator = set.iterator();

    Hashtable<Integer, KioskStatusResource> map = new Hashtable<Integer, KioskStatusResource>();

    while (iterator.hasNext()) {
        Map.Entry<String, JsonElement> entry = iterator.next();

        Integer key = Integer.parseInt(entry.getKey());
        KioskStatusResource value = new Gson().fromJson(entry.getValue(), KioskStatusResource.class);

        if (value != null) {
            map.put(key, value);
        }

    }
    return map;
}

Replace KioskStatusResource to your class and Integer to your key class.

If my interface must return Task what is the best way to have a no-operation implementation?

Today, I would recommend using Task.CompletedTask to accomplish this.


Pre .net 4.6:

Using Task.FromResult(0) or Task.FromResult<object>(null) will incur less overhead than creating a Task with a no-op expression. When creating a Task with a result pre-determined, there is no scheduling overhead involved.

What is the difference between response.sendRedirect() and request.getRequestDispatcher().forward(request,response)

Simply difference between Forward(ServletRequest request, ServletResponse response) and sendRedirect(String url) is

forward():

  1. The forward() method is executed in the server side.
  2. The request is transfer to other resource within same server.
  3. It does not depend on the client’s request protocol since the forward () method is provided by the servlet container.
  4. The request is shared by the target resource.
  5. Only one call is consumed in this method.
  6. It can be used within server.
  7. We cannot see forwarded message, it is transparent.
  8. The forward() method is faster than sendRedirect() method.
  9. It is declared in RequestDispatcher interface.

sendRedirect():

  1. The sendRedirect() method is executed in the client side.
  2. The request is transfer to other resource to different server.
  3. The sendRedirect() method is provided under HTTP so it can be used only with HTTP clients.
  4. New request is created for the destination resource.
  5. Two request and response calls are consumed.
  6. It can be used within and outside the server.
  7. We can see redirected address, it is not transparent.
  8. The sendRedirect() method is slower because when new request is created old request object is lost.
  9. It is declared in HttpServletResponse.

regular expression to validate datetime format (MM/DD/YYYY)

Try your regex with a tool like http://jsregex.com/ (There is many) or better, a unit test.

For a naive validation:

function validateDate(testdate) {
    var date_regex = /^\d{2}\/\d{2}\/\d{4}$/ ;
    return date_regex.test(testdate);
}

In your case, to validate (MM/DD/YYYY), with a year between 1900 and 2099, I'll write it like that:

function validateDate(testdate) {
    var date_regex = /^(0[1-9]|1[0-2])\/(0[1-9]|1\d|2\d|3[01])\/(19|20)\d{2}$/ ;
    return date_regex.test(testdate);
}

Why am I getting tree conflicts in Subversion?

I came across this problem today as well, though my particular issue probably isn't related to yours. After inspecting the list of files, I realized what I had done -- I had temporarily been using a file in one assembly from another assembly. I have made lots of changes to it and didn't want to orphan the SVN history, so in my branch I had moved the file over from the other assembly's folder. This isn't tracked by SVN, so it just looks like the file is deleted and then re-added. This ends up causing a tree conflict.

I resolved the problem by moving the file back, committing, and then merging my branch. Then I moved the file back afterward. :) That seemed to do the trick.

Set value to an entire column of a pandas dataframe

Python can do unexpected things when new objects are defined from existing ones. You stated in a comment above that your dataframe is defined along the lines of df = df_all.loc[df_all['issueid']==specific_id,:]. In this case, df is really just a stand-in for the rows stored in the df_all object: a new object is NOT created in memory.

To avoid these issues altogether, I often have to remind myself to use the copy module, which explicitly forces objects to be copied in memory so that methods called on the new objects are not applied to the source object. I had the same problem as you, and avoided it using the deepcopy function.

In your case, this should get rid of the warning message:

from copy import deepcopy
df = deepcopy(df_all.loc[df_all['issueid']==specific_id,:])
df['industry'] = 'yyy'

EDIT: Also see David M.'s excellent comment below!

df = df_all.loc[df_all['issueid']==specific_id,:].copy()
df['industry'] = 'yyy'

PHP & MySQL: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given

The query either returned no rows or is erroneus, thus FALSE is returned. Change it to

if (!$dbc || mysqli_num_rows($dbc) == 0)

mysqli_num_rows:

Return Values

Returns TRUE on success or FALSE on failure. For SELECT, SHOW, DESCRIBE or EXPLAIN mysqli_query() will return a result object.

Convert Iterable to Stream using Java 8 JDK

I would like to suggest using JOOL library, it hides spliterator magic behind the Seq.seq(iterable) call and also provides a whole bunch of additional useful functionality.

SecurityError: The operation is insecure - window.history.pushState()

We experienced the SecurityError: The operation is insecure when a user disabled their cookies prior to visiting our site, any subsequent XHR requests trying to use the session would obviously fail and cause this error.

python numpy/scipy curve fitting

You'll first need to separate your numpy array into two separate arrays containing x and y values.

x = [1, 2, 3, 9]
y = [1, 4, 1, 3]

curve_fit also requires a function that provides the type of fit you would like. For instance, a linear fit would use a function like

def func(x, a, b):
    return a*x + b

scipy.optimize.curve_fit(func, x, y) will return a numpy array containing two arrays: the first will contain values for a and b that best fit your data, and the second will be the covariance of the optimal fit parameters.

Here's an example for a linear fit with the data you provided.

import numpy as np
from scipy.optimize import curve_fit

x = np.array([1, 2, 3, 9])
y = np.array([1, 4, 1, 3])

def fit_func(x, a, b):
    return a*x + b

params = curve_fit(fit_func, x, y)

[a, b] = params[0]

This code will return a = 0.135483870968 and b = 1.74193548387

Here's a plot with your points and the linear fit... which is clearly a bad one, but you can change the fitting function to obtain whatever type of fit you would like.

enter image description here

Display rows with one or more NaN values in pandas dataframe

You can use DataFrame.any with parameter axis=1 for check at least one True in row by DataFrame.isna with boolean indexing:

df1 = df[df.isna().any(axis=1)]

d = {'filename': ['M66_MI_NSRh35d32kpoints.dat', 'F71_sMI_DMRI51d.dat', 'F62_sMI_St22d7.dat', 'F41_Car_HOC498d.dat', 'F78_MI_547d.dat'], 'alpha1': [0.8016, 0.0, 1.721, 1.167, 1.897], 'alpha2': [0.9283, 0.0, 3.833, 2.809, 5.459], 'gamma1': [1.0, np.nan, 0.23748000000000002, 0.36419, 0.095319], 'gamma2': [0.074804, 0.0, 0.15, 0.3, np.nan], 'chi2min': [39.855990000000006, 1e+25, 10.91832, 7.966335000000001, 25.93468]}
df = pd.DataFrame(d).set_index('filename')

print (df)
                             alpha1  alpha2    gamma1    gamma2       chi2min
filename                                                                     
M66_MI_NSRh35d32kpoints.dat  0.8016  0.9283  1.000000  0.074804  3.985599e+01
F71_sMI_DMRI51d.dat          0.0000  0.0000       NaN  0.000000  1.000000e+25
F62_sMI_St22d7.dat           1.7210  3.8330  0.237480  0.150000  1.091832e+01
F41_Car_HOC498d.dat          1.1670  2.8090  0.364190  0.300000  7.966335e+00
F78_MI_547d.dat              1.8970  5.4590  0.095319       NaN  2.593468e+01

Explanation:

print (df.isna())
                            alpha1 alpha2 gamma1 gamma2 chi2min
filename                                                       
M66_MI_NSRh35d32kpoints.dat  False  False  False  False   False
F71_sMI_DMRI51d.dat          False  False   True  False   False
F62_sMI_St22d7.dat           False  False  False  False   False
F41_Car_HOC498d.dat          False  False  False  False   False
F78_MI_547d.dat              False  False  False   True   False

print (df.isna().any(axis=1))
filename
M66_MI_NSRh35d32kpoints.dat    False
F71_sMI_DMRI51d.dat             True
F62_sMI_St22d7.dat             False
F41_Car_HOC498d.dat            False
F78_MI_547d.dat                 True
dtype: bool

df1 = df[df.isna().any(axis=1)]
print (df1)
                     alpha1  alpha2    gamma1  gamma2       chi2min
filename                                                           
F71_sMI_DMRI51d.dat   0.000   0.000       NaN     0.0  1.000000e+25
F78_MI_547d.dat       1.897   5.459  0.095319     NaN  2.593468e+01

How do I copy items from list to list without foreach?

This method will create a copy of your list but your type should be serializable.

Use:

List<Student> lstStudent = db.Students.Where(s => s.DOB < DateTime.Now).ToList().CopyList(); 

Method:

public static List<T> CopyList<T>(this List<T> lst)
    {
        List<T> lstCopy = new List<T>();
        foreach (var item in lst)
        {
            using (MemoryStream stream = new MemoryStream())
            {
                BinaryFormatter formatter = new BinaryFormatter();
                formatter.Serialize(stream, item);
                stream.Position = 0;
                lstCopy.Add((T)formatter.Deserialize(stream));
            }
        }
        return lstCopy;
    }

How to convert a list into data table

private DataTable CreateDataTable(IList<T> item)
{
    Type type = typeof(T);
    var properties = type.GetProperties();

    DataTable dataTable = new DataTable();
    foreach (PropertyInfo info in properties)
    {
        dataTable.Columns.Add(new DataColumn(info.Name, Nullable.GetUnderlyingType(info.PropertyType) ?? info.PropertyType));
    }

    foreach (T entity in item)
    {
        object[] values = new object[properties.Length];
        for (int i = 0; i < properties.Length; i++)
        {
            values[i] = properties[i].GetValue(entity);
        }

        dataTable.Rows.Add(values);
    }
    return dataTable;
}

'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine

If the installed "AccessDatabaseEngine" still does not help, below is solution:

You need to change the Active Solution Platform from "Any CPU" to "x86".

OLEDB Provider is Not Registered on the Local Machine

From CodeProject.com

Oracle date function for the previous month

Modifying Ben's query little bit,

 select count(distinct switch_id)   
  from [email protected]  
 where dealer_name =  'XXXX'    
   and creation_date between add_months(trunc(sysdate,'mm'),-1) and last_day(add_months(trunc(sysdate,'mm'),-1))

How to compare two dates in php

I think this one is very simple function

function terminateOrNotStringtoDate($currentDate, $terminationdate)
{
    $crtDate = new DateTime($currentDate);
    $termDate = new DateTime($terminationdate);
    if($crtDate >= $termDate)
    {
        return true;
    } else {
    return false;
    }
}

invalid multibyte char (US-ASCII) with Rails and Ruby 1.9

Those slanted double quotes are not ASCII characters. The error message is misleading about them being 'multi-byte'.

DBMS_OUTPUT.PUT_LINE not printing

this statement

DBMS_OUTPUT.PUT_LINE('a.firstName' || 'a.lastName');

means to print the string as it is.. remove the quotes to get the values to be printed.So the correct syntax is

DBMS_OUTPUT.PUT_LINE(a.firstName || a.lastName);

How can I change the font-size of a select option?

select[value="value"]{
   background-color: red;
   padding: 3px;
   font-weight:bold;
}

How to reload a page after the OK click on the Alert Page

I may be wrong here but I had the same problem, after spending more time than I'm proud of I realised I had set chrome to block all pop ups and hence kept reloading without showing me the alert box. So close your window and open the page again.

If that doesn't work then you problem might be something deeper because all the solutions already given should work.

How do you check if a certain index exists in a table?

If the hidden purpose of your question is to DROP the index before making INSERT to a large table, then this is useful one-liner:

DROP INDEX IF EXISTS [IndexName] ON [dbo].[TableName]

This syntax is available since SQL Server 2016. Documentation for IF EXISTS:

https://blogs.msdn.microsoft.com/sqlserverstorageengine/2015/11/03/drop-if-exists-new-thing-in-sql-server-2016/

In case you deal with a primery key instead, then use this:

ALTER TABLE [TableName] DROP CONSTRAINT IF EXISTS [PK_name] 

How to resolve the error "Unable to access jarfile ApacheJMeter.jar errorlevel=1" while initiating Jmeter?

I faced with the same error, when i downloaded the Jmeter Source, and it got fixed once i downloaded Jmeter Binary. Please watch this video.

HTML encoding issues - "Â" character showing up instead of "&nbsp;"

Well I got this Issue too in my few websites and all i need to do is customize the content fetler for HTML entites. before that more i delete them more i got, so just change you html fiter or parsing function for the page and it worked. Its mainly due to HTML editors in most of CMSs. the way they store parse the data caused this issue (In My case). May this would Help in your case too

How to send Request payload to REST API in java?

I tried with a rest client.

Headers :

  • POST /r/gerrit/rpc/ChangeDetailService HTTP/1.1
  • Host: git.eclipse.org
  • User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:18.0) Gecko/20100101 Firefox/18.0
  • Accept: application/json
  • Accept-Language: null
  • Accept-Encoding: gzip,deflate,sdch
  • accept-charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
  • Content-Type: application/json; charset=UTF-8
  • Content-Length: 73
  • Connection: keep-alive

it works fine. I retrieve 200 OK with a good body.

Why do you set a status code in your request? and multiple declaration "Accept" with Accept:application/json,application/json,application/jsonrequest. just a statement is enough.

test if display = none

You can use the following code to test if display is equivalent to none:

if ($(element).css('display') === 'none' ){
    // do the stuff
}

Python lookup hostname from IP with 1 second timeout

>>> import socket
>>> socket.gethostbyaddr("69.59.196.211")
('stackoverflow.com', ['211.196.59.69.in-addr.arpa'], ['69.59.196.211'])

For implementing the timeout on the function, this stackoverflow thread has answers on that.

Import JSON file in React

One nice way (without adding a fake .js extension which is for code not for data and configs) is to use json-loader module. If you have used create-react-app to scaffold your project, the module is already included, you just need to import your json:

import Profile from './components/profile';

This answer explains more.

Set element width or height in Standards Mode

Try declaring the unit of width:

e1.style.width = "400px"; // width in PIXELS

Serialize an object to string

I know this is not really an answer to the question, but based on the number of votes for the question and the accepted answer, I suspect the people are actually using the code to serialize an object to a string.

Using XML serialization adds unnecessary extra text rubbish to the output.

For the following class

public class UserData
{
    public int UserId { get; set; }
}

it generates

<?xml version="1.0" encoding="utf-16"?>
<UserData xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <UserId>0</UserId>
</UserData>

Better solution is to use JSON serialization (one of the best is Json.NET). To serialize an object:

var userData = new UserData {UserId = 0};
var userDataString = JsonConvert.SerializeObject(userData);

To deserialize an object:

var userData = JsonConvert.DeserializeObject<UserData>(userDataString);

The serialized JSON string would look like:

{"UserId":0}

Invalid self signed SSL cert - "Subject Alternative Name Missing"

Here is a very simple way to create an IP certificate that Chrome will trust.

The ssl.conf file...

[ req ]
default_bits       = 4096
distinguished_name = req_distinguished_name
req_extensions     = req_ext
prompt             = no

[ req_distinguished_name ]
commonName                  = 192.168.1.10

[ req_ext ]
subjectAltName = IP:192.168.1.10

Where, of course 192.168.1.10 is the local network IP we want Chrome to trust.

Create the certificate:

openssl genrsa -out key1.pem
openssl req -new -key key1.pem -out csr1.pem -config ssl.conf
openssl x509 -req -days 9999 -in csr1.pem -signkey key1.pem -out cert1.pem -extensions req_ext -extfile ssl.conf
rm csr1.pem

On Windows import the certificate into the Trusted Root Certificate Store on all client machines. On Android Phone or Tablet download the certificate to install it. Now Chrome will trust the certificate on windows and Android.

On windows dev box the best place to get openssl.exe is from "c:\Program Files\Git\usr\bin\openssl.exe"

PDO Prepared Inserts multiple rows in single query

Although an old question all the contributions helped me a lot so here's my solution, which works within my own DbContext class. The $rows parameter is simply an array of associative arrays representing rows or models: field name => insert value.

If you use a pattern that uses models this fits in nicely when passed model data as an array, say from a ToRowArray method within the model class.

Note: It should go without saying but never allow the arguments passed to this method to be exposed to the user or reliant on any user input, other than the insert values, which have been validated and sanitised. The $tableName argument and the column names should be defined by the calling logic; for instance a User model could be mapped to the user table, which has its column list mapped to the model's member fields.

public function InsertRange($tableName, $rows)
{
    // Get column list
    $columnList = array_keys($rows[0]);
    $numColumns = count($columnList);
    $columnListString = implode(",", $columnList);

    // Generate pdo param placeholders
    $placeHolders = array();

    foreach($rows as $row)
    {
        $temp = array();

        for($i = 0; $i < count($row); $i++)
            $temp[] = "?";

        $placeHolders[] = "(" . implode(",", $temp) . ")";
    }

    $placeHolders = implode(",", $placeHolders);

    // Construct the query
    $sql = "insert into $tableName ($columnListString) values $placeHolders";
    $stmt = $this->pdo->prepare($sql);

    $j = 1;
    foreach($rows as $row)
    {
        for($i = 0; $i < $numColumns; $i++)
        {
            $stmt->bindParam($j, $row[$columnList[$i]]);
            $j++;
        }
    }

    $stmt->execute();
}

What is the cause for "angular is not defined"

You have not placed the script tags for angular js

you can do so by using cdn or downloading the angularjs for your project and then referencing it

after this you have to add your own java script in your case main.js

that should do

How to get a Color from hexadecimal Color String

I use this and it works great for me for setting any color I want.

public static final int MY_COLOR = Color.rgb(255, 102, 153);

Set the colors using 0-255 for each red, green and blue then anywhere you want that color used just put MY_COLOR instead of Color.BLUE or Color.RED or any of the other static colors the Color class offers.

Just do a Google search for color chart and it you can find a chart with the correct RGB codes using 0-255.

How can I initialize an ArrayList with all zeroes in Java?

// apparently this is broken. Whoops for me!
java.util.Collections.fill(list,new Integer(0));

// this is better
Integer[] data = new Integer[60];
Arrays.fill(data,new Integer(0));
List<Integer> list = Arrays.asList(data);

TypeError: coercing to Unicode: need string or buffer

You're trying to open each file twice! First you do:

infile=open('110331_HS1A_1_rtTA.result','r')

and then you pass infile (which is a file object) to the open function again:

with open (infile, mode='r', buffering=-1)

open is of course expecting its first argument to be a file name, not an opened file!

Open the file once only and you should be fine.

m2e error in MavenArchiver.getManifest()

I had the same problem with a spring boot project. The solution was to downgrade the spring-boot-starter-parent dependency version from 2.0.0.RELEASE to 1.5.10.RELEASE(you can move to any stable version)

from:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.0.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

to

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.10.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

Java Thread Example?

A simple example:

public class Test extends Thread {
    public synchronized void run() {
        for (int i = 0; i <= 10; i++) {
            System.out.println("i::"+i);
        }
    }

    public static void main(String[] args) {
        Test obj = new Test();

        Thread t1 = new Thread(obj);
        Thread t2 = new Thread(obj);
        Thread t3 = new Thread(obj);

        t1.start();
        t2.start();
        t3.start();
    }
}

Image Greyscale with CSS & re-color on mouse-over?

I use the following code on http://www.diagnomics.com/

Smooth transition from b/w to color with magnifying effect (scale)

    img.color_flip {
      filter: url(filters.svg#grayscale); /* Firefox 3.5+ */
      filter: gray; /* IE5+ */
      -webkit-filter: grayscale(1); /* Webkit Nightlies & Chrome Canary */
      -webkit-transition: all .5s ease-in-out;
    }

    img.color_flip:hover {
      filter: none;
      -webkit-filter: grayscale(0);
      -webkit-transform: scale(1.1);
    }

Imported a csv-dataset to R but the values becomes factors

I'm new to R as well and faced the exact same problem. But then I looked at my data and noticed that it is being caused due to the fact that my csv file was using a comma separator (,) in all numeric columns (Ex: 1,233,444.56 instead of 1233444.56).

I removed the comma separator in my csv file and then reloaded into R. My data frame now recognises all columns as numbers.

I'm sure there's a way to handle this within the read.csv function itself.

Android: converting String to int

barcode often consist of large number so i think your app crashes because of the size of the string that you are trying to convert to int. you can use BigInteger

BigInteger reallyBig = new BigInteger(myString);

Remove large .pack file created by git

I am a little late for the show but in case the above answer didn't solve the query then I found another way. Simply remove the specific large file from .pack. I had this issue where I checked in a large 2GB file accidentally. I followed the steps explained in this link: http://www.ducea.com/2012/02/07/howto-completely-remove-a-file-from-git-history/

What is the use of verbose in Keras while validating the model?

Check documentation for model.fit here.

By setting verbose 0, 1 or 2 you just say how do you want to 'see' the training progress for each epoch.

verbose=0 will show you nothing (silent)

verbose=1 will show you an animated progress bar like this:

progres_bar

verbose=2 will just mention the number of epoch like this:

enter image description here

Python 3 Building an array of bytes

Use a bytearray:

>>> frame = bytearray()
>>> frame.append(0xA2)
>>> frame.append(0x01)
>>> frame.append(0x02)
>>> frame.append(0x03)
>>> frame.append(0x04)
>>> frame
bytearray(b'\xa2\x01\x02\x03\x04')

or, using your code but fixing the errors:

frame = b""
frame += b'\xA2' 
frame += b'\x01' 
frame += b'\x02' 
frame += b'\x03'
frame += b'\x04'

Jquery $.ajax fails in IE on cross domain calls

Jquery does this for you, only thing is to set $.support.cors = true; Then cross domain request works fine in all browsers for jquery users.

A KeyValuePair in Java

My favorite is

HashMap<Type1, Type2>

All you have to do is specify the datatype for the key for Type1 and the datatype for the value for Type2. It's the most common key-value object I've seen in Java.

https://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html

Saving images in Python at a very high quality

Okay, I found spencerlyon2's answer working. However, in case anybody would find himself/herself not knowing what to do with that one line, I had to do it this way:

beingsaved = plt.figure()

# Some scatter plots
plt.scatter(X_1_x, X_1_y)
plt.scatter(X_2_x, X_2_y)

beingsaved.savefig('destination_path.eps', format='eps', dpi=1000)

How to set session timeout dynamically in Java web applications?

Instead of using a ServletContextListener, use a HttpSessionListener.

In the sessionCreated() method, you can set the session timeout programmatically:

public class MyHttpSessionListener implements HttpSessionListener {

  public void sessionCreated(HttpSessionEvent event){
      event.getSession().setMaxInactiveInterval(15 * 60); // in seconds
  }

  public void sessionDestroyed(HttpSessionEvent event) {}

}

And don't forget to define the listener in the deployment descriptor:

<webapp>
...      
  <listener>                                  
    <listener-class>com.example.MyHttpSessionListener</listener-class>
  </listener>
</webapp>

(or since Servlet version 3.0 you can use @WebListener annotation instead).


Still, I would recommend creating different web.xml files for each application and defining the session timeout there:

<webapp>
...
  <session-config>
    <session-timeout>15</session-timeout> <!-- in minutes -->
  </session-config>
</webapp>

Why split the <script> tag when writing it with document.write()?

Here's another variation I've used when wanting to generate a script tag inline (so it executes immediately) without needing any form of escapes:

<script>
    var script = document.createElement('script');
    script.src = '/path/to/script.js';
    document.write(script.outerHTML);
</script>

(Note: contrary to most examples on the net, I'm not setting type="text/javascript" on neither the enclosing tag, nor the generated one: there is no browser not having that as the default, and so it is redundant, but will not hurt either, if you disagree).

Display UIViewController as Popup in iPhone

You can use EzPopup (https://github.com/huynguyencong/EzPopup), it is a Swift pod and very easy to use:

// init YourViewController
let contentVC = ...

// Init popup view controller with content is your content view controller
let popupVC = PopupViewController(contentController: contentVC, popupWidth: 100, popupHeight: 200)

// show it by call present(_ , animated:) method from a current UIViewController
present(popupVC, animated: true)

How to start IDLE (Python editor) without using the shortcut on Windows Vista?

The idle shortcut is an "Advertised Shortcut" which breaks certain features like the "find target" button. Google for more info.

You can view the link with a hex editor or download LNK Parser to see where it points to.

In my case it runs:
..\..\..\..\..\Python27\pythonw.exe "C:\Python27\Lib\idlelib\idle.pyw"

remove all variables except functions

I wrote this to remove all objects apart from functions from the current environment (Programming language used is R with IDE R-Studio):

    remove_list=c()                             # create a vector

      for(i in 1:NROW(ls())){                   # repeat over all objects in environment
        if(class(get(ls()[i]))!="function"){    # if object is *not* a function
         remove_list=c(remove_list,ls()[i])     # ..add to vector remove_list
         }    
      }

    rm(list=remove_list)                        # remove all objects named in remove_list

Notes-

The argument "list" in rm(list=) must be a character vector.

The name of an object in position i of the current environment is returned from ls()[i] and the object itself from get(ls()[i]). Therefore the class of an object is returned from class(get(ls()[i]))

What is the best (and safest) way to merge a Git branch into master?

I'll answer as per develop and feature branches,

if you're on feature branch and need to update it with develop use the below commands:

git checkout develop
git pull
git checkout feature/xyz
git merge develop

Now your feature/xyz is updated with develop branch and you can push your changes to remote feature/xyz.

Android: How to stretch an image to the screen width while maintaining aspect ratio?

I've been struggling with this problem in one form or another for AGES, thank you, Thank You, THANK YOU.... :)

I just wanted to point out that you can get a generalizable solution from what Bob Lee's done by just extending View and overriding onMeasure. That way you can use this with any drawable you want, and it won't break if there's no image:

    public class CardImageView extends View {
        public CardImageView(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);
        }

        public CardImageView(Context context, AttributeSet attrs) {
            super(context, attrs);
        }

        public CardImageView(Context context) {
            super(context);
        }

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            Drawable bg = getBackground();
            if (bg != null) {
                int width = MeasureSpec.getSize(widthMeasureSpec);
                int height = width * bg.getIntrinsicHeight() / bg.getIntrinsicWidth();
                setMeasuredDimension(width,height);
            }
            else {
                super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            }
        }
    }

Defining an abstract class without any abstract methods

Yes we can have an abstract class without Abstract Methods as both are independent concepts. Declaring a class abstract means that it can not be instantiated on its own and can only be sub classed. Declaring a method abstract means that Method will be defined in the subclass.

How to use range-based for() loop with std::map?

From this paper: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2049.pdf

for( type-speci?er-seq simple-declarator : expression ) statement

is syntactically equivalent to

{
    typedef decltype(expression) C;
    auto&& rng(expression);
    for (auto begin(std::For<C>::begin(rng)), end(std::For<C>::end(rng)); begin != end; ++ begin) {
        type-speci?er-seq simple-declarator(*begin);
        statement
    }
}

So you can clearly see that what is abc in your case will be std::pair<key_type, value_type >. So for printing you can do access each element by abc.first and abc.second

How to loop through a directory recursively to delete files with certain extensions

The following function would recursively iterate through all the directories in the \home\ubuntu directory( whole directory structure under ubuntu ) and apply the necessary checks in else block.

function check {
        for file in $1/*      
        do
        if [ -d "$file" ]
        then
                check $file                          
        else
               ##check for the file
               if [ $(head -c 4 "$file") = "%PDF" ]; then
                         rm -r $file
               fi
        fi
        done     
}
domain=/home/ubuntu
check $domain

100% height minus header?

If your browser supports CSS3, try using the CSS element Calc()

height: calc(100% - 65px);

you might also want to adding browser compatibility options:

height: -o-calc(100% - 65px); /* opera */
height: -webkit-calc(100% - 65px); /* google, safari */
height: -moz-calc(100% - 65px); /* firefox */

also make sure you have spaces between values, see: https://stackoverflow.com/a/16291105/427622

Apache 2.4.6 on Ubuntu Server: Client denied by server configuration (PHP FPM) [While loading PHP file]

I have exactly the same issue. I ran a couple of virtual hosts on my local machine for developing.

First, I changed /etc/apache2/conf-available/php5-fpm.conf. I replaced every

Order Deny,Allow
Deny from all

to

Require all granted

The configuration has to be enabled by a2enconf php5-fpm. I did the same with my virtual hosts configurations and made the replacements.

I think this is not advised for security reasons, but as long as I use my server for local purposes only I can live with it.

pod has unbound PersistentVolumeClaims

You have to define a PersistentVolume providing disc space to be consumed by the PersistentVolumeClaim.

When using storageClass Kubernetes is going to enable "Dynamic Volume Provisioning" which is not working with the local file system.


To solve your issue:

  • Provide a PersistentVolume fulfilling the constraints of the claim (a size >= 100Mi)
  • Remove the storageClass-line from the PersistentVolumeClaim
  • Remove the StorageClass from your cluster

How do these pieces play together?

At creation of the deployment state-description it is usually known which kind (amount, speed, ...) of storage that application will need.
To make a deployment versatile you'd like to avoid a hard dependency on storage. Kubernetes' volume-abstraction allows you to provide and consume storage in a standardized way.

The PersistentVolumeClaim is used to provide a storage-constraint alongside the deployment of an application.

The PersistentVolume offers cluster-wide volume-instances ready to be consumed ("bound"). One PersistentVolume will be bound to one claim. But since multiple instances of that claim may be run on multiple nodes, that volume may be accessed by multiple nodes.

A PersistentVolume without StorageClass is considered to be static.

"Dynamic Volume Provisioning" alongside with a StorageClass allows the cluster to provision PersistentVolumes on demand. In order to make that work, the given storage provider must support provisioning - this allows the cluster to request the provisioning of a "new" PersistentVolume when an unsatisfied PersistentVolumeClaim pops up.


Example PersistentVolume

In order to find how to specify things you're best advised to take a look at the API for your Kubernetes version, so the following example is build from the API-Reference of K8S 1.17:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: ckan-pv-home
  labels:
    type: local
spec:
  capacity:
    storage: 100Mi
  hostPath:
    path: "/mnt/data/ckan"

The PersistentVolumeSpec allows us to define multiple attributes. I chose a hostPath volume which maps a local directory as content for the volume. The capacity allows the resource scheduler to recognize this volume as applicable in terms of resource needs.


Additional Resources:

How to make program go back to the top of the code instead of closing

You can easily do it with loops, there are two types of loops

For Loops:

for i in range(0,5):
    print 'Hello World'

While Loops:

count = 1
while count <= 5:
    print 'Hello World'
    count += 1

Each of these loops print "Hello World" five times

Jetty: HTTP ERROR: 503/ Service Unavailable

2012-04-20 11:14:32.617:WARN:oejx.XmlParser:FATAL@file:/C:/Users/***/workspace/Test/WEB-INF/web.xml line:1 col:7 : org.xml.sax.SAXParseException: The processing instruction target matching "[xX][mM][lL]" is not allowed.

You Log says, that you web.xml is malformed. Line 1, colum 7. It may be a UTF-8 Byte-Order-Marker

Try to verify, that your xml is wellformed and does not have a BOM. Java doesn't use BOMs.

Adding null values to arraylist

You can add nulls to the ArrayList, and you will have to check for nulls in the loop:

for(Item i : itemList) {
   if (i != null) {

   }
}

itemsList.size(); would take the null into account.

 List<Integer> list = new ArrayList<Integer>();
 list.add(null);
 list.add (5);
 System.out.println (list.size());
 for (Integer value : list) {
   if (value == null)
       System.out.println ("null value");
   else 
       System.out.println (value);
 }

Output :

2
null value
5

Largest and smallest number in an array

You (normally) cannot modify the collection you are iterating over when using foreach.

Although for and foreach seem to be similar from a developer perspective they are quite different from an implementation perspective.

Foreach uses an Iterator to access the individual objects while for doesn't know (or care) about the underlying object sequence.

How to install JRE 1.7 on Mac OS X and use it with Eclipse?

The download from java.com which installs in /Library/Internet Plug-Ins is only the JRE, for development you probably want to download the JDK from http://www.oracle.com/technetwork/java/javase/downloads/index.html and install that instead. This will install the JDK at /Library/Java/JavaVirtualMachines/jdk1.7.0_<something>.jdk/Contents/Home which you can then add to Eclipse via Preferences -> Java -> Installed JREs.

How to disable back swipe gesture in UINavigationController on iOS 7

This is the way on Swift 3

works for me

    self.navigationController?.interactivePopGestureRecognizer?.isEnabled = false

Set background colour of cell to RGB value of data in cell

To color each cell based on its current integer value, the following should work, if you have a recent version of Excel. (Older versions don't handle rgb as well)

Sub Colourise()
'
' Colourise Macro
'
' Colours all selected cells, based on their current integer rgb value
' For e.g. (it's a bit backward from what you might expect)
' 255 = #ff0000 = red
' 256*255 = #00ff00 = green
' 256*256*255 #0000ff = blue
' 255 + 256*256*255 #ff00ff = magenta
' and so on...
'
' Keyboard Shortcut: Ctrl+Shift+C (or whatever you want to set it to)
'
  For Each cell In Selection
    If WorksheetFunction.IsNumber(cell) Then
      cell.Interior.Color = cell.Value
    End If
  Next cell
End Sub

If instead of a number you have a string then you can split the string into three numbers and combine them using rgb().

How to position a table at the center of div horizontally & vertically

Additionally, if you want to center both horizontally and vertically -instead of having a flow-design (in such cases, the previous solutions apply)- you could do:

  1. Declare the main div as absolute or relative positioning (I call it content).
  2. Declare an inner div, which will actually hold the table (I call it wrapper).
  3. Declare the table itself, inside wrapper div.
  4. Apply CSS transform to change the "registration point" of the wrapper object to it's center.
  5. Move the wrapper object to the center of the parent object.

_x000D_
_x000D_
#content {_x000D_
  width: 5em;_x000D_
  height: 5em;_x000D_
  border: 1px solid;_x000D_
  border-color: red;_x000D_
  position: relative;_x000D_
  }_x000D_
_x000D_
#wrapper {_x000D_
  width: 4em;_x000D_
  height: 4em;_x000D_
  border: 3px solid;_x000D_
  border-color: black;_x000D_
  position: absolute;_x000D_
  left: 50%; top: 50%; /*move the object to the center of the parent object*/_x000D_
  -webkit-transform: translate(-50%, -50%);_x000D_
  -moz-transform: translate(-50%, -50%);_x000D_
  -ms-transform: translate(-50%, -50%);_x000D_
  -o-transform: translate(-50%, -50%);_x000D_
  transform: translate(-50%, -50%);_x000D_
  /*these 5 settings change the base (or registration) point of the wrapper object to it's own center - so we align child center with parent center*/_x000D_
  }_x000D_
_x000D_
table {_x000D_
  width: 100%;_x000D_
  height: 100%;_x000D_
  border: 1px solid;_x000D_
  border-color: yellow;_x000D_
  display: inline-block;_x000D_
  }
_x000D_
<div id="content">_x000D_
    <div id="wrapper">_x000D_
        <table>_x000D_
        </table>_x000D_
    </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Note: You cannot get rid of the wrapper div, since this style does not work directly on tables, so I use a div to wrap it and position it, while the table is flowed inside the div.

Is it possible to read from a InputStream with a timeout?

As jt said, NIO is the best (and correct) solution. If you really are stuck with an InputStream though, you could either

  1. Spawn a thread who's exclusive job is to read from the InputStream and put the result into a buffer which can be read from your original thread without blocking. This should work well if you only ever have one instance of the stream. Otherwise you may be able to kill the thread using the deprecated methods in the Thread class, though this may cause resource leaks.

  2. Rely on isAvailable to indicate data that can be read without blocking. However in some cases (such as with Sockets) it can take a potentially blocking read for isAvailable to report something other than 0.

How do I disable form resizing for users?

Change this property and try this at design time:

FormBorderStyle = FormBorderStyle.FixedDialog;

Designer view before the change:

Enter image description here

What's the difference between 'r+' and 'a+' when open file in python?

Python opens files almost in the same way as in C:

  • r+ Open for reading and writing. The stream is positioned at the beginning of the file.

  • a+ Open for reading and appending (writing at end of file). The file is created if it does not exist. The initial file position for reading is at the beginning of the file, but output is appended to the end of the file (but in some Unix systems regardless of the current seek position).

How can I make a checkbox readonly? not disabled?

<input type="checkbox" checked onclick="return false;" onkeydown="return false;"/>

http://jsfiddle.net/2srjc/

If you are worried about tab order, only return false for the keydown event when the tab key was not pressed:

<input type="checkbox" checked onclick="return false;" onkeydown="e = e || window.event; if(e.keyCode !== 9) return false;"/>

http://jsfiddle.net/2srjc/149/

Making a <button> that's a link in HTML

IMPORTANT: <button> should never be a descendent of <a>.

Try <a href="http://stackoverflow.com"><button>Link Text</button></a> in any html validator like https://validator.w3.org and you'll get an error. There's really no point in using a button if you're not using the button. Just style the <a> with css to look like a button. If you're using a framework like Bootstrap, you could apply the button style(s) btn, btn-primary etc.

jsfiddle : button styled link

_x000D_
_x000D_
.btnStack {_x000D_
  font-family: Oswald;_x000D_
  background-color: orange;_x000D_
  color: white;_x000D_
  text-decoration: none;_x000D_
  display: inline-block;_x000D_
  padding: 6px 12px;_x000D_
  margin-bottom: 0;_x000D_
  font-size: 14px;_x000D_
  font-weight: normal;_x000D_
  line-height: 1.428571429;_x000D_
  text-align: center;_x000D_
  white-space: nowrap;_x000D_
  vertical-align: middle;_x000D_
  cursor: pointer;_x000D_
  border: 1px solid transparent;_x000D_
  border-radius: 4px;_x000D_
  -webkit-user-select: none;_x000D_
  -moz-user-select: none;_x000D_
  -ms-user-select: none;_x000D_
  -o-user-select: none;_x000D_
  user-select: none;_x000D_
}_x000D_
_x000D_
a.btnStack:hover {_x000D_
  background-color: #000;_x000D_
}
_x000D_
<link href='https://fonts.googleapis.com/css?family=Oswald:400' rel='stylesheet' type='text/css'>_x000D_
<a href="http://stackoverflow.com" class="btnStack">stackoverflow.com</a>
_x000D_
_x000D_
_x000D_

Create a directory if it doesn't exist

You can use cstdlib

Although- http://www.cplusplus.com/articles/j3wTURfi/

#include <cstdlib>

const int dir= system("mkdir -p foo");
if (dir< 0)
{
     return;
}

you can also check if the directory exists already by using

#include <dirent.h>

How to "EXPIRE" the "HSET" child key in redis?

You could store key/values in Redis differently to achieve this, by just adding a prefix or namespace to your keys when you store them e.g. "hset_"

  • Get a key/value GET hset_key equals to HGET hset key

  • Add a key/value SET hset_key value equals to HSET hset key

  • Get all keys KEYS hset_* equals to HGETALL hset

  • Get all vals should be done in 2 ops, first get all keys KEYS hset_* then get the value for each key

  • Add a key/value with TTL or expire which is the topic of question:

 SET hset_key value
 EXPIRE hset_key

Note: KEYS will lookup up for matching the key in the whole database which may affect on performance especially if you have big database.

Note:

  • KEYS will lookup up for matching the key in the whole database which may affect on performance especially if you have big database. while SCAN 0 MATCH hset_* might be better as long as it doesn't block the server but still performance is an issue in case of big database.

  • You may create a new database for storing separately these keys that you want to expire especially if they are small set of keys.

Thanks to @DanFarrell who highlighted the performance issue related to KEYS

Get Path from another app (WhatsApp)

You can also convert the URI to file and then to bytes if you want to upload the photo to your server.

Check out : https://www.stackoverflow.com/a/49575321

Convert an integer to an array of digits

Use:

public static void main(String[] args)
{
    int num = 1234567;
    int[] digits = Integer.toString(num).chars().map(c -> c-'0').toArray();
    for(int d : digits)
        System.out.print(d);
}

The main idea is

  1. Convert the int to its String value

    Integer.toString(num);
    
  2. Get a stream of int that represents the ASCII value of each char(~digit) composing the String version of our integer

    Integer.toString(num).chars();
    
  3. Convert the ASCII value of each character to its value. To get the actual int value of a character, we have to subtract the ASCII code value of the character '0' from the ASCII code of the actual character. To get all the digits of our number, this operation has to be applied on each character (corresponding to the digit) composing the string equivalent of our number which is done by applying the map function below to our IntStream.

    Integer.toString(num).chars().map(c -> c-'0');
    
  4. Convert the stream of int to an array of int using toArray()

     Integer.toString(num).chars().map(c -> c-'0').toArray();
    

Convert byte[] to char[]

System.Text.Encoding.ChooseYourEncoding.GetString(bytes).ToCharArray();

Substitute the right encoding above: e.g.

System.Text.Encoding.UTF8.GetString(bytes).ToCharArray();

Quickly reading very large tables as dataframes

A minor additional points worth mentioning. If you have a very large file you can on the fly calculate the number of rows (if no header) using (where bedGraph is the name of your file in your working directory):

>numRow=as.integer(system(paste("wc -l", bedGraph, "| sed 's/[^0-9.]*\\([0-9.]*\\).*/\\1/'"), intern=T))

You can then use that either in read.csv , read.table ...

>system.time((BG=read.table(bedGraph, nrows=numRow, col.names=c('chr', 'start', 'end', 'score'),colClasses=c('character', rep('integer',3)))))
   user  system elapsed 
 25.877   0.887  26.752 
>object.size(BG)
203949432 bytes

How do I create an empty array/matrix in NumPy?

I think you want to handle most of the work with lists then use the result as a matrix. Maybe this is a way ;

ur_list = []
for col in columns:
    ur_list.append(list(col))

mat = np.matrix(ur_list)

Angular - POST uploaded file

your http service file:

import { Injectable } from "@angular/core";
import { ActivatedRoute, Router } from '@angular/router';
import { Http, Headers, Response, Request, RequestMethod, URLSearchParams, RequestOptions } from "@angular/http";
import {Observable} from 'rxjs/Rx';
import { Constants } from './constants';
declare var $: any;

@Injectable()
export class HttpClient {
  requestUrl: string;
  responseData: any;
  handleError: any;

  constructor(private router: Router, 
  private http: Http, 
  private constants: Constants, 
  ) {
    this.http = http;
  }

  postWithFile (url: string, postData: any, files: File[]) {

    let headers = new Headers();
    let formData:FormData = new FormData();
    formData.append('files', files[0], files[0].name);
    // For multiple files
    // for (let i = 0; i < files.length; i++) {
    //     formData.append(`files[]`, files[i], files[i].name);
    // }

    if(postData !=="" && postData !== undefined && postData !==null){
      for (var property in postData) {
          if (postData.hasOwnProperty(property)) {
              formData.append(property, postData[property]);
          }
      }
    }
    var returnReponse = new Promise((resolve, reject) => {
      this.http.post(this.constants.root_dir + url, formData, {
        headers: headers
      }).subscribe(
          res => {
            this.responseData = res.json();
            resolve(this.responseData);
          },
          error => {
            this.router.navigate(['/login']);
            reject(error);
          }
      );
    });
    return returnReponse;
  }
}

call your function (Component file):

onChange(event) {
    let file = event.srcElement.files;
    let postData = {field1:"field1", field2:"field2"}; // Put your form data variable. This is only example.
    this._service.postWithFile(this.baseUrl + "add-update",postData,file).then(result => {
        console.log(result);
    });
}

your html code:

<input type="file" class="form-control" name="documents" (change)="onChange($event)" [(ngModel)]="stock.documents" #documents="ngModel">

cast or convert a float to nvarchar?

Do not use floats to store fixed-point, accuracy-required data. This example shows how to convert a float to NVARCHAR(50) properly, while also showing why it is a bad idea to use floats for precision data.

create table #f ([Column_Name] float)
insert #f select 9072351234
insert #f select 907235123400000000000

select
    cast([Column_Name] as nvarchar(50)),
    --cast([Column_Name] as int), Arithmetic overflow
    --cast([Column_Name] as bigint), Arithmetic overflow
    CAST(LTRIM(STR([Column_Name],50)) AS NVARCHAR(50))
from #f

Output

9.07235e+009    9072351234
9.07235e+020    907235123400000010000

You may notice that the 2nd output ends with '10000' even though the data we tried to store in the table ends with '00000'. It is because float datatype has a fixed number of significant figures supported, which doesn't extend that far.

How to store Query Result in variable using mysql

Select count(*) from table_name into @var1; 
Select @var1;

How to set min-height for bootstrap container

Usually, if you are using bootstrap you can do this to set a min-height of 100%.

 <div class="container-fluid min-vh-100"></div>

this will also solve the footer not sticking at the bottom.

you can also do this from CSS with the following class

.stickDamnFooter{min-height: 100vh;}

if this class does not stick your footer just add position: fixed; to that same css class and you will not have this issue in a lifetime. Cheers.

Iterating over each line of ls -l output

You can also try the find command. If you only want files in the current directory:

find . -d 1 -prune -ls

Run a command on each of them?

find . -d 1 -prune -exec echo {} \;

Count lines, but only in files?

find . -d 1 -prune -type f -exec wc -l {} \;

how to get vlc logs?

I found the following command to run from command line:

vlc.exe --extraintf=http:logger --verbose=2 --file-logging --logfile=vlc-log.txt

Using an image caption in Markdown Jekyll

You can use table for this. It works fine.

| ![space-1.jpg](http://www.storywarren.com/wp-content/uploads/2016/09/space-1.jpg) | 
|:--:| 
| *Space* |

Result:

enter image description here

A monad is just a monoid in the category of endofunctors, what's the problem?

That particular phrasing is by James Iry, from his highly entertaining Brief, Incomplete and Mostly Wrong History of Programming Languages, in which he fictionally attributes it to Philip Wadler.

The original quote is from Saunders Mac Lane in Categories for the Working Mathematician, one of the foundational texts of Category Theory. Here it is in context, which is probably the best place to learn exactly what it means.

But, I'll take a stab. The original sentence is this:

All told, a monad in X is just a monoid in the category of endofunctors of X, with product × replaced by composition of endofunctors and unit set by the identity endofunctor.

X here is a category. Endofunctors are functors from a category to itself (which is usually all Functors as far as functional programmers are concerned, since they're mostly dealing with just one category; the category of types - but I digress). But you could imagine another category which is the category of "endofunctors on X". This is a category in which the objects are endofunctors and the morphisms are natural transformations.

And of those endofunctors, some of them might be monads. Which ones are monads? Exactly the ones which are monoidal in a particular sense. Instead of spelling out the exact mapping from monads to monoids (since Mac Lane does that far better than I could hope to), I'll just put their respective definitions side by side and let you compare:

A monoid is...

  • A set, S
  • An operation, • : S × S ? S
  • An element of S, e : 1 ? S

...satisfying these laws:

  • (a • b) • c = a • (b • c), for all a, b and c in S
  • e • a = a • e = a, for all a in S

A monad is...

  • An endofunctor, T : X ? X (in Haskell, a type constructor of kind * -> * with a Functor instance)
  • A natural transformation, µ : T × T ? T, where × means functor composition (µ is known as join in Haskell)
  • A natural transformation, ? : I ? T, where I is the identity endofunctor on X (? is known as return in Haskell)

...satisfying these laws:

  • µ ° Tµ = µ ° µT
  • µ ° T? = µ ° ?T = 1 (the identity natural transformation)

With a bit of squinting you might be able to see that both of these definitions are instances of the same abstract concept.

Bulk Record Update with SQL

Or you can simply update without using join like this:

Update t1 set  t1.Description = t2.Description from @tbl2 t2,tbl1 t1
where t1.ID= t2.ID

Creating a SOAP call using PHP with an XML body

There are a couple of ways to solve this. The least hackiest and almost what you want:

$client = new SoapClient(
    null,
    array(
        'location' => 'https://example.com/ExampleWebServiceDL/services/ExampleHandler',
        'uri' => 'http://example.com/wsdl',
        'trace' => 1,
        'use' => SOAP_LITERAL,
    )
);
$params = new \SoapVar("<Acquirer><Id>MyId</Id><UserId>MyUserId</UserId><Password>MyPassword</Password></Acquirer>", XSD_ANYXML);
$result = $client->Echo($params);

This gets you the following XML:

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="http://example.com/wsdl">
    <SOAP-ENV:Body>
        <ns1:Echo>
            <Acquirer>
                <Id>MyId</Id>
                <UserId>MyUserId</UserId>
                <Password>MyPassword</Password>
            </Acquirer>
        </ns1:Echo>
    </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

That is almost exactly what you want, except for the namespace on the method name. I don't know if this is a problem. If so, you can hack it even further. You could put the <Echo> tag in the XML string by hand and have the SoapClient not set the method by adding 'style' => SOAP_DOCUMENT, to the options array like this:

$client = new SoapClient(
    null,
    array(
        'location' => 'https://example.com/ExampleWebServiceDL/services/ExampleHandler',
        'uri' => 'http://example.com/wsdl',
        'trace' => 1,
        'use' => SOAP_LITERAL,
        'style' => SOAP_DOCUMENT,
    )
);
$params = new \SoapVar("<Echo><Acquirer><Id>MyId</Id><UserId>MyUserId</UserId><Password>MyPassword</Password></Acquirer></Echo>", XSD_ANYXML);
$result = $client->MethodNameIsIgnored($params);

This results in the following request XML:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
    <SOAP-ENV:Body>
        <Echo>
            <Acquirer>
                <Id>MyId</Id>
                <UserId>MyUserId</UserId>
                <Password>MyPassword</Password>
            </Acquirer>
        </Echo>
    </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Finally, if you want to play around with SoapVar and SoapParam objects, you can find a good reference in this comment in the PHP manual: http://www.php.net/manual/en/soapvar.soapvar.php#104065. If you get that to work, please let me know, I failed miserably.

Update one MySQL table with values from another

UPDATE tobeupdated
INNER JOIN original ON (tobeupdated.value = original.value)
SET tobeupdated.id = original.id

That should do it, and really its doing exactly what yours is. However, I prefer 'JOIN' syntax for joins rather than multiple 'WHERE' conditions, I think its easier to read

As for running slow, how large are the tables? You should have indexes on tobeupdated.value and original.value

EDIT: we can also simplify the query

UPDATE tobeupdated
INNER JOIN original USING (value)
SET tobeupdated.id = original.id

USING is shorthand when both tables of a join have an identical named key such as id. ie an equi-join - http://en.wikipedia.org/wiki/Join_(SQL)#Equi-join

how do you insert null values into sql server

If you're using SSMS (or old school Enterprise Manager) to edit the table directly, press CTRL+0 to add a null.

Android TextView Text not getting wrapped

I know, that in question it is correct, but in my case, the problem was in setting textSize property in 'dp' - I've changed it to 'sp' and it works fine.

How can I enable Assembly binding logging?

If you sometimes run different versions of your application, make sure you delete 'Bla' from the application bin directory if the version running doesn't need it.

Is there a max size for POST parameter content?

There is no defined maximum size for HTTP POST requests. If you notice such a limit then it's an arbitrary limitation of your HTTP Server/Client.

You might get a better answer if you tell how big the XML is.

Using BeautifulSoup to extract text without tags

I think you can get it using subc1.text.

>>> html = """
<p>
    <strong class="offender">YOB:</strong> 1987<br />
    <strong class="offender">RACE:</strong> WHITE<br />
    <strong class="offender">GENDER:</strong> FEMALE<br />
    <strong class="offender">HEIGHT:</strong> 5'05''<br />
    <strong class="offender">WEIGHT:</strong> 118<br />
    <strong class="offender">EYE COLOR:</strong> GREEN<br />
    <strong class="offender">HAIR COLOR:</strong> BROWN<br />
</p>
"""
>>> from bs4 import BeautifulSoup
>>> soup = BeautifulSoup(html)
>>> print soup.text


YOB: 1987
RACE: WHITE
GENDER: FEMALE
HEIGHT: 5'05''
WEIGHT: 118
EYE COLOR: GREEN
HAIR COLOR: BROWN

Or if you want to explore it, you can use .contents :

>>> p = soup.find('p')
>>> from pprint import pprint
>>> pprint(p.contents)
[u'\n',
 <strong class="offender">YOB:</strong>,
 u' 1987',
 <br/>,
 u'\n',
 <strong class="offender">RACE:</strong>,
 u' WHITE',
 <br/>,
 u'\n',
 <strong class="offender">GENDER:</strong>,
 u' FEMALE',
 <br/>,
 u'\n',
 <strong class="offender">HEIGHT:</strong>,
 u" 5'05''",
 <br/>,
 u'\n',
 <strong class="offender">WEIGHT:</strong>,
 u' 118',
 <br/>,
 u'\n',
 <strong class="offender">EYE COLOR:</strong>,
 u' GREEN',
 <br/>,
 u'\n',
 <strong class="offender">HAIR COLOR:</strong>,
 u' BROWN',
 <br/>,
 u'\n']

and filter out the necessary items from the list:

>>> data = dict(zip([x.text for x in p.contents[1::4]], [x.strip() for x in p.contents[2::4]]))
>>> pprint(data)
{u'EYE COLOR:': u'GREEN',
 u'GENDER:': u'FEMALE',
 u'HAIR COLOR:': u'BROWN',
 u'HEIGHT:': u"5'05''",
 u'RACE:': u'WHITE',
 u'WEIGHT:': u'118',
 u'YOB:': u'1987'}

java.io.IOException: Could not locate executable null\bin\winutils.exe in the Hadoop binaries. spark Eclipse on windows 7

You can alternatively download winutils.exe from GITHub:

https://github.com/steveloughran/winutils/tree/master/hadoop-2.7.1/bin

replace hadoop-2.7.1 with the version you want and place the file in D:\hadoop\bin

If you do not have access rights to the environment variable settings on your machine, simply add the below line to your code:

System.setProperty("hadoop.home.dir", "D:\\hadoop");

Error: "Adb connection Error:An existing connection was forcibly closed by the remote host"

In my case, which none of the answers above stated. If your device is using the miniUsb connector, make sure you are using a cable that is not charge-only. I became accustom to using developing with a newer Usb-C device and could not fathom a charge-only cable got mixed with my pack especially since there is no visible way to tell the difference.

Before you uninstall and go through a nightmare of driver reinstall and android menu options. Try a different cable first.

Does calling clone() on an array also clone its contents?

If I invoke clone() method on array of Objects of type A, how will it clone its elements?

The elements of the array will not be cloned.

Will the copy be referencing to the same objects?

Yes.

Or will it call (element of type A).clone() for each of them?

No, it will not call clone() on any of the elements.

How do I fix maven error The JAVA_HOME environment variable is not defined correctly?

This is how I fixed this issue on Windows 10:

My JDK is located in C:\Program Files\Java\jdk-11.0.2 and the problem I had was the space in Program Files. If I set JAVA_HOME using set JAVA_HOME="C:\Program Files\Java\jdk-11.0.2" then Maven had an issue with the double quotes:

C:\Users>set JAVA_HOME="C:\Program Files\Java\jdk-11.0.2"

C:\Users>echo %JAVA_HOME%
"C:\Program Files\Java\jdk-11.0.2"

C:\Users>mvn -version
Files\Java\jdk-11.0.2""=="" was unexpected at this time.

Referring to Program Files as PROGRA~1 didn't help either. The solution is using the PROGRAMFILES variable inside of JAVA_HOME:

C:\Users>echo %PROGRAMFILES%
C:\Program Files

C:\Program Files>set JAVA_HOME=%PROGRAMFILES%\Java\jdk-11.0.2

C:\Program Files>echo %JAVA_HOME%
C:\Program Files\Java\jdk-11.0.2

C:\Program Files>mvn -version
Apache Maven 3.6.2 (40f52333136460af0dc0d7232c0dc0bcf0d9e117; 2019-08-27T17:06:16+02:00)
Maven home: C:\apache-maven-3.6.2\bin\..
Java version: 11.0.2, vendor: Oracle Corporation, runtime: C:\Program Files\Java\jdk-11.0.2
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 10", version: "10.0", arch: "amd64", family: "windows"

How to set image in circle in swift

If your image is rounded, it would have a height and width of the exact same size (i.e 120). You simply take half of that number and use that in your code (image.layer.cornerRadius = 60).

This application has no explicit mapping for /error

You can solve this by adding an ErrorController in your application. You can have the error controller return a view that you need.

Error Controller in my application looks like below:

import org.springframework.boot.autoconfigure.web.ErrorAttributes;
import org.springframework.boot.autoconfigure.web.ErrorController;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import java.util.Map;

/**
 * Basic Controller which is called for unhandled errors
 */
@Controller
public class AppErrorController implements ErrorController{

    /**
     * Error Attributes in the Application
     */
    private ErrorAttributes errorAttributes;

    private final static String ERROR_PATH = "/error";

    /**
     * Controller for the Error Controller
     * @param errorAttributes
     */
    public AppErrorController(ErrorAttributes errorAttributes) {
        this.errorAttributes = errorAttributes;
    }

    /**
     * Supports the HTML Error View
     * @param request
     * @return
     */
    @RequestMapping(value = ERROR_PATH, produces = "text/html")
    public ModelAndView errorHtml(HttpServletRequest request) {
        return new ModelAndView("/errors/error", getErrorAttributes(request, false));
    }

    /**
     * Supports other formats like JSON, XML
     * @param request
     * @return
     */
    @RequestMapping(value = ERROR_PATH)
    @ResponseBody
    public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
        Map<String, Object> body = getErrorAttributes(request, getTraceParameter(request));
        HttpStatus status = getStatus(request);
        return new ResponseEntity<Map<String, Object>>(body, status);
    }

    /**
     * Returns the path of the error page.
     *
     * @return the error path
     */
    @Override
    public String getErrorPath() {
        return ERROR_PATH;
    }


    private boolean getTraceParameter(HttpServletRequest request) {
        String parameter = request.getParameter("trace");
        if (parameter == null) {
            return false;
        }
        return !"false".equals(parameter.toLowerCase());
    }

    private Map<String, Object> getErrorAttributes(HttpServletRequest request,
                                                   boolean includeStackTrace) {
        RequestAttributes requestAttributes = new ServletRequestAttributes(request);
        return this.errorAttributes.getErrorAttributes(requestAttributes,
                includeStackTrace);
    }

    private HttpStatus getStatus(HttpServletRequest request) {
        Integer statusCode = (Integer) request
                .getAttribute("javax.servlet.error.status_code");
        if (statusCode != null) {
            try {
                return HttpStatus.valueOf(statusCode);
            }
            catch (Exception ex) {
            }
        }
        return HttpStatus.INTERNAL_SERVER_ERROR;
    }
}

The above class is based on Springs BasicErrorController class.

You can instantiate the above ErrorController like this in a @Configuration file:

 @Autowired
 private ErrorAttributes errorAttributes;

 @Bean
 public AppErrorController appErrorController(){return new AppErrorController(errorAttributes);}

You can choose override the default ErrorAttributes by implementing ErrorAttributes. But in most cases the DefaultErrorAttributes should suffice.

How to add Tomcat Server in eclipse

This is very simple steps involved as you mentioned you have already installed JAVAEE plugin so the first step for you is go to Windows->Show View->Server in add select the AppacheTOMcat and select the tomcat version you have downloaded and set the path and start the server after that.

Execution failed for task ':app:processDebugResources' even with latest build tools

this issue comes up with 2 reasons

1) the android SDK has not been install 2) the build toold version corresponsind to the android SDK is not installed

to start open terminal and type android and install API 26(updated one) and build tools version 26.0.1 or 26.0.2 then try to run using command ionic cordova build android

How to set default value to all keys of a dict object in python?

You can use the following class. Just change zero to any default value you like. The solution was tested in Python 2.7.

class cDefaultDict(dict):
    # dictionary that returns zero for missing keys
    # keys with zero values are not stored

    def __missing__(self,key):
        return 0

    def __setitem__(self, key, value):
        if value==0:
            if key in self:  # returns zero anyway, so no need to store it
                del self[key]
        else:
            dict.__setitem__(self, key, value)

How to generate java classes from WSDL file

You can use the WSDL2JAVA Codegen (or) You can simply use the 'Web Service/WebServiceClient' Wizard available in the Eclipse IDE. Open the IDE and press 'Ctrl+N', selectfor 'Web Service/WebServiceClient', specify the wsdl URL, ouput folder and select finish.

It creates the complete source files that you would need.

Difference between Pragma and Cache-Control headers?

Stop using (HTTP 1.0) Replaced with (HTTP 1.1 since 1999)
Expires: [date] Cache-Control: max-age=[seconds]
Pragma: no-cache Cache-Control: no-cache

If it's after 1999, and you're still using Expires or Pragma, you're doing it wrong.

I'm looking at you Stackoverflow:

200 OK
Pragma: no-cache
Content-Type: application/json
X-Frame-Options: SAMEORIGIN
X-Request-Guid: a3433194-4a03-4206-91ea-6a40f9bfd824
Strict-Transport-Security: max-age=15552000
Content-Length: 54
Accept-Ranges: bytes
Date: Tue, 03 Apr 2018 19:03:12 GMT
Via: 1.1 varnish
Connection: keep-alive
X-Served-By: cache-yyz8333-YYZ
X-Cache: MISS
X-Cache-Hits: 0
X-Timer: S1522782193.766958,VS0,VE30
Vary: Fastly-SSL
X-DNS-Prefetch-Control: off
Cache-Control: private

tl;dr: Pragma is a legacy of HTTP/1.0 and hasn't been needed since Internet Explorer 5, or Netscape 4.7. Unless you expect some of your users to be using IE5: it's safe to stop using it.


  • Expires: [date] (deprecated - HTTP 1.0)
  • Pragma: no-cache (deprecated - HTTP 1.0)
  • Cache-Control: max-age=[seconds]
  • Cache-Control: no-cache (must re-validate the cached copy every time)

And the conditional requests:

  • Etag (entity tag) based conditional requests
    • Server: Etag: W/“1d2e7–1648e509289”
    • Client: If-None-Match: W/“1d2e7–1648e509289”
    • Server: 304 Not Modified
  • Modified date based conditional requests
    • Server: last-modified: Thu, 09 May 2019 19:15:47 GMT
    • Client: If-Modified-Since: Fri, 13 Jul 2018 10:49:23 GMT
    • Server: 304 Not Modified

last-modified: Thu, 09 May 2019 19:15:47 GMT

How to force a view refresh without having it trigger automatically from an observable?

In some circumstances it might be useful to simply remove the bindings and then re-apply:

ko.cleanNode(document.getElementById(element_id))
ko.applyBindings(viewModel, document.getElementById(element_id))

Move existing, uncommitted work to a new branch in Git

If you have been making commits on your main branch while you coded, but you now want to move those commits to a different branch, this is a quick way:

  1. Copy your current history onto a new branch, bringing along any uncommitted changes too:

     git checkout -b <new-feature-branch>
    
  2. Now force the original "messy" branch to roll back: (without switching to it)

     git branch -f <previous-branch> <earlier-commit-id>
    

    For example:

     git branch -f master origin/master
    

    or if you had made 4 commits:

     git branch -f master HEAD~4
    

Warning: git branch -f master origin/master will reset the tracking information for that branch. So if you have configured your master branch to push to somewhere other than origin/master then that configuration will be lost.

Warning: If you rebase after branching, there is a danger that some commits may be lost, which is described here. The only way to avoid that is to create a new history using cherry-pick. That link describes the safest fool-proof method, although less convenient. (If you have uncommitted changes, you may need to git stash at the start and git stash pop at the end.)

How do I insert a drop-down menu for a simple Windows Forms app in Visual Studio 2008?

You can use a ComboBox with its ComboBoxStyle (appears as DropDownStyle in later versions) set to DropDownList. See: http://msdn.microsoft.com/en-us/library/system.windows.forms.comboboxstyle.aspx

How to change MySQL column definition?

This should do it:

ALTER TABLE test MODIFY locationExpert VARCHAR(120)