Programs & Examples On #Vim7.2

Compile to stand alone exe for C# app in Visual Studio 2010

Press the start button in visual studio. Then go to the location where your solution is stored and open the folder of your main project then the bin folder. If your application was running in debug mode then go to the debug folder. If running in release mode then go to the release folder. You should find your exe there.

Internet Explorer 11- issue with security certificate error prompt

If you updated Internet Explorer and began having technical problems, you can use the Compatibility View feature to emulate a previous version of Internet Explorer.

For instructions, see the section below that corresponds with your version. To find your version number, click Help > About Internet Explorer. Internet Explorer 11

To edit the Compatibility View list:

Open the desktop, and then tap or click the Internet Explorer icon on the taskbar.
Tap or click the Tools button (Image), and then tap or click Compatibility View settings.
To remove a website:
Click the website(s) where you would like to turn off Compatibility View, clicking Remove after each one.
To add a website:
Under Add this website, enter the website(s) where you would like to turn on Compatibility View, clicking Add after each one.

UILabel font size?

very simple, yet effective method to adjust the size of label text progmatically :-

label.font=[UIFont fontWithName:@"Chalkduster" size:36];

:-)

Install numpy on python3.3 - Install pip for python3

My issue was the failure to import numpy into my python files. I was receiving the "ModuleNotFoundError: No module named 'numpy'". I ran into the same issue and I was not referencing python3 on the installation of numpy. I inputted the following into my terminal for OSX and my problems were solved:

python3 -m pip install numpy

Changing Placeholder Text Color with Swift

    extension UITextField{
            @IBInspectable var placeHolderColor: UIColor? {
                get {
                    return self.placeHolderColor
                }
                set {
                    self.attributedPlaceholder = NSAttributedString(string:self.placeholder != nil ?
        self.placeholder! : "",
        attributes:[NSAttributedString.Key.foregroundColor : newValue!])
                }
            } 
}

How to save a data frame as CSV to a user selected location using tcltk

write.csv([enter name of dataframe here],file = file.choose(new = T))

After running above script this window will open :

enter image description here

Type the new file name with extension in the File name field and click Open, it'll ask you to create a new file to which you should select Yes and the file will be created and saved in the desired location.

How to return more than one value from a function in Python?

You separate the values you want to return by commas:

def get_name():
   # you code
   return first_name, last_name

The commas indicate it's a tuple, so you could wrap your values by parentheses:

return (first_name, last_name)

Then when you call the function you a) save all values to one variable as a tuple, or b) separate your variable names by commas

name = get_name() # this is a tuple
first_name, last_name = get_name()
(first_name, last_name) = get_name() # You can put parentheses, but I find it ugly

git pull error :error: remote ref is at but expected

A hard reset will also resolve the problem

git reset --hard origin/master

How do I check particular attributes exist or not in XML?

var splitEle = xn.Attributes["split"];

if (splitEle !=null){
    return splitEle .Value;
}

How to assign execute permission to a .sh file in windows to be executed in linux

The ZIP file format does allow to store the permission bits, but Windows programs normally ignore it. The zip utility on Cygwin however does preserve the x bit, just like it does on Linux. If you do not want to use Cygwin, you can take a source code and tweak it so that all *.sh files get the executable bit set. Or write a script like explained here

How to add pandas data to an existing csv file?

with open(filename, 'a') as f:
    df.to_csv(f, header=f.tell()==0)
  • Create file unless exists, otherwise append
  • Add header if file is being created, otherwise skip it

Warning about `$HTTP_RAW_POST_DATA` being deprecated

It turns out that my understanding of the error message was wrong. I'd say it features very poor choice of words. Googling around shown me someone else misunderstood the message exactly like I did - see PHP bug #66763.

After totally unhelpful "This is the way the RMs wanted it to be." response to that bug by Mike, Tyrael explains that setting it to "-1" doesn't make just the warning to go away. It does the right thing, i.e. it completely disables populating the culprit variable. Turns out that having it set to 0 STILL populates data under some circumstances. Talk about bad design! To cite PHP RFC:

Change always_populate_raw_post_data INI setting to accept three values instead of two.

  • -1: The behavior of master; don't ever populate $GLOBALS[HTTP_RAW_POST_DATA]
  • 0/off/whatever: BC behavior (populate if content-type is not registered or request method is other than POST)
  • 1/on/yes/true: BC behavior (always populate $GLOBALS[HTTP_RAW_POST_DATA])

So yeah, setting it to -1 not only avoids the warning, like the message said, but it also finally disables populating this variable, which is what I wanted.

How to position one element relative to another with jQuery?

This works for me:

var posPersonTooltip = function(event) {
var tPosX = event.pageX - 5;
var tPosY = event.pageY + 10;
$('#personTooltipContainer').css({top: tPosY, left: tPosX});

<code> vs <pre> vs <samp> for inline and block code snippets

Something I completely missed: the non-wrapping behaviour of <pre> can be controlled with CSS. So this gives the exact result I was looking for:

_x000D_
_x000D_
code { _x000D_
    background: hsl(220, 80%, 90%); _x000D_
}_x000D_
_x000D_
pre {_x000D_
    white-space: pre-wrap;_x000D_
    background: hsl(30,80%,90%);_x000D_
}
_x000D_
Here's an example demonstrating the <code>&lt;code&gt;</code> tag._x000D_
_x000D_
<pre>_x000D_
Here's a very long pre-formatted formatted using the &lt;pre&gt; tag. Notice how it wraps?  It goes on and on and on and on and on and on and on and on and on and on..._x000D_
</pre>
_x000D_
_x000D_
_x000D_

http://jsfiddle.net/9mCN7/

how to disable DIV element and everything inside

The following css statement disables click events

pointer-events:none;

How can I set response header on express.js assets

You can do this by using cors. cors will handle your CORS response

var cors = require('cors')

app.use(cors());

What does `return` keyword mean inside `forEach` function?

From the Mozilla Developer Network:

There is no way to stop or break a forEach() loop other than by throwing an exception. If you need such behavior, the forEach() method is the wrong tool.

Early termination may be accomplished with:

The other Array methods: every(), some(), find(), and findIndex() test the array elements with a predicate returning a truthy value to determine if further iteration is required.

Execute a SQL Stored Procedure and process the results

Dim sqlConnection1 As New SqlConnection("Your Connection String")
Dim cmd As New SqlCommand

cmd.CommandText = "StoredProcedureName"
cmd.CommandType = CommandType.StoredProcedure
cmd.Connection = sqlConnection1

sqlConnection1.Open()

Dim adapter As System.Data.SqlClient.SqlDataAdapter
Dim dsdetailwk As New DataSet

Try
   adapter = New System.Data.SqlClient.SqlDataAdapter
   adapter.SelectCommand = cmd
   adapter.Fill(dsdetailwk, "delivery")
   Catch Err As System.Exception
End Try

sqlConnection1.Close()

datagridview1.DataSource = dsdetailwk.Tables(0)

How to get first character of string?

Example of all method

First : string.charAt(index)

Return the caract at the index index

_x000D_
_x000D_
var str = "Stack overflow";_x000D_
_x000D_
console.log(str.charAt(0));
_x000D_
_x000D_
_x000D_

Second : string.substring(start,length);

Return the substring in the string who start at the index start and stop after the length length

Here you only want the first caract so : start = 0 and length = 1

_x000D_
_x000D_
var str = "Stack overflow";_x000D_
_x000D_
console.log(str.substring(0,1));
_x000D_
_x000D_
_x000D_

Alternative : string[index]

A string is an array of caract. So you can get the first caract like the first cell of an array.

Return the caract at the index index of the string

_x000D_
_x000D_
var str = "Stack overflow";_x000D_
_x000D_
console.log(str[0]);
_x000D_
_x000D_
_x000D_

iterating quickly through list of tuples

I think that you can use

for j,k in my_list:
  [ ... stuff ... ]

How to create virtual column using MySQL SELECT?

Something like:

SELECT id, email, IF(active = 1, 'enabled', 'disabled') AS account_status FROM users

This allows you to make operations and show it as columns.

EDIT:

you can also use joins and show operations as columns:

SELECT u.id, e.email, IF(c.id IS NULL, 'no selected', c.name) AS country
FROM users u LEFT JOIN countries c ON u.country_id = c.id

Find string between two substrings

Parsing text with delimiters from different email platforms posed a larger-sized version of this problem. They generally have a START and a STOP. Delimiter characters for wildcards kept choking regex. The problem with split is mentioned here & elsewhere - oops, delimiter character gone. It occurred to me to use replace() to give split() something else to consume. Chunk of code:

nuke = '~~~'
start = '|*'
stop = '*|'
julien = (textIn.replace(start,nuke + start).replace(stop,stop + nuke).split(nuke))
keep = [chunk for chunk in julien if start in chunk and stop in chunk]
logging.info('keep: %s',keep)

TSQL DATETIME ISO 8601

If you just need to output the date in ISO8601 format including the trailing Z and you are on at least SQL Server 2012, then you may use FORMAT:

SELECT FORMAT(GetUtcDate(),'yyyy-MM-ddTHH:mm:ssZ')

This will give you something like:

2016-02-18T21:34:14Z

Just as @Pxtl points out in a comment FORMAT may have performance implications, a cost that has to be considered compared to any flexibility it brings.

Python Finding Prime Factors

My code:

# METHOD: PRIME FACTORS
def prime_factors(n):
    '''PRIME FACTORS: generates a list of prime factors for the number given
    RETURNS: number(being factored), list(prime factors), count(how many loops to find factors, for optimization)
    '''
    num = n                         #number at the end
    count = 0                       #optimization (to count iterations)
    index = 0                       #index (to test)
    t = [2, 3, 5, 7]                #list (to test)
    f = []                          #prime factors list
    while t[index] ** 2 <= n:
        count += 1                  #increment (how many loops to find factors)
        if len(t) == (index + 1):
            t.append(t[-2] + 6)     #extend test list (as much as needed) [2, 3, 5, 7, 11, 13...]
        if n % t[index]:            #if 0 does else (otherwise increments, or try next t[index])
            index += 1              #increment index
        else:
            n = n // t[index]       #drop max number we are testing... (this should drastically shorten the loops)
            f.append(t[index])      #append factor to list
    if n > 1:
        f.append(n)                 #add last factor...
    return num, f, f'count optimization: {count}'

Which I compared to the code with the most votes, which was very fast

    def prime_factors2(n):
        i = 2
        factors = []
        count = 0                           #added to test optimization
        while i * i <= n:
            count += 1                      #added to test optimization
            if n % i:
                i += 1
            else:
                n //= i
                factors.append(i)
        if n > 1:
            factors.append(n)
        return factors, f'count: {count}'   #print with (count added)

TESTING, (note, I added a COUNT in each loop to test the optimization)

# >>> prime_factors2(600851475143)
# ([71, 839, 1471, 6857], 'count: 1472')
# >>> prime_factors(600851475143)
# (600851475143, [71, 839, 1471, 6857], 'count optimization: 494')

I figure this code could be modified easily to get the (largest factor) or whatever else is needed. I'm open to any questions, my goal is to improve this much more as well for larger primes and factors.

How to check if an app is installed from a web-page on an iPhone?

As of 2017, it seems there's no reliable way to detect an app is installed, and the redirection trick won't work everywhere.

For those like me who needs to deep link directly from emails (quite common), it is worth noting the following:

  • Sending emails with appScheme:// won't work fine because the links will be filtered in Gmail

  • Redirecting automatically to appScheme:// is blocked by Chrome: I suspect Chrome requires the redirection to be synchronous to an user interaction (like a click)

  • You can now deep link without appScheme:// and it's better but it requires a modern platform and additional setup. Android iOS


It is worth noting that other people already thought about this in depth. If you look at how Slack implements his "magic link" feature, you can notice that:

  • It sends an email with a regular http link (ok with Gmail)
  • The web page have a big button that links to appScheme:// (ok with Chrome)

How to programmatically clear application data

Following up to @edovino's answer, the way of clearing all of an application's preferences programmatically would be

private void clearPreferences() {
    try {
        // clearing app data
        Runtime runtime = Runtime.getRuntime();
        runtime.exec("pm clear YOUR_APP_PACKAGE_GOES HERE");

    } catch (Exception e) {
        e.printStackTrace();
    }
}

Warning: the application will force close.

how to stop a loop arduino

Matti Virkkunen said it right, there's no "decent" way of stopping the loop. Nonetheless, by looking at your code and making several assumptions, I imagine you're trying to output a signal with a given frequency, but you want to be able to stop it.

If that's the case, there are several solutions:

  1. If you want to generate the signal with the input of a button you could do the following

    int speakerOut = A0;
    int buttonPin = 13;
    
    void setup() {
        pinMode(speakerOut, OUTPUT);
        pinMode(buttonPin, INPUT_PULLUP);
    }
    
    int a = 0;
    
    void loop() {
        if(digitalRead(buttonPin) == LOW) {
            a ++;
            Serial.println(a);
            analogWrite(speakerOut, NULL);
    
            if(a > 50 && a < 300) {
                analogWrite(speakerOut, 200);
            }
    
            if(a <= 49) {
                analogWrite(speakerOut, NULL);
            }
    
            if(a >= 300 && a <= 2499) {
                analogWrite(speakerOut, NULL);
            }
        }
    }
    

    In this case we're using a button pin as an INPUT_PULLUP. You can read the Arduino reference for more information about this topic, but in a nutshell this configuration sets an internal pullup resistor, this way you can just have your button connected to ground, with no need of external resistors. Note: This will invert the levels of the button, LOW will be pressed and HIGH will be released.

  2. The other option would be using one of the built-ins hardware timers to get a function called periodically with interruptions. I won't go in depth be here's a great description of what it is and how to use it.

Sorting a list using Lambda/Linq to objects

Answer for 1.:

You should be able to manually build an expression tree that can be passed into OrderBy using the name as a string. Or you could use reflection as suggested in another answer, which might be less work.

Edit: Here is a working example of building an expression tree manually. (Sorting on X.Value, when only knowing the name "Value" of the property). You could (should) build a generic method for doing it.

using System;
using System.Linq;
using System.Linq.Expressions;

class Program
{
    private static readonly Random rand = new Random();
    static void Main(string[] args)
    {
        var randX = from n in Enumerable.Range(0, 100)
                    select new X { Value = rand.Next(1000) };

        ParameterExpression pe = Expression.Parameter(typeof(X), "value");
        var expression = Expression.Property(pe, "Value");
        var exp = Expression.Lambda<Func<X, int>>(expression, pe).Compile();

        foreach (var n in randX.OrderBy(exp))
            Console.WriteLine(n.Value);
    }

    public class X
    {
        public int Value { get; set; }
    }
}

Building an expression tree requires you to know the particpating types, however. That might or might not be a problem in your usage scenario. If you don't know what type you should be sorting on, it will propably be easier using reflection.

Answer for 2.:

Yes, since Comparer<T>.Default will be used for the comparison, if you do not explicitly define the comparer.

How to normalize an array in NumPy to a unit vector?

There is also the function unit_vector() to normalize vectors in the popular transformations module by Christoph Gohlke:

import transformations as trafo
import numpy as np

data = np.array([[1.0, 1.0, 0.0],
                 [1.0, 1.0, 1.0],
                 [1.0, 2.0, 3.0]])

print(trafo.unit_vector(data, axis=1))

Casting to string in JavaScript

In addition to all the above, one should note that, for a defined value v:

  • String(v) calls v.toString()
  • '' + v calls v.valueOf() prior to any other type cast

So we could do something like:

var mixin = {
  valueOf:  function () { return false },
  toString: function () { return 'true' }
};
mixin === false;  // false
mixin == false;    // true
'' + mixin;       // "false"
String(mixin)     // "true"

Tested in FF 34.0 and Node 0.10

How to use Regular Expressions (Regex) in Microsoft Excel both in-cell and loops

I don't want to have to enable a reference library as I need my scripts to be portable. The Dim foo As New VBScript_RegExp_55.RegExp line caused User Defined Type Not Defined errors, but I found a solution that worked for me.

Update RE comments w/ @chrisneilsen :

I was under the impression that enabling a reference library was tied to the local computers settings, but it is in fact, tied directly to the workbook. So, you can enable a reference library, share a macro enabled workbook and the end user wouldn't have to enable the library as well. Caveat: The advantage to Late Binding is that the developer does not have to worry about the wrong version of an object library being installed on the user's computer. This likely would not be an issue w/ the VBScript_RegExp_55.RegExp library, but I'm not sold that the "performance" benifit is worth it for me at this time, as we are talking imperceptible milliseconds in my code. I felt this deserved an update to help others understand. If you enable the reference library, you can use "early bind", but if you don't, as far as I can tell, the code will work fine, but you need to "late bind" and loose on some performance/debugging features.

Source: https://peltiertech.com/Excel/EarlyLateBinding.html

What you'll want to do is put an example string in cell A1, then test your strPattern. Once that's working adjust then rng as desired.

Public Sub RegExSearch()
'https://stackoverflow.com/questions/22542834/how-to-use-regular-expressions-regex-in-microsoft-excel-both-in-cell-and-loops
'https://wellsr.com/vba/2018/excel/vba-regex-regular-expressions-guide/
'https://www.vitoshacademy.com/vba-regex-in-excel/
    Dim regexp As Object
    'Dim regex As New VBScript_RegExp_55.regexp 'Caused "User Defined Type Not Defined" Error
    Dim rng As Range, rcell As Range
    Dim strInput As String, strPattern As String
    
    Set regexp = CreateObject("vbscript.regexp")
    Set rng = ActiveSheet.Range("A1:A1")
        
    strPattern = "([a-z]{2})([0-9]{8})"
    'Search for 2 Letters then 8 Digits Eg: XY12345678 = Matched

    With regexp
        .Global = False
        .MultiLine = False
        .ignoreCase = True
        .Pattern = strPattern
    End With

    For Each rcell In rng.Cells

        If strPattern <> "" Then
            strInput = rcell.Value

            If regexp.test(strInput) Then
                MsgBox rcell & " Matched in Cell " & rcell.Address
            Else
                MsgBox "No Matches!"
            End If
        End If
    Next
End Sub

Remove sensitive files and their commits from Git history

Use filter-branch:

git filter-branch --force --index-filter 'git rm --cached --ignore-unmatch *file_path_relative_to_git_repo*' --prune-empty --tag-name-filter cat -- --all

git push origin *branch_name* -f

Arrays vs Vectors: Introductory Similarities and Differences

Those reference pretty much answered your question. Simply put, vectors' lengths are dynamic while arrays have a fixed size. when using an array, you specify its size upon declaration:

int myArray[100];
myArray[0]=1;
myArray[1]=2;
myArray[2]=3;

for vectors, you just declare it and add elements

vector<int> myVector;
myVector.push_back(1);
myVector.push_back(2);
myVector.push_back(3);
...

at times you wont know the number of elements needed so a vector would be ideal for such a situation.

Python Sets vs Lists

List performance:

>>> import timeit
>>> timeit.timeit(stmt='10**6 in a', setup='a = range(10**6)', number=100000)
0.008128150348026608

Set performance:

>>> timeit.timeit(stmt='10**6 in a', setup='a = set(range(10**6))', number=100000)
0.005674857488571661

You may want to consider Tuples as they're similar to lists but can’t be modified. They take up slightly less memory and are faster to access. They aren’t as flexible but are more efficient than lists. Their normal use is to serve as dictionary keys.

Sets are also sequence structures but with two differences from lists and tuples. Although sets do have an order, that order is arbitrary and not under the programmer’s control. The second difference is that the elements in a set must be unique.

set by definition. [python | wiki].

>>> x = set([1, 1, 2, 2, 3, 3])
>>> x
{1, 2, 3}

Javascript Get Element by Id and set the value

Given

<div id="This-is-the-real-id"></div>

then

function setText(id,newvalue) {
  var s= document.getElementById(id);
  s.innerHTML = newvalue;
}    
window.onload=function() { // or window.addEventListener("load",function() {
  setText("This-is-the-real-id","Hello there");
}

will do what you want


Given

<input id="This-is-the-real-id" type="text" value="">

then

function setValue(id,newvalue) {
  var s= document.getElementById(id);
  s.value = newvalue;
}    
window.onload=function() {
  setValue("This-is-the-real-id","Hello there");
}

will do what you want

_x000D_
_x000D_
function setContent(id, newvalue) {_x000D_
  var s = document.getElementById(id);_x000D_
  if (s.tagName.toUpperCase()==="INPUT") s.value = newvalue;_x000D_
  else s.innerHTML = newvalue;_x000D_
  _x000D_
}_x000D_
window.addEventListener("load", function() {_x000D_
  setContent("This-is-the-real-id-div", "Hello there");_x000D_
  setContent("This-is-the-real-id-input", "Hello there");_x000D_
})
_x000D_
<div id="This-is-the-real-id-div"></div>_x000D_
<input id="This-is-the-real-id-input" type="text" value="">
_x000D_
_x000D_
_x000D_

Is it possible to capture the stdout from the sh DSL command in the pipeline

Try this:

def get_git_sha(git_dir='') {
    dir(git_dir) {
        return sh(returnStdout: true, script: 'git rev-parse HEAD').trim()
    }
}

node(BUILD_NODE) {
    ...
    repo_SHA = get_git_sha('src/FooBar.git')
    echo repo_SHA
    ...
}

Tested on:

  • Jenkins ver. 2.19.1
  • Pipeline 2.4

Counting the number of elements in array

Best practice of getting length is use length filter returns the number of items of a sequence or mapping, or the length of a string. For example: {{ notcount | length }}

But you can calculate count of elements in for loop. For example:

{% set count = 0 %}
{% for nc in notcount %}
    {% set count = count + 1 %}
{% endfor %}

{{ count }}

This solution helps if you want to calculate count of elements by condition, for example you have a property name inside object and you want to calculate count of objects with not empty names:

{% set countNotEmpty = 0 %}
{% for nc in notcount if nc.name %}
    {% set countNotEmpty = countNotEmpty + 1 %}
{% endfor %}

{{ countNotEmpty }}

Useful links:

How to put a link on a button with bootstrap?

You can call a function on click event of button.

<input type="button" class="btn btn-info" value="Input Button" onclick=" relocate_home()">

<script>
function relocate_home()
{
     location.href = "www.yoursite.com";
} 
</script>

OR Use this Code

<a href="#link" class="btn btn-info" role="button">Link Button</a>

How to list the tables in a SQLite database file that was opened with ATTACH?

There are a few steps to see the tables in an SQLite database:

  1. List the tables in your database:

    .tables
    
  2. List how the table looks:

    .schema tablename
    
  3. Print the entire table:

    SELECT * FROM tablename;
    
  4. List all of the available SQLite prompt commands:

    .help
    

How do I use modulus for float/double?

You probably had a typo when you first ran it.

evaluating 0.5 % 0.3 returns '0.2' (A double) as expected.

Mindprod has a good overview of how modulus works in Java.

Strange out of memory issue while loading an image to a Bitmap object

None of the answers above worked for me, but I did come up with a horribly ugly workaround that solved the problem. I added a very small, 1x1 pixel image to my project as a resource, and loaded it into my ImageView before calling into garbage collection. I think it might be that the ImageView was not releasing the Bitmap, so GC never picked it up. It's ugly, but it seems to be working for now.

if (bitmap != null)
{
  bitmap.recycle();
  bitmap = null;
}
if (imageView != null)
{
  imageView.setImageResource(R.drawable.tiny); // This is my 1x1 png.
}
System.gc();

imageView.setImageBitmap(...); // Do whatever you need to do to load the image you want.

Preventing scroll bars from being hidden for MacOS trackpad users in WebKit/Blink

Browser scrollbars don't work at all on iPhone/iPad. At work we are using custom JavaScript scrollbars like jScrollPane to provide a consistent cross-browser UI: http://jscrollpane.kelvinluck.com/

It works very well for me - you can make some really beautiful custom scrollbars that fit the design of your site.

How do I limit the number of returned items?

I am a bit lazy, so I like simple things:

let users = await Users.find({}, null, {limit: 50});

How to configure WAMP (localhost) to send email using Gmail?

I've answered that here: (WAMP/XAMP) send Mail using SMTP localhost (works not only GMAIL, but for others too).

socket programming multiple client to one server

See O'Reilly "Java Cookbook", Ian Darwin - recipe 17.4 Handling Multiple Clients.

Pay attention that accept() is not thread safe, so the call is wrapped within synchronized.

64: synchronized(servSock) {
65:     clientSocket = servSock.accept();
66: }

Assembly - JG/JNLE/JL/JNGE after CMP

Wikibooks has a fairly good summary of jump instructions. Basically, there's actually two stages:

cmp_instruction op1, op2

Which sets various flags based on the result, and

jmp_conditional_instruction address

which will execute the jump based on the results of those flags.

Compare (cmp) will basically compute the subtraction op1-op2, however, this is not stored; instead only flag results are set. So if you did cmp eax, ebx that's the same as saying eax-ebx - then deciding based on whether that is positive, negative or zero which flags to set.

More detailed reference here.

Does the Java &= operator apply & or &&?

From the Java Language Specification - 15.26.2 Compound Assignment Operators.

A compound assignment expression of the form E1 op= E2 is equivalent to E1 = (T)((E1) op (E2)), where T is the type of E1, except that E1 is evaluated only once.

So a &= b; is equivalent to a = a & b;.

(In some usages, the type-casting makes a difference to the result, but in this one b has to be boolean and the type-cast does nothing.)

And, for the record, a &&= b; is not valid Java. There is no &&= operator.


In practice, there is little semantic difference between a = a & b; and a = a && b;. (If b is a variable or a constant, the result is going to be the same for both versions. There is only a semantic difference when b is a subexpression that has side-effects. In the & case, the side-effect always occurs. In the && case it occurs depending on the value of a.)

On the performance side, the trade-off is between the cost of evaluating b, and the cost of a test and branch of the value of a, and the potential saving of avoiding an unnecessary assignment to a. The analysis is not straight-forward, but unless the cost of calculating b is non-trivial, the performance difference between the two versions is too small to be worth considering.

How do I download a binary file over HTTP?

I had problems, if the file contained German Umlauts (ä,ö,ü). I could solve the problem by using:

ec = Encoding::Converter.new('iso-8859-1', 'utf-8')
...
f << ec.convert(seg)
...

Jinja2 template variable if None Object set a default value

Use the none test (not to be confused with Python's None object!):

{% if p is not none %}   
    {{ p.User['first_name'] }}
{% else %}
    NONE
{% endif %}

or:

{{ p.User['first_name'] if p is not none else 'NONE' }}

or if you need an empty string:

{{ p.User['first_name'] if p is not none }}

Jquery and HTML FormData returns "Uncaught TypeError: Illegal invocation"

Adding processData: false to the $.ajax options will fix this issue.

Return from a promise then()

What I have done here is that I have returned a promise from the justTesting function. You can then get the result when the function is resolved.

// new answer

function justTesting() {
  return new Promise((resolve, reject) => {
    if (true) {
      return resolve("testing");
    } else {
      return reject("promise failed");
   }
 });
}

justTesting()
  .then(res => {
     let test = res;
     // do something with the output :)
  })
  .catch(err => {
    console.log(err);
  });

Hope this helps!

// old answer

function justTesting() {
  return promise.then(function(output) {
    return output + 1;
  });
}

justTesting().then((res) => {
     var test = res;
    // do something with the output :)
    }

Android: how to hide ActionBar on certain activities

If you want to get full screen without actionBar and Title.

Add it in style.xml

<style name="AppTheme.NoActionBar" parent="Theme.AppCompat.Light.DarkActionBar">
      <item name="windowActionBar">false</item>
      <item name="windowNoTitle">true</item>
      <item name="android:windowFullscreen">true</item>
</style>

and use the style at activity of manifest.xml.

<activity ....
      android:theme="@style/AppTheme.NoActionBar" > ......
</activity> 

Are PDO prepared statements sufficient to prevent SQL injection?

No this is not enough (in some specific cases)! By default PDO uses emulated prepared statements when using MySQL as a database driver. You should always disable emulated prepared statements when using MySQL and PDO:

$dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);

Another thing that always should be done it set the correct encoding of the database:

$dbh = new PDO('mysql:dbname=dbtest;host=127.0.0.1;charset=utf8', 'user', 'pass');

Also see this related question: How can I prevent SQL injection in PHP?

Also note that that only is about the database side of the things you would still have to watch yourself when displaying the data. E.g. by using htmlspecialchars() again with the correct encoding and quoting style.

DropdownList DataSource

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        drpCategory.DataSource = CategoryHelper.Categories;
        drpCategory.DataTextField = "Name";
        drpCategory.DataValueField = "Id";
        drpCategory.DataBind();
    }
}

ResultSet exception - before start of result set

Basically you are positioning the cursor before the first row and then requesting data. You need to move the cursor to the first row.

 result.next();
 String foundType = result.getString(1);

It is common to do this in an if statement or loop.

if(result.next()){
   foundType = result.getString(1);
}

How to import or copy images to the "res" folder in Android Studio?

To import files from OS X Finder into Android Studio, just drag the relevant files to your resource folder.

  • Drag & Drop by default moves files to your project (not what you always want)
  • Pressing ? (Alt) while dragging copies files

Don't find a permanent config option for this, but this is the workaround I'm using

How can I present a file for download from an MVC controller?

Use .ashx file type and use the same code

Getting full JS autocompletion under Sublime Text

Ternjs is a new alternative for getting JS autocompletion. http://ternjs.net/

Sublime Plugin

The most well-maintained Tern plugin for Sublime Text is called 'tern_for_sublime'

There is also an older plugin called 'TernJS'. It is unmaintained and contains several performance related bugs, that cause Sublime Text to crash, so avoid that.

Postman: sending nested JSON object

For a nested Json(example below), you can form a query using postman as shown below.

{
    "Items": {
        "sku": "10 Units",
        "Price": "20 Rs"
    },
    "Characteristics": {
        "color": "blue",
        "weight": "2 lb"
    }
}

enter image description here

JavaScript module pattern with example

In order to approach to Modular design pattern, you need to understand these concept first:

Immediately-Invoked Function Expression (IIFE):

(function() {
      // Your code goes here 
}());

There are two ways you can use the functions. 1. Function declaration 2. Function expression.

Here are using function expression.

What is namespace? Now if we add the namespace to the above piece of code then

var anoyn = (function() {
}());

What is closure in JS?

It means if we declare any function with any variable scope/inside another function (in JS we can declare a function inside another function!) then it will count that function scope always. This means that any variable in outer function will be read always. It will not read the global variable (if any) with the same name. This is also one of the objective of using modular design pattern avoiding naming conflict.

var scope = "I am global";
function whatismyscope() {
    var scope = "I am just a local";
    function func() {return scope;}
    return func;
}
whatismyscope()()

Now we will apply these three concepts I mentioned above to define our first modular design pattern:

var modularpattern = (function() {
    // your module code goes here
    var sum = 0 ;

    return {
        add:function() {
            sum = sum + 1;
            return sum;
        },
        reset:function() {
            return sum = 0;    
        }  
    }   
}());
alert(modularpattern.add());    // alerts: 1
alert(modularpattern.add());    // alerts: 2
alert(modularpattern.reset());  // alerts: 0

jsfiddle for the code above.

The objective is to hide the variable accessibility from the outside world.

Hope this helps. Good Luck.

How do I add a new column to a Spark DataFrame (using PySpark)?

You cannot add an arbitrary column to a DataFrame in Spark. New columns can be created only by using literals (other literal types are described in How to add a constant column in a Spark DataFrame?)

from pyspark.sql.functions import lit

df = sqlContext.createDataFrame(
    [(1, "a", 23.0), (3, "B", -23.0)], ("x1", "x2", "x3"))

df_with_x4 = df.withColumn("x4", lit(0))
df_with_x4.show()

## +---+---+-----+---+
## | x1| x2|   x3| x4|
## +---+---+-----+---+
## |  1|  a| 23.0|  0|
## |  3|  B|-23.0|  0|
## +---+---+-----+---+

transforming an existing column:

from pyspark.sql.functions import exp

df_with_x5 = df_with_x4.withColumn("x5", exp("x3"))
df_with_x5.show()

## +---+---+-----+---+--------------------+
## | x1| x2|   x3| x4|                  x5|
## +---+---+-----+---+--------------------+
## |  1|  a| 23.0|  0| 9.744803446248903E9|
## |  3|  B|-23.0|  0|1.026187963170189...|
## +---+---+-----+---+--------------------+

included using join:

from pyspark.sql.functions import exp

lookup = sqlContext.createDataFrame([(1, "foo"), (2, "bar")], ("k", "v"))
df_with_x6 = (df_with_x5
    .join(lookup, col("x1") == col("k"), "leftouter")
    .drop("k")
    .withColumnRenamed("v", "x6"))

## +---+---+-----+---+--------------------+----+
## | x1| x2|   x3| x4|                  x5|  x6|
## +---+---+-----+---+--------------------+----+
## |  1|  a| 23.0|  0| 9.744803446248903E9| foo|
## |  3|  B|-23.0|  0|1.026187963170189...|null|
## +---+---+-----+---+--------------------+----+

or generated with function / udf:

from pyspark.sql.functions import rand

df_with_x7 = df_with_x6.withColumn("x7", rand())
df_with_x7.show()

## +---+---+-----+---+--------------------+----+-------------------+
## | x1| x2|   x3| x4|                  x5|  x6|                 x7|
## +---+---+-----+---+--------------------+----+-------------------+
## |  1|  a| 23.0|  0| 9.744803446248903E9| foo|0.41930610446846617|
## |  3|  B|-23.0|  0|1.026187963170189...|null|0.37801881545497873|
## +---+---+-----+---+--------------------+----+-------------------+

Performance-wise, built-in functions (pyspark.sql.functions), which map to Catalyst expression, are usually preferred over Python user defined functions.

If you want to add content of an arbitrary RDD as a column you can

How can I quickly and easily convert spreadsheet data to JSON?

Assuming you really mean easiest and are not necessarily looking for a way to do this programmatically, you can do this:

  1. Add, if not already there, a row of "column Musicians" to the spreadsheet. That is, if you have data in columns such as:

    Rory Gallagher      Guitar
    Gerry McAvoy        Bass
    Rod de'Ath          Drums
    Lou Martin          Keyboards
    Donkey Kong Sioux   Self-Appointed Semi-official Stomper
    

    Note: you might want to add "Musician" and "Instrument" in row 0 (you might have to insert a row there)

  2. Save the file as a CSV file.

  3. Copy the contents of the CSV file to the clipboard

  4. Go to http://www.convertcsv.com/csv-to-json.htm

  5. Verify that the "First row is column names" checkbox is checked

  6. Paste the CSV data into the content area

  7. Mash the "Convert CSV to JSON" button

    With the data shown above, you will now have:

    [
      {
        "MUSICIAN":"Rory Gallagher",
        "INSTRUMENT":"Guitar"
      },
      {
        "MUSICIAN":"Gerry McAvoy",
        "INSTRUMENT":"Bass"
      },
      {
        "MUSICIAN":"Rod D'Ath",
        "INSTRUMENT":"Drums"
      },
      {
        "MUSICIAN":"Lou Martin",
        "INSTRUMENT":"Keyboards"
      }
      {
        "MUSICIAN":"Donkey Kong Sioux",
        "INSTRUMENT":"Self-Appointed Semi-Official Stomper"
      }
    ]
    

    With this simple/minimalistic data, it's probably not required, but with large sets of data, it can save you time and headache in the proverbial long run by checking this data for aberrations and abnormalcy.

  8. Go here: http://jsonlint.com/

  9. Paste the JSON into the content area

  10. Pres the "Validate" button.

If the JSON is good, you will see a "Valid JSON" remark in the Results section below; if not, it will tell you where the problem[s] lie so that you can fix it/them.

Find the files existing in one directory but not in the other

diff -r dir1 dir2 | grep dir1 | awk '{print $4}' > difference1.txt

Explanation:

  • diff -r dir1 dir2 shows which files are only in dir1 and those only in dir2 and also the changes of the files present in both directories if any.

  • diff -r dir1 dir2 | grep dir1 shows which files are only in dir1

  • awk to print only filename.

Make absolute positioned div expand parent div height

I came up with another solution, which I don't love but gets the job done.

Basically duplicate the child elements in such a way that the duplicates are not visible.

<div id="parent">
    <div class="width-calc">
        <div class="child1"></div>
        <div class="child2"></div>
    </div>

    <div class="child1"></div>
    <div class="child2"></div>
</div>

CSS:

.width-calc {
    height: 0;
    overflow: hidden;
}

If those child elements contain little markup, then the impact will be small.

Log.INFO vs. Log.DEBUG

I usually try to use it like this:

  • DEBUG: Information interesting for Developers, when trying to debug a problem.
  • INFO: Information interesting for Support staff trying to figure out the context of a given error
  • WARN to FATAL: Problems and Errors depending on level of damage.

How to remove all the punctuation in a string? (Python)

import string

asking = "".join(l for l in asking if l not in string.punctuation)

filter with string.punctuation.

Create nice column output in python

Scolp is a new library that lets you pretty print streaming columnar data easily while auto-adjusting column width.

(Disclaimer: I am the author)

How to extract one column of a csv file

yes. cat mycsv.csv | cut -d ',' -f3 will print 3rd column.

How to update parent's state in React?

so, if you want to update parent component,

 class ParentComponent extends React.Component {
        constructor(props){
            super(props);
            this.state = {
               page:0
            }
        }

        handler(val){
            console.log(val) // 1
        }

        render(){
          return (
              <ChildComponent onChange={this.handler} />
           )
       }
   }


class ChildComponent extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
             page:1
        };
    }

    someMethod = (page) => {
        this.setState({ page: page });
        this.props.onChange(page)
    }

    render() {
        return (
       <Button
            onClick={() => this.someMethod()} 
       > Click
        </Button>
      )
   }
}

Here onChange is an attribute with "handler" method bound to it's instance. we passed the method handler to the Child class component, to receive via onChange property in its props argument.

The attribute onChange will be set in a props object like this:

props ={
onChange : this.handler
}

and passed to the child component

So the Child component can access the value of name in the props object like this props.onChange

Its done through the use of render props.

Now the Child component has a button “Click” with an onclick event set to call the handler method passed to it via onChnge in its props argument object. So now this.props.onChange in Child holds the output method in the Parent class Reference and credits: Bits and Pieces

How can I make a SQL temp table with primary key and auto-incrementing field?

If you're just doing some quick and dirty temporary work, you can also skip typing out an explicit CREATE TABLE statement and just make the temp table with a SELECT...INTO and include an Identity field in the select list.

select IDENTITY(int, 1, 1) as ROW_ID,
       Name
into #tmp
from (select 'Bob' as Name union all
      select 'Susan' as Name union all
      select 'Alice' as Name) some_data

select *
from #tmp

Iterating through all nodes in XML file

This is what I quickly wrote for myself:

public static class XmlDocumentExtensions
{
    public static void IterateThroughAllNodes(
        this XmlDocument doc, 
        Action<XmlNode> elementVisitor)
    {
        if (doc != null && elementVisitor != null)
        {
            foreach (XmlNode node in doc.ChildNodes)
            {
                doIterateNode(node, elementVisitor);
            }
        }
    }

    private static void doIterateNode(
        XmlNode node, 
        Action<XmlNode> elementVisitor)
    {
        elementVisitor(node);

        foreach (XmlNode childNode in node.ChildNodes)
        {
            doIterateNode(childNode, elementVisitor);
        }
    }
}

To use it, I've used something like:

var doc = new XmlDocument();
doc.Load(somePath);

doc.IterateThroughAllNodes(
    delegate(XmlNode node)
    {
        // ...Do something with the node...
    });

Maybe it helps someone out there.

EF Core add-migration Build Failed

Open Output window in Visual Studio and check your build log. In my case, even though my current configuration was Release, Add-Migration built the project in Debug, which had an error. For some reason, VS didn't display the error anywhere except Output window for me.

How do I create an Android Spinner as a popup?

You can create your own custom Dialog. It's fairly easy. If you want to dismiss it with a selection in the spinner, then add an OnItemClickListener and add

int n = mSpinner.getSelectedItemPosition();
mReadyListener.ready(n);
SpinnerDialog.this.dismiss();

as in the OnClickListener for the OK button. There's one caveat, though, and it's that the onclick listener does not fire if you reselect the default option. You need the OK button also.

Start with the layout:

res/layout/spinner_dialog.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content">
<TextView 
    android:id="@+id/dialog_label" 
    android:layout_height="wrap_content" 
    android:layout_width="fill_parent"
    android:hint="Please select an option" 
    />
<Spinner
    android:id="@+id/dialog_spinner" 
    android:layout_height="wrap_content" 
    android:layout_width="fill_parent"
    />
<Button
    android:id="@+id/dialogOK" 
    android:layout_width="120dp"
    android:layout_height="wrap_content" 
    android:text="OK"
    android:layout_below="@id/dialog_spinner"
    />
<Button
    android:id="@+id/dialogCancel" 
    android:layout_width="120dp"
    android:layout_height="wrap_content" 
    android:text="Cancel"
    android:layout_below="@id/dialog_spinner"
    android:layout_toRightOf="@id/dialogOK"
    />
</RelativeLayout>

Then, create the class:

src/your/package/SpinnerDialog.java:

public class SpinnerDialog extends Dialog {
    private ArrayList<String> mList;
    private Context mContext;
    private Spinner mSpinner;

   public interface DialogListener {
        public void ready(int n);
        public void cancelled();
    }

    private DialogListener mReadyListener;

    public SpinnerDialog(Context context, ArrayList<String> list, DialogListener readyListener) {
        super(context);
        mReadyListener = readyListener;
        mContext = context;
        mList = new ArrayList<String>();
        mList = list;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.spinner_dialog);
        mSpinner = (Spinner) findViewById (R.id.dialog_spinner);
        ArrayAdapter<String> adapter = new ArrayAdapter<String> (mContext, android.R.layout.simple_spinner_dropdown_item, mList);
        mSpinner.setAdapter(adapter);

        Button buttonOK = (Button) findViewById(R.id.dialogOK);
        Button buttonCancel = (Button) findViewById(R.id.dialogCancel);
        buttonOK.setOnClickListener(new android.view.View.OnClickListener(){
            public void onClick(View v) {
                int n = mSpinner.getSelectedItemPosition();
                mReadyListener.ready(n);
                SpinnerDialog.this.dismiss();
            }
        });
        buttonCancel.setOnClickListener(new android.view.View.OnClickListener(){
            public void onClick(View v) {
                mReadyListener.cancelled();
                SpinnerDialog.this.dismiss();
            }
        });
    }
}

Finally, use it as:

mSpinnerDialog = new SpinnerDialog(this, mTimers, new SpinnerDialog.DialogListener() {
  public void cancelled() {
    // do your code here
  }
  public void ready(int n) {
    // do your code here
  }
});

Cannot authenticate into mongo, "auth fails"

The proper way to login into mongo shell is

mongo localhost:27017 -u 'uuuuu' -p '>xxxxxx' --authenticationDatabase dbname

Angular ngClass and click event for toggling class

If you want to toggle text with a toggle button.

HTMLfile which is using bootstrap:

<input class="btn" (click)="muteStream()"  type="button"
          [ngClass]="status ? 'btn-success' : 'btn-danger'" 
          [value]="status ? 'unmute' : 'mute'"/>

TS file:

muteStream() {
   this.status = !this.status;
}

Why can't I use Docker CMD multiple times to run multiple services?

To address why CMD is designed to run only one service per container, let's just realize what would happen if the secondary servers run in the same container are not trivial / auxiliary but "major" (e.g. storage bundled with the frontend app). For starters, it would break down several important containerization features such as horizontal (auto-)scaling and rescheduling between nodes, both of which assume there is only one application (source of CPU load) per container. Then there is the issue of vulnerabilities - more servers exposed in a container means more frequent patching of CVEs...

So let's admit that it is a 'nudge' from Docker (and Kubernetes/Openshift) designers towards good practices and we should not reinvent workarounds (SSH is not necessary - we have docker exec / kubectl exec / oc rsh designed to replace it).

  • More info

https://devops.stackexchange.com/questions/447/why-it-is-recommended-to-run-only-one-process-in-a-container

How to resolve Unable to load authentication plugin 'caching_sha2_password' issue

You need just to delete your older connector and download new version (mysql-connector-java-5.1.46)

Command-line svn for Windows?

cygwin is another option. It has a port of svn.

Using Javascript: How to create a 'Go Back' link that takes the user to a link if there's no history for the tab or window?

The following code did the trick for me.

html:

<div class="back" onclick="goBackOrGoHome()">
  Back
</div>

js:

home_url = [YOUR BASE URL];

pathArray = document.referrer.split( '/' );
protocol = pathArray[0];
host = pathArray[2];

url_before = protocol + '//' + host;

url_now = window.location.protocol + "//" + window.location.host;


function goBackOrGoHome(){
  if ( url_before == url_now) {
    window.history.back();    
  }else{
    window.location = home_url;
  };
}

So, you use document.referrer to set the domain of the page you come from. Then you compare that with your current url using window.location.

If they are from the same domain, it means you are coming from your own site and you send them window.history.back(). If they are not the same, you are coming from somewhere else and you should redirect home or do whatever you like.

How to list the size of each file and directory and sort by descending size in Bash?

Apparently --max-depth option is not in Mac OS X's version of the du command. You can use the following instead.

du -h -d 1 | sort -n

ASP.NET Core Web API exception handling

A simple way to handle an exception on any particular method is:

using Microsoft.AspNetCore.Http;
...

public ActionResult MyAPIMethod()
{
    try
    {
       var myObject = ... something;

       return Json(myObject);
    }
    catch (Exception ex)
    {
        Log.Error($"Error: {ex.Message}");
        return StatusCode(StatusCodes.Status500InternalServerError);
    }         
}

How do you set, clear, and toggle a single bit?

Expanding on the bitset answer:

#include <iostream>
#include <bitset>
#include <string>

using namespace std;
int main() {
  bitset<8> byte(std::string("10010011");

  // Set Bit
  byte.set(3); // 10010111

  // Clear Bit
  byte.reset(2); // 10010101

  // Toggle Bit
  byte.flip(7); // 00010101

  cout << byte << endl;

  return 0;
}

SQL error "ORA-01722: invalid number"

The ORA-01722 error is pretty straightforward. According to Tom Kyte:

We've attempted to either explicity or implicity convert a character string to a number and it is failing.

However, where the problem is is often not apparent at first. This page helped me to troubleshoot, find, and fix my problem. Hint: look for places where you are explicitly or implicitly converting a string to a number. (I had NVL(number_field, 'string') in my code.)

How to disable the ability to select in a DataGridView?

Use the DataGridView.ReadOnly property

The code in the MSDN example illustrates the use of this property in a DataGridView control intended primarily for display. In this example, the visual appearance of the control is customized in several ways and the control is configured for limited interactivity.

Observe these settings in the sample code:

// Set property values appropriate for read-only
// display and limited interactivity
dataGridView1.AllowUserToAddRows = false;
dataGridView1.AllowUserToDeleteRows = false;
dataGridView1.AllowUserToOrderColumns = true;
dataGridView1.ReadOnly = true;
dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
dataGridView1.MultiSelect = false;
dataGridView1.AutoSizeRowsMode = DataGridViewAutoSizeRowsMode.None;
dataGridView1.AllowUserToResizeColumns = false;
dataGridView1.ColumnHeadersHeightSizeMode = 
DataGridViewColumnHeadersHeightSizeMode.DisableResizing;
dataGridView1.AllowUserToResizeRows = false;
dataGridView1.RowHeadersWidthSizeMode = 
DataGridViewRowHeadersWidthSizeMode.DisableResizing;

Multiple aggregate functions in HAVING clause

Something like this?

HAVING COUNT(caseID) > 2
AND COUNT(caseID) < 4

Software Design vs. Software Architecture

ARCHITECTURE:- An architecture creats the plans layout in various stages of the constructions as acording to the specifications.

DESINER:- A desiner is activity that it fullfil all the essential requirments of the archecture plans with the functional,asthetectic & appreance to the layouts.

Built in Python hash() function

Use hashlib as hash() was designed to be used to:

quickly compare dictionary keys during a dictionary lookup

and therefore does not guarantee that it will be the same across Python implementations.

How to import keras from tf.keras in Tensorflow?

To make it simple I will take the two versions of the code in keras and tf.keras. The example here is a simple Neural Network Model with different layers in it.

In Keras (v2.1.5)

from keras.models import Sequential
from keras.layers import Dense

def get_model(n_x, n_h1, n_h2):
    model = Sequential()
    model.add(Dense(n_h1, input_dim=n_x, activation='relu'))
    model.add(Dense(n_h2, activation='relu'))
    model.add(Dropout(0.5))
    model.add(Dense(4, activation='softmax'))
    model.compile(loss='binary_crossentropy', optimizer='adam', metrics=['accuracy'])
    print(model.summary())
    return model

In tf.keras (v1.9)

import tensorflow as tf

def get_model(n_x, n_h1, n_h2):
    model = tf.keras.Sequential()
    model.add(tf.keras.layers.Dense(n_h1, input_dim=n_x, activation='relu'))
    model.add(tf.keras.layers.Dense(n_h2, activation='relu'))
    model.add(tf.keras.layers.Dropout(0.5))
    model.add(tf.keras.layers.Dense(4, activation='softmax'))
    model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
    print(model.summary())

    return model

or it can be imported the following way instead of the above-mentioned way

from tensorflow.keras.layers import Dense

The official documentation of tf.keras

Note: TensorFlow Version is 1.9

Javascript objects: get parent

No. There is no way of knowing which object it came from.

s and obj.subObj both simply have references to the same object.

You could also do:

var obj = { subObj: {foo: 'hello world'} };
var obj2 = {};
obj2.subObj = obj.subObj;
var s = obj.subObj;

You now have three references, obj.subObj, obj2.subObj, and s, to the same object. None of them is special.

Difference between / and /* in servlet mapping url pattern

<url-pattern>/*</url-pattern>

The /* on a servlet overrides all other servlets, including all servlets provided by the servletcontainer such as the default servlet and the JSP servlet. Whatever request you fire, it will end up in that servlet. This is thus a bad URL pattern for servlets. Usually, you'd like to use /* on a Filter only. It is able to let the request continue to any of the servlets listening on a more specific URL pattern by calling FilterChain#doFilter().

<url-pattern>/</url-pattern>

The / doesn't override any other servlet. It only replaces the servletcontainer's builtin default servlet for all requests which doesn't match any other registered servlet. This is normally only invoked on static resources (CSS/JS/image/etc) and directory listings. The servletcontainer's builtin default servlet is also capable of dealing with HTTP cache requests, media (audio/video) streaming and file download resumes. Usually, you don't want to override the default servlet as you would otherwise have to take care of all its tasks, which is not exactly trivial (JSF utility library OmniFaces has an open source example). This is thus also a bad URL pattern for servlets. As to why JSP pages doesn't hit this servlet, it's because the servletcontainer's builtin JSP servlet will be invoked, which is already by default mapped on the more specific URL pattern *.jsp.

<url-pattern></url-pattern>

Then there's also the empty string URL pattern . This will be invoked when the context root is requested. This is different from the <welcome-file> approach that it isn't invoked when any subfolder is requested. This is most likely the URL pattern you're actually looking for in case you want a "home page servlet". I only have to admit that I'd intuitively expect the empty string URL pattern and the slash URL pattern / be defined exactly the other way round, so I can understand that a lot of starters got confused on this. But it is what it is.

Front Controller

In case you actually intend to have a front controller servlet, then you'd best map it on a more specific URL pattern like *.html, *.do, /pages/*, /app/*, etc. You can hide away the front controller URL pattern and cover static resources on a common URL pattern like /resources/*, /static/*, etc with help of a servlet filter. See also How to prevent static resources from being handled by front controller servlet which is mapped on /*. Noted should be that Spring MVC has a builtin static resource servlet, so that's why you could map its front controller on / if you configure a common URL pattern for static resources in Spring. See also How to handle static content in Spring MVC?

Return list from async/await method

Instead of doing all these, one can simply use ".Result" to get the result from a particular task.

eg: List list = GetListAsync().Result;

Which as per the definition => Gets the result value of this Task < TResult >

Pass request headers in a jQuery AJAX GET call

_x000D_
_x000D_
$.ajax({_x000D_
            url: URL,_x000D_
            type: 'GET',_x000D_
            dataType: 'json',_x000D_
            headers: {_x000D_
                'header1': 'value1',_x000D_
                'header2': 'value2'_x000D_
            },_x000D_
            contentType: 'application/json; charset=utf-8',_x000D_
            success: function (result) {_x000D_
               // CallBack(result);_x000D_
            },_x000D_
            error: function (error) {_x000D_
                _x000D_
            }_x000D_
        });
_x000D_
_x000D_
_x000D_

axios post request to send form data

https://www.npmjs.com/package/axios

Its Working

// "content-type": "application/x-www-form-urlencoded", // commit this

import axios from 'axios';

let requestData = {
      username : "[email protected]",
      password: "123456
    };
   
    const url = "Your Url Paste Here";

    let options = {
      method: "POST",
      headers: { 
        'Content-type': 'application/json; charset=UTF-8',

        Authorization: 'Bearer ' + "your token Paste Here",
      },
      data: JSON.stringify(requestData),
      url
    };
    axios(options)
      .then(response => {
        console.log("K_____ res :- ", response);
        console.log("K_____ res status:- ", response.status);
      })
      .catch(error => {
        console.log("K_____ error :- ", error);
      });

fetch request

fetch(url, {
    method: 'POST',
    body: JSON.stringify(requestPayload),           
    headers: {
        'Content-type': 'application/json; charset=UTF-8',
        Authorization: 'Bearer ' + token,
    },
})
    // .then((response) => response.json()) .  // commit out this part if response body is empty
    .then((json) => {
        console.log("response :- ", json);
    }).catch((error)=>{
        console.log("Api call error ", error.message);
        alert(error.message);
});

How to check for an undefined or null variable in JavaScript?

I think the most efficient way to test for "value is null or undefined" is

if ( some_variable == null ){
  // some_variable is either null or undefined
}

So these two lines are equivalent:

if ( typeof(some_variable) !== "undefined" && some_variable !== null ) {}
if ( some_variable != null ) {}

Note 1

As mentioned in the question, the short variant requires that some_variable has been declared, otherwise a ReferenceError will be thrown. However in many use cases you can assume that this is safe:

check for optional arguments:

function(foo){
    if( foo == null ) {...}

check for properties on an existing object

if(my_obj.foo == null) {...}

On the other hand typeof can deal with undeclared global variables (simply returns undefined). Yet these cases should be reduced to a minimum for good reasons, as Alsciende explained.

Note 2

This - even shorter - variant is not equivalent:

if ( !some_variable ) {
  // some_variable is either null, undefined, 0, NaN, false, or an empty string
}

so

if ( some_variable ) {
  // we don't get here if some_variable is null, undefined, 0, NaN, false, or ""
}

Note 3

In general it is recommended to use === instead of ==. The proposed solution is an exception to this rule. The JSHint syntax checker even provides the eqnull option for this reason.

From the jQuery style guide:

Strict equality checks (===) should be used in favor of ==. The only exception is when checking for undefined and null by way of null.

// Check for both undefined and null values, for some important reason. 
undefOrNull == null;

What is difference between Implicit wait and Explicit wait in Selenium WebDriver?

Check the below links:

  • Implicit Wait - It instructs the web driver to wait for some time by poll the DOM. Once you declared implicit wait it will be available for the entire life of web driver instance. By default the value will be 0. If you set a longer default, then the behavior will poll the DOM on a periodic basis depending on the browser/driver implementation.

  • Explicit Wait + ExpectedConditions - It is the custom one. It will be used if we want the execution to wait for some time until some condition achieved.

Multiple parameters in a List. How to create without a class?

Get Schema Name and Table Name from a database.

        public IList<Tuple<string, string>> ListTables()
        {

            DataTable dt = con.GetSchema("Tables");

            var tables = new List<Tuple<string, string>>();

            foreach (DataRow row in dt.Rows)
            {
            string schemaName = (string)row[1];
            string tableName = (string)row[2];
            //AddToList();
            tables.Add(Tuple.Create(schemaName, tableName));
            Console.WriteLine(schemaName +" " + tableName) ;
            }
            return tables;
        }

Query to get all rows from previous month

WHERE created_date >= DATE_ADD(LAST_DAY(DATE_SUB(NOW(), INTERVAL 2 MONTH)), INTERVAL 1 DAY) 
  AND created_date <= DATE_ADD(LAST_DAY(DATE_SUB(NOW(), INTERVAL 1 MONTH)), INTERVAL 0 DAY) 

This worked for me (Selects all records created from last month, regardless of the day you run the query this month)

PHP 5.4 Call-time pass-by-reference - Easy fix available?

PHP and references are somewhat unintuitive. If used appropriately references in the right places can provide large performance improvements or avoid very ugly workarounds and unusual code.

The following will produce an error:

 function f(&$v){$v = true;}
 f(&$v);

 function f($v){$v = true;}
 f(&$v);

None of these have to fail as they could follow the rules below but have no doubt been removed or disabled to prevent a lot of legacy confusion.

If they did work, both involve a redundant conversion to reference and the second also involves a redundant conversion back to a scoped contained variable.

The second one used to be possible allowing a reference to be passed to code that wasn't intended to work with references. This is extremely ugly for maintainability.

This will do nothing:

 function f($v){$v = true;}
 $r = &$v;
 f($r);

More specifically, it turns the reference back into a normal variable as you have not asked for a reference.

This will work:

 function f(&$v){$v = true;}
 f($v);

This sees that you are passing a non-reference but want a reference so turns it into a reference.

What this means is that you can't pass a reference to a function where a reference is not explicitly asked for making it one of the few areas where PHP is strict on passing types or in this case more of a meta type.

If you need more dynamic behaviour this will work:

 function f(&$v){$v = true;}
 $v = array(false,false,false);
 $r = &$v[1];
 f($r);

Here it sees that you want a reference and already have a reference so leaves it alone. It may also chain the reference but I doubt this.

Target WSGI script cannot be loaded as Python module

The solution that finally worked for me, after trying many of these options unsuccessfully was simple, but elusive because I struggled to figure out what actual paths to use.

I created a mezzanine project, which is based on django, with the following commands. I list them here to make the paths explicit.

/var/www/mysite$ python3 -m venv ./venv
/var/www/mysite$ source ./venv/bin/activate
(venv) /var/www/mysite$ mezzanine-project mysite
(venv) /var/www/mysite$ cd mysite
(venv) /var/www/mysite/mysite$

Now, the path to the wsgi.py file is:

/var/www/mysite/mysite/mysite/wsgi.py

The directives that worked for this installation within my /etc/apache2/sites-available/mysite.conf file follow:

...<VirtualHost...>
    ...
    WSGIDaemonProcess mysite python-home=/var/www/mysite/venv python-path=/var/www/mysite/mysite
    WSGIProcessGroup mysite
    WSGIScriptAlias / /var/www/mysite/mysite/mysite/wsgi.py process-group=accounting
    <Directory /var/www/mysite/mysite/mysite>
        <Files wsgi.py>
            Require all granted
        </Files>
    </Directory>
    ...
</VirtualHost>...

I tried numerous versions of python-home and python-path and got the OP's error repeatedly. Using the correct paths here should also accomplish the same things as @Dev's answer without having to add paths in the wsgi.py file (supplied by mezzanine, and no editing necessary in my case).

for or while loop to do something n times

but on the other hand it creates a completely useless list of integers just to loop over them. Isn't it a waste of memory, especially as far as big numbers of iterations are concerned?

That is what xrange(n) is for. It avoids creating a list of numbers, and instead just provides an iterator object.

In Python 3, xrange() was renamed to range() - if you want a list, you have to specifically request it via list(range(n)).

TypeScript function overloading

As a heads up to others, I've oberserved that at least as manifested by TypeScript compiled by WebPack for Angular 2, you quietly get overWRITTEN instead of overLOADED methods.

myComponent {
  method(): { console.info("no args"); },
  method(arg): { console.info("with arg"); }
}

Calling:

myComponent.method()

seems to execute the method with arguments, silently ignoring the no-arg version, with output:

with arg

Converting an int to std::string

You can use std::to_string in C++11

int i = 3;
std::string str = std::to_string(i);

Command line for looking at specific port

I use:

netstat –aon | find "<port number>"

here o represents process ID. now you can do whatever with the process ID. To terminate the process, for e.g., use:

taskkill /F /pid <process ID>

Understanding the order() function

Running this little piece of code allowed me to understand the order function

x <- c(3, 22, 5, 1, 77)

cbind(
  index=1:length(x),
  rank=rank(x),
  x, 
  order=order(x), 
  sort=sort(x)
)

     index rank  x order sort
[1,]     1    2  3     4    1
[2,]     2    4 22     1    3
[3,]     3    3  5     3    5
[4,]     4    1  1     2   22
[5,]     5    5 77     5   77

Reference: http://r.789695.n4.nabble.com/I-don-t-understand-the-order-function-td4664384.html

jQuery add required to input fields

$("input").prop('required',true);

DEMO FIDDLE

ng-if check if array is empty

In my experience, doing this on the HTML template proved difficult so I decided to use an event to call a function on TS and then check the condition. If true make condition equals to true and then use that variable on the ngIf on HTML

    emptyClause(array:any) {


        if (array.length === 0) {
            // array empty or does not exist

            this.emptyMessage=false;

    }else{

            this.emptyMessage=true;
        }
}

HTML

        <div class="row">

        <form>
            <div class="col-md-1 col-sm-1 col-xs-1"></div>
            <div class="col-md-10 col-sm-10 col-xs-10">
        <div [hidden]="emptyMessage" class="alert alert-danger">

            No Clauses Have Been Identified For the Search Criteria

        </div>
            </div>
            <div class="col-md-1 col-sm-1 col-xs-1"></div>
        </form>

How to check if an array value exists?

You could use the PHP in_array function

if( in_array( "bla" ,$yourarray ) )
{
    echo "has bla";
}

Angular2 dynamic change CSS property

You don't have any example code but I assume you want to do something like this?

@View({
directives: [NgClass],
styles: [`
    .${TodoModel.COMPLETED}  {
        text-decoration: line-through;
    }
    .${TodoModel.STARTED} {
        color: green;
    }
`],
template: `<div>
                <span [ng-class]="todo.status" >{{todo.title}}</span>
                <button (click)="todo.toggle()" >Toggle status</button>
            </div>`
})

You assign ng-class to a variable which is dynamic (a property of a model called TodoModel as you can guess).

todo.toggle() is changing the value of todo.status and there for the class of the input is changing.

This is an example for class name but actually you could do the same think for css properties.

I hope this is what you meant.

This example is taken for the great egghead tutorial here.

MySQl Error #1064

Sometimes when your table has a similar name to the database name you should use back tick. so instead of:

INSERT INTO books.book(field1, field2) VALUES ('value1', 'value2');

You should have this:

INSERT INTO `books`.`book`(`field1`, `field2`) VALUES ('value1', 'value2');

hibernate: LazyInitializationException: could not initialize proxy

The problem is that you are trying to access a collection in an object that is detached. You need to re-attach the object before accessing the collection to the current session. You can do that through

session.update(object);

Using lazy=false is not a good solution because you are throwing away the Lazy Initialization feature of hibernate. When lazy=false, the collection is loaded in memory at the same time that the object is requested. This means that if we have a collection with 1000 items, they all will be loaded in memory, despite we are going to access them or not. And this is not good.

Please read this article where it explains the problem, the possible solutions and why is implemented this way. Also, to understand Sessions and Transactions you must read this other article.

How to pass a JSON array as a parameter in URL

& is a keyword for the next parameter like this ur?param1=1&param2=2

so effectively you send a second param named R". You should urlencode your string. Isn't POST an option?

How to convert int to float in C?

This can give you the correct Answer

#include <stdio.h>
int main()
{
    float total=100, number=50;
    float percentage;
    percentage=(number/total)*100;
    printf("%0.2f",percentage);
    return 0;
}

Best way to get value from Collection by index

I agree with Matthew Flaschen's answer and just wanted to show examples of the options for the case you cannot switch to List (because a library returns you a Collection):

List list = new ArrayList(theCollection);
list.get(5);

Or

Object[] list2 = theCollection.toArray();
doSomethingWith(list[2]);

If you know what generics is I can provide samples for that too.

Edit: It's another question what the intent and semantics of the original collection is.

"Multiple definition", "first defined here" errors

Maybe you included the .c file in makefile multiple times.

"java.lang.OutOfMemoryError : unable to create new native Thread"

This is not a memory problem even though the exception name highly suggests so, but an operating system resource problem. You are running out of native threads, i.e. how many threads the operating system will allow your JVM to use.

This is an uncommon problem, because you rarely need that many. Do you have a lot of unconditional thread spawning where the threads should but doesn't finish?

You might consider rewriting into using Callable/Runnables under the control of an Executor if at all possible. There are plenty of standard executors with various behavior which your code can easily control.

(There are many reasons why the number of threads is limited, but they vary from operating system to operating system)

How to git-svn clone the last n revisions from a Subversion repository?

You've already discovered the simplest way to specify a shallow clone in Git-SVN, by specifying the SVN revision number that you want to start your clone at ( -r$REV:HEAD).

For example: git svn clone -s -r1450:HEAD some/svn/repo

Git's data structure is based on pointers in a directed acyclic graph (DAG), which makes it trivial to walk back n commits. But in SVN ( and therefore in Git-SVN) you will have to find the revision number yourself.

What does ||= (or-equals) mean in Ruby?

unless x x = y end

unless x has a value (it's not nil or false), set it equal to y

is equivalent to

x ||= y

Difference between SurfaceView and View?

A SurfaceView is a custom view in Android that can be used to drawn inside it.

The main difference between a View and a SurfaceView is that a View is drawn in the UI Thread, which is used for all the user interaction.

If you want to update the UI rapidly enough and render a good amount of information in it, a SurfaceView is a better choice.

But there are a few technical insides to the SurfaceView:

1. They are not hardware accelerated.

2. Normal views are rendered when you call the methods invalidate or postInvalidate(), but this does not mean the view will be immediately updated (A VSYNC will be sent, and the OS decides when it gets updated. The SurfaceView can be immediately updated.

3. A SurfaceView has an allocated surface buffer, so it is more costly

Understanding CUDA grid dimensions, block dimensions and threads organization (simple explanation)

Hardware

If a GPU device has, for example, 4 multiprocessing units, and they can run 768 threads each: then at a given moment no more than 4*768 threads will be really running in parallel (if you planned more threads, they will be waiting their turn).

Software

threads are organized in blocks. A block is executed by a multiprocessing unit. The threads of a block can be indentified (indexed) using 1Dimension(x), 2Dimensions (x,y) or 3Dim indexes (x,y,z) but in any case xyz <= 768 for our example (other restrictions apply to x,y,z, see the guide and your device capability).

Obviously, if you need more than those 4*768 threads you need more than 4 blocks. Blocks may be also indexed 1D, 2D or 3D. There is a queue of blocks waiting to enter the GPU (because, in our example, the GPU has 4 multiprocessors and only 4 blocks are being executed simultaneously).

Now a simple case: processing a 512x512 image

Suppose we want one thread to process one pixel (i,j).

We can use blocks of 64 threads each. Then we need 512*512/64 = 4096 blocks (so to have 512x512 threads = 4096*64)

It's common to organize (to make indexing the image easier) the threads in 2D blocks having blockDim = 8 x 8 (the 64 threads per block). I prefer to call it threadsPerBlock.

dim3 threadsPerBlock(8, 8);  // 64 threads

and 2D gridDim = 64 x 64 blocks (the 4096 blocks needed). I prefer to call it numBlocks.

dim3 numBlocks(imageWidth/threadsPerBlock.x,  /* for instance 512/8 = 64*/
              imageHeight/threadsPerBlock.y); 

The kernel is launched like this:

myKernel <<<numBlocks,threadsPerBlock>>>( /* params for the kernel function */ );       

Finally: there will be something like "a queue of 4096 blocks", where a block is waiting to be assigned one of the multiprocessors of the GPU to get its 64 threads executed.

In the kernel the pixel (i,j) to be processed by a thread is calculated this way:

uint i = (blockIdx.x * blockDim.x) + threadIdx.x;
uint j = (blockIdx.y * blockDim.y) + threadIdx.y;

macro - open all files in a folder

You have to add this line just before loop

    MyFile = Dir
Loop

Convert dataframe column to 1 or 0 for "true"/"false" values and assign to dataframe

Try this, it will convert True into 1 and False into 0:

data.frame$column.name.num  <- as.numeric(data.frame$column.name)

Then you can convert into factor if you want:

data.frame$column.name.num.factor <- as .factor(data.frame$column.name.num)

Mercurial stuck "waiting for lock"

Coworker had this exact problem today, after a BSoD while trying to push. He had to:

Then his repo worked again.

EDIT: As per @Marmoute's comment - when dealing with lock-related issues, using hg debuglock is a safer alternative to blindly deleting the .hg/store/lock file.

nodejs vs node on ubuntu 12.04

I think this is it:

sudo update-alternatives --install /usr/bin/node node /usr/bin/nodejs 10

Using Debian alternatives.

invalid operands of types int and double to binary 'operator%'

Because % is only defined for integer types. That's the modulus operator.

5.6.2 of the standard:

The operands of * and / shall have arithmetic or enumeration type; the operands of % shall have integral or enumeration type. [...]

As Oli pointed out, you can use fmod(). Don't forget to include math.h.

grep a file, but show several surrounding lines?

For BSD or GNU grep you can use -B num to set how many lines before the match and -A num for the number of lines after the match.

grep -B 3 -A 2 foo README.txt

If you want the same number of lines before and after you can use -C num.

grep -C 3 foo README.txt

This will show 3 lines before and 3 lines after.

How to open an Excel file in C#?

you should open like this

        Excel.Application xlApp ;
        Excel.Workbook xlWorkBook ;
        Excel.Worksheet xlWorkSheet ;
        object misValue = System.Reflection.Missing.Value;

        xlApp = new Excel.ApplicationClass();
        xlWorkBook = xlApp.Workbooks.Open("csharp.net-informations.xls", 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
        xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

source : http://csharp.net-informations.com/excel/csharp-open-excel.htm

ruden

Best timestamp format for CSV/Excel?

"yyyy-mm-dd hh:mm:ss.000" format does not work in all locales. For some (at least Danish) "yyyy-mm-dd hh:mm:ss,000" will work better.

as replied by user662894.

I want to add: Don't try to get the microseconds from, say, SQL Server's datetime2 datatype: Excel can't handle more than 3 fractional seconds (i.e. milliseconds).

So "yyyy-mm-dd hh:mm:ss.000000" won't work, and when Excel is fed this kind of string (from the CSV file), it will perform rounding rather than truncation.

This may be fine except when microsecond precision matters, in which case you are better off by NOT triggering an automatic datatype recognition but just keep the string as string...

SQL Server, How to set auto increment after creating a table without data loss?

If you don't want to add a new column, and you can guarantee that your current int column is unique, you could select all of the data out into a temporary table, drop the table and recreate with the IDENTITY column specified. Then using SET IDENTITY INSERT ON you can insert all of your data in the temporary table into the new table.

Getting Class type from String

String clsName = "Ex";  // use fully qualified name
Class cls = Class.forName(clsName);
Object clsInstance = (Object) cls.newInstance();

Check the Java Tutorial trail on Reflection at http://java.sun.com/docs/books/tutorial/reflect/TOC.html for further details.

Using PHP Replace SPACES in URLS with %20

No need for a regex here, if you just want to replace a piece of string by another: using str_replace() should be more than enough :

$new = str_replace(' ', '%20', $your_string);


But, if you want a bit more than that, and you probably do, if you are working with URLs, you should take a look at the urlencode() function.

Bootstrap 3 Multi-column within a single ul not floating properly

you are thinking too much... Take a look at this [i think this is what you wanted - if not let me know]

http://www.bootply.com/118886

css

.even{background: red; color:white;}
.odd{background: darkred; color:white;}

html

<div class="container">
  <ul class="list-unstyled">
    <li class="col-md-6 odd">Dumby Content</li>
    <li class="col-md-6 odd">Dumby Content</li>
    <li class="col-md-6 even">Dumby Content</li>
    <li class="col-md-6 even">Dumby Content</li>
    <li class="col-md-6 odd">Dumby Content</li>
    <li class="col-md-6 odd">Dumby Content</li>
  </ul>
</div>

How can I find the length of a number?

var x = 1234567;

x.toString().length;

This process will also work forFloat Number and for Exponential number also.

Datetime BETWEEN statement not working in SQL Server

From Sql Server 2008 you have "date" format.

So you can use

SELECT * FROM LOGS WHERE CONVERT(date,[CHECK_IN]) BETWEEN '2013-10-18' AND '2013-10-18'

https://docs.microsoft.com/en-us/sql/t-sql/data-types/date-transact-sql

How to count days between two dates in PHP?

Use DateTime::diff (aka date_diff):

$datetime1 = new DateTime('2009-10-11');
$datetime2 = new DateTime('2009-10-13');
$interval = $datetime1->diff($datetime2);

Or:

$datetime1 = date_create('2009-10-11');
$datetime2 = date_create('2009-10-13');
$interval = date_diff($datetime1, $datetime2);

You can then get the interval as a integer by calling $interval->days.

How can I loop through a C++ map of maps?

Do something like this:

typedef std::map<std::string, std::string> InnerMap;
typedef std::map<std::string, InnerMap> OuterMap;

Outermap mm;

...//set the initial values

for (OuterMap::iterator i = mm.begin(); i != mm.end(); ++i) {
    InnerMap &im = i->second;
    for (InnerMap::iterator ii = im.begin(); ii != im.end(); ++ii) {
        std::cout << "map[" 
                  << i->first 
                  << "][" 
                  << ii->first 
                  << "] =" 
                  << ii->second 
                  << '\n';
    }
}   

Maximum length of the textual representation of an IPv6 address?

45 characters.

You might expect an address to be

0000:0000:0000:0000:0000:0000:0000:0000

8 * 4 + 7 = 39

8 groups of 4 digits with 7 : between them.

But if you have an IPv4-mapped IPv6 address, the last two groups can be written in base 10 separated by ., eg. [::ffff:192.168.100.228]. Written out fully:

0000:0000:0000:0000:0000:ffff:192.168.100.228

(6 * 4 + 5) + 1 + (4 * 3 + 3) = 29 + 1 + 15 = 45

Note, this is an input/display convention - it's still a 128 bit address and for storage it would probably be best to standardise on the raw colon separated format, i.e. [0000:0000:0000:0000:0000:ffff:c0a8:64e4] for the address above.

Angular exception: Can't bind to 'ngForIn' since it isn't a known native property

Q:Can't bind to 'pSelectableRow' since it isn't a known property of 'tr'.

A:you need to configure the primeng tabulemodule in ngmodule

How to sum the values of one column of a dataframe in spark/scala

Using spark sql query..just incase if it helps anyone!

import org.apache.spark.sql.SparkSession 
import org.apache.spark.SparkConf 
import org.apache.spark.sql.functions._ 
import org.apache.spark.SparkContext 
import java.util.stream.Collectors

val conf = new SparkConf().setMaster("local[2]").setAppName("test")
val spark = SparkSession.builder.config(conf).getOrCreate()
val df = spark.sparkContext.parallelize(Seq(1, 2, 3, 4, 5, 6, 7)).toDF()

df.createOrReplaceTempView("steps")
val sum = spark.sql("select  sum(steps) as stepsSum from steps").map(row => row.getAs("stepsSum").asInstanceOf[Long]).collect()(0)
println("steps sum = " + sum) //prints 28

How to select ALL children (in any level) from a parent in jQuery?

I think you could do:

$('#google_translate_element').find('*').each(function(){
    $(this).unbind('click');
});

but it would cause a lot of overhead

How to merge many PDF files into a single one?

You can use http://www.mergepdf.net/ for example

Or:

PDFTK http://www.pdflabs.com/tools/pdftk-the-pdf-toolkit/

If you are NOT on Ubuntu and you have the same problem (and you wanted to start a new topic on SO and SO suggested to have a look at this question) you can also do it like this:

Things You'll Need:

* Full Version of Adobe Acrobat
  1. Open all the .pdf files you wish to merge. These can be minimized on your desktop as individual tabs.

  2. Pull up what you wish to be the first page of your merged document.

  3. Click the 'Combine Files' icon on the top left portion of the screen.

  4. The 'Combine Files' window that pops up is divided into three sections. The first section is titled, 'Choose the files you wish to combine'. Select the 'Add Open Files' option.

  5. Select the other open .pdf documents on your desktop when prompted.

  6. Rearrange the documents as you wish in the second window, titled, 'Arrange the files in the order you want them to appear in the new PDF'

  7. The final window, titled, 'Choose a file size and conversion setting' allows you to control the size of your merged PDF document. Consider the purpose of your new document. If its to be sent as an e-mail attachment, use a low size setting. If the PDF contains images or is to be used for presentation, choose a high setting. When finished, select 'Next'.

  8. A final choice: choose between either a single PDF document, or a PDF package, which comes with the option of creating a specialized cover sheet. When finished, hit 'Create', and save to your preferred location.

    • Tips & Warnings

Double check the PDF documents prior to merging to make sure all pertinent information is included. Its much easier to re-create a single PDF page than a multi-page document.

What is the purpose for using OPTION(MAXDOP 1) in SQL Server?

Adding my two cents, based on a performance issue I observed.

If simple queries are getting parellelized unnecessarily, it can bring more problems than solving one. However, before adding MAXDOP into the query as "knee-jerk" fix, there are some server settings to check.

In Jeremiah Peschka - Five SQL Server Settings to Change, MAXDOP and "COST THRESHOLD FOR PARALLELISM" (CTFP) are mentioned as important settings to check.

Note: Paul White mentioned max server memory aslo as a setting to check, in a response to Performance problem after migration from SQL Server 2005 to 2012. A good kb article to read is Using large amounts of memory can result in an inefficient plan in SQL Server

Jonathan Kehayias - Tuning ‘cost threshold for parallelism’ from the Plan Cache helps to find out good value for CTFP.

Why is cost threshold for parallelism ignored?

Aaron Bertrand - Six reasons you should be nervous about parallelism has a discussion about some scenario where MAXDOP is the solution.

Parallelism-Inhibiting Components are mentioned in Paul White - Forcing a Parallel Query Execution Plan

How to Change Margin of TextView

        TextView tv = (TextView)findViewById(R.id.item_title));
        RelativeLayout.LayoutParams mRelativelp = (RelativeLayout.LayoutParams) tv
                    .getLayoutParams();
        mRelativelp.setMargins(DptoPxConvertion(15), 0, DptoPxConvertion (15), 0);
        tv.setLayoutParams(mRelativelp);

    private int DptoPxConvertion(int dpValue)
    {
       return (int)((dpValue * mContext.getResources().getDisplayMetrics().density) + 0.5);
    }

getLayoutParams() of textview should be casted to the corresponding Params based on the Parent of the textview in xml.

<RelativeLayout>
   <TextView
    android:id="@+id/item_title">
</RelativeLayout>

To render the same real size on different devices use DptoPxConvertion() method which I have used above. setMargin(left,top,right,bottom) params will take values in pixel not in dp. For further reference see this Link Answer

How do I run SSH commands on remote system using Java?

I created solution based on JSch library:

import com.google.common.io.CharStreams
import com.jcraft.jsch.ChannelExec
import com.jcraft.jsch.JSch
import com.jcraft.jsch.JSchException
import com.jcraft.jsch.Session

import static java.util.Arrays.asList

class RunCommandViaSsh {

    private static final String SSH_HOST = "test.domain.com"
    private static final String SSH_LOGIN = "username"
    private static final String SSH_PASSWORD = "password"

    public static void main() {
        System.out.println(runCommand("pwd"))
        System.out.println(runCommand("ls -la"));
    }

    private static List<String> runCommand(String command) {
        Session session = setupSshSession();
        session.connect();

        ChannelExec channel = (ChannelExec) session.openChannel("exec");
        try {
            channel.setCommand(command);
            channel.setInputStream(null);
            InputStream output = channel.getInputStream();
            channel.connect();

            String result = CharStreams.toString(new InputStreamReader(output));
            return asList(result.split("\n"));

        } catch (JSchException | IOException e) {
            closeConnection(channel, session)
            throw new RuntimeException(e)

        } finally {
            closeConnection(channel, session)
        }
    }

    private static Session setupSshSession() {
        Session session = new JSch().getSession(SSH_LOGIN, SSH_HOST, 22);
        session.setPassword(SSH_PASSWORD);
        session.setConfig("PreferredAuthentications", "publickey,keyboard-interactive,password");
        session.setConfig("StrictHostKeyChecking", "no"); // disable check for RSA key
        return session;
    }

    private static void closeConnection(ChannelExec channel, Session session) {
        try {
            channel.disconnect()
        } catch (Exception ignored) {
        }
        session.disconnect()
    }
}

How to check ASP.NET Version loaded on a system?

Here is some code that will return the installed .NET details:

<%@ Page Language="VB" Debug="true" %>
<%@ Import namespace="System" %>
<%@ Import namespace="System.IO" %>
<% 
Dim cmnNETver, cmnNETdiv, aspNETver, aspNETdiv As Object
Dim winOSver, cmnNETfix, aspNETfil(2), aspNETtxt(2), aspNETpth(2), aspNETfix(2) As String

winOSver = Environment.OSVersion.ToString
cmnNETver = Environment.Version.ToString
cmnNETdiv = cmnNETver.Split(".")
cmnNETfix = "v" & cmnNETdiv(0) & "." & cmnNETdiv(1) & "." & cmnNETdiv(2)

For filndx As Integer = 0 To 2
  aspNETfil(0) = "ngen.exe"
  aspNETfil(1) = "clr.dll"
  aspNETfil(2) = "KernelBase.dll"

  If filndx = 2   
    aspNETpth(filndx) = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.System), aspNETfil(filndx))
  Else
    aspNETpth(filndx) = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Windows), "Microsoft.NET\Framework64", cmnNETfix, aspNETfil(filndx))
  End If

  If File.Exists(aspNETpth(filndx)) Then
    aspNETver = Diagnostics.FileVersionInfo.GetVersionInfo(aspNETpth(filndx))
    aspNETtxt(filndx) = aspNETver.FileVersion.ToString
    aspNETdiv = aspNETtxt(filndx).Split(" ")
    aspNETfix(filndx) = aspNETdiv(0)
  Else
    aspNETfix(filndx) = "Path not found... No version found..."
  End If
Next

Response.Write("Common MS.NET Version (raw): " & cmnNETver & "<br>")
Response.Write("Common MS.NET path: " & cmnNETfix & "<br>")
Response.Write("Microsoft.NET full path: " & aspNETpth(0) & "<br>")
Response.Write("Microsoft.NET Version (raw): " & aspNETtxt(0) & "<br>")
Response.Write("<b>Microsoft.NET Version: " & aspNETfix(0) & "</b><br>")
Response.Write("ASP.NET full path: " & aspNETpth(1) & "<br>")
Response.Write("ASP.NET Version (raw): " & aspNETtxt(1) & "<br>")
Response.Write("<b>ASP.NET Version: " & aspNETfix(1) & "</b><br>")
Response.Write("OS Version (system): " & winOSver & "<br>")
Response.Write("OS Version full path: " & aspNETpth(2) & "<br>")
Response.Write("OS Version (raw): " & aspNETtxt(2) & "<br>")
Response.Write("<b>OS Version: " & aspNETfix(2) & "</b><br>")
%>

Here is the new output, cleaner code, more output:

Common MS.NET Version (raw): 4.0.30319.42000
Common MS.NET path: v4.0.30319
Microsoft.NET full path: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\ngen.exe
Microsoft.NET Version (raw): 4.6.1586.0 built by: NETFXREL2
Microsoft.NET Version: 4.6.1586.0
ASP.NET full path: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\clr.dll
ASP.NET Version (raw): 4.7.2110.0 built by: NET47REL1LAST
ASP.NET Version: 4.7.2110.0
OS Version (system): Microsoft Windows NT 10.0.14393.0
OS Version full path: C:\Windows\system32\KernelBase.dll
OS Version (raw): 10.0.14393.1715 (rs1_release_inmarket.170906-1810)
OS Version: 10.0.14393.1715

android lollipop toolbar: how to hide/show the toolbar while scrolling?

For hiding the toolbar you can just do :

getSupportActionBar().hide();

So you just have to had a scroll listener and hide the toolbar when the user scroll !

Min/Max-value validators in asp.net mvc

A complete example of how this could be done. To avoid having to write client-side validation scripts, the existing ValidationType = "range" has been used.

public class MinValueAttribute : ValidationAttribute, IClientValidatable
{
    private readonly double _minValue;

    public MinValueAttribute(double minValue)
    {
        _minValue = minValue;
        ErrorMessage = "Enter a value greater than or equal to " + _minValue;  
    }

    public MinValueAttribute(int minValue)
    {
        _minValue = minValue;
        ErrorMessage = "Enter a value greater than or equal to " + _minValue;
    }

    public override bool IsValid(object value)
    {
        return Convert.ToDouble(value) >= _minValue;
    }

    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
        var rule = new ModelClientValidationRule();
        rule.ErrorMessage = ErrorMessage;
        rule.ValidationParameters.Add("min", _minValue);
        rule.ValidationParameters.Add("max", Double.MaxValue);
        rule.ValidationType = "range";
        yield return rule;
    }

}

How to find which version of Oracle is installed on a Linux server (In terminal)

A bit manual searching but its an alternative way...
Find the Oracle home or where the installation files for Oracle is installed on your linux server.

cd / <-- Goto root directory
find . -print| grep -i dbm*.sql

Result varies on how you installed Oracle but mine displays this

/db/oracle

Goto the folder

less /db/oracle/db1/sqlplus/doc/README.htm

scroll down and you should see something like this

SQL*Plus Release Notes - Release 11.2.0.2

How to run a PowerShell script

You can run from cmd like this:

type "script_path" | powershell.exe -c -

How to match all occurrences of a regex

Using scan should do the trick:

string.scan(/regex/)

Passing an Object from an Activity to a Fragment

Passing arguments by bundle is restricted to some data types. But you can transfer any data to your fragment this way:

In your fragment create a public method like this

public void passData(Context context, List<LexItem> list, int pos) {
    mContext = context;
    mLexItemList = list;
    mIndex = pos;
}

and in your activity call passData() with all your needed data types after instantiating the fragment

        WebViewFragment myFragment = new WebViewFragment();
        myFragment.passData(getApplicationContext(), mLexItemList, index);
        FragmentManager fm = getSupportFragmentManager();
        FragmentTransaction ft = fm.beginTransaction();
        ft.add(R.id.my_fragment_container, myFragment);
        ft.addToBackStack(null);
        ft.commit();

Remark: My fragment extends "android.support.v4.app.Fragment", therefore I have to use "getSupportFragmentManager()". Of course, this principle will work also with a fragment class extending "Fragment", but then you have to use "getFragmentManager()".

What is a Sticky Broadcast?

A normal broadcast Intent is not available anymore after is was send and processed by the system. If you use the sendStickyBroadcast(Intent) method, the Intent is sticky, meaning the Intent you are sending stays around after the broadcast is complete.

you refer to my blog:enter link description here

Where does Console.WriteLine go in ASP.NET?

System.Diagnostics.Debug.WriteLine(...); gets it into the Immediate Window in Visual Studio 2008.

Go to menu Debug -> Windows -> Immediate:

Enter image description here

Uploading/Displaying Images in MVC 4

Have a look at the following

@using (Html.BeginForm("FileUpload", "Home", FormMethod.Post, 
                            new { enctype = "multipart/form-data" }))
{  
    <label for="file">Upload Image:</label> 
    <input type="file" name="file" id="file" style="width: 100%;" /> 
    <input type="submit" value="Upload" class="submit" /> 
}

your controller should have action method which would accept HttpPostedFileBase;

 public ActionResult FileUpload(HttpPostedFileBase file)
    {
        if (file != null)
        {
            string pic = System.IO.Path.GetFileName(file.FileName);
            string path = System.IO.Path.Combine(
                                   Server.MapPath("~/images/profile"), pic); 
            // file is uploaded
            file.SaveAs(path);

            // save the image path path to the database or you can send image 
            // directly to database
            // in-case if you want to store byte[] ie. for DB
            using (MemoryStream ms = new MemoryStream()) 
            {
                 file.InputStream.CopyTo(ms);
                 byte[] array = ms.GetBuffer();
            }

        }
        // after successfully uploading redirect the user
        return RedirectToAction("actionname", "controller name");
    }

Update 1

In case you want to upload files using jQuery with asynchornously, then try this article.

the code to handle the server side (for multiple upload) is;

 try
    {
        HttpFileCollection hfc = HttpContext.Current.Request.Files;
        string path = "/content/files/contact/";

        for (int i = 0; i < hfc.Count; i++)
        {
            HttpPostedFile hpf = hfc[i];
            if (hpf.ContentLength > 0)
            {
                string fileName = "";
                if (Request.Browser.Browser == "IE")
                {
                    fileName = Path.GetFileName(hpf.FileName);
                }
                else
                {
                    fileName = hpf.FileName;
                }
                string fullPathWithFileName = path + fileName;
                hpf.SaveAs(Server.MapPath(fullPathWithFileName));
            }
        }

    }
    catch (Exception ex)
    {
        throw ex;
    }

this control also return image name (in a javascript call back) which then you can use it to display image in the DOM.

UPDATE 2

Alternatively, you can try Async File Uploads in MVC 4.

How can I show dots ("...") in a span with hidden overflow?

For this you can use text-overflow: ellipsis; property. Write like this

_x000D_
_x000D_
span {_x000D_
    display: inline-block;_x000D_
    width: 180px;_x000D_
    white-space: nowrap;_x000D_
    overflow: hidden !important;_x000D_
    text-overflow: ellipsis;_x000D_
}
_x000D_
<span>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book</span>
_x000D_
_x000D_
_x000D_

JSFiddle

CASE .. WHEN expression in Oracle SQL

Of course...

select case substr(status,1,1) -- you're only interested in the first character.
            when 'a' then 'Active'
            when 'i' then 'Inactive'
            when 't' then 'Terminated'
       end as statustext
  from stage.tst

However, there's a few worrying things about this schema. Firstly if you have a column that means something, appending a number onto the end it not necessarily the best way to go. Also, depending on the number of status' you have you might want to consider turning this column into a foreign key to a separate table.


Based on your comment you definitely want to turn this into a foreign key. For instance

create table statuses ( -- Not a good table name :-)
    status varchar2(10)
  , description varchar2(10)
  , constraint pk_statuses primary key (status)
    )

create table tst (
    id number
  , status varchar2(10)
  , constraint pk_tst primary key (id)
  , constraint fk_tst foreign key (status) references statuses (status)
    )

Your query then becomes

select a.status, b.description
  from tst a
  left outer join statuses b
    on a.status = b.status

Here's a SQL Fiddle to demonstrate.

How to get value by class name in JavaScript or jquery?

Without jQuery:

textContent:

var text = document.querySelector('.someClassname').textContent;

Markup:

var text = document.querySelector('.someClassname').innerHTML;

Markup including the matched element:

var text = document.querySelector('.someClassname').outerHTML;

though outerHTML may not be supported by all browsers of interest and document.querySelector requires IE 8 or higher.

Proper use of mutexes in Python

I would like to improve answer from chris-b a little bit more.

See below for my code:

from threading import Thread, Lock
import threading
mutex = Lock()


def processData(data, thread_safe):
    if thread_safe:
        mutex.acquire()
    try:
        thread_id = threading.get_ident()
        print('\nProcessing data:', data, "ThreadId:", thread_id)
    finally:
        if thread_safe:
            mutex.release()


counter = 0
max_run = 100
thread_safe = False
while True:
    some_data = counter        
    t = Thread(target=processData, args=(some_data, thread_safe))
    t.start()
    counter = counter + 1
    if counter >= max_run:
        break

In your first run if you set thread_safe = False in while loop, mutex will not be used, and threads will step over each others in print method as below;

Not Thread safe

but, if you set thread_safe = True and run it, you will see all the output comes perfectly fine;

Thread safe

hope this helps.

How do I create a simple 'Hello World' module in Magento?

A Magento Module is a group of directories containing blocks, controllers, helpers, and models that are needed to create a specific store feature. It is the unit of customization in the Magento platform. Magento Modules can be created to perform multiple functions with supporting logic to influence user experience and storefront appearance. It has a life cycle that allows them to be installed, deleted, or disabled. From the perspective of both merchants and extension developers, modules are the central unit of the Magento platform.

Declaration of Module

We have to declare the module by using the configuration file. As Magento 2 search for configuration module in etc directory of the module. So now we will create configuration file module.xml.

The code will look like this:

<?xml version="1.0"?> <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd"> <module name="Cloudways_Mymodule" setup_version="1.0.0"></module> </config>

Registration of Module The module must be registered in the Magento 2 system by using Magento Component Registrar class. Now we will create the file registration.php in the module root directory:

app/code/Cloudways/Mymodule/registration.php

The Code will look like this:

?php
\Magento\Framework\Component\ComponentRegistrar::register(
\Magento\Framework\Component\ComponentRegistrar::MODULE,
'Cloudways_Mymodule',
__DIR__
);

Check Module Status After following the steps above, we would have created a simple module. Now we are going to check the status of the module and whether it is enabled or disabled by using the following command line:

php bin/magento module:status

php bin/magento module:enable Cloudways_Mymodule

Share your feedback once you have gone through complete process

How to get child process from parent process

For the case when the process tree of interest has more than 2 levels (e.g. Chromium spawns 4-level deep process tree), pgrep isn't of much use. As others have mentioned above, procfs files contain all the information about processes and one just needs to read them. I built a CLI tool called Procpath which does exactly this. It reads all /proc/N/stat files, represents the contents as a JSON tree and expose it to JSONPath queries.

To get all descendant process' comma-separated PIDs of a non-root process (for the root it's ..stat.pid) it's:

$ procpath query -d, "..children[?(@.stat.pid == 24243)]..pid"
24243,24259,24284,24289,24260,24262,24333,24337,24439,24570,24592,24606,...

libpthread.so.0: error adding symbols: DSO missing from command line

You should mention the library on the command line after the object files being compiled:

 gcc -Wstrict-prototypes -Wall -Wno-sign-compare -Wpointer-arith -Wdeclaration-after-statement -Wformat-security -Wswitch-enum -Wunused-parameter -Wstrict-aliasing -Wbad-function-cast -Wcast-align -Wstrict-prototypes -Wold-style-definition -Wmissing-prototypes -Wmissing-field-initializers -Wno-override-init \
     -g -O2 -export-dynamic -o utilities/ovs-dpctl utilities/ovs-dpctl.o \
     lib/libopenvswitch.a \
     /home/jyyoo/src/dpdk/build/lib/librte_eal.a /home/jyyoo/src/dpdk/build/lib/libethdev.a /home/jyyoo/src/dpdk/build/lib/librte_cmdline.a /home/jyyoo/src/dpdk/build/lib/librte_hash.a /home/jyyoo/src/dpdk/build/lib/librte_lpm.a /home/jyyoo/src/dpdk/build/lib/librte_mbuf.a /home/jyyoo/src/dpdk/build/lib/librte_ring.a /home/jyyoo/src/dpdk/build/lib/librte_mempool.a /home/jyyoo/src/dpdk/build/lib/librte_malloc.a \
     -lrt -lm -lpthread 

Explanation: the linking is dependent on the order of modules. Symbols are first requested, and then linked in from a library that has them. So you have to specify modules that use libraries first, and libraries after them. Like this:

gcc x.o y.o z.o -la -lb -lc

Moreover, in case there's a circular dependency, you should specify the same library on the command line several times. So in case libb needs symbol from libc and libc needs symbol from libb, the command line should be:

gcc x.o y.o z.o -la -lb -lc -lb

Hiding a password in a python script (insecure obfuscation only)

Place the configuration information in a encrypted config file. Query this info in your code using an key. Place this key in a separate file per environment, and don't store it with your code.

Numpy `ValueError: operands could not be broadcast together with shape ...`

If X and beta do not have the same shape as the second term in the rhs of your last line (i.e. nsample), then you will get this type of error. To add an array to a tuple of arrays, they all must be the same shape.

I would recommend looking at the numpy broadcasting rules.

How to use mongoose findOne

Mongoose basically wraps mongodb's api to give you a pseudo relational db api so queries are not going to be exactly like mongodb queries. Mongoose findOne query returns a query object, not a document. You can either use a callback as the solution suggests or as of v4+ findOne returns a thenable so you can use .then or await/async to retrieve the document.

// thenables
Auth.findOne({nick: 'noname'}).then(err, result) {console.log(result)};
Auth.findOne({nick: 'noname'}).then(function (doc) {console.log(doc)});

// To use a full fledge promise you will need to use .exec()
var auth = Auth.findOne({nick: 'noname'}).exec();
auth.then(function (doc) {console.log(doc)});

// async/await
async function auth() {
  const doc = await Auth.findOne({nick: 'noname'}).exec();
  return doc;
}
auth();

See the docs if you would like to use a third party promise library.

Cannot install Aptana Studio 3.6 on Windows

You have to use portable git not installer.Extract the folder to Program Files and rename the folder name from PortableGit to Git.

How to increase the max connections in postgres?

Just increasing max_connections is bad idea. You need to increase shared_buffers and kernel.shmmax as well.


Considerations

max_connections determines the maximum number of concurrent connections to the database server. The default is typically 100 connections.

Before increasing your connection count you might need to scale up your deployment. But before that, you should consider whether you really need an increased connection limit.

Each PostgreSQL connection consumes RAM for managing the connection or the client using it. The more connections you have, the more RAM you will be using that could instead be used to run the database.

A well-written app typically doesn't need a large number of connections. If you have an app that does need a large number of connections then consider using a tool such as pg_bouncer which can pool connections for you. As each connection consumes RAM, you should be looking to minimize their use.


How to increase max connections

1. Increase max_connection and shared_buffers

in /var/lib/pgsql/{version_number}/data/postgresql.conf

change

max_connections = 100
shared_buffers = 24MB

to

max_connections = 300
shared_buffers = 80MB

The shared_buffers configuration parameter determines how much memory is dedicated to PostgreSQL to use for caching data.

  • If you have a system with 1GB or more of RAM, a reasonable starting value for shared_buffers is 1/4 of the memory in your system.
  • it's unlikely you'll find using more than 40% of RAM to work better than a smaller amount (like 25%)
  • Be aware that if your system or PostgreSQL build is 32-bit, it might not be practical to set shared_buffers above 2 ~ 2.5GB.
  • Note that on Windows, large values for shared_buffers aren't as effective, and you may find better results keeping it relatively low and using the OS cache more instead. On Windows the useful range is 64MB to 512MB.

2. Change kernel.shmmax

You would need to increase kernel max segment size to be slightly larger than the shared_buffers.

In file /etc/sysctl.conf set the parameter as shown below. It will take effect when postgresql reboots (The following line makes the kernel max to 96Mb)

kernel.shmmax=100663296

References

Postgres Max Connections And Shared Buffers

Tuning Your PostgreSQL Server

psql: FATAL: Peer authentication failed for user "dev"

While @flaviodesousa's answer would work, it also makes it mandatory for all users (everyone else) to enter a password.

Sometime it makes sense to keep peer authentication for everyone else, but make an exception for a service user. In that case you would want to add a line to the pg_hba.conf that looks like:

local   all             some_batch_user                         md5

I would recommend that you add this line right below the commented header line:

# TYPE  DATABASE        USER            ADDRESS                 METHOD
local   all             some_batch_user                         md5

You will need to restart PostgreSQL using

sudo service postgresql restart

If you're using 9.3, your pg_hba.conf would most likely be:

/etc/postgresql/9.3/main/pg_hba.conf

JavaScript is in array

As mentioned before, if your browser supports indexOf(), great! If not, you need to pollyfil it or rely on an utility belt like lodash/underscore.

Just wanted to add this newer ES2016 addition (to keep this question updated):

Array.prototype.includes()

if (blockedTile.includes("118")) {
    // found element
}

Write to CSV file and export it?

A comment about Will's answer, you might want to replace HttpContext.Current.Response.End(); with HttpContext.Current.ApplicationInstance.CompleteRequest(); The reason is that Response.End() throws a System.Threading.ThreadAbortException. It aborts a thread. If you have an exception logger, it will be littered with ThreadAbortExceptions, which in this case is expected behavior.

Intuitively, sending a CSV file to the browser should not raise an exception.

See here for more Is Response.End() considered harmful?

How do I disable TextBox using JavaScript?

Form elements can be accessed via the form's DOM element by name, not by "id" value. Give your form elements names if you want to access them like that, or else access them directly by "id" value:

document.getElementById("color").disabled = true;

edit — oh also, as pointed out by others, it's just "text", not "TextBox", for the "type" attribute.

You might want to invest a little time in reading some front-end development tutorials.

Efficient way to remove ALL whitespace from String?

Just an alternative because it looks quite nice :) - NOTE: Henks answer is the quickest of these.

input.ToCharArray()
 .Where(c => !Char.IsWhiteSpace(c))
 .Select(c => c.ToString())
 .Aggregate((a, b) => a + b);

Testing 1,000,000 loops on "This is a simple Test"

This method = 1.74 seconds
Regex = 2.58 seconds
new String (Henks) = 0.82 seconds

ng-options with simple array init

You can use ng-repeat with option like this:

<form>
    <select ng-model="yourSelect" 
        ng-options="option as option for option in ['var1', 'var2', 'var3']"
        ng-init="yourSelect='var1'"></select>
    <input type="hidden" name="yourSelect" value="{{yourSelect}}" />
</form>

When you submit your form you can get value of input hidden.


DEMO

ng-selected ng-repeat

how to use html2canvas and jspdf to export to pdf in a proper and simple way

I have made a jsfiddle for you.

 <canvas id="canvas" width="480" height="320"></canvas> 
      <button id="download">Download Pdf</button>

'

        html2canvas($("#canvas"), {
            onrendered: function(canvas) {         
                var imgData = canvas.toDataURL(
                    'image/png');              
                var doc = new jsPDF('p', 'mm');
                doc.addImage(imgData, 'PNG', 10, 10);
                doc.save('sample-file.pdf');
            }
        });

jsfiddle: http://jsfiddle.net/rpaul/p4s5k59s/5/

Tested in Chrome38, IE11 and Firefox 33. Seems to have issues with Safari. However, Andrew got it working in Safari 8 on Mac OSx by switching to JPEG from PNG. For details, see his comment below.

memcpy() vs memmove()

I'm not entirely surprised that your example exhibits no strange behaviour. Try copying str1 to str1+2 instead and see what happens then. (May not actually make a difference, depends on compiler/libraries.)

In general, memcpy is implemented in a simple (but fast) manner. Simplistically, it just loops over the data (in order), copying from one location to the other. This can result in the source being overwritten while it's being read.

Memmove does more work to ensure it handles the overlap correctly.

EDIT:

(Unfortunately, I can't find decent examples, but these will do). Contrast the memcpy and memmove implementations shown here. memcpy just loops, while memmove performs a test to determine which direction to loop in to avoid corrupting the data. These implementations are rather simple. Most high-performance implementations are more complicated (involving copying word-size blocks at a time rather than bytes).

How to asynchronously call a method in Java

You can use @Async annotation from jcabi-aspects and AspectJ:

public class Foo {
  @Async
  public void save() {
    // to be executed in the background
  }
}

When you call save(), a new thread starts and executes its body. Your main thread continues without waiting for the result of save().

How to force deletion of a python object?

  1. Add an exit handler that closes all the bars.
  2. __del__() gets called when the number of references to an object hits 0 while the VM is still running. This may be caused by the GC.
  3. If __init__() raises an exception then the object is assumed to be incomplete and __del__() won't be invoked.

urllib and "SSL: CERTIFICATE_VERIFY_FAILED" Error

I was having a similar problem, though I was using urllib.request.urlopen in Python 3.4, 3.5, and 3.6. (This is a portion of the Python 3 equivalent of urllib2, per the note at the head of Python 2's urllib2 documentation page.)

My solution was to pip install certifi to install certifi, which has:

... a carefully curated collection of Root Certificates for validating the trustworthiness of SSL certificates while verifying the identity of TLS hosts.

Then, in my code where I previously just had:

import urllib.request as urlrq

resp = urlrq.urlopen('https://example.com/bar/baz.html')

I revised it to:

import urllib.request as urlrq
import certifi

resp = urlrq.urlopen('https://example.com/bar/baz.html', cafile=certifi.where())

If I read the urllib2.urlopen documentation correctly, it also has a cafile argument. So, urllib2.urlopen([...], certifi.where()) might work for Python 2.7 as well.


UPDATE (2020-01-01): As of Python 3.6, the cafile argument to urlopen has been deprecated, with the context argument supposed to be specified instead. I found the following to work equally well on 3.5 through 3.8:

import urllib.request as urlrq
import certifi
import ssl

resp = urlrq.urlopen('https://example.com/bar/baz.html', context=ssl.create_default_context(cafile=certifi.where()))

Re-enabling window.alert in Chrome

In Chrome Browser go to setting , clear browsing history and then reload the page

HTTP could not register URL http://+:8000/HelloWCF/. Your process does not have access rights to this namespace

Unfortunately the link in the exception text, http://go.microsoft.com/fwlink/?LinkId=70353, is broken. However, it used to lead to http://msdn.microsoft.com/en-us/library/ms733768.aspx which explains how to set the permissions.

It basically informs you to use the following command:

netsh http add urlacl url=http://+:80/MyUri user=DOMAIN\user

You can get more help on the details using the help of netsh

For example: netsh http add ?

Gives help on the http add command.

How to get UTC time in Python?

Timezone aware with zero external dependencies:

from datetime import datetime, timezone

def utc_now():
    return datetime.utcnow().replace(tzinfo=timezone.utc)

LD_LIBRARY_PATH vs LIBRARY_PATH

LIBRARY_PATH is used by gcc before compilation to search directories containing static and shared libraries that need to be linked to your program.

LD_LIBRARY_PATH is used by your program to search directories containing shared libraries after it has been successfully compiled and linked.

EDIT: As pointed below, your libraries can be static or shared. If it is static then the code is copied over into your program and you don't need to search for the library after your program is compiled and linked. If your library is shared then it needs to be dynamically linked to your program and that's when LD_LIBRARY_PATH comes into play.

Inserting HTML elements with JavaScript

If you want to insert HTML code inside existing page's tag use Jnerator. This tool was created specially for this goal.

Instead of writing next code

    var htmlCode = '<ul class=\'menu-countries\'><li
        class=\'item\'><img src=\'au.png\'></img><span>Australia </span></li><li
        class=\'item\'><img src=\'br.png\'> </img><span>Brazil</span></li><li
        class=\'item\'> <img src=\'ca.png\'></img><span>Canada</span></li></ul>';
    var element = document.getElementById('myTag');
    element.innerHTML = htmlCode;

You can write more understandable structure

    var jtag = $j.ul({
        class: 'menu-countries',
        child: [
            $j.li({ class: 'item', child: [
                $j.img({ src: 'au.png' }),
                $j.span({ child: 'Australia' })
            ]}),
            $j.li({ class: 'item', child: [
                $j.img({ src: 'br.png' }),
                $j.span({ child: 'Brazil' })
            ]}),
            $j.li({ class: 'item', child: [
                $j.img({ src: 'ca.png' }),
                $j.span({ child: 'Canada' })
            ]})
        ]
    });
    var htmlCode = jtag.html();
    var element = document.getElementById('myTag');
    element.innerHTML = htmlCode;

Include headers when using SELECT INTO OUTFILE?

Here is a way to get the header titles from the column names dynamically.

/* Change table_name and database_name */
SET @table_name = 'table_name';
SET @table_schema = 'database_name';
SET @default_group_concat_max_len = (SELECT @@group_concat_max_len);

/* Sets Group Concat Max Limit larger for tables with a lot of columns */
SET SESSION group_concat_max_len = 1000000;

SET @col_names = (
  SELECT GROUP_CONCAT(QUOTE(`column_name`)) AS columns
  FROM information_schema.columns
  WHERE table_schema = @table_schema
  AND table_name = @table_name);

SET @cols = CONCAT('(SELECT ', @col_names, ')');

SET @query = CONCAT('(SELECT * FROM ', @table_schema, '.', @table_name,
  ' INTO OUTFILE \'/tmp/your_csv_file.csv\'
  FIELDS ENCLOSED BY \'\\\'\' TERMINATED BY \'\t\' ESCAPED BY \'\'
  LINES TERMINATED BY \'\n\')');

/* Concatenates column names to query */
SET @sql = CONCAT(@cols, ' UNION ALL ', @query);

/* Resets Group Contact Max Limit back to original value */
SET SESSION group_concat_max_len = @default_group_concat_max_len;

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

How to display Base64 images in HTML?

Try this one too:

let base64="iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==";
let buffer=Uint8Array.from(atob(base64), c => c.charCodeAt(0));
let blob=new Blob([buffer], { type: "image/gif" });
let url=URL.createObjectURL(blob);
let img=document.createElement("img");
img.src=url;
document.body.appendChild(img);

Not recommended for production as it is only compatible with modern browsers.

How can I read a text file from the SD card in Android?

Beware: some phones have 2 sdcards , an internal fixed one and a removable card. You can find the name of the last one via a standard app:"Mijn Bestanden" ( in English: "MyFiles" ? ) When I open this app (item:all files) the path of the open folder is "/sdcard" ,scrolling down there is an entry "external-sd" , clicking this opens the folder "/sdcard/external_sd/" . Suppose I want to open a text-file "MyBooks.txt" I would use something as :

   String Filename = "/mnt/sdcard/external_sd/MyBooks.txt" ;
   File file = new File(fname);...etc...

Get current URL path in PHP

You want $_SERVER['REQUEST_URI']. From the docs:

'REQUEST_URI'

The URI which was given in order to access this page; for instance, '/index.html'.

ssh "permissions are too open" error

I have got the similar issue when i was trying to login to remote ftp server using public keys..        
To solve this issue initially i have done the following process
    First find the location of the public keys because when you try to login to ftp using this public key. first we need to create a key and we set to set that keys permissions to 600.
            Make sure you are in correct location.
            step1:
            go the correct location
            step2:
            After you are in right location
 command: 
     chmod 600 id_rsa

        This has solved my issue.

What is perm space?

It stands for permanent generation:

The permanent generation is special because it holds meta-data describing user classes (classes that are not part of the Java language). Examples of such meta-data are objects describing classes and methods and they are stored in the Permanent Generation. Applications with large code-base can quickly fill up this segment of the heap which will cause java.lang.OutOfMemoryError: PermGen no matter how high your -Xmx and how much memory you have on the machine.

Create an Android GPS tracking application

The source code for the Android mobile application open-gpstracker which you appreciated is available here.

You can checkout the code using SVN client application or via Git:

Debugging the source code will surely help you.

Makefile - missing separator

You need to precede the lines starting with gcc and rm with a hard tab. Commands in make rules are required to start with a tab (unless they follow a semicolon on the same line). The result should look like this:

PROG = semsearch
all: $(PROG)
%: %.c
        gcc -o $@ $< -lpthread

clean:
        rm $(PROG)

Note that some editors may be configured to insert a sequence of spaces instead of a hard tab. If there are spaces at the start of these lines you'll also see the "missing separator" error. If you do have problems inserting hard tabs, use the semicolon way:

PROG = semsearch
all: $(PROG)
%: %.c ; gcc -o $@ $< -lpthread

clean: ; rm $(PROG)

MVC - Set selected value of SelectList

Further to @Womp answer, it's worth noting that the "Where" Can be dropped, and the predicate can be put into the "First" call directly, like this:

list.First(x => x.Value == "selectedValue").Selected = true;

jQuery UI DatePicker - Change Date Format

Here's one specific for your code:

var date = $('#datepicker').datepicker({ dateFormat: 'dd-mm-yy' }).val();

More general info available here:

How can I kill a process by name instead of PID?

Using #killall command:

#killall -9 <processname>

Cut Corners using CSS

CSS Clip-Path

Using a clip-path is a new, up and coming alternative. Its starting to get supported more and more and is now becoming well documented. Since it uses SVG to create the shape, it is responsive straight out of the box.

_x000D_
_x000D_
div {_x000D_
  width: 200px;_x000D_
  min-height: 200px;_x000D_
  -webkit-clip-path: polygon(0 0, 0 100%, 100% 100%, 100% 25%, 75% 0);_x000D_
  clip-path: polygon(0 0, 0 100%, 100% 100%, 100% 25%, 75% 0);_x000D_
  background: lightblue;_x000D_
}
_x000D_
<div>_x000D_
  <p>Some Text</p>_x000D_
</div>
_x000D_
_x000D_
_x000D_

CSS Transform

I have an alternative to web-tiki's transform answer.

_x000D_
_x000D_
body {_x000D_
  background: lightgreen;_x000D_
}_x000D_
div {_x000D_
  width: 200px;_x000D_
  height: 200px;_x000D_
  background: transparent;_x000D_
  position: relative;_x000D_
  overflow: hidden;_x000D_
}_x000D_
div.bg {_x000D_
  width: 200%;_x000D_
  height: 200%;_x000D_
  background: lightblue;_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  left: -75%;_x000D_
  transform-origin: 50% 50%;_x000D_
  transform: rotate(45deg);_x000D_
  z-index: -1;_x000D_
}
_x000D_
<div>_x000D_
  <div class="bg"></div>_x000D_
  <p>Some Text</p>_x000D_
</div>
_x000D_
_x000D_
_x000D_

What could cause an error related to npm not being able to find a file? No contents in my node_modules subfolder. Why is that?

In my case I tried to run npm i [email protected] and got the error because the dev server was running in another terminal on vsc. Hit ctrl+c, y to stop it in that terminal, and then installation works.

How do I use two submit buttons, and differentiate between which one was used to submit the form?

Give each input a name attribute. Only the clicked input's name attribute will be sent to the server.

<input type="submit" name="publish" value="Publish">
<input type="submit" name="save" value="Save">

And then

<?php
    if (isset($_POST['publish'])) {
        # Publish-button was clicked
    }
    elseif (isset($_POST['save'])) {
        # Save-button was clicked
    }
?>

Edit: Changed value attributes to alt. Not sure this is the best approach for image buttons though, any particular reason you don't want to use input[type=image]?

Edit: Since this keeps getting upvotes I went ahead and changed the weird alt/value code to real submit inputs. I believe the original question asked for some sort of image buttons but there are so much better ways to achieve that nowadays instead of using input[type=image].