Programs & Examples On #Documentpaginator

pandas: best way to select all columns whose names start with X

The simplest way is to use str directly on column names, there is no need for pd.Series

df.loc[:,df.columns.str.startswith("foo")]


Get records of current month

Check the MySQL Datetime Functions:

Try this:

SELECT * 
FROM tableA 
WHERE YEAR(columnName) = YEAR(CURRENT_DATE()) AND 
      MONTH(columnName) = MONTH(CURRENT_DATE());

tell pip to install the dependencies of packages listed in a requirement file

Given your comment to the question (where you say that executing the install for a single package works as expected), I would suggest looping over your requirement file. In bash:

#!/bin/sh
while read p; do
  pip install $p
done < requirements.pip

HTH!

Default Values to Stored Procedure in Oracle

Default-Values are only considered for parameters NOT given to the function.

So given a function

procedure foo( bar1 IN number DEFAULT 3,
     bar2 IN number DEFAULT 5,
     bar3 IN number DEFAULT 8 );

if you call this procedure with no arguments then it will behave as if called with

foo( bar1 => 3,
     bar2 => 5,
     bar3 => 8 );

but 'NULL' is still a parameter.

foo( 4,
     bar3 => NULL );

This will then act like

foo( bar1 => 4,
     bar2 => 5,
     bar3 => Null );

( oracle allows you to either give the parameter in order they are specified in the procedure, specified by name, or first in order and then by name )

one way to treat NULL the same as a default value would be to default the value to NULL

procedure foo( bar1 IN number DEFAULT NULL,
     bar2 IN number DEFAULT NULL,
     bar3 IN number DEFAULT NULL );

and using a variable with the desired value then

procedure foo( bar1 IN number DEFAULT NULL,
     bar2 IN number DEFAULT NULL,
     bar3 IN number DEFAULT NULL )
AS
     v_bar1    number := NVL( bar1, 3);
     v_bar2    number := NVL( bar2, 5);
     v_bar3    number := NVL( bar3, 8);

Node / Express: EADDRINUSE, Address already in use - Kill server

I had the same problem and I found out that it was the nodemon problem. First I was using this script to start my process:

{"dev": "nodemon -r dotenv/config app.js"}

the app boots correctly, but as soon as any file changes, nodemon can't restart it. In the meantime, the app still continues to run in the background. If I do Ctrl+C, it quits, but there's no more process on port 3000, so killing it by port fuser -k 3000/tcp doesn't do anything.

And, I was using .env port in app.js file.

const port = process.env.PORT || 3000;

So, I changed the port value to 3000 only and it worked.

const port = 3000;

I had to find another way to load .env file, but this solved the issue for me. Hope that helps.

With form validation: why onsubmit="return functionname()" instead of onsubmit="functionname()"?

When onsubmit (or any other event) is supplied as an HTML attribute, the string value of the attribute (e.g. "return validate();") is injected as the body of the actual onsubmit handler function when the DOM object is created for the element.

Here's a brief proof in the browser console:

var p = document.createElement('p');
p.innerHTML = '<form onsubmit="return validate(); // my statement"></form>';
var form = p.childNodes[0];

console.log(typeof form.onsubmit);
// => function

console.log(form.onsubmit.toString());
// => function onsubmit(event) {
//      return validate(); // my statement
//    }

So in case the return keyword is supplied in the injected statement; when the submit handler is triggered the return value received from validate function call will be passed over as the return value of the submit handler and thus take effect on controlling the submit behavior of the form.

Without the supplied return in the string, the generated onsubmit handler would not have an explicit return statement and when triggered it would return undefined (the default function return value) irrespective of whether validate() returns true or false and the form would be submitted in both cases.

How can I run specific migration in laravel

use this command php artisan migrate --path=/database/migrations/my_migration.php it worked for me..

Jquery $.ajax fails in IE on cross domain calls

I had a similar problem in IE9 where some CORS calls were aborting, while others weren't. My app is also dependent on a promise interface, so the XDomainRequest suggestions above weren't EXACTLY what I needed, so I added a deferred into my service.get workaround for IE9. Hopefully it can be useful to someone else running across this problem. :

    get: function (url) {
        if ('XDomainRequest' in window && window.XDomainRequest !== null) {
            var deferred = $.Deferred();
            var xdr      = new XDomainRequest();

            xdr.open("get", url);

            xdr.onload = function() {
              json = xdr.responseText;
              parsed_json = $.parseJSON(json);
              deferred.resolve(parsed_json);
            }

            xdr.send();
            return deferred;
        } else {
            return $.ajax({
                url: url,
                type: 'GET',
                dataType: 'json',
                crossDomain: true
            });
        }
    }

How to make a GUI for bash scripts?

You could use dialog that is ncurses based or whiptail that is slang based.

I think both have GTK or Tcl/Tk bindings.

Reading value from console, interactively

A common use case would probably be for the app to display a generic prompt and handle it in a switch statement.

You could get a behaviour equivalent to a while loop by using a helper function that would call itself in the callback:

const readline = require('readline');
const rl = readline.createInterface(process.stdin, process.stdout);

function promptInput (prompt, handler)
{
    rl.question(prompt, input =>
    {
        if (handler(input) !== false)
        {
            promptInput(prompt, handler);
        }
        else
        {
            rl.close();
        }
    });
}

promptInput('app> ', input =>
{
    switch (input)
    {
        case 'my command':
            // handle this command
            break;
        case 'exit':
            console.log('Bye!');
            return false;
    }
});

You could pass an empty string instead of 'app> ' if your app already prints something to the screen outside of this loop.

XAMPP - Error: MySQL shutdown unexpectedly

just run your xammp as an administrator, it works

Grant all on a specific schema in the db to a group role in PostgreSQL

My answer is similar to this one on ServerFault.com.

To Be Conservative

If you want to be more conservative than granting "all privileges", you might want to try something more like these.

GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO some_user_;
GRANT EXECUTE ON ALL FUNCTIONS IN SCHEMA public TO some_user_;

The use of public there refers to the name of the default schema created for every new database/catalog. Replace with your own name if you created a schema.

Access to the Schema

To access a schema at all, for any action, the user must be granted "usage" rights. Before a user can select, insert, update, or delete, a user must first be granted "usage" to a schema.

You will not notice this requirement when first using Postgres. By default every database has a first schema named public. And every user by default has been automatically been granted "usage" rights to that particular schema. When adding additional schema, then you must explicitly grant usage rights.

GRANT USAGE ON SCHEMA some_schema_ TO some_user_ ;

Excerpt from the Postgres doc:

For schemas, allows access to objects contained in the specified schema (assuming that the objects' own privilege requirements are also met). Essentially this allows the grantee to "look up" objects within the schema. Without this permission, it is still possible to see the object names, e.g. by querying the system tables. Also, after revoking this permission, existing backends might have statements that have previously performed this lookup, so this is not a completely secure way to prevent object access.

For more discussion see the Question, What GRANT USAGE ON SCHEMA exactly do?. Pay special attention to the Answer by Postgres expert Craig Ringer.

Existing Objects Versus Future

These commands only affect existing objects. Tables and such you create in the future get default privileges until you re-execute those lines above. See the other answer by Erwin Brandstetter to change the defaults thereby affecting future objects.

LoDash: Get an array of values from an array of object properties

With pure JS:

var userIds = users.map( function(obj) { return obj.id; } );

How to specify "does not contain" in dplyr filter

Note that %in% returns a logical vector of TRUE and FALSE. To negate it, you can use ! in front of the logical statement:

SE_CSVLinelist_filtered <- filter(SE_CSVLinelist_clean, 
 !where_case_travelled_1 %in% 
   c('Outside Canada','Outside province/territory of residence but within Canada'))

Regarding your original approach with -c(...), - is a unary operator that "performs arithmetic on numeric or complex vectors (or objects which can be coerced to them)" (from help("-")). Since you are dealing with a character vector that cannot be coerced to numeric or complex, you cannot use -.

Make Error 127 when running trying to compile code

Error 127 means one of two things:

  1. file not found: the path you're using is incorrect. double check that the program is actually in your $PATH, or in this case, the relative path is correct -- remember that the current working directory for a random terminal might not be the same for the IDE you're using. it might be better to just use an absolute path instead.
  2. ldso is not found: you're using a pre-compiled binary and it wants an interpreter that isn't on your system. maybe you're using an x86_64 (64-bit) distro, but the prebuilt is for x86 (32-bit). you can determine whether this is the answer by opening a terminal and attempting to execute it directly. or by running file -L on /bin/sh (to get your default/native format) and on the compiler itself (to see what format it is).

if the problem is (2), then you can solve it in a few diff ways:

  1. get a better binary. talk to the vendor that gave you the toolchain and ask them for one that doesn't suck.
  2. see if your distro can install the multilib set of files. most x86_64 64-bit distros allow you to install x86 32-bit libraries in parallel.
  3. build your own cross-compiler using something like crosstool-ng.
  4. you could switch between an x86_64 & x86 install, but that seems a bit drastic ;).

Order by in Inner Join

In SQL, the order of the output is not defined unless you specify it in the ORDER BY clause.

Try this:

SELECT  *
FROM    one
JOIN    two
ON      one.one_name = two.one_name
ORDER BY
        one.id

In bash, how to store a return value in a variable?

Use the special bash variable "$?" like so:

function_output=$(my_function)
function_return_value=$?

What's the best way to build a string of delimited items in Java?

You should probably use a StringBuilder with the append method to construct your result, but otherwise this is as good of a solution as Java has to offer.

jQueryUI modal dialog does not show close button (x)

a solution can be having the close inside your modal

take a look at this simple example

Calling a javascript function in another js file

I have had same problem. I have had defined functions inside jquery document ready function.

$(document).ready(function() {
   function xyz()
   {
       //some code
   }
});

And this function xyz() I have called in another file. This doesn't working :) You have to defined function above document ready.

Convert Xml to DataTable

I would first create a DataTable with the columns that you require, then populate it via Linq-to-XML.

You could use a Select query to create an object that represents each row, then use the standard approach for creating DataRows for each item ...

class Quest
{
    public string Answer1;
    public string Answer2;
    public string Answer3;
    public string Answer4;
}

public static void Main()
{
    var doc = XDocument.Load("filename.xml");

    var rows = doc.Descendants("QuestId").Select(el => new Quest
    {
        Answer1 = el.Element("Answer1").Value,
        Answer2 = el.Element("Answer2").Value,
        Answer3 = el.Element("Answer3").Value,
        Answer4 = el.Element("Answer4").Value,
    });

    // iterate over the rows and add to DataTable ...

}

Accessing post variables using Java Servlets

Here's a simple example. I didn't get fancy with the html or the servlet, but you should get the idea.

I hope this helps you out.

<html>
<body>
<form method="post" action="/myServlet">
<input type="text" name="username" />
<input type="password" name="password" />
<input type="submit" />
</form>
</body>
</html>

Now for the Servlet

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class MyServlet extends HttpServlet {
  public void doPost(HttpServletRequest request,
                    HttpServletResponse response)
      throws ServletException, IOException {

    String userName = request.getParameter("username");
    String password = request.getParameter("password");
    ....
    ....
  }
}

Python: avoid new line with print command

In Python 2.x just put a , at the end of your print statement. If you want to avoid the blank space that print puts between items, use sys.stdout.write.

import sys

sys.stdout.write('hi there')
sys.stdout.write('Bob here.')

yields:

hi thereBob here.

Note that there is no newline or blank space between the two strings.

In Python 3.x, with its print() function, you can just say

print('this is a string', end="")
print(' and this is on the same line')

and get:

this is a string and this is on the same line

There is also a parameter called sep that you can set in print with Python 3.x to control how adjoining strings will be separated (or not depending on the value assigned to sep)

E.g.,

Python 2.x

print 'hi', 'there'

gives

hi there

Python 3.x

print('hi', 'there', sep='')

gives

hithere

What do $? $0 $1 $2 mean in shell script?

These are positional arguments of the script.

Executing

./script.sh Hello World

Will make

$0 = ./script.sh
$1 = Hello
$2 = World

Note

If you execute ./script.sh, $0 will give output ./script.sh but if you execute it with bash script.sh it will give output script.sh.

What is the strict aliasing rule?

As addendum to what Doug T. already wrote, here is a simple test case which probably triggers it with gcc :

check.c

#include <stdio.h>

void check(short *h,long *k)
{
    *h=5;
    *k=6;
    if (*h == 5)
        printf("strict aliasing problem\n");
}

int main(void)
{
    long      k[1];
    check((short *)k,k);
    return 0;
}

Compile with gcc -O2 -o check check.c . Usually (with most gcc versions I tried) this outputs "strict aliasing problem", because the compiler assumes that "h" cannot be the same address as "k" in the "check" function. Because of that the compiler optimizes the if (*h == 5) away and always calls the printf.

For those who are interested here is the x64 assembler code, produced by gcc 4.6.3, running on ubuntu 12.04.2 for x64:

movw    $5, (%rdi)
movq    $6, (%rsi)
movl    $.LC0, %edi
jmp puts

So the if condition is completely gone from the assembler code.

What do 1.#INF00, -1.#IND00 and -1.#IND mean?

For anyone wondering about the difference between -1.#IND00 and -1.#IND (which the question specifically asked, and none of the answers address):

-1.#IND00

This specifically means a non-zero number divided by zero, e.g. 3.14 / 0 (source)

-1.#IND (a synonym for NaN)

This means one of four things (see wiki from source):

1) sqrt or log of a negative number

2) operations where both variables are 0 or infinity, e.g. 0 / 0

3) operations where at least one variable is already NaN, e.g. NaN * 5

4) out of range trig, e.g. arcsin(2)

C++ template constructor

Here's a workaround.

Make a template subclass B of A. Do the template-argument-independent part of the construction in A's constructor. Do the template-argument-dependent part in B's constructor.

Vertically centering Bootstrap modal window

e(document).on('show.bs.modal', function () {
        if($winWidth < $(window).width()){
            $('body.modal-open,.navbar-fixed-top,.navbar-fixed-bottom').css('marginRight',$(window).width()-$winWidth)
        }
    });
    e(document).on('hidden.bs.modal', function () {
        $('body,.navbar-fixed-top,.navbar-fixed-bottom').css('marginRight',0)
    });

Is there a limit on how much JSON can hold?

There is no fixed limit on how large a JSON data block is or any of the fields.

There are limits to how much JSON the JavaScript implementation of various browsers can handle (e.g. around 40MB in my experience). See this question for example.

How do I make the method return type generic?

Not really, because as you say, the compiler only knows that callFriend() is returning an Animal, not a Dog or Duck.

Can you not add an abstract makeNoise() method to Animal that would be implemented as a bark or quack by its subclasses?

How to initialize an array in Java?

If you want to initialize an array in a constructor, you can't use those array initializer like.

data= {10,20,30,40,50,60,71,80,90,91};

Just change it to

data = new int[] {10,20,30,40,50,60,71,80,90,91};

You don't have to specify the size with data[10] = new int[] { 10,...,91} Just declare the property / field with int[] data; and initialize it like above. The corrected version of your code would look like the following:

public class Array {

    int[] data;

    public Array() {
        data = new int[] {10,20,30,40,50,60,71,80,90,91};
    }

}

As you see the bracket are empty. There isn't any need to tell the size between the brackets, because the initialization and its size are specified by the count of the elements between the curly brackets.

Gson library in Android Studio

There is no need of adding JAR to your project by yourself, just add dependency in build.gradle (Module lavel). ALSO always try to use the upgraded version, as of now is

dependencies {
  implementation 'com.google.code.gson:gson:2.8.5'
}

As every incremental version has some bugs fixes or up-gradations as mentioned here

ValueError: cannot reshape array of size 30470400 into shape (50,1104,104)

It seems that there is a typo, since 1104*1104*50=60940800 and you are trying to reshape to dimensions 50,1104,104. So it seems that you need to change 104 to 1104.

How can javascript upload a blob?

Try this

var fd = new FormData();
fd.append('fname', 'test.wav');
fd.append('data', soundBlob);
$.ajax({
    type: 'POST',
    url: '/upload.php',
    data: fd,
    processData: false,
    contentType: false
}).done(function(data) {
       console.log(data);
});

You need to use the FormData API and set the jQuery.ajax's processData and contentType to false.

SQL for ordering by number - 1,2,3,4 etc instead of 1,10,11,12

This problem is just because you have declared the column in CHAR, VARCHAR or TEXT datatype. Just change the datatype to INT, BIGINT etc. This is will solved the problem of your custom ordering.

Create a remote branch on GitHub

It looks like github has a simple UI for creating branches. I opened the branch drop-down and it prompts me to "Find or create a branch ...". Type the name of your new branch, then click the "create" button that appears.

To retrieve your new branch from github, use the standard git fetch command.

create branch github ui

I'm not sure this will help your underlying problem, though, since the underlying data being pushed to the server (the commit objects) is the same no matter what branch it's being pushed to.

In Java, what is the best way to determine the size of an object?

I accidentally found a java class "jdk.nashorn.internal.ir.debug.ObjectSizeCalculator", already in jdk, which is easy to use and seems quite useful for determining the size of an object.

System.out.println(ObjectSizeCalculator.getObjectSize(new gnu.trove.map.hash.TObjectIntHashMap<String>(12000, 0.6f, -1)));
System.out.println(ObjectSizeCalculator.getObjectSize(new HashMap<String, Integer>(100000)));
System.out.println(ObjectSizeCalculator.getObjectSize(3));
System.out.println(ObjectSizeCalculator.getObjectSize(new int[]{1, 2, 3, 4, 5, 6, 7 }));
System.out.println(ObjectSizeCalculator.getObjectSize(new int[100]));

results:

164192
48
16
48
416

Maven – Always download sources and javadocs

As @xecaps12 said, the simplest/efficient approach is to change your Maven settings file (~/.m2/settings.xml) but if it is a default settings for you, you can also set it like that

<profile>
  <id>downloadSources</id>
  <activation>
    <activeByDefault>true</activeByDefault>
  </activation>
  <properties>
      <downloadSources>true</downloadSources>
      <downloadJavadocs>true</downloadJavadocs>
  </properties>
</profile>

Laravel Check If Related Model Exists

A Relation object passes unknown method calls through to an Eloquent query Builder, which is set up to only select the related objects. That Builder in turn passes unknown method calls through to its underlying query Builder.

This means you can use the exists() or count() methods directly from a relation object:

$model->relation()->exists(); // bool: true if there is at least one row
$model->relation()->count(); // int: number of related rows

Note the parentheses after relation: ->relation() is a function call (getting the relation object), as opposed to ->relation which a magic property getter set up for you by Laravel (getting the related object/objects).

Using the count method on the relation object (that is, using the parentheses) will be much faster than doing $model->relation->count() or count($model->relation) (unless the relation has already been eager-loaded) since it runs a count query rather than pulling all of the data for any related objects from the database, just to count them. Likewise, using exists doesn't need to pull model data either.

Both exists() and count() work on all relation types I've tried, so at least belongsTo, hasOne, hasMany, and belongsToMany.

Validation failed for one or more entities. See 'EntityValidationErrors' property for more details

just Check Your Database Table Field Length . Your Input Text Is Greater than the length of column field data type length

Python + Django page redirect

If you want to redirect a whole subfolder, the url argument in RedirectView is actually interpolated, so you can do something like this in urls.py:

from django.conf.urls.defaults import url
from django.views.generic import RedirectView

urlpatterns = [
    url(r'^old/(?P<path>.*)$', RedirectView.as_view(url='/new_path/%(path)s')),
]

The ?P<path> you capture will be fed into RedirectView. This captured variable will then be replaced in the url argument you gave, giving us /new_path/yay/mypath if your original path was /old/yay/mypath.

You can also do ….as_view(url='…', query_string=True) if you want to copy the query string over as well.

jQuery function to get all unique elements from an array?

Walk the array and push items into a hash as you come across them. Cross-reference the hash for each new element.

Note that this will ONLY work properly for primitives (strings, numbers, null, undefined, NaN) and a few objects that serialize to the same thing (functions, strings, dates, possibly arrays depending on content). Hashes in this will collide as they all serialize to the same thing, e.g. "[object Object]"

Array.prototype.distinct = function(){
   var map = {}, out = [];

   for(var i=0, l=this.length; i<l; i++){
      if(map[this[i]]){ continue; }

      out.push(this[i]);
      map[this[i]] = 1;
   }

   return out;
}

There's also no reason you can't use jQuery.unique. The only thing I don't like about it is that it destroys the ordering of your array. Here's the exact code for it if you're interested:

Sizzle.uniqueSort = function(results){
    if ( sortOrder ) {
        hasDuplicate = baseHasDuplicate;
        results.sort(sortOrder);

        if ( hasDuplicate ) {
            for ( var i = 1; i < results.length; i++ ) {
                if ( results[i] === results[i-1] ) {
                    results.splice(i--, 1);
                }
            }
        }
    }

    return results;
};

C library function to perform sort

I think you are looking for qsort.
qsort function is the implementation of quicksort algorithm found in stdlib.h in C/C++.

Here is the syntax to call qsort function:

void qsort(void *base, size_t nmemb, size_t size,int (*compar)(const void *, const void *));

List of arguments:

base: pointer to the first element or base address of the array
nmemb: number of elements in the array
size: size in bytes of each element
compar: a function that compares two elements

Here is a code example which uses qsort to sort an array:

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

int arr[] = { 33, 12, 6, 2, 76 };

// compare function, compares two elements
int compare (const void * num1, const void * num2) {
   if(*(int*)num1 > *(int*)num2)
    return 1;
   else
    return -1;
}

int main () {
   int i;

   printf("Before sorting the array: \n");
   for( i = 0 ; i < 5; i++ ) {
      printf("%d ", arr[i]);
   }
   // calling qsort
   qsort(arr, 5, sizeof(int), compare);

   printf("\nAfter sorting the array: \n");
   for( i = 0 ; i < 5; i++ ) {   
      printf("%d ", arr[i]);
   }
  
   return 0;
}

You can type man 3 qsort in Linux/Mac terminal to get a detailed info about qsort.
Link to qsort man page

How to validate domain name in PHP?

Check the php function checkdnsrr

function validate_email($email){

   $exp = "^[a-z\'0-9]+([._-][a-z\'0-9]+)*@([a-z0-9]+([._-][a-z0-9]+))+$";

   if(eregi($exp,$email)){

      if(checkdnsrr(array_pop(explode("@",$email)),"MX")){
        return true;
      }else{
        return false;
      }

   }else{

      return false;

   }   
}

Caused By: java.lang.NoClassDefFoundError: org/apache/log4j/Logger

java.lang.ClassNotFoundException is indicate that class is not found in class path. it could be the version of log4j is not compatible. check for different log4j version.

Go build: "Cannot find package" (even though GOPATH is set)

Edit: since you meant GOPATH, see fasmat's answer (upvoted)

As mentioned in "How do I make go find my package?", you need to put a package xxx in a directory xxx.

See the Go language spec:

package math

A set of files sharing the same PackageName form the implementation of a package.
An implementation may require that all source files for a package inhabit the same directory.

The Code organization mentions:

When building a program that imports the package "widget" the go command looks for src/pkg/widget inside the Go root, and then—if the package source isn't found there—it searches for src/widget inside each workspace in order.

(a "workspace" is a path entry in your GOPATH: that variable can reference multiple paths for your 'src, bin, pkg' to be)


(Original answer)

You also should set GOPATH to ~/go, not GOROOT, as illustrated in "How to Write Go Code".

The Go path is used to resolve import statements. It is implemented by and documented in the go/build package.

The GOPATH environment variable lists places to look for Go code.
On Unix, the value is a colon-separated string.
On Windows, the value is a semicolon-separated string.
On Plan 9, the value is a list.

That is different from GOROOT:

The Go binary distributions assume they will be installed in /usr/local/go (or c:\Go under Windows), but it is possible to install them in a different location.
If you do this, you will need to set the GOROOT environment variable to that directory when using the Go tools.

What is process.env.PORT in Node.js?

When hosting your application on another service (like Heroku, Nodejitsu, and AWS), your host may independently configure the process.env.PORT variable for you; after all, your script runs in their environment.

Amazon's Elastic Beanstalk does this. If you try to set a static port value like 3000 instead of process.env.PORT || 3000 where 3000 is your static setting, then your application will result in a 500 gateway error because Amazon is configuring the port for you.

This is a minimal Express application that will deploy on Amazon's Elastic Beanstalk:

var express = require('express');
var app = express();

app.get('/', function (req, res) {
  res.send('Hello World!');
});

// use port 3000 unless there exists a preconfigured port
var port = process.env.PORT || 3000;

app.listen(port);

How can I extract a number from a string in JavaScript?

And this is a snippet which extracts prices with currency and formatting:

var price = "£1,739.12";
parseFloat(price.replace( /[^\d\.]*/g, '')); // 1739.12

How to set default value to all keys of a dict object in python?

Not after creating it, no. But you could use a defaultdict in the first place, which sets default values when you initialize it.

What is an .inc and why use it?

Generally means that its a file that needs to be included and does not make standalone script in itself.

This is a convention not a programming technique.

Although if your web server is not configured properly it could expose files with extensions like .inc.

Load CSV file with Spark

This is in-line with what JP Mercier initially suggested about using Pandas, but with a major modification: If you read data into Pandas in chunks, it should be more malleable. Meaning, that you can parse a much larger file than Pandas can actually handle as a single piece and pass it to Spark in smaller sizes. (This also answers the comment about why one would want to use Spark if they can load everything into Pandas anyways.)

from pyspark import SparkContext
from pyspark.sql import SQLContext
import pandas as pd

sc = SparkContext('local','example')  # if using locally
sql_sc = SQLContext(sc)

Spark_Full = sc.emptyRDD()
chunk_100k = pd.read_csv("Your_Data_File.csv", chunksize=100000)
# if you have headers in your csv file:
headers = list(pd.read_csv("Your_Data_File.csv", nrows=0).columns)

for chunky in chunk_100k:
    Spark_Full +=  sc.parallelize(chunky.values.tolist())

YourSparkDataFrame = Spark_Full.toDF(headers)
# if you do not have headers, leave empty instead:
# YourSparkDataFrame = Spark_Full.toDF()
YourSparkDataFrame.show()

MySQL - UPDATE query with LIMIT

You can do it with a LIMIT, just not with a LIMIT and an OFFSET.

Can't access Eclipse marketplace

Im my case, I changed the default browser to internet explorer from google chrome and the issue was resolved.

Where is Maven's settings.xml located on Mac OS?

->It is located in $MAVEN_HOME/conf/settings.xml... where $MAVEN_HOME is your environmental variable of Maven that you have downloaded. Else you can do like this also.. ->Path to Maven can also be found from /etc/bashrc file in mac. Get Path to Maven from that file and in that Maven directory you can find conf/ directory inside that directory you can find settings.xml of maven

Volatile boolean vs AtomicBoolean

Volatile boolean vs AtomicBoolean

The Atomic* classes wrap a volatile primitive of the same type. From the source:

public class AtomicLong extends Number implements java.io.Serializable {
   ...
   private volatile long value;
   ...
   public final long get() {
       return value;
   }
   ...
   public final void set(long newValue) {
       value = newValue;
   }

So if all you are doing is getting and setting a Atomic* then you might as well just have a volatile field instead.

What does AtomicBoolean do that a volatile boolean cannot achieve?

Atomic* classes give you methods that provide more advanced functionality such as incrementAndGet() for numbers, compareAndSet() for booleans, and other methods that implement multiple operations (get/increment/set, test/set) without locking. That's why the Atomic* classes are so powerful.

For example, if multiple threads are using the following code using ++, there will be race conditions because ++ is actually: get, increment, and set.

private volatile value;
...
// race conditions here
value++;

However, the following code will work in a multi-threaded environment safely without locks:

private final AtomicLong value = new AtomicLong();
...
value.incrementAndGet();

It's also important to note that wrapping your volatile field using Atomic* class is a good way to encapsulate the critical shared resource from an object standpoint. This means that developers can't just deal with the field assuming it is not shared possibly injecting problems with a field++; or other code that introducing race conditions.

How do I refresh a DIV content?

To reload a section of the page, you could use jquerys load with the current url and specify the fragment you need, which would be the same element that load is called on, in this case #here:

function updateDiv()
{ 
    $( "#here" ).load(window.location.href + " #here" );
}
  • Don't disregard the space within the load element selector: + " #here"

This function can be called within an interval, or attached to a click event

What is the "double tilde" (~~) operator in JavaScript?

~(5.5)   // => -6
~(-6)    // => 5
~~5.5    // => 5  (same as Math.floor(5.5))
~~(-5.5) // => -5 (NOT the same as Math.floor(-5.5), which would give -6 )

For more info, see:

Center a column using Twitter Bootstrap 3

Simply add the following to your custom CSS file. Editing Bootstrap CSS files directly is not recommended and cancels your ability to use a CDN.

.center-block {
    float: none !important
}

Why?

Bootstrap CSS (version 3.7 and lower) uses margin: 0 auto;, but it gets overridden by the float property of the size container.

PS:

After you add this class, don't forget to set classes by the right order.

<div class="col-md-6 center-block">Example</div>

Remove the last character in a string in T-SQL?

select left('TEST STRING', len('TEST STRING')-1)

Meaning of Choreographer messages in Logcat

Choreographer lets apps to connect themselves to the vsync, and properly time things to improve performance.

Android view animations internally uses Choreographer for the same purpose: to properly time the animations and possibly improve performance.

Since Choreographer is told about every vsync events, it can tell if one of the Runnables passed along by the Choreographer.post* apis doesn't finish in one frame's time, causing frames to be skipped.

In my understanding Choreographer can only detect the frame skipping. It has no way of telling why this happens.

The message "The application may be doing too much work on its main thread." could be misleading.

No converter found capable of converting from type to type

You may already have this working, but the I created a test project with the classes below allowing you to retrieve the data into an entity, projection or dto.

Projection - this will return the code column twice, once named code and also named text (for example only). As you say above, you don't need the @Projection annotation

import org.springframework.beans.factory.annotation.Value;

public interface DeadlineTypeProjection {
    String getId();

    // can get code and or change name of getter below
    String getCode();

    // Points to the code attribute of entity class
    @Value(value = "#{target.code}")
    String getText();
}

DTO class - not sure why this was inheriting from your base class and then redefining the attributes. JsonProperty just an example of how you'd change the name of the field passed back to a REST end point

import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.AllArgsConstructor;
import lombok.Data;

@Data
@AllArgsConstructor
public class DeadlineType {
    String id;

    // Use this annotation if you need to change the name of the property that is passed back from controller
    // Needs to be called code to be used in Repository
    @JsonProperty(value = "text")
    String code;

}

Entity class

import lombok.Data;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Data
@Entity
@Table(name = "deadline_type")
public class ABDeadlineType {

    @Id
    private String id;
    private String code;
}

Repository - your repository extends JpaRepository<ABDeadlineType, Long> but the Id is a String, so updated below to JpaRepository<ABDeadlineType, String>

import com.example.demo.entity.ABDeadlineType;
import com.example.demo.projection.DeadlineTypeProjection;
import com.example.demo.transfer.DeadlineType;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;

public interface ABDeadlineTypeRepository extends JpaRepository<ABDeadlineType, String> {

    List<ABDeadlineType> findAll();

    List<DeadlineType> findAllDtoBy();

    List<DeadlineTypeProjection> findAllProjectionBy();

}

Example Controller - accesses the repository directly to simplify code

@RequestMapping(value = "deadlinetype")
@RestController
public class DeadlineTypeController {

    private final ABDeadlineTypeRepository abDeadlineTypeRepository;

    @Autowired
    public DeadlineTypeController(ABDeadlineTypeRepository abDeadlineTypeRepository) {
        this.abDeadlineTypeRepository = abDeadlineTypeRepository;
    }

    @GetMapping(value = "/list")
    public ResponseEntity<List<ABDeadlineType>> list() {

        List<ABDeadlineType> types = abDeadlineTypeRepository.findAll();
        return ResponseEntity.ok(types);
    }

    @GetMapping(value = "/listdto")
    public ResponseEntity<List<DeadlineType>> listDto() {

        List<DeadlineType> types = abDeadlineTypeRepository.findAllDtoBy();
        return ResponseEntity.ok(types);
    }

    @GetMapping(value = "/listprojection")
    public ResponseEntity<List<DeadlineTypeProjection>> listProjection() {

        List<DeadlineTypeProjection> types = abDeadlineTypeRepository.findAllProjectionBy();
        return ResponseEntity.ok(types);
    }
}

Hope that helps

Les

Is there a cross-browser onload event when clicking the back button?

Guys, I found that JQuery has only one effect: the page is reloaded when the back button is pressed. This has nothing to do with "ready".

How does this work? Well, JQuery adds an onunload event listener.

// http://code.jquery.com/jquery-latest.js
jQuery(window).bind("unload", function() { // ...

By default, it does nothing. But somehow this seems to trigger a reload in Safari, Opera and Mozilla -- no matter what the event handler contains.

[edit(Nickolay): here's why it works that way: webkit.org, developer.mozilla.org. Please read those articles (or my summary in a separate answer below) and consider whether you really need to do this and make your page load slower for your users.]

Can't believe it? Try this:

<body onunload=""><!-- This does the trick -->
<script type="text/javascript">
    alert('first load / reload');
    window.onload = function(){alert('onload')};
</script>
<a href="http://stackoverflow.com">click me, then press the back button</a>
</body>

You will see similar results when using JQuery.

You may want to compare to this one without onunload

<body><!-- Will not reload on back button -->
<script type="text/javascript">
    alert('first load / reload');
    window.onload = function(){alert('onload')};
</script>
<a href="http://stackoverflow.com">click me, then press the back button</a>
</body>

How many concurrent AJAX (XmlHttpRequest) requests are allowed in popular browsers?

With IE6 / IE7 one can tweak the number of concurrent requests in the registry. Here's how to set it to four each.

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
"MaxConnectionsPerServer"=dword:00000004
"MaxConnectionsPer1_0Server"=dword:00000004

How to read an external local JSON file in JavaScript?

One simple workaround is to put your JSON file inside a locally running server. for that from the terminal go to your project folder and start the local server on some port number e.g 8181

python -m SimpleHTTPServer 8181

Then browsing to http://localhost:8181/ should display all of your files including the JSON. Remember to install python if you don't already have.

Can I force pip to reinstall the current version?

If you have a text file with loads of packages you need to add the -r flag

pip install --upgrade --no-deps --force-reinstall -r requirements.txt

Error 1046 No database Selected, how to resolve?

If you're trying to do this via the command line...

If you're trying to run the CREATE TABLE statement from the command line interface, you need to specify the database you're working in before executing the query:

USE your_database;

Here's the documentation.

If you're trying to do this via MySQL Workbench...

...you need to select the appropriate database/catalog in the drop down menu found above the :Object Browser: tab. You can specify the default schema/database/catalog for the connection - click the "Manage Connections" options under the SQL Development heading of the Workbench splash screen.

Addendum

This all assumes there's a database you want to create the table inside of - if not, you need to create the database before anything else:

CREATE DATABASE your_database;

How to apply `git diff` patch without Git installed?

git diff > patchfile

and

patch -p1 < patchfile

work but as many people noticed in comments and other answers patch does not understand adds, deletes and renames. There is no option but git apply patchfile if you need handle file adds, deletes and renames.


EDIT December 2015

Latest versions of patch command (2.7, released in September 2012) support most features of the "diff --git" format, including renames and copies, permission changes, and symlink diffs (but not yet binary diffs) (release announcement).

So provided one uses current/latest version of patch there is no need to use git to be able to apply its diff as a patch.

Can I have multiple primary keys in a single table?

Some people use the term "primary key" to mean exactly an integer column that gets its values generated by some automatic mechanism. For example AUTO_INCREMENT in MySQL or IDENTITY in Microsoft SQL Server. Are you using primary key in this sense?

If so, the answer depends on the brand of database you're using. In MySQL, you can't do this, you get an error:

mysql> create table foo (
  id int primary key auto_increment, 
  id2 int auto_increment
);
ERROR 1075 (42000): Incorrect table definition; 
there can be only one auto column and it must be defined as a key

In some other brands of database, you are able to define more than one auto-generating column in a table.

How to Resize image in Swift?

For Swift 5.0 and iOS 12

extension UIImage {
    func imageResized(to size: CGSize) -> UIImage {
        return UIGraphicsImageRenderer(size: size).image { _ in
            draw(in: CGRect(origin: .zero, size: size))
        }
    }
}

use:

let image = #imageLiteral(resourceName: "ic_search")
cell!.search.image = image.imageResized(to: cell!.search.frame.size)

How to copy static files to build directory with Webpack?

Above suggestions are good. But to try to answer your question directly I'd suggest using cpy-cli in a script defined in your package.json.

This example expects node to somewhere on your path. Install cpy-cli as a development dependency:

npm install --save-dev cpy-cli

Then create a couple of nodejs files. One to do the copy and the other to display a checkmark and message.

copy.js

#!/usr/bin/env node

var shelljs = require('shelljs');
var addCheckMark = require('./helpers/checkmark');
var path = require('path');

var cpy = path.join(__dirname, '../node_modules/cpy-cli/cli.js');

shelljs.exec(cpy + ' /static/* /build/', addCheckMark.bind(null, callback));

function callback() {
  process.stdout.write(' Copied /static/* to the /build/ directory\n\n');
}

checkmark.js

var chalk = require('chalk');

/**
 * Adds mark check symbol
 */
function addCheckMark(callback) {
  process.stdout.write(chalk.green(' ?'));
  callback();
}

module.exports = addCheckMark;

Add the script in package.json. Assuming scripts are in <project-root>/scripts/

...
"scripts": {
  "copy": "node scripts/copy.js",
...

To run the sript:

npm run copy

Get the current file name in gulp.src()

I'm not sure how you want to use the file names, but one of these should help:

  • If you just want to see the names, you can use something like gulp-debug, which lists the details of the vinyl file. Insert this anywhere you want a list, like so:

    var gulp = require('gulp'),
        debug = require('gulp-debug');
    
    gulp.task('examples', function() {
        return gulp.src('./examples/*.html')
            .pipe(debug())
            .pipe(gulp.dest('./build'));
    });
    
  • Another option is gulp-filelog, which I haven't used, but sounds similar (it might be a bit cleaner).

  • Another options is gulp-filesize, which outputs both the file and it's size.

  • If you want more control, you can use something like gulp-tap, which lets you provide your own function and look at the files in the pipe.

Simple C example of doing an HTTP POST and consuming the response

Handle added.
Added Host header.
Added linux / windows support, tested (XP,WIN7).
WARNING: ERROR : "segmentation fault" if no host,path or port as argument.

#include <stdio.h> /* printf, sprintf */
#include <stdlib.h> /* exit, atoi, malloc, free */
#include <unistd.h> /* read, write, close */
#include <string.h> /* memcpy, memset */
#ifdef __linux__ 
    #include <sys/socket.h> /* socket, connect */
    #include <netdb.h> /* struct hostent, gethostbyname */
    #include <netinet/in.h> /* struct sockaddr_in, struct sockaddr */
#elif _WIN32
    #include <winsock2.h>
    #include <ws2tcpip.h>
    #include <windows.h>
    #pragma comment(lib,"ws2_32.lib") //Winsock Library

#else

#endif

void error(const char *msg) { perror(msg); exit(0); }

int main(int argc,char *argv[])
{

    int i;
    struct hostent *server;
    struct sockaddr_in serv_addr;
    int bytes, sent, received, total, message_size;
    char *message, response[4096];
    int portno = atoi(argv[2])>0?atoi(argv[2]):80;
    char *host = strlen(argv[1])>0?argv[1]:"localhost";
    char *path = strlen(argv[4])>0?argv[4]:"/";
    if (argc < 5) { puts("Parameters: <host> <port> <method> <path> [<data> [<headers>]]"); exit(0); }
    /* How big is the message? */
    message_size=0;
    if(!strcmp(argv[3],"GET"))
    {
                printf("Process 1\n");
        message_size+=strlen("%s %s%s%s HTTP/1.0\r\nHost: %s\r\n");        /* method         */
        message_size+=strlen(argv[3]);                         /* path           */
        message_size+=strlen(path);                         /* headers        */
        if(argc>5)
            message_size+=strlen(argv[5]);                     /* query string   */
        for(i=6;i<argc;i++)                                    /* headers        */
            message_size+=strlen(argv[i])+strlen("\r\n");
        message_size+=strlen("\r\n");                          /* blank line     */
    }
    else
    {
                printf("Process 2\n");
        message_size+=strlen("%s %s HTTP/1.0\r\nHost: %s\r\n");
        message_size+=strlen(argv[3]);                         /* method         */
        message_size+=strlen(path);                            /* path           */
        for(i=6;i<argc;i++)                                    /* headers        */
            message_size+=strlen(argv[i])+strlen("\r\n");
        if(argc>5)
            message_size+=strlen("Content-Length: %d\r\n")+10; /* content length */
        message_size+=strlen("\r\n");                          /* blank line     */
        if(argc>5)
            message_size+=strlen(argv[5]);                     /* body           */
    }
            printf("Allocating...\n");
    /* allocate space for the message */
    message=malloc(message_size);

    /* fill in the parameters */
    if(!strcmp(argv[3],"GET"))
    {
        if(argc>5)
            sprintf(message,"%s %s%s%s HTTP/1.0\r\nHost: %s\r\n",
                strlen(argv[3])>0?argv[3]:"GET",               /* method         */
                path,                                          /* path           */
                strlen(argv[5])>0?"?":"",                      /* ?              */
                strlen(argv[5])>0?argv[5]:"",host);            /* query string   */
        else
            sprintf(message,"%s %s HTTP/1.0\r\nHost: %s\r\n",
                strlen(argv[3])>0?argv[3]:"GET",               /* method         */
                path,host);                                    /* path           */
        for(i=6;i<argc;i++)                                    /* headers        */
            {strcat(message,argv[i]);strcat(message,"\r\n");}
        strcat(message,"\r\n");                                /* blank line     */
    }
    else
    {
        sprintf(message,"%s %s HTTP/1.0\r\nHost: %s\r\n",
            strlen(argv[3])>0?argv[3]:"POST",                  /* method         */
            path,host);                                        /* path           */
        for(i=6;i<argc;i++)                                    /* headers        */
            {strcat(message,argv[i]);strcat(message,"\r\n");}
        if(argc>5)
            sprintf(message+strlen(message),"Content-Length: %d\r\n",(int)strlen(argv[5]));
        strcat(message,"\r\n");                                /* blank line     */
        if(argc>5)
            strcat(message,argv[5]);                           /* body           */
    }
    printf("Processed\n");
    /* What are we going to send? */
    printf("Request:\n%s\n",message);
        /* lookup the ip address */

    total = strlen(message);
    /* create the socket */
    #ifdef _WIN32
WSADATA wsa;
SOCKET s;

printf("\nInitialising Winsock...");
if (WSAStartup(MAKEWORD(2,2),&wsa) != 0)
{
    printf("Failed. Error Code : %d",WSAGetLastError());
    return 1;
}

printf("Initialised.\n");

//Create a socket
if((s = socket(AF_INET , SOCK_STREAM , 0 )) == INVALID_SOCKET)
{
    printf("Could not create socket : %d" , WSAGetLastError());
}

printf("Socket created.\n");

server = gethostbyname(host);
serv_addr.sin_addr.s_addr = inet_addr(server->h_addr);
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(portno);
memset(&serv_addr,0,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(portno);
memcpy(&serv_addr.sin_addr.s_addr,server->h_addr,server->h_length);
//Connect to remote server
if (connect(s , (struct sockaddr *)&serv_addr , sizeof(serv_addr)) < 0)
{
    printf("connect failed with error code : %d" , WSAGetLastError());
    return 1;
}

puts("Connected");
if( send(s , message , strlen(message) , 0) < 0)
{
    printf("Send failed with error code : %d" , WSAGetLastError());
    return 1;
}
puts("Data Send\n");

//Receive a reply from the server
if((received = recv(s , response , 2000 , 0)) == SOCKET_ERROR)
{
    printf("recv failed with error code : %d" , WSAGetLastError());
}

puts("Reply received\n");

//Add a NULL terminating character to make it a proper string before printing
response[received] = '\0';
puts(response);

closesocket(s);
WSACleanup();
    #endif
    #ifdef __linux__ 
    int sockfd;
    server = gethostbyname(host);
    if (server == NULL) error("ERROR, no such host");
        sockfd = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd < 0) error("ERROR opening socket");
        /* fill in the structure */
        memset(&serv_addr,0,sizeof(serv_addr));
        serv_addr.sin_family = AF_INET;
        serv_addr.sin_port = htons(portno);
        memcpy(&serv_addr.sin_addr.s_addr,server->h_addr,server->h_length);
                /* connect the socket */
        if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
            error("ERROR connecting");
                /* send the request */

    sent = 0;
    do {
        bytes = write(sockfd,message+sent,total-sent);
        if (bytes < 0)
            error("ERROR writing message to socket");
        if (bytes == 0)
            break;
        sent+=bytes;
    } while (sent < total);
    /* receive the response */
    memset(response, 0, sizeof(response));
    total = sizeof(response)-1;
    received = 0;
    printf("Response: \n");
    do {
       printf("%s", response);
       memset(response, 0, sizeof(response));
       bytes = recv(sockfd, response, 1024, 0);
        if (bytes < 0)
           printf("ERROR reading response from socket");
       if (bytes == 0)
           break;
       received+=bytes;
    } while (1);

    if (received == total)
        error("ERROR storing complete response from socket");

    /* close the socket */
    close(sockfd);
    #endif


    free(message);

    return 0;
}

How can I use Html.Action?

first, create a class to hold your parameters:

public class PkRk {
    public int pk { get; set; }
    public int rk { get; set; }
}

then, use the Html.Action passing the parameters:

Html.Action("PkRkAction", new { pkrk = new PkRk { pk=400, rk=500} })

and use in Controller:

public ActionResult PkRkAction(PkRk pkrk) {
    return PartialView(pkrk);
}

Best way to check for IE less than 9 in JavaScript without library

You could do it in a quick and dirty fashion with a regular expression and .match():

if (navigator.userAgent.match(/MSIE\s(?!9.0)/)) {
    // ie less than version 9
}

Disable password authentication for SSH

In file /etc/ssh/sshd_config

# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication no

Uncomment the second line, and, if needed, change yes to no.

Then run

service ssh restart

How to copy text to the client's clipboard using jQuery?

Copying to the clipboard is a tricky task to do in Javascript in terms of browser compatibility. The best way to do it is using a small flash. It will work on every browser. You can check it in this article.

Here's how to do it for Internet Explorer:

function copy (str)
{
    //for IE ONLY!
    window.clipboardData.setData('Text',str);
}

Java Runtime.getRuntime(): getting output from executing a command line program

Adapted from the previous answer:

public static String execCmdSync(String cmd, CmdExecResult callback) throws java.io.IOException, InterruptedException {
    RLog.i(TAG, "Running command:", cmd);

    Runtime rt = Runtime.getRuntime();
    Process proc = rt.exec(cmd);

    //String[] commands = {"system.exe", "-get t"};

    BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream()));
    BufferedReader stdError = new BufferedReader(new InputStreamReader(proc.getErrorStream()));

    StringBuffer stdOut = new StringBuffer();
    StringBuffer errOut = new StringBuffer();

    // Read the output from the command:
    System.out.println("Here is the standard output of the command:\n");
    String s = null;
    while ((s = stdInput.readLine()) != null) {
        System.out.println(s);
        stdOut.append(s);
    }

    // Read any errors from the attempted command:
    System.out.println("Here is the standard error of the command (if any):\n");
    while ((s = stdError.readLine()) != null) {
        System.out.println(s);
        errOut.append(s);
    }

    if (callback == null) {
        return stdInput.toString();
    }

    int exitVal = proc.waitFor();
    callback.onComplete(exitVal == 0, exitVal, errOut.toString(), stdOut.toString(), cmd);

    return stdInput.toString();
}

public interface CmdExecResult{
    void onComplete(boolean success, int exitVal, String error, String output, String originalCmd);
}

What is the (best) way to manage permissions for Docker shared volumes?

In my specific case, I was trying to build my node package with the node docker image so that I wouldn't have to install npm on the deployment server. It worked well until, outside out the container and on the host machine, I tried to move a file into the node_modules directory that the node docker image had created, to which I was denied permissions because it was owned by root. I realized that I could work around this by copying the directory out of the container onto the host machine. Via docker docs...

Files copied to the local machine are created with the UID:GID of the user which invoked the docker cp command.

This is the bash code I used to change ownership of the directory created by and within the docker container.

NODE_IMAGE=node_builder
docker run -v $(pwd)/build:/build -w="/build" --name $NODE_IMAGE node:6-slim npm i --production
# node_modules is owned by root, so we need to copy it out 
docker cp $NODE_IMAGE:/build/node_modules build/lambda 
# you might have issues trying to remove the directory "node_modules" within the shared volume "build", because it is owned by root, so remove the image and its volumes
docker rm -vf $NODE_IMAGE || true

If needed, you can remove the directory with a second docker container.

docker run -v $(pwd)/build:/build -w="/build" --name $RMR_IMAGE node:6-slim rm -r node_modules

Difference between map, applymap and apply methods in Pandas

Comparing map, applymap and apply: Context Matters

First major difference: DEFINITION

  • map is defined on Series ONLY
  • applymap is defined on DataFrames ONLY
  • apply is defined on BOTH

Second major difference: INPUT ARGUMENT

  • map accepts dicts, Series, or callable
  • applymap and apply accept callables only

Third major difference: BEHAVIOR

  • map is elementwise for Series
  • applymap is elementwise for DataFrames
  • apply also works elementwise but is suited to more complex operations and aggregation. The behaviour and return value depends on the function.

Fourth major difference (the most important one): USE CASE

  • map is meant for mapping values from one domain to another, so is optimised for performance (e.g., df['A'].map({1:'a', 2:'b', 3:'c'}))
  • applymap is good for elementwise transformations across multiple rows/columns (e.g., df[['A', 'B', 'C']].applymap(str.strip))
  • apply is for applying any function that cannot be vectorised (e.g., df['sentences'].apply(nltk.sent_tokenize))

Summarising

enter image description here

Footnotes

  1. map when passed a dictionary/Series will map elements based on the keys in that dictionary/Series. Missing values will be recorded as NaN in the output.
  2. applymap in more recent versions has been optimised for some operations. You will find applymap slightly faster than apply in some cases. My suggestion is to test them both and use whatever works better.

  3. map is optimised for elementwise mappings and transformation. Operations that involve dictionaries or Series will enable pandas to use faster code paths for better performance.

  4. Series.apply returns a scalar for aggregating operations, Series otherwise. Similarly for DataFrame.apply. Note that apply also has fastpaths when called with certain NumPy functions such as mean, sum, etc.

How to create a file in a directory in java?

String path = "C:"+File.separator+"hello";
String fname= path+File.separator+"abc.txt";
    File f = new File(path);
    File f1 = new File(fname);

    f.mkdirs() ;
    try {
        f1.createNewFile();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

This should create a new file inside a directory

php/mySQL on XAMPP: password for phpMyAdmin and mysql_connect different?

You need to change the password directly in the database because at mysql the users and their profiles are saved in the database.

So there are several ways. At phpMyAdmin you simple go to user admin, choose root and change the password.

What is the difference between JVM, JDK, JRE & OpenJDK?

JVM

The Java Virtual Machine (JVM) is the virtual machine that runs the Java bytecodes. The JVM doesn't understand Java source code; that's why you need compile your *.java files to obtain *.class files that contain the bytecodes understood by the JVM. It's also the entity that allows Java to be a "portable language" (write once, run anywhere). Indeed, there are specific implementations of the JVM for different systems (Windows, Linux, macOS, see the Wikipedia list), the aim is that with the same bytecodes they all give the same results.

JDK and JRE

To explain the difference between JDK and JRE, the best is to read the Oracle documentation and consult the diagram:

Java Runtime Environment (JRE)

The Java Runtime Environment (JRE) provides the libraries, the Java Virtual Machine, and other components to run applets and applications written in the Java programming language. In addition, two key deployment technologies are part of the JRE: Java Plug-in, which enables applets to run in popular browsers; and Java Web Start, which deploys standalone applications over a network. It is also the foundation for the technologies in the Java 2 Platform, Enterprise Edition (J2EE) for enterprise software development and deployment. The JRE does not contain tools and utilities such as compilers or debuggers for developing applets and applications.

Java Development Kit (JDK)

The JDK is a superset of the JRE, and contains everything that is in the JRE, plus tools such as the compilers and debuggers necessary for developing applets and applications.

Note that Oracle is not the only one to provide JDKs.

OpenJDK

OpenJDK is an open-source implementation of the JDK and the base for the Oracle JDK. There is almost no difference between the Oracle JDK and the OpenJDK.

The differences are stated in this blog:

Q: What is the difference between the source code found in the OpenJDK repository, and the code you use to build the Oracle JDK?

A: It is very close - our build process for Oracle JDK releases builds on OpenJDK 7 by adding just a couple of pieces, like the deployment code, which includes Oracle's implementation of the Java Plugin and Java WebStart, as well as some closed source third party components like a graphics rasterizer, some open source third party components, like Rhino, and a few bits and pieces here and there, like additional documentation or third party fonts. Moving forward, our intent is to open source all pieces of the Oracle JDK except those that we consider commercial features such as JRockit Mission Control (not yet available in Oracle JDK), and replace encumbered third party components with open source alternatives to achieve closer parity between the code bases.

Update for JDK 11 - An article from Donald Smith try to disambiguate the difference between Oracle JDK and Oracle's OpenJDK : https://blogs.oracle.com/java-platform-group/oracle-jdk-releases-for-java-11-and-later

How to upgrade Python version to 3.7?

On ubuntu you can add this PPA Repository and use it to install python 3.7: https://launchpad.net/~jonathonf/+archive/ubuntu/python-3.7

Or a different PPA that provides several Python versions is Deadsnakes: https://launchpad.net/~deadsnakes/+archive/ubuntu/ppa

See also here: https://askubuntu.com/questions/865554/how-do-i-install-python-3-6-using-apt-get (I know it says 3.6 in the url, but the deadsnakes ppa also contains 3.7 so you can use it for 3.7 just the same)

If you want "official" you'd have to install it from the sources from the site, get the code (which you already downloaded) and do this:

tar -xf Python-3.7.0.tar.xz
cd Python-3.7.0
./configure
make
sudo make install        <-- sudo is required.

This might take a while

How to install multiple python packages at once using pip

pip install -r requirements.txt

and in the requirements.txt file you put your modules in a list, with one item per line.

  • Django=1.3.1

  • South>=0.7

  • django-debug-toolbar

How might I extract the property values of a JavaScript object into an array?

Maybe a bit verbose, but robust and fast

var result = [];
var keys = Object.keys(myObject);
for (var i = 0, len = keys.length; i < len; i++) {
    result.push(myObject[keys[i]]);
}

SQL to find the number of distinct values in a column

SELECT COUNT(DISTINCT column_name) FROM table as column_name_count;

you've got to count that distinct col, then give it an alias.

Getting random numbers in Java

The first solution is to use the java.util.Random class:

import java.util.Random;

Random rand = new Random();

// Obtain a number between [0 - 49].
int n = rand.nextInt(50);

// Add 1 to the result to get a number from the required range
// (i.e., [1 - 50]).
n += 1;

Another solution is using Math.random():

double random = Math.random() * 49 + 1;

or

int random = (int)(Math.random() * 50 + 1);

enable or disable checkbox in html

If you specify the disabled attribute then the value you give it must be disabled. (In HTML 5 you may leave off everything except the attribute value. In HTML 4 you may leave off everything except the attribute name.)

If you do not want the control to be disabled then do not specify the attribute at all.

Disabled:

<input type="checkbox" disabled>
<input type="checkbox" disabled="disabled">

Enabled:

<input type="checkbox">

Invalid (but usually error recovered to be treated as disabled):

<input type="checkbox" disabled="1">
<input type="checkbox" disabled="true">
<input type="checkbox" disabled="false">

So, without knowing your template language, I guess you are looking for:

<td><input type="checkbox" name="repriseCheckBox" {checkStat == 1 ? disabled : }/></td>

Casting a variable using a Type variable

When it comes to casting to Enum type:

private static Enum GetEnum(Type type, int value)
    {
        if (type.IsEnum)
            if (Enum.IsDefined(type, value))
            {
                return (Enum)Enum.ToObject(type, value);
            }

        return null;
    }

And you will call it like that:

var enumValue = GetEnum(typeof(YourEnum), foo);

This was essential for me in case of getting Description attribute value of several enum types by int value:

public enum YourEnum
{
    [Description("Desc1")]
    Val1,
    [Description("Desc2")]
    Val2,
    Val3,
}

public static string GetDescriptionFromEnum(Enum value, bool inherit)
    {
        Type type = value.GetType();

        System.Reflection.MemberInfo[] memInfo = type.GetMember(value.ToString());

        if (memInfo.Length > 0)
        {
            object[] attrs = memInfo[0].GetCustomAttributes(typeof(DescriptionAttribute), inherit);
            if (attrs.Length > 0)
                return ((DescriptionAttribute)attrs[0]).Description;
        }

        return value.ToString();
    }

and then:

string description = GetDescriptionFromEnum(GetEnum(typeof(YourEnum), foo));
string description2 = GetDescriptionFromEnum(GetEnum(typeof(YourEnum2), foo2));
string description3 = GetDescriptionFromEnum(GetEnum(typeof(YourEnum3), foo3));

Alternatively (better approach), such casting could look like that:

 private static T GetEnum<T>(int v) where T : struct, IConvertible
    {
        if (typeof(T).IsEnum)
            if (Enum.IsDefined(typeof(T), v))
            {
                return (T)Enum.ToObject(typeof(T), v);
            }

        throw new ArgumentException(string.Format("{0} is not a valid value of {1}", v, typeof(T).Name));
    }

Deployment error:Starting of Tomcat failed, the server port 8080 is already in use

Change your Tomcat port address to 8084 and Shut Down Port to 8025. This will resolve your problem.

In other cases antivirus programs may cause problems. I had this problem with K7 total security. In my case K7 Firewall was blocking the 8084 port. The simple solution is to add an exception to Netbeans in K7 Firewall list.

In order to do that, open K7 and goto Settings -> Firewall Settings -> select Applications tab and find Netbeans.

Select Netbeans and click on edit link. On next screen select Grant Full Network access radio button.

Now goto Netbeans and start the server.

What do *args and **kwargs mean?

Just to clarify how to unpack the arguments, and take care of missing arguments etc.

def func(**keyword_args):
  #-->keyword_args is a dictionary
  print 'func:'
  print keyword_args
  if keyword_args.has_key('b'): print keyword_args['b']
  if keyword_args.has_key('c'): print keyword_args['c']

def func2(*positional_args):
  #-->positional_args is a tuple
  print 'func2:'
  print positional_args
  if len(positional_args) > 1:
    print positional_args[1]

def func3(*positional_args, **keyword_args):
  #It is an error to switch the order ie. def func3(**keyword_args, *positional_args):
  print 'func3:'
  print positional_args
  print keyword_args

func(a='apple',b='banana')
func(c='candle')
func2('apple','banana')#It is an error to do func2(a='apple',b='banana')
func3('apple','banana',a='apple',b='banana')
func3('apple',b='banana')#It is an error to do func3(b='banana','apple')

Java 8 Filter Array Using Lambda

even simpler, adding up to String[],

use built-in filter filter(StringUtils::isNotEmpty) of org.apache.commons.lang3

import org.apache.commons.lang3.StringUtils;

    String test = "a\nb\n\nc\n";
    String[] lines = test.split("\\n", -1);


    String[]  result = Arrays.stream(lines).filter(StringUtils::isNotEmpty).toArray(String[]::new);
    System.out.println(Arrays.toString(lines));
    System.out.println(Arrays.toString(result));

and output: [a, b, , c, ] [a, b, c]

How to concatenate string variables in Bash

Here is a concise summary of what most answers are talking about.

Let's say we have two variables and $1 is set to 'one':

set one two
a=hello
b=world

The table below explains the different contexts where we can combine the values of a and b to create a new variable, c.

Context                               | Expression            | Result (value of c)
--------------------------------------+-----------------------+---------------------
Two variables                         | c=$a$b                | helloworld
A variable and a literal              | c=${a}_world          | hello_world
A variable and a literal              | c=$1world             | oneworld
A variable and a literal              | c=$a/world            | hello/world
A variable, a literal, with a space   | c=${a}" world"        | hello world
A more complex expression             | c="${a}_one|${b}_2"   | hello_one|world_2
Using += operator (Bash 3.1 or later) | c=$a; c+=$b           | helloworld
Append literal with +=                | c=$a; c+=" world"     | hello world

A few notes:

  • enclosing the RHS of an assignment in double quotes is generally a good practice, though it is quite optional in many cases
  • += is better from a performance standpoint if a big string is being constructed in small increments, especially in a loop
  • use {} around variable names to disambiguate their expansion (as in row 2 in the table above). As seen on rows 3 and 4, there is no need for {} unless a variable is being concatenated with a string that starts with a character that is a valid first character in shell variable name, that is alphabet or underscore.

See also:

Are static methods inherited in Java?

This concept is not that easy as it looks. We can access static members without inheritance, which is HasA-relation. We can access static members by extending the parent class also. That doesn't imply that it is an ISA-relation (Inheritance). Actually static members belong to the class, and static is not an access modifier. As long as the access modifiers permit to access the static members we can use them in other classes. Like if it is public then it will be accessible inside the same package and also outside the package. For private we can't use it anywhere. For default, we can use it only within the package. But for protected we have to extend the super class. So getting the static method to other class does not depend on being Static. It depends on Access modifiers. So, in my opinion, Static members can access if the access modifiers permit. Otherwise, we can use them like we use by Hasa-relation. And has a relation is not inheritance. Again we can not override the static method. If we can use other method but cant override it, then it is HasA-relation. If we can't override them it won't be inheritance.So the writer was 100% correct.

Trim to remove white space

Why not try this?

html:

<p>
  a b c
</p>

js:

$("p").text().trim();

Extract matrix column values by matrix column name

> myMatrix <- matrix(1:10, nrow=2)
> rownames(myMatrix) <- c("A", "B")
> colnames(myMatrix) <- c("A", "B", "C", "D", "E")

> myMatrix
  A B C D  E
A 1 3 5 7  9
B 2 4 6 8 10

> myMatrix["A", "A"]
[1] 1

> myMatrix["A", ]
A B C D E 
1 3 5 7 9 

> myMatrix[, "A"]
A B 
1 2 

Export a list into a CSV or TXT file in R

You can write your For loop to individually store dataframes from a list:

allocation = list()

for(i in 1:length(allocation)){
    write.csv(data.frame(allocation[[i]]), file = paste0(path, names(allocation)[i], '.csv'))
}

HTML Agility pack - parsing tables

In my case, there is a single table which happens to be a device list from a router. If you wish to read the table using TR/TH/TD (row, header, data) instead of a matrix as mentioned above, you can do something like the following:

    List<TableRow> deviceTable = (from table in document.DocumentNode.SelectNodes(XPathQueries.SELECT_TABLE)
                                       from row in table?.SelectNodes(HtmlBody.TR)
                                       let rows = row.SelectSingleNode(HtmlBody.TR)
                                       where row.FirstChild.OriginalName != null && row.FirstChild.OriginalName.Equals(HtmlBody.T_HEADER)
                                       select new TableRow
                                       {
                                           Header = row.SelectSingleNode(HtmlBody.T_HEADER)?.InnerText,
                                           Data = row.SelectSingleNode(HtmlBody.T_DATA)?.InnerText}).ToList();
                                       }  

TableRow is just a simple object with Header and Data as properties. The approach takes care of null-ness and this case:

_x000D_
_x000D_
<tr>_x000D_
    <td width="28%">&nbsp;</td>_x000D_
</tr>
_x000D_
_x000D_
_x000D_

which is row without a header. The HtmlBody object with the constants hanging off of it are probably readily deduced but I apologize for it even still. I came from the world where if you have " in your code, it should either be constant or localizable.

When and Why to use abstract classes/methods?

At a very high level:

Abstraction of any kind comes down to separating concerns. "Client" code of an abstraction doesn't care how the contract exposed by the abstraction is fulfilled. You usually don't care if a string class uses a null-terminated or buffer-length-tracked internal storage implementation, for example. Encapsulation hides the details, but by making classes/methods/etc. abstract, you allow the implementation to change or for new implementations to be added without affecting the client code.

Has Facebook sharer.php changed to no longer accept detailed parameters?

I review your url in use:

https://www.facebook.com/sharer/sharer.php?s=100&p[title]=EXAMPLE&p[summary]=EXAMPLE&p[url]=EXAMPLE&p[images][0]=EXAMPLE

and see this differences:

  1. The sharer URL not is same.
  2. The strings are in different order. ( Do not know if this affects ).

I use this URL string:

http://www.facebook.com/sharer.php?s=100&p[url]=http://www.example.com/&p[images][0]=/images/image.jpg&p[title]=Title&p[summary]=Summary

In the "title" and "summary" section, I use the php function urlencode(); like this:

<?php echo urlencode($detail->title); ?>

And working fine for me.

Java8: sum values from specific field of the objects in a list

In Java 8 for an Obj entity with field and getField() method you can use:

List<Obj> objs ...

Stream<Obj> notNullObjs =
  objs.stream().filter(obj -> obj.getValue() != null);

Double sum = notNullObjs.mapToDouble(Obj::getField).sum();

How can I export Excel files using JavaScript?

I recommend you to generate an open format XML Excel file, is much more flexible than CSV.
Read Generating an Excel file in ASP.NET for more info

Using lambda expressions for event handlers

There are no performance implications since the compiler will translate your lambda expression into an equivalent delegate. Lambda expressions are nothing more than a language feature that the compiler translates into the exact same code that you are used to working with.

The compiler will convert the code you have to something like this:

public partial class MyPage : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //snip
        MyButton.Click += new EventHandler(delegate (Object o, EventArgs a) 
        {
            //snip
        });
    }
}

Accessing certain pixel RGB value in openCV

Try the following:

cv::Mat image = ...do some stuff...;

image.at<cv::Vec3b>(y,x); gives you the RGB (it might be ordered as BGR) vector of type cv::Vec3b

image.at<cv::Vec3b>(y,x)[0] = newval[0];
image.at<cv::Vec3b>(y,x)[1] = newval[1];
image.at<cv::Vec3b>(y,x)[2] = newval[2];

Simple parse JSON from URL on Android and display in listview

HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI(url));
HttpResponse response = client.execute(request);
BufferedReader in = new BufferedReader(new InputStreamReader(response
        .getEntity().getContent()));
String line = "";

while ((line = in.readLine()) != null) {

    JSONObject jObject = new JSONObject(line);

    if (jObject.has("name")) {

        String temp = jObject.getString("name");
        Log.e("name",temp);

    }

}

How can I use optional parameters in a T-SQL stored procedure?

This also works:

    ...
    WHERE
        (FirstName IS NULL OR FirstName = ISNULL(@FirstName, FirstName)) AND
        (LastName IS NULL OR LastName = ISNULL(@LastName, LastName)) AND
        (Title IS NULL OR Title = ISNULL(@Title, Title))

Returning a boolean value in a JavaScript function

An old thread, sure, but a popular one apparently. It's 2020 now and none of these answers have addressed the issue of unreadable code. @pimvdb's answer takes up less lines, but it's also pretty complicated to follow. For easier debugging and better readability, I should suggest refactoring the OP's code to something like this, and adopting an early return pattern, as this is likely the main reason you were unsure of why the were getting undefined:

function validatePassword() {
   const password = document.getElementById("password");
   const confirm_password = document.getElementById("password_confirm");

   if (password.value.length === 0) {
      return false;
   }

   if (password.value !== confirm_password.value) {
      return false;
   }
  
   return true;
}

Stack, Static, and Heap in C++

It's been said elaborately, just as "the short answer":

  • static variable (class)
    lifetime = program runtime (1)
    visibility = determined by access modifiers (private/protected/public)

  • static variable (global scope)
    lifetime = program runtime (1)
    visibility = the compilation unit it is instantiated in (2)

  • heap variable
    lifetime = defined by you (new to delete)
    visibility = defined by you (whatever you assign the pointer to)

  • stack variable
    visibility = from declaration until scope is exited
    lifetime = from declaration until declaring scope is exited


(1) more exactly: from initialization until deinitialization of the compilation unit (i.e. C / C++ file). Order of initialization of compilation units is not defined by the standard.

(2) Beware: if you instantiate a static variable in a header, each compilation unit gets its own copy.

Use URI builder in Android or create URL with variables

There is another way of using Uri and we can achieve the same goal

http://api.example.org/data/2.5/forecast/daily?q=94043&mode=json&units=metric&cnt=7

To build the Uri you can use this:

final String FORECAST_BASE_URL = 
    "http://api.example.org/data/2.5/forecast/daily?";
final String QUERY_PARAM = "q";
final String FORMAT_PARAM = "mode";
final String UNITS_PARAM = "units";
final String DAYS_PARAM = "cnt";

You can declare all this the above way or even inside the Uri.parse() and appendQueryParameter()

Uri builtUri = Uri.parse(FORECAST_BASE_URL)
    .buildUpon()
    .appendQueryParameter(QUERY_PARAM, params[0])
    .appendQueryParameter(FORMAT_PARAM, "json")
    .appendQueryParameter(UNITS_PARAM, "metric")
    .appendQueryParameter(DAYS_PARAM, Integer.toString(7))
    .build();

At last

URL url = new URL(builtUri.toString());

When to use static classes in C#

For C# 3.0, extension methods may only exist in top-level static classes.

String comparison technique used by Python

Take a look also at How do I sort unicode strings alphabetically in Python? where the discussion is about sorting rules given by the Unicode Collation Algorithm (http://www.unicode.org/reports/tr10/).

To reply to the comment

What? How else can ordering be defined other than left-to-right?

by S.Lott, there is a famous counter-example when sorting French language. It involves accents: indeed, one could say that, in French, letters are sorted left-to-right and accents right-to-left. Here is the counter-example: we have e < é and o < ô, so you would expect the words cote, coté, côte, côté to be sorted as cote < coté < côte < côté. Well, this is not what happens, in fact you have: cote < côte < coté < côté, i.e., if we remove "c" and "t", we get oe < ôe < oé < ôé, which is exactly right-to-left ordering.

And a last remark: you shouldn't be talking about left-to-right and right-to-left sorting but rather about forward and backward sorting.

Indeed there are languages written from right to left and if you think Arabic and Hebrew are sorted right-to-left you may be right from a graphical point of view, but you are wrong on the logical level!

Indeed, Unicode considers character strings encoded in logical order, and writing direction is a phenomenon occurring on the glyph level. In other words, even if in the word ???? the letter shin appears on the right of the lamed, logically it occurs before it. To sort this word one will first consider the shin, then the lamed, then the vav, then the mem, and this is forward ordering (although Hebrew is written right-to-left), while French accents are sorted backwards (although French is written left-to-right).

Convert a String to Modified Camel Case in Java or Title Case as is otherwise called

From commons-lang3

org.apache.commons.lang3.text.WordUtils.capitalizeFully(String str)

Inserting created_at data with Laravel

In your User model, add the following line in the User class:

public $timestamps = true;

Now, whenever you save or update a user, Laravel will automatically update the created_at and updated_at fields.


Update:
If you want to set the created at manually you should use the date format Y-m-d H:i:s. The problem is that the format you have used is not the same as Laravel uses for the created_at field.

Update: Nov 2018 Laravel 5.6 "message": "Access level to App\\Note::$timestamps must be public", Make sure you have the proper access level as well. Laravel 5.6 is public.

A url resource that is a dot (%2E)

It's actually not really clearly stated in the standard (RFC 3986) whether a percent-encoded version of . or .. is supposed to have the same this-folder/up-a-folder meaning as the unescaped version. Section 3.3 only talks about “The path segments . and ..”, without clarifying whether they match . and .. before or after pct-encoding.

Personally I find Firefox's interpretation that %2E does not mean . most practical, but unfortunately all the other browsers disagree. This would mean that you can't have a path component containing only . or ...

I think the only possible suggestion is “don't do that”! There are other path components that are troublesome too, typically due to server limitations: %2F, %00 and %5C sequences in paths may also be blocked by some web servers, and the empty path segment can also cause problems. So in general it's not possible to fit all possible byte sequences into a path component.

Python Pandas Replacing Header with Top Row

new_header = df.iloc[0] #grab the first row for the header
df = df[1:] #take the data less the header row
df.columns = new_header #set the header row as the df header

How does one add keyboard languages and switch between them in Linux Mint 16?

Mint 18.2 (Cinnamon)
Menu > Keyboard Preferences > Layouts > Options > Switching to another layout:

Menu > Keyboard Preferences > Layouts > Options > Switching to another layout

How to dynamically change the color of the selected menu item of a web page?

I'm late to this question, but it's really super easy. You just define multiple tab classes in your css file, and then load the required tab as your class in the php file while creating the LI tag.

Here's an example of doing it entirely on the server:

CSS

html ul.tabs li.activeTab1, html ul.tabs li.activeTab1 a:hover, html ul.tabs li.activeTab1 a  { 
    background: #0076B5;
    color: white;
    border-bottom: 1px solid #0076B5;
}

html ul.tabs li.activeTab2, html ul.tabs li.activeTab2 a:hover, html ul.tabs li.activeTab2 a {
    background: #008C5D;
    color: white;
    border-bottom: 1px solid #008C5D;
}

PHP

<ul class="tabs">
    <li <?php print 'class="activeTab1"' ?>>
        <a href="<?php print 'Tab1.php';?>">Tab 1</a>
    </li>

    <li <?php print 'class="activeTab2"' ?>>
        <a href="<?php print 'Tab2.php';?>">Tab 2</a>
    </li>
</ul>

Regular expression for URL validation (in JavaScript)

You can simple use type="url" in your input and the check it with checkValidity() in js

E.g:

your.html

<input id="foo" type="url">

your.js

$("#foo").on("keyup", function() {
    if (this.checkValidity()) {
        // The url is valid
    } else {
        // The url is invalid
    }
});

How to get a JavaScript object's class?

There is one another technique to identify your class You can store ref to your class in instance like bellow.

class MyClass {
    static myStaticProperty = 'default';
    constructor() {
        this.__class__ = new.target;
        this.showStaticProperty = function() {
            console.log(this.__class__.myStaticProperty);
        }
    }
}

class MyChildClass extends MyClass {
    static myStaticProperty = 'custom';
}

let myClass = new MyClass();
let child = new MyChildClass();

myClass.showStaticProperty(); // default
child.showStaticProperty(); // custom

myClass.__class__ === MyClass; // true
child.__class__ === MyClass; // false
child.__class__ === MyChildClass; // true

Copy table without copying data

Only want to clone the structure of table:

CREATE TABLE foo SELECT * FROM bar WHERE 1 = 2;

Also wants to copy the data:

CREATE TABLE foo as SELECT * FROM bar;

How to hide a column (GridView) but still access its value?

You can make the column hidden on the server side and for some reason this is different to doing it the aspx code. It can still be referenced as if it was visible. Just add this code to your OnDataBound event.

protected void gvSearchResults_DataBound(object sender, EventArgs e)
{
    GridView gridView = (GridView)sender;

    if (gridView.HeaderRow != null && gridView.HeaderRow.Cells.Count > 0)
    {
        gridView.HeaderRow.Cells[UserIdColumnIndex].Visible = false;
    }

    foreach (GridViewRow row in gvSearchResults.Rows)
    {
        row.Cells[UserIdColumnIndex].Visible = false;
    }
}

Generic Property in C#

You can make a generic class like this:

public class MyProp<T>
{
    private T _value;

    public T Value
    {
        get
        {
            // insert desired logic here
            return _value;
        }
        set
        {
            // insert desired logic here
            _value = value;
        }
    }

    public static implicit operator T(MyProp<T> value)
    {
        return value.Value;
    }

    public static implicit operator MyProp<T>(T value)
    {
        return new MyProp<T> { Value = value };
    }
}

...then use it in a class like so:

class SomeClass
{
    public MyProp<int> SomeProperty { get; set; }
}

The implicit operators means that you do not need to explicitly set or get the Value property of MyProp, but can write code to access the value in a more "natural" way:

SomeClass instance = new SomeClass();
instance.SomeProperty = 32;
int someInt = instance.SomeProperty;

How to fix the session_register() deprecated issue?

if you need a fallback function you could use this

function session_register($name){
    global $$name;
    $_SESSION[$name] = $$name;
    $$name = &$_SESSION[$name]; 
}

SQLRecoverableException: I/O Exception: Connection reset

The error occurs on some RedHat distributions. The only thing you need to do is to run your application with parameter java.security.egd=file:///dev/urandom:

java -Djava.security.egd=file:///dev/urandom [your command]

Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist

If you move your datadir, you not only need to give the new datadir permissions, but you need to ensure all parent directories have permission.

I moved my datadir to a hard drive, mounted in Ubuntu as:

/media/*user*/Data/

and my datadir was Databases.

I had to set permissions to 771 to each of the media, user and Data directories:

sudo chmod 771 *DIR*

If this does not work, another way you can get mysql to work is to change user in /etc/mysql/my.cnf to root; though there are no doubt some issues with doing that from a security perspective.

Where does the slf4j log file get saved?

slf4j is only an API. You should have a concrete implementation (for example log4j). This concrete implementation has a config file which tells you where to store the logs.

enter image description here

When slf4j catches a log messages with a logger, it is given to an appender which decides what to do with the message. By default, the ConsoleAppender displays the message in the console.

The default configuration file is :

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">

  <Appenders>
    <!-- By default => console -->
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
  </Appenders>

  <Loggers>
    <Root level="error">
      <AppenderRef ref="Console"/>
    </Root>
  </Loggers>
</Configuration>

If you put a configuration file available in the classpath, then your concrete implementation (in your case, log4j) will find and use it. See Log4J documentation.

Example of file appender :

<Appenders>
<File name="File" fileName="${filename}">
  <PatternLayout>
    <pattern>%d %p %C{1.} [%t] %m%n</pattern>
  </PatternLayout>
</File>

...
</Appenders>

Complete example with a file appender :

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">

  <Appenders>
    <File name="File" fileName="${filename}">
      <PatternLayout>
        <pattern>%d %p %C{1.} [%t] %m%n</pattern>
      </PatternLayout>
    </File>
  </Appenders>

  <Loggers>
    <Root level="error">
      <AppenderRef ref="File"/>
    </Root>
  </Loggers>

</Configuration>

Populate nested array in mongoose

If you would like to populate another level deeper, here's what you need to do:

Airlines.findById(id)
      .populate({
        path: 'flights',
        populate:[
          {
            path: 'planeType',
            model: 'Plane'
          },
          {
          path: 'destination',
          model: 'Location',
          populate: { // deeper
            path: 'state',
            model: 'State',
            populate: { // even deeper
              path: 'region',
              model: 'Region'
            }
          }
        }]
      })

How to override a JavaScript function

You can do it like this:

alert(parseFloat("1.1531531414")); // alerts the float
parseFloat = function(input) { return 1; };
alert(parseFloat("1.1531531414")); // alerts '1'

Check out a working example here: http://jsfiddle.net/LtjzW/1/

Bootstrap change carousel height

For Bootstrap 4

In the same line as image add height: 300px;

<img src="..." style="height: 300px;" class="d-block w-100" alt="image">

Javascript add leading zeroes to date

There is another approach to solve this problem, using slice in JavaScript.

var d = new Date();
var datestring = d.getFullYear() + "-" + ("0"+(d.getMonth()+1)).slice(-2) +"-"+("0" + d.getDate()).slice(-2);

the datestring return date with format as you expect: 2019-09-01

another approach is using dateformat library: https://github.com/felixge/node-dateformat

Redis: Show database size/size for keys

I usually prefer the key sampling method to troubleshoot such scenarios.

redis-cli -p 6379 -n db_number --bigkeys

Eg:-

redis-cli -p 6370 -n 0 --bigkeys

What's the easiest way to install a missing Perl module?

On Unix:

usually you start cpan in your shell:

$ cpan

and type

install Chocolate::Belgian

or in short form:

cpan Chocolate::Belgian

On Windows:

If you're using ActivePerl on Windows, the PPM (Perl Package Manager) has much of the same functionality as CPAN.pm.

Example:

$ ppm
ppm> search net-smtp
ppm> install Net-SMTP-Multipart

see How do I install Perl modules? in the CPAN FAQ

Many distributions ship a lot of perl modules as packages.

  • Debian/Ubuntu: apt-cache search 'perl$'
  • Arch Linux: pacman -Ss '^perl-'
  • Gentoo: category dev-perl

You should always prefer them as you benefit from automatic (security) updates and the ease of removal. This can be pretty tricky with the cpan tool itself.

For Gentoo there's a nice tool called g-cpan which builds/installs the module from CPAN and creates a Gentoo package (ebuild) for you.

Error 415 Unsupported Media Type: POST not reaching REST if JSON, but it does if XML

Don't return Strings in your methods but Customer objects it self and let JAXB take care of the de/serialization.

How to store an output of shell script to a variable in Unix?

You should probably re-write the script to return a value rather than output it. Instead of:

a=$( script.sh ) # Now a is a string, either "success" or "Failed"
case "$a" in
   success) echo script succeeded;;
   Failed) echo script failed;;
esac

you would be able to do:

if script.sh > /dev/null; then
    echo script succeeded
else
    echo script failed
fi

It is much simpler for other programs to work with you script if they do not have to parse the output. This is a simple change to make. Just exit 0 instead of printing success, and exit 1 instead of printing Failed. Of course, you can also print those values as well as exiting with a reasonable return value, so that wrapper scripts have flexibility in how they work with the script.

How to set a Postgresql default value datestamp like 'YYYYMM'?

It's a common misconception that you can denormalise like this for performance. Use date_trunc('month', date) for your queries and add an index expression for this if you find it running slow.

Java: How to access methods from another class

You need to somehow give class Alpha a reference to cBeta. There are three ways of doing this.

1) Give Alphas a Beta in the constructor. In class Alpha write:

public class Alpha {
   private Beta beta;
   public Alpha(Beta beta) {
     this.beta = beta; 
   }

and call cAlpha = new Alpha(cBeta) from main()

2) give Alphas a mutator that gives them a beta. In class Alpha write:

public class Alpha {
   private Beta beta;
   public void setBeta (Beta newBeta) {
     this.beta = beta;
   }

and call cAlpha = new Alpha(); cAlpha.setBeta(beta); from main(), or

3) have a beta as an argument to doSomethingAlpha. in class Alpha write:

public void DoSomethingAlpha(Beta cBeta) {
      cbeta.DoSomethingBeta()
}

Which strategy you use depends on a few things. If you want every single Alpha to have a Beta, use number 1. If you want only some Alphas to have a Beta, but you want them to hold onto their Betas indefinitely, use number 2. If you want Alphas to deal with Betas only while you're calling doSomethingAlpha, use number 3. Variable scope is complicated at first, but it gets easier when you get the hang of it. Let me know if you have any more questions!

Catching FULL exception message

I found it!

Simply print out $Error[0] for the last error message.

How to add directory to classpath in an application run profile in IntelliJ IDEA?

I am using Idea 8. in your module dependancies tab (in the project structure dialog). Add a "Module Library". There you can select a Jar Directory to add. Then make sure the run profile is using the Classpath and JDK of the correct module when it runs (this is in the run config dialog.

convert date string to mysql datetime field

I assume we are talking about doing this in Bash?

I like to use sed to load the date values into an array so I can break down each field and do whatever I want with it. The following example assumes and input format of mm/dd/yyyy...

DATE=$2
DATE_ARRAY=(`echo $DATE | sed -e 's/\// /g'`)
MONTH=(`echo ${DATE_ARRAY[0]}`)
DAY=(`echo ${DATE_ARRAY[1]}`)
YEAR=(`echo ${DATE_ARRAY[2]}`)
LOAD_DATE=$YEAR$MONTH$DAY

you also may want to read up on the date command in linux. It can be very useful: http://unixhelp.ed.ac.uk/CGI/man-cgi?date

Hope that helps... :)

-Ryan

Is the practice of returning a C++ reference variable evil?

Not only is it not evil, it is sometimes essential. For example, it would be impossible to implement the [] operator of std::vector without using a reference return value.

R Not in subset

The expression df1$id %in% idNums1 produces a logical vector. To negate it, you need to negate the whole vector:

!(df1$id %in% idNums1)

UITextField border color

Import the following class:

#import <QuartzCore/QuartzCore.h> 

//Code for setting the grey color for the border of the text field

[[textField layer] setBorderColor:[[UIColor colorWithRed:171.0/255.0
                                                   green:171.0/255.0
                                                    blue:171.0/255.0
                                                   alpha:1.0] CGColor]];

Replace 171.0 with the respective color number as required.

Open link in new tab or window

You should add the target="_blank" and rel="noopener noreferrer" in the anchor tag.

For example:

<a target="_blank" rel="noopener noreferrer" href="http://your_url_here.html">Link</a>

Adding rel="noopener noreferrer" is not mandatory, but it's a recommended security measure. More information can be found in the links below.

Source:

How to catch all exceptions in c# using try and catch?

Both approaches will catch all exceptions. There is no significant difference between your two code examples except that the first will generate a compiler warning because ex is declared but not used.

But note that some exceptions are special and will be rethrown automatically.

ThreadAbortException is a special exception that can be caught, but it will automatically be raised again at the end of the catch block.

http://msdn.microsoft.com/en-us/library/system.threading.threadabortexception.aspx


As mentioned in the comments, it is usually a very bad idea to catch and ignore all exceptions. Usually you want to do one of the following instead:

  • Catch and ignore a specific exception that you know is not fatal.

    catch (SomeSpecificException)
    {
        // Ignore this exception.
    }
    
  • Catch and log all exceptions.

    catch (Exception e)
    {
        // Something unexpected went wrong.
        Log(e);
        // Maybe it is also necessary to terminate / restart the application.
    }
    
  • Catch all exceptions, do some cleanup, then rethrow the exception.

    catch
    {
        SomeCleanUp();
        throw;
    }
    

Note that in the last case the exception is rethrown using throw; and not throw ex;.

Mysql - delete from multiple tables with one query

Normally you can't DELETE from multiple tables at once, unless you'll use JOINs as shown in other answers.

However if all yours tables starts with certain name, then this query will generate query which would do that task:

SELECT CONCAT('DELETE FROM ', GROUP_CONCAT(TABLE_NAME SEPARATOR ' WHERE user_id=123;DELETE FROM ') , 'FROM table1;' ) AS statement FROM information_schema.TABLES WHERE TABLE_NAME LIKE 'table%'

then pipe it (in shell) into mysql command for execution.

For example it'll generate something like:

DELETE FROM table1 WHERE user_id=123;
DELETE FROM table2 WHERE user_id=123;
DELETE FROM table3 WHERE user_id=123;

More shell oriented example would be:

echo "SHOW TABLES LIKE 'table%'" | mysql | tail -n +2 | xargs -L1 -I% echo "DELETE FROM % WHERE user_id=123;" | mysql -v

If you want to use only MySQL for that, you can think of more advanced query, such as this:

SET @TABLES = (SELECT GROUP_CONCAT(TABLE_NAME) FROM information_schema.TABLES WHERE TABLE_NAME LIKE 'table%');
PREPARE drop_statement FROM 'DELETE FROM @tables';
EXECUTE drop_statement USING @TABLES;
DEALLOCATE PREPARE drop_statement;

The above example is based on: MySQL – Delete/Drop all tables with specific prefix.

Goal Seek Macro with Goal as a Formula

I think your issue is that Range("H18") doesn't contain a formula. Also, you could make your code more efficient by eliminating x. Instead, change your code to

Range("H18").GoalSeek Goal:=Range("H32").Value, ChangingCell:=Range("G18")

Enable CORS in Web API 2

Make sure that you are accessing the WebAPI through HTTPS.

I also enabled cors in the WebApi.config.

var cors = new EnableCorsAttribute("*", "*", "*");
config.EnableCors(cors);

But my CORS request did not work until I used HTTPS urls.

Nginx sites-enabled, sites-available: Cannot create soft-link between config files in Ubuntu 12.04

You need to start by understanding that the target of a symlink is a pathname. And it can be absolute or relative to the directory which contains the symlink

Assuming you have foo.conf in sites-available

Try

cd sites-enabled
sudo ln -s ../sites-available/foo.conf .
ls -l

Now you will have a symlink in sites-enabled called foo.conf which has a target ../sites-available/foo.conf

Just to be clear, the normal configuration for Apache is that the config files for potential sites live in sites-available and the symlinks for the enabled sites live in sites-enabled, pointing at targets in sites-available. That doesn't quite seem to be the case the way you describe your setup, but that is not your primary problem.

If you want a symlink to ALWAYS point at the same file, regardless of the where the symlink is located, then the target should be the full path.

ln -s /etc/apache2/sites-available/foo.conf mysimlink-whatever.conf

Here is (line 1 of) the output of my ls -l /etc/apache2/sites-enabled:

lrwxrwxrwx 1 root root  26 Jun 24 21:06 000-default -> ../sites-available/default

See how the target of the symlink is relative to the directory that contains the symlink (it starts with ".." meaning go up one directory).

Hardlinks are totally different because the target of a hardlink is not a directory entry but a filing system Inode.

set dropdown value by text using jquery

$("#HowYouKnow option:eq(XXX)").attr('selected', 'selected');

where XXX is the index of the one you want.

'True' and 'False' in Python

While the other posters addressed why is True does what it does, I wanted to respond to this part of your post:

I thought Python treats anything with value as True. Why is this happening?

Coming from Java, I got tripped up by this, too. Python does not treat anything with a value as True. Witness:

if 0:
    print("Won't get here")

This will print nothing because 0 is treated as False. In fact, zero of any numeric type evaluates to False. They also made decimal work the way you'd expect:

from decimal import *
from fractions import *

if 0 or 0.0 or 0j or Decimal(0) or Fraction(0, 1):
    print("Won't get here")

Here are the other value which evaluate to False:

if None or False or '' or () or [] or {} or set() or range(0):
    print("Won't get here")

Sources:

  1. Python Truth Value Testing is Awesome
  2. Truth Value Testing (in Built-in Types)

Open directory dialog

As stated in earlier answers, FolderBrowserDialog is the class to use for this. Some people have (justifiable) concerns with the appearance and behaviour of this dialog. The good news is that it was "modernized" in NET Core 3.0, so is now a viable option for those writing either Windows Forms or WPF apps targeting that version or later (you're out of luck if still using NET Framework though).

In .NET Core 3.0, Windows Forms users [sic] a newer COM-based control that was introduced in Windows Vista: FolderBrowserDialog in NET Core 3.0

To reference System.Windows.Forms in a NET Core WPF app, it is necessary to edit the project file and add the following line:

<UseWindowsForms>true</UseWindowsForms>

This can be placed directly after the existing <UseWPF> element.

Then it's just a case of using the dialog:

using System;
using System.Windows.Forms;

...

using var dialog = new FolderBrowserDialog
{
    Description = "Time to select a folder",
    UseDescriptionForTitle = true,
    SelectedPath = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory)
        + Path.DirectorySeparatorChar,
    ShowNewFolderButton = true
};

if (dialog.ShowDialog() == DialogResult.OK)
{
    ...
}

FolderBrowserDialog has a RootFolder property that supposedly "sets the root folder where the browsing starts from" but whatever I set this to it didn't make any difference; SelectedPath seemed to be the better property to use for this purpose, however the trailing backslash is required.

Also, the ShowNewFolderButton property seems to be ignored as well, the button is always shown regardless.

Force IE10 to run in IE10 Compatibility View?

See here:

https://softwareengineering.stackexchange.com/questions/194687/how-the-compatibility-view-in-ie-works-behind-the-scenes

Use

<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE10">

I just tried it and it showed IE10 compatibility mode in the debug window.

Platform.runLater and Task in JavaFX

Use Platform.runLater(...) for quick and simple operations and Task for complex and big operations .

Example: Why Can't we use Platform.runLater(...) for long calculations (Taken from below reference).

Problem: Background thread which just counts from 0 to 1 million and update progress bar in UI.

Code using Platform.runLater(...):

final ProgressBar bar = new ProgressBar();
new Thread(new Runnable() {
    @Override public void run() {
    for (int i = 1; i <= 1000000; i++) {
        final int counter = i;
        Platform.runLater(new Runnable() {
            @Override public void run() {
                bar.setProgress(counter / 1000000.0);
            }
        });
    }
}).start();

This is a hideous hunk of code, a crime against nature (and programming in general). First, you’ll lose brain cells just looking at this double nesting of Runnables. Second, it is going to swamp the event queue with little Runnables — a million of them in fact. Clearly, we needed some API to make it easier to write background workers which then communicate back with the UI.

Code using Task :

Task task = new Task<Void>() {
    @Override public Void call() {
        static final int max = 1000000;
        for (int i = 1; i <= max; i++) {
            updateProgress(i, max);
        }
        return null;
    }
};

ProgressBar bar = new ProgressBar();
bar.progressProperty().bind(task.progressProperty());
new Thread(task).start();

it suffers from none of the flaws exhibited in the previous code

Reference : Worker Threading in JavaFX 2.0

How to decode viewstate

Here is the source code for a ViewState visualizer from Scott Mitchell's article on ViewState (25 pages)

using System;
using System.Collections;
using System.Text;
using System.IO;
using System.Web.UI;


namespace ViewStateArticle.ExtendedPageClasses
{
    /// <summary>
    /// Parses the view state, constructing a viaully-accessible object graph.
    /// </summary>
    public class ViewStateParser
    {
        // private member variables
        private TextWriter tw;
        private string indentString = "   ";

        #region Constructor
        /// <summary>
        /// Creates a new ViewStateParser instance, specifying the TextWriter to emit the output to.
        /// </summary>
        public ViewStateParser(TextWriter writer)
        {
            tw = writer;
        }
        #endregion

        #region Methods
        #region ParseViewStateGraph Methods
        /// <summary>
        /// Emits a readable version of the view state to the TextWriter passed into the object's constructor.
        /// </summary>
        /// <param name="viewState">The view state object to start parsing at.</param>
        public virtual void ParseViewStateGraph(object viewState)
        {
            ParseViewStateGraph(viewState, 0, string.Empty);    
        }

        /// <summary>
        /// Emits a readable version of the view state to the TextWriter passed into the object's constructor.
        /// </summary>
        /// <param name="viewStateAsString">A base-64 encoded representation of the view state to parse.</param>
        public virtual void ParseViewStateGraph(string viewStateAsString)
        {
            // First, deserialize the string into a Triplet
            LosFormatter los = new LosFormatter();
            object viewState = los.Deserialize(viewStateAsString);

            ParseViewStateGraph(viewState, 0, string.Empty);    
        }

        /// <summary>
        /// Recursively parses the view state.
        /// </summary>
        /// <param name="node">The current view state node.</param>
        /// <param name="depth">The "depth" of the view state tree.</param>
        /// <param name="label">A label to display in the emitted output next to the current node.</param>
        protected virtual void ParseViewStateGraph(object node, int depth, string label)
        {
            tw.Write(System.Environment.NewLine);

            if (node == null)
            {
                tw.Write(String.Concat(Indent(depth), label, "NODE IS NULL"));
            } 
            else if (node is Triplet)
            {
                tw.Write(String.Concat(Indent(depth), label, "TRIPLET"));
                ParseViewStateGraph(((Triplet) node).First, depth+1, "First: ");
                ParseViewStateGraph(((Triplet) node).Second, depth+1, "Second: ");
                ParseViewStateGraph(((Triplet) node).Third, depth+1, "Third: ");
            }
            else if (node is Pair)
            {
                tw.Write(String.Concat(Indent(depth), label, "PAIR"));
                ParseViewStateGraph(((Pair) node).First, depth+1, "First: ");
                ParseViewStateGraph(((Pair) node).Second, depth+1, "Second: ");
            }
            else if (node is ArrayList)
            {
                tw.Write(String.Concat(Indent(depth), label, "ARRAYLIST"));

                // display array values
                for (int i = 0; i < ((ArrayList) node).Count; i++)
                    ParseViewStateGraph(((ArrayList) node)[i], depth+1, String.Format("({0}) ", i));
            }
            else if (node.GetType().IsArray)
            {
                tw.Write(String.Concat(Indent(depth), label, "ARRAY "));
                tw.Write(String.Concat("(", node.GetType().ToString(), ")"));
                IEnumerator e = ((Array) node).GetEnumerator();
                int count = 0;
                while (e.MoveNext())
                    ParseViewStateGraph(e.Current, depth+1, String.Format("({0}) ", count++));
            }
            else if (node.GetType().IsPrimitive || node is string)
            {
                tw.Write(String.Concat(Indent(depth), label));
                tw.Write(node.ToString() + " (" + node.GetType().ToString() + ")");
            }
            else
            {
                tw.Write(String.Concat(Indent(depth), label, "OTHER - "));
                tw.Write(node.GetType().ToString());
            }
        }
        #endregion

        /// <summary>
        /// Returns a string containing the <see cref="IndentString"/> property value a specified number of times.
        /// </summary>
        /// <param name="depth">The number of times to repeat the <see cref="IndentString"/> property.</param>
        /// <returns>A string containing the <see cref="IndentString"/> property value a specified number of times.</returns>
        protected virtual string Indent(int depth)
        {
            StringBuilder sb = new StringBuilder(IndentString.Length * depth);
            for (int i = 0; i < depth; i++)
                sb.Append(IndentString);

            return sb.ToString();
        }
        #endregion

        #region Properties
        /// <summary>
        /// Specifies the indentation to use for each level when displaying the object graph.
        /// </summary>
        /// <value>A string value; the default is three blank spaces.</value>
        public string IndentString
        {
            get
            {
                return indentString;
            }
            set
            {
                indentString = value;
            }
        }
        #endregion
    }
}

And here's a simple page to read the viewstate from a textbox and graph it using the above code

private void btnParse_Click(object sender, System.EventArgs e)
        {
            // parse the viewState
            StringWriter writer = new StringWriter();
            ViewStateParser p = new ViewStateParser(writer);

            p.ParseViewStateGraph(txtViewState.Text);
            ltlViewState.Text = writer.ToString();
        }

How to install JDBC driver in Eclipse web project without facing java.lang.ClassNotFoundexception

What you should not do do (especially when working on a shared project)

Ok, after had the same issue and after reading some answers here and other places. it seems that putting external lib into WEB-INF/lib is not that good idea as it pollute webapp/JRE libs with server-specific libraries - for more information check this answer"

Another solution that i do NOT recommend is: to copy it into tomcat/lib folder. although this may work, it will be hard to manage dependency for a shared(git for example) project.

Good solution 1

Create vendor folder. put there all your external lib. then, map this folder as dependency to your project. in eclipse you need to

  1. add your folder to the build path
    1. Project Properties -> Java build path
    2. Libraries -> add external lib or any other solution to add your files/folder
  2. add your build path to deployment Assembly (reference)
    1. Project Properties -> Deployment Assembly
    2. Add -> Java Build Path Entries
    3. You should now see the list of libraries on your build path that you can specify for inclusion into your finished WAR.
    4. Select the ones you want and hit Finish.

Good solution 2

Use maven (or any alternative) to manage project dependency

AWS CLI S3 A client error (403) occurred when calling the HeadObject operation: Forbidden

In my case, i got this error trying to get an object on an S3 bucket folder. But in that folder my object was not here (i put the wrong folder), so S3 send this message. Hope it could help you too.

How to find distinct rows with field in list using JPA and Spring?

@Query("SELECT distinct new com.model.referential.Asset(firefCode,firefDescription) FROM AssetClass ")
List<AssetClass> findDistinctAsset();

AngularJS: ng-repeat list is not updated when a model element is spliced from the model array

There's an easy way to do that. Very easy. Since I noticed that

$scope.yourModel = [];

removes all $scope.yourModel array list you can do like this

function deleteAnObjectByKey(objects, key) {
    var clonedObjects = Object.assign({}, objects);

     for (var x in clonedObjects)
        if (clonedObjects.hasOwnProperty(x))
             if (clonedObjects[x].id == key)
                 delete clonedObjects[x];

    $scope.yourModel = clonedObjects;
}

The $scope.yourModel will be updated with the clonedObjects.

Hope that helps.

document.getElementById vs jQuery $()

All the answers above are correct. In case you want to see it in action, don't forget you have Console in a browser where you can see the actual result crystal clear :

I have an HTML :

<div id="contents"></div>

Go to console (cntrl+shift+c) and use these commands to see your result clearly

document.getElementById('contents')
>>> div#contents

$('#contents')
>>> [div#contents,
 context: document,
 selector: "#contents",
 jquery: "1.10.1",
 constructor: function,
 init: function …]

As we can see, in the first case we got the tag itself (that is, strictly speaking, an HTMLDivElement object). In the latter we actually don’t have a plain object, but an array of objects. And as mentioned by other answers above, you can use the following command:

$('#contents')[0]
>>> div#contents

MySQLDump one INSERT statement for each data row

Use:

mysqldump --extended-insert=FALSE 

Be aware that multiple inserts will be slower than one big insert.

Text in a flex container doesn't wrap in IE11

As Tyler has suggested in one of the comments here, using

max-width: 100%;

on the child may work (worked for me). Using align-self: stretch only works if you aren't using align-items: center (which I did). width: 100% only works if you haven't multiple childs inside your flexbox which you want to show side by side.

How to retry after exception?

Here is a solution similar to others, but it will raise the exception if it doesn't succeed in the prescribed number or retries.

tries = 3
for i in range(tries):
    try:
        do_the_thing()
    except KeyError as e:
        if i < tries - 1: # i is zero indexed
            continue
        else:
            raise
    break

Make a td fixed size (width,height) while rest of td's can expand

This will take care of the empty td:

<td style="min-width: 20px;"></td>

C# DateTime to "YYYYMMDDHHMMSS" format

It is not a big deal. you can simply put like this

WriteLine($"{DateTime.Now.ToString("yyyy-MM-dd-HH:mm:ss")}");

Excuse here for I used $ which is for string Interpolation .

How do I manually create a file with a . (dot) prefix in Windows? For example, .htaccess

Use something like Notepad++ (or even Notepad), 'Save As', and enter the name .htaccess that way. I always found it weird, but it lets you do it from a program!

oracle sql: update if exists else insert

Please refer to this question if you want to use UPSERT/MERGE command in Oracle. Otherwise, just resolve your issue on the client side by doing a count(1) first and then deciding whether to insert or update.

Python: CSV write by column rather than row

The reason csv doesn't support that is because variable-length lines are not really supported on most filesystems. What you should do instead is collect all the data in lists, then call zip() on them to transpose them after.

>>> l = [('Result_1', 'Result_2', 'Result_3', 'Result_4'), (1, 2, 3, 4), (5, 6, 7, 8)]
>>> zip(*l)
[('Result_1', 1, 5), ('Result_2', 2, 6), ('Result_3', 3, 7), ('Result_4', 4, 8)]

python pip on Windows - command 'cl.exe' failed

Refer to this link:

https://www.lfd.uci.edu/~gohlke/pythonlibs/#cytoolz

Download the right whl package for you python version(if you have trouble knowing what version of python you have, just lunch the interpreter )

use pip to install the package, assuming that the file is in downloads folder and you have python 3.6 32 bit :

python -m pip install C:\Users\%USER%\Downloads\cytoolz-0.9.0.1-cp36-cp36m-win32.whl

this is not valid for just this package, but for any package that cannot compile under your own windows installation.

How to access Spring MVC model object in javascript file?

I recently faced the same need. So I tried Aurand's way but it seems the code is missing ${}. So the code inside SomeJsp.jsp <head></head>is:

<script>
  var model=[];
  model.paramOne="${model.paramOne}";
  model.paramTwo="${model.paramTwo}";
  model.paramThree="${model.paramThree}";
</script>

Note that you can't asssign using var model = ${model} as it will assign a java object reference. So to access this in external JS:

$(document).ready(function() {
   alert(model.paramOne);
});

javascript node.js next()

It is naming convention used when passing callbacks in situations that require serial execution of actions, e.g. scan directory -> read file data -> do something with data. This is in preference to deeply nesting the callbacks. The first three sections of the following article on Tim Caswell's HowToNode blog give a good overview of this:

http://howtonode.org/control-flow

Also see the Sequential Actions section of the second part of that posting:

http://howtonode.org/control-flow-part-ii

Change value of input and submit form in JavaScript

You can use the onchange event:

<form name="myform" id="myform" action="action.php">
    <input type="hidden" name="myinput" value="0" onchange="this.form.submit()"/>
    <input type="text" name="message" value="" />
    <input type="submit" name="submit" onclick="DoSubmit()" />
</form>

Basic HTTP authentication with Node and Express 4

A lot of the middleware was pulled out of the Express core in v4, and put into separate modules. The basic auth module is here: https://github.com/expressjs/basic-auth-connect

Your example would just need to change to this:

var basicAuth = require('basic-auth-connect');
app.use(basicAuth('username', 'password'));

mysqli_real_connect(): (HY000/2002): No such file or directory

Maybe your SQL server has been stopped

sudo /etc/init.d/mysql start

or

sudo service mysqld start

and useservice mysql status to check status

EDIT adding from comments:

Use:

sudo systemctl enable mysql 

to keep running MySQL.

MySQL INSERT INTO table VALUES.. vs INSERT INTO table SET

As far as I can tell, both syntaxes are equivalent. The first is SQL standard, the second is MySQL's extension.

So they should be exactly equivalent performance wise.

http://dev.mysql.com/doc/refman/5.6/en/insert.html says:

INSERT inserts new rows into an existing table. The INSERT ... VALUES and INSERT ... SET forms of the statement insert rows based on explicitly specified values. The INSERT ... SELECT form inserts rows selected from another table or tables.

Dump a mysql database to a plaintext (CSV) backup from the command line

If you really need a "Backup" then you also need database schema, like table definitions, view definitions, store procedures and so on. A backup of a database isn't just the data.

The value of the mysqldump format for backup is specifically that it is very EASY to use it to restore mysql databases. A backup that isn't easily restored is far less useful. If you are looking for a method to reliably backup mysql data to so you can restore to a mysql server then I think you should stick with the mysqldump tool.

Mysql is free and runs on many different platforms. Setting up a new mysql server that I can restore to is simple. I am not at all worried about not being able to setup mysql so I can do a restore.

I would be far more worried about a custom backup/restore based on a fragile format like csv/tsv failing. Are you sure that all your quotes, commas, or tabs that are in your data would get escaped correctly and then parsed correctly by your restore tool?

If you are looking for a method to extract the data then see several in the other answers.

Adding items to end of linked list

The addLast() needs some optimisation as the while loop inside addLast() has O(n) complexity. Below is my implementation of LinkedList. Run the code with ll.addLastx(i) once and run it with ll.addLast(i) again , you can see their is a lot of difference in processing time of addLastx() with addLast().

Node.java

package in.datastructure.java.LinkedList;

/**
* Created by abhishek.panda on 07/07/17.
*/
public final class Node {
    int data;
    Node next;

    Node (int data){
       this.data = data;
    }
    public String toString(){
      return this.data+"--"+ this.next;
    }
}

LinkedList.java

package in.datastructure.java.LinkedList;
import java.util.ArrayList;
import java.util.Date;

public class LinkedList {

    Node head;
    Node lastx;
    /**
     * @description To append node at end looping all nodes from head
     * @param data
     */
    public void addLast(int data){

        if(head == null){
            head = new Node(data);
            return;
        }
        Node last = head;
        while(last.next != null) {
            last = last.next;
        }
        last.next = new Node(data);
    }


    /**
     * @description This keep track on last node and append to it
     * @param data
     */
    public void addLastx(int data){

        if(head == null){
            head = new Node(data);
            lastx = head;
            return;
        }
        if(lastx.next == null){
            lastx.next = new Node(data);
            lastx = lastx.next;
        }

    }

    public String toString(){
        ArrayList<Integer> arrayList = new ArrayList<Integer>(10);
        Node current = head;
        while(current.next != null) {
            arrayList.add(current.data);
            current = current.next;
        }
        if(current.next == null) {
            arrayList.add(current.data);
        }
        return arrayList.toString();
    }


    public static void main(String[] args) {
        LinkedList ll = new LinkedList();
        /**
         * @description Checking the code optimization of append code
         */
        Date startTime = new Date();
        for (int i = 0 ; i < 100000 ; i++){
            ll.addLastx(i);
        }
        Date endTime = new Date();
        System.out.println("To total processing time : " + (endTime.getTime()-startTime.getTime()));
        System.out.println(ll.toString());
    }

}

Incorrect syntax near ''

I got this error because I pasted alias columns into a DECLARE statement.

DECLARE @userdata TABLE(
f.TABLE_CATALOG nvarchar(100),
f.TABLE_NAME nvarchar(100),
f.COLUMN_NAME nvarchar(100),
p.COLUMN_NAME nvarchar(100)
)
SELECT * FROM @userdata 

ERROR: Msg 102, Level 15, State 1, Line 2 Incorrect syntax near '.'.

DECLARE @userdata TABLE(
f_TABLE_CATALOG nvarchar(100),
f_TABLE_NAME nvarchar(100),
f_COLUMN_NAME nvarchar(100),
p_COLUMN_NAME nvarchar(100)
)
SELECT * FROM @userdata

NO ERROR

array_push() with key value pair

If you need to add multiple key=>value, then try this.

$data = array_merge($data, array("cat"=>"wagon","foo"=>"baar"));

Retrieve Button value with jQuery

try this for your button:

<input type="button" class="my_button" name="buttonName" value="buttonValue" />

jQuery Clone table row

Try this variation:

$(".tr_clone_add").live('click', CloneRow);

function CloneRow()
{
    $(this).closest('.tr_clone').clone().insertAfter(".tr_clone:last");
}

Git workflow and rebase vs merge questions

In your situation I think your partner is correct. What's nice about rebasing is that to the outsider your changes look like they all happened in a clean sequence all by themselves. This means

  • your changes are very easy to review
  • you can continue to make nice, small commits and yet you can make sets of those commits public (by merging into master) all at once
  • when you look at the public master branch you'll see different series of commits for different features by different developers but they won't all be intermixed

You can still continue to push your private development branch to the remote repository for the sake of backup but others should not treat that as a "public" branch since you'll be rebasing. BTW, an easy command for doing this is git push --mirror origin .

The article Packaging software using Git does a fairly nice job explaining the trade offs in merging versus rebasing. It's a little different context but the principals are the same -- it basically comes down to whether your branches are public or private and how you plan to integrate them into the mainline.

Chrome disable SSL checking for sites?

Mac Users please execute the below command from terminal to disable the certificate warning.

/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --ignore-certificate-errors --ignore-urlfetcher-cert-requests &> /dev/null

Note that this will also have Google Chrome mark all HTTPS sites as insecure in the URL bar.

'ng' is not recognized as an internal or external command, operable program or batch file

Just adding a little info to the previous answers, If you have windows 7 or above then go to start and search Node.js command prompt and you will be directly shown the app. Click on it, and start working by using that command prompt for angular.

How do I assign a null value to a variable in PowerShell?

These are automatic variables, like $null, $true, $false etc.

about_Automatic_Variables, see https://technet.microsoft.com/en-us/library/hh847768.aspx?f=255&MSPPError=-2147217396

$NULL
$null is an automatic variable that contains a NULL or empty value. You can use this variable to represent an absent or undefined value in commands and scripts.

Windows PowerShell treats $null as an object with a value, that is, as an explicit placeholder, so you can use $null to represent an empty value in a series of values.

For example, when $null is included in a collection, it is counted as one of the objects.

C:\PS> $a = ".dir", $null, ".pdf"
C:\PS> $a.count
3

If you pipe the $null variable to the ForEach-Object cmdlet, it generates a value for $null, just as it does for the other objects.

PS C:\ps-test> ".dir", $null, ".pdf" | Foreach {"Hello"}
Hello
Hello
Hello

As a result, you cannot use $null to mean "no parameter value." A parameter value of $null overrides the default parameter value.

However, because Windows PowerShell treats the $null variable as a placeholder, you can use it scripts like the following one, which would not work if $null were ignored.

$calendar = @($null, $null, “Meeting”, $null, $null, “Team Lunch”, $null)
$days = Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"
$currentDay = 0

foreach($day in $calendar)
{
    if($day –ne $null)
    {
        "Appointment on $($days[$currentDay]): $day"
    }

    $currentDay++
}

output:

Appointment on Tuesday: Meeting
Appointment on Friday: Team lunch

How to pass ArrayList of Objects from one to another activity using Intent in android?

You must need to also implement Parcelable interface and must add writeToParcel method to your Questions class with Parcel argument in Constructor in addition to Serializable. otherwise app will crash.

Xcopy Command excluding files and folders

It is same as above answers, but is simple in steps

c:\SRC\folder1

c:\SRC\folder2

c:\SRC\folder3

c:\SRC\folder4

to copy all above folders to c:\DST\ except folder1 and folder2.

Step1: create a file c:\list.txt with below content, one folder name per one line

folder1\

folder2\

Step2: Go to command pompt and run as below xcopy c:\SRC*.* c:\DST*.* /EXCLUDE:c:\list.txt

Search input with an icon Bootstrap 4

Here is an input box with a search icon on the right.

  <div class="input-group">
      <input class="form-control py-2 border-right-0 border" type="search" placeholder="Search">
      <div class="input-group-append">
          <div class="input-group-text" id="btnGroupAddon2"><i class="fa fa-search"></i></div>
      </div>
  </div>

Here is an input box with a search icon on the left.

  <div class="input-group">
      <div class="input-group-prepend">
          <div class="input-group-text" id="btnGroupAddon2"><i class="fa fa-search"></i></div>
      </div>
      <input class="form-control py-2 border-right-0 border" type="search" placeholder="Search">
  </div>

Query to select data between two dates with the format m/d/yyyy

Try this:

select * from xxx where dates between convert(datetime,'10/10/2012',103) and convert(dattime,'10/12/2012',103)

Splitting string with pipe character ("|")

String rat_values = "Food 1 | Service 3 | Atmosphere 3 | Value for money 1 ";
    String[] value_split = rat_values.split("\\|");
    for (String string : value_split) {

        System.out.println(string);

    }

How to Convert date into MM/DD/YY format in C#

Look into using the ToString() method with a specified format.

How to make an autocomplete TextBox in ASP.NET?

aspx Page Coding

<form id="form1" runat="server">
       <input type="search" name="Search" placeholder="Search for a Product..." list="datalist1"
                    required="">
       <datalist id="datalist1" runat="server">

       </datalist>
 </form>

.cs Page Coding

protected void Page_Load(object sender, EventArgs e)
{
     autocomplete();
}
protected void autocomplete()
{
    Database p = new Database();
    DataSet ds = new DataSet();
    ds = p.sqlcall("select [name] from [stu_reg]");
    int row = ds.Tables[0].Rows.Count;
    string abc="";
    for (int i = 0; i < row;i++ )
        abc = abc + "<option>"+ds.Tables[0].Rows[i][0].ToString()+"</option>";
    datalist1.InnerHtml = abc;
}

Here Database is a File (Database.cs) In Which i have created on method named sqlcall for retriving data from database.

Selenium: Can I set any of the attribute value of a WebElement in Selenium?

    JavascriptExecutor js = (JavascriptExecutor) driver;        
    js.executeScript("document.getElementsByClassName('featured-heading')[0].setAttribute('style', 'background-color: green')");

I could add an attribute using the above code in java

List of IP Space used by Facebook

The list from 2020-05-23 is:

31.13.24.0/21
31.13.64.0/18
45.64.40.0/22
66.220.144.0/20
69.63.176.0/20
69.171.224.0/19
74.119.76.0/22
102.132.96.0/20
103.4.96.0/22
129.134.0.0/16
147.75.208.0/20
157.240.0.0/16
173.252.64.0/18
179.60.192.0/22
185.60.216.0/22
185.89.216.0/22
199.201.64.0/22
204.15.20.0/22

The method to fetch this list is already documented on Facebook's Developer site, you can make a whois call to see all IPs assigned to Facebook:

whois -h whois.radb.net -- '-i origin AS32934' | grep ^route

How to use bootstrap datepicker

I believe you have to reference bootstrap.js before bootstrap-datepicker.js

jquery get all input from specific form

To iterate through all the inputs in a form you can do this:

$("form#formID :input").each(function(){
 var input = $(this); // This is the jquery object of the input, do what you will
});

This uses the jquery :input selector to get ALL types of inputs, if you just want text you can do :

$("form#formID input[type=text]")//...

etc.

urllib2.HTTPError: HTTP Error 403: Forbidden

By adding a few more headers I was able to get the data:

import urllib2,cookielib

site= "http://www.nseindia.com/live_market/dynaContent/live_watch/get_quote/getHistoricalData.jsp?symbol=JPASSOCIAT&fromDate=1-JAN-2012&toDate=1-AUG-2012&datePeriod=unselected&hiddDwnld=true"
hdr = {'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11',
       'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
       'Accept-Charset': 'ISO-8859-1,utf-8;q=0.7,*;q=0.3',
       'Accept-Encoding': 'none',
       'Accept-Language': 'en-US,en;q=0.8',
       'Connection': 'keep-alive'}

req = urllib2.Request(site, headers=hdr)

try:
    page = urllib2.urlopen(req)
except urllib2.HTTPError, e:
    print e.fp.read()

content = page.read()
print content

Actually, it works with just this one additional header:

'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',

Can I delete a git commit but keep the changes?

One more way to do it.

Add commit on the top of temporary commit and then do:

git rebase -i

To merge two commits into one (command will open text file with explicit instructions, edit it).

String.contains in Java

The obvious answer to this is "that's what the JLS says."

Thinking about why that is, consider that this behavior can be useful in certain cases. Let's say you want to check a string against a set of other strings, but the number of other strings can vary.

So you have something like this:

for(String s : myStrings) {
   check(aString.contains(s));
}

where some s's are empty strings.

If the empty string is interpreted as "no input," and if your purpose here is ensure that aString contains all the "inputs" in myStrings, then it is misleading for the empty string to return false. All strings contain it because it is nothing. To say they didn't contain it would imply that the empty string had some substance that was not captured in the string, which is false.