Programs & Examples On #Windowing

In signal processing windowing allows to work on overlapping segments of the signal.

How to use requirements.txt to install all dependencies in a python project

(Taken from my comment)

pip won't handle system level dependencies. You'll have to apt-get install libfreetype6-dev before continuing. (It even says so right in your output. Try skimming over it for such errors next time, usually build outputs are very detailed)

Disable Drag and Drop on HTML elements?

using @SyntaxError's answer,

I've managed to do this in React; the only way I could figure out was to attach the ondragstart and ondrop methods to a ref, like so:

  const panelManagerBody = React.createRef<HTMLDivElement>();
  useEffect(() => {
    if (panelManagerBody.current) {
      panelManagerBody.current.ondragstart = () => false;
      panelManagerBody.current.ondrop = () => false;
  }, [panelManagerBody]);

  return (
    <div ref={panelManagerBody}>

Div width 100% minus fixed amount of pixels

While Guffa's answer works in many situations, in some cases you may not want the left and/or right pieces of padding to be the parent of the center div. In these cases, you can use a block formatting context on the center and float the padding divs left and right. Here's the code


<div class="container">
    <div class="left"></div>
    <div class="right"></div>
    <div class="center"></div>

The CSS:

.container {
    width: 100px;
    height: 20px;

.left, .right {
    width: 20px;
    height: 100%;
    float: left;
    background: black;   

.right {
    float: right;

.center {
    overflow: auto;
    height: 100%;
    background: blue;

I feel that this element hierarchy is more natural when compared to nested nested divs, and better represents what's on the page. Because of this, borders, padding, and margin can be applied normally to all elements (ie: this 'naturality' goes beyond style and has ramifications).

Note that this only works on divs and other elements that share its 'fill 100% of the width by default' property. Inputs, tables, and possibly others will require you to wrap them in a container div and add a little more css to restore this quality. If you're unlucky enough to be in that situation, contact me and I'll dig up the css.

jsfiddle here:


Creating a SearchView that looks like the material design guidelines

The following will create a SearchView identical to the one in Gmail and add it to the given Toolbar. You'll just have to implement your own "ViewUtil.convertDpToPixel" method.

private SearchView createMaterialSearchView(Toolbar toolbar, String hintText) {

    ActionBar actionBar = getSupportActionBar();

    SearchView searchView = new SearchView(this);

    int rightMarginFrame = 0;
    View frame = searchView.findViewById(getResources().getIdentifier("android:id/search_edit_frame", null, null));
    if (frame != null) {
        LinearLayout.LayoutParams frameParams = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
        rightMarginFrame = ((LinearLayout.LayoutParams) frame.getLayoutParams()).rightMargin;
        frameParams.setMargins(0, 0, 0, 0);

    View plate = searchView.findViewById(getResources().getIdentifier("android:id/search_plate", null, null));
    if (plate != null) {
        plate.setLayoutParams(new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
        plate.setPadding(0, 0, rightMarginFrame, 0);

    int autoCompleteId = getResources().getIdentifier("android:id/search_src_text", null, null);
    if (searchView.findViewById(autoCompleteId) != null) {
        EditText autoComplete = (EditText) searchView.findViewById(autoCompleteId);
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(0, (int) ViewUtil.convertDpToPixel(36));
        params.weight = 1;
        params.gravity = Gravity.CENTER_VERTICAL;
        params.leftMargin = rightMarginFrame;

    int searchMagId = getResources().getIdentifier("android:id/search_mag_icon", null, null);
    if (searchView.findViewById(searchMagId) != null) {
        ImageView v = (ImageView) searchView.findViewById(searchMagId);
        v.setPadding(0, 0, 0, 0);
        LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
        params.setMargins(0, 0, 0, 0);

    toolbar.setContentInsetsAbsolute(0, 0);

    return searchView;

React with ES7: Uncaught TypeError: Cannot read property 'state' of undefined

Make sure you're calling super() as the first thing in your constructor.

You should set this for setAuthorState method

class ManageAuthorPage extends Component {

  state = {
    author: { id: '', firstName: '', lastName: '' }

  constructor(props) {
    this.handleAuthorChange = this.handleAuthorChange.bind(this);

  handleAuthorChange(event) {
    let {name: fieldName, value} =;

      [fieldName]: value

  render() {
    return (

Another alternative based on arrow function:

class ManageAuthorPage extends Component {

  state = {
    author: { id: '', firstName: '', lastName: '' }

  handleAuthorChange = (event) => {
    const {name: fieldName, value} =;

      [fieldName]: value

  render() {
    return (

Could not load file or assembly 'System.Web.WebPages.Razor, Version=

You have upgraded to Razor 3. Remember that VS 12 (until update 4) doesn't support it. Install The Razor 3 from nuget or downgrade it through these step

Scala Doubles, and Precision

You can do:Math.round(<double precision value> * 100.0) / 100.0 But Math.round is fastest but it breaks down badly in corner cases with either a very high number of decimal places (e.g. round(1000.0d, 17)) or large integer part (e.g. round(90080070060.1d, 9)).

Use Bigdecimal it is bit inefficient as it converts the values to string but more relieval: BigDecimal(<value>).setScale(<places>, RoundingMode.HALF_UP).doubleValue() use your preference of Rounding mode.

If you are curious and want to know more detail why this happens you can read this: enter image description here

Java: How to resolve java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException

You can use --add-modules=java.xml.bind JVM option to add xml bind module to JVM run-time environment.

Eg: java --add-modules=java.xml.bind XmlTestClass

Reset local repository branch to be just like remote repository HEAD

Here is a script that automates what the most popular answer suggests ... See for an improved version that supports branches

# reset the current repository
# WF 2012-10-15
# see
timestamp=`date "+%Y-%m-%d-%H_%M_%S"`
git commit -a -m "auto commit at $timestamp"
if [ $? -eq 0 ]
  git branch "auto-save-at-$timestamp" 
git fetch origin
git reset --hard origin/master

Redirect all to index.php using htaccess

There is one "trick" for this problem that fits all scenarios, a so obvious solution that you will have to try it to believe it actually works... :)

Here it is...

<IfModule mod_rewrite.c>

   RewriteEngine On

   RewriteCond %{REQUEST_FILENAME}  -f [OR]
   RewriteCond %{REQUEST_FILENAME} !-f
   RewriteRule ^(.*)$ index.php [L,QSA]


Basically, you are asking MOD_REWRITE to forward to index.php the URI request always when a file exists AND always when the requested file doesn't exist!

When investigating the source code of MOD-REWRITE to understand how it works I realized that all its checks always happen after the verification if the referenced file exists or not. Only then the RegEx are processed. Even when your URI points to a folder, Apache will enforce the check for the index files listed in its configuration file.

Based on that simple discovery, turned obvious a simple file validation would be enough for all possible calls, as far as we double-tap the file presence check and route both results to the same end-point, covering 100% of the possibilities.

IMPORTANT: Notice there is no "/" in index.php. By default, MOD_REWRITE will use the folder it is set as "base folder" for the forwarding. The beauty of it is that it doesn't necessarily need to be the "root folder" of the site, allowing this solution work for localhost/ and/or any subfolder you apply it.

Ultimately, some other solutions I tested before (the ones that appeared to be working fine) broke the PHP ability to "require" a file via its relative path, which is a bummer. Be careful.

Some people may say this is an inelegant solution. It may be, actually, but as far as tests, in several scenarios, several servers, several different Apache versions, etc., this solution worked 100% on all cases!

How to install Guest addition in Mac OS as guest and Windows machine as host

Before you start, close VirtualBox! After those manipulations start VB as Administrator!

  1. Run CMD as Administrator
  2. Use lines below one by one:
  • cd "C:\Program Files\Oracle\Virtualbox"
  • VBoxManage setextradata “macOS_Catalina” VBoxInternal2/EfiGraphicsResolution 1920x1080

Screen Resolutions: 1280x720, 1920x1080, 2048x1080, 2560x1440, 3840x2160, 1280x800, 1280x1024, 1440x900, 1600x900


  • macOS_Catalina - insert your VB machine name.

  • 1920x1080 - put here your Screen Resolution.


Finding the id of a parent div using Jquery

find() and closest() seems slightly slower than:


How do I download a tarball from GitHub using cURL?

Use the -L option to follow redirects:

curl -L | tar zx

Daylight saving time and time zone best practices

Here is my experience:-

(Does not require any third-party library)

  • On server-side, store times in UTC format so that all date/time values in database are in a single standard regardless of location of users, servers, timezones or DST.
  • On the UI layer or in emails sent out to user, you need to show times according to user. For that matter, you need to have user's timezone offset so that you can add this offset to your database's UTC value which will result in user's local time. You can either take user's timezone offset when they are signing up or you can auto-detect them in web and mobile platforms. For websites, JavaScript's function getTimezoneOffset() method is a standard since version 1.0 and compatible with all browsers. (Ref:

Set height of chart in Chart.js

This one worked for me:

I set the height from HTML[height="200"][height="200"][height="200"]

Then I disabled to maintaining aspect ratio

options: {
  responsive: true,
  maintainAspectRatio: false,

window.onload vs $(document).ready()

window.onload is the built-in JavaScript event, but as its implementation had subtle quirks across browsers (Firefox, Internet Explorer 6, Internet Explorer 8, and Opera), jQuery provides document.ready, which abstracts those away, and fires as soon as the page's DOM is ready (doesn't wait for images, etc.).

$(document).ready (note that it's not document.ready, which is undefined) is a jQuery function, wrapping and providing consistency to the following events:

  • document.ondomcontentready / document.ondomcontentloaded - a newish event which fires when the document's DOM is loaded (which may be some time before the images, etc. are loaded); again, slightly different in Internet Explorer and in rest of the world
  • and window.onload (which is implemented even in old browsers), which fires when the entire page loads (images, styles, etc.)

Check OS version in Swift?


  • Xcode 10.2.1 (10E1001), Swift 5




extension OperatingSystemVersion {
    func getFullVersion(separator: String = ".") -> String {
        return "\(majorVersion)\(separator)\(minorVersion)\(separator)\(patchVersion)"

let os = ProcessInfo().operatingSystemVersion
print(os.majorVersion)          // 12
print(os.minorVersion)          // 2
print(os.patchVersion)          // 0
print(os.getFullVersion())      // 12.2.0

How to hide Bootstrap modal with javascript?

I used this code -

Hide modal with smooth effect using Fade Out.



$('.modal-open').css({'overflow': 'visible'});

The executable gets signed with invalid entitlements in Xcode

For those who have the same problem with Provisioning Profile Automatic in the targets Build Settings:

Be very careful when you edit your targets entitlements file! This might break the correspondence to the automatically generated provisioning profile, and you will get this error.

In my case, I had to use temporarily the iCloud production containers with debug builds. To do so, I inserted


in the entitlements file and this worked!
To remind me that I had later to remove these lines, I further inserted simply the following comment:

<string>The entry below must be out commented or deleted to use the iCloud development environment.</string>  

And this broke the correspondence, and created the error.

Vue js error: Component template should contain exactly one root element

I was confused as I knew VueJS should only contain 1 root element and yet I was still getting this same "template syntax error Component template should contain exactly one root element..." error on an extremely simple component. Turns out I had just mispelled </template> as </tempate> and that was giving me this same error in a few files I copied and pasted. In summary, check your syntax for any mispellings in your component.

Error CS1705: "which has a higher version than referenced assembly"

I had this error because "Rebuild" was not really rebuilding.

Solution: Close Visual Studio, really go and delete the bin folder, then rebuild, it might work better.

Also, sometimes Visual Studio lies about references, so check the HintPathin your .csproj files.

Get the distance between two geo points

Location loc1 = new Location("");

Location loc2 = new Location("");

float distanceInMeters = loc1.distanceTo(loc2);


how to show confirmation alert with three buttons 'Yes' 'No' and 'Cancel' as it shows in MS Word

If you don't want to use a separate JS library to create a custom control for that, you could use two confirm dialogs to do the checks:

if (confirm("Are you sure you want to quit?") ) {
    if (confirm("Save your work before leaving?") ) {
        // code here for save then leave (Yes)
    } else {
        //code here for no save but leave (No)
} else {
    //code here for don't leave (Cancel)

How to convert a unix timestamp (seconds since epoch) to Ruby DateTime?

Time Zone Handling

I just want to clarify, even though this has been commented so future people don't miss this very important distinction.

DateTime.strptime("1318996912",'%s') # => Wed, 19 Oct 2011 04:01:52 +0000

displays a return value in UTC and requires the seconds to be a String and outputs a UTC Time object, whereas # => 2011-10-19 00:01:52 -0400

displays a return value in the LOCAL time zone, normally requires a FixNum argument, but the Time object itself is still in UTC even though the display is not.

So even though I passed the same integer to both methods, I seemingly two different results because of how the class' #to_s method works. However, as @Eero had to remind me twice of: == DateTime.strptime("1318996912",'%s') # => true

An equality comparison between the two return values still returns true. Again, this is because the values are basically the same (although different classes, the #== method takes care of this for you), but the #to_s method prints drastically different strings. Although, if we look at the strings, we can see they are indeed the same time, just printed in different time zones.

Method Argument Clarification

The docs also say "If a numeric argument is given, the result is in local time." which makes sense, but was a little confusing to me because they don't give any examples of non-integer arguments in the docs. So, for some non-integer argument examples:"1318996912")
TypeError: can't convert String into an exact number

you can't use a String argument, but you can use a Time argument into and it will return the result in the time zone of the argument:,11,1,15,25,0, "+09:00"))
=> 2007-11-01 15:25:00 +0900


After a discussion with @AdamEberlin on his answer, I decided to publish slightly changed benchmarks to make everything as equal as possible. Also, I never want to have to build these again so this is as good a place as any to save them. ~ 2.8x faster

09:10:58-watsw018:~$ ruby -v
ruby 2.3.7p456 (2018-03-28 revision 63024) [universal.x86_64-darwin18]
09:11:00-watsw018:~$ irb
irb(main):001:0> require 'benchmark'
=> true
irb(main):002:0> require 'date'
=> true
irb(main):004:0* format = '%s'
=> "%s"
irb(main):005:0> times = ['1318996912', '1318496913']
=> ["1318996912", "1318496913"]
irb(main):006:0> int_times =
=> [1318996912, 1318496913]
irb(main):008:0* datetime_from_strptime = DateTime.strptime(times.first, format)
=> #<DateTime: 2011-10-19T04:01:52+00:00 ((2455854j,14512s,0n),+0s,2299161j)>
irb(main):009:0> datetime_from_time =
=> #<DateTime: 2011-10-19T00:01:52-04:00 ((2455854j,14512s,0n),-14400s,2299161j)>
irb(main):011:0* datetime_from_strptime === datetime_from_time
=> true
irb(main):013:0* Benchmark.measure do
irb(main):014:1*   100_000.times {
irb(main):015:2*     times.each do |i|
irb(main):016:3*       DateTime.strptime(i, format)
irb(main):017:3>     end
irb(main):018:2>   }
irb(main):019:1> end
=> #<Benchmark::Tms:0x00007fbdc18f0d28 @label="", @real=0.8680500000045868, @cstime=0.0, @cutime=0.0, @stime=0.009999999999999998, @utime=0.86, @total=0.87>
irb(main):021:0* Benchmark.measure do
irb(main):022:1*   100_000.times {
irb(main):023:2*     int_times.each do |i|
irb(main):025:3>     end
irb(main):026:2>   }
irb(main):027:1> end
=> #<Benchmark::Tms:0x00007fbdc3108be0 @label="", @real=0.33059399999910966, @cstime=0.0, @cutime=0.0, @stime=0.0, @utime=0.32000000000000006, @total=0.32000000000000006>

****edited to not be completely and totally incorrect in every way****

****added benchmarks****

Conditional replacement of values in a data.frame

Here is one approach. ifelse is vectorized and it checks all rows for zero values of b and replaces est with (a - 5)/2.53 if that is the case.

df <- transform(df, est = ifelse(b == 0, (a - 5)/2.53, est))

Google Spreadsheet, Count IF contains a string

In case someone is still looking for the answer, this worked for me:

=COUNTIF(A2:A51, "*" & B1 & "*")

B1 containing the iPad string.

How to get Java Decompiler / JD / JD-Eclipse running in Eclipse Helios

Simple thing i did to get it working:

Went in eclipse > Window > Preferences

(Optional)typed in the search box "file" to help trim the tree of options. Went to General > Editors > File associations.

Clicked the ".class" type. Below there were 2 editors present, i clicked on the "Class File Editor" - the one with the icon from JD, clicked the "Default" button on the right.

Done. Now all ur class are belong to us.

Sort a list of tuples by 2nd item (integer value)

As a python neophyte, I just wanted to mention that if the data did actually look like this:

data = [('abc', 121),('abc', 231),('abc', 148), ('abc',221)]

then sorted() would automatically sort by the second element in the tuple, as the first elements are all identical.

Switch on Enum in Java

You might be using the enums incorrectly in the switch cases. In comparison with the above example by CoolBeans.. you might be doing the following:

switch(day) {
    case Day.MONDAY:
        // Something..
    case Day.FRIDAY:
        // Something friday

Make sure that you use the actual enum values instead of EnumType.EnumValue

Eclipse points out this mistake though..

module.exports vs exports in Node.js

in node js module.js file is use to run the module.load system.every time when node execute a file it wrap your js file content as follow

'(function (exports, require, module, __filename, __dirname) {',+
     //your js file content

because of this wrapping inside ur js source code you can access exports,require,module,etc.. this approach is used because there is no other way to get functionalities wrote in on js file to another.

then node execute this wrapped function using c++. at that moment exports object that passed into this function will be filled.

you can see inside this function parameters exports and module. actually exports is a public member of module constructor function.

look at following code

copy this code into b.js

console.log("module is ";
console.log("object.keys "+Object.keys(module));
console.log(exports === module.exports);
console.log("exports is ";
var foo = require('a.js');
console.log("object.keys of foo: "+Object.keys(foo));
console.log('name is '+ foo);

copy this code to a.js = 'hello'; = 'hi';
module.exports.age = 23;
module.exports = function(){console.log('function to module exports')};
//exports = function(){console.log('function to export');}

now run using node

this is the output

module is [object Object]
object.keys id,exports,parent,filename,loaded,children,paths

exports is [object Object]

object.keys of foo: name is function (){console.log('function to module exports')} function to module exports

now remove the commented line in a.js and comment the line above that line and remove the last line of b.js and run.

in javascript world you cannot reassign object that passed as parameter but you can change function's public member when object of that function set as a parameter to another function

do remember

use module.exports on and only if you wants to get a function when you use require keyword . in above example we var foo = require(a.js); you can see we can call foo as a function;

this is how node documentation explain it "The exports object is created by the Module system. Sometimes this is not acceptable, many want their module to be an instance of some class. To do this assign the desired export object to module.exports."

Create a List that contain each Line of a File

my_list = [line.split(',') for line in open("filename.txt")]

Multidimensional arrays in Swift

You are creating an array of three elements and assigning all three to the same thing, which is itself an array of three elements (three Doubles).

When you do the modifications you are modifying the floats in the internal array.

Uncaught TypeError: Cannot read property 'value' of null

Instead of document or $(document) to avoid JQuery, you can add a TimeOut to validate the objects. TimeOut is executed after loading all objects within the page and other events...

setTimeout(function () { 

var str = document.getElementById("cal_preview").value;
var str1 = document.getElementById("year").value;

}, 0);

Get selected value/text from Select on change

I wonder that everyone has posted about value and text option to get from <option> and no one suggested label.

So I am suggesting label too, as supported by all browsers

To get value (same as others suggested)

function test(a) {
var x = a.options[a.selectedIndex].value;

To get option text (i.e. Communication or -Select-)

function test(a) {
var x = a.options[a.selectedIndex].text;

OR (New suggestion)

function test(a) {
var x = a.options[a.selectedIndex].label;


<select onchange="test(this)" id="select_id">
    <option value="0">-Select-</option>
    <option value="1">Communication</option>
    <option value="2" label=‘newText’>Communication</option>

Note: In above HTML for option value 2, label will return newText instead of Communication


Note: It is not possible to set the label property in Firefox (only return).

jQuery Validation plugin: disable validation for specified submit buttons

Other (undocumented) way to do it, is to call:

$("form").validate().cancelSubmit = true;

on the click event of the button (for example).

Select subset of columns in data.table R

Option using dplyr

dt <- select(dt, -V1, -V2, -V3, -V4)

How to count items in JSON data

You're close. A really simple solution is just to get the length from the 'run' objects returned. No need to bother with 'load' or 'loads':


Which rows are returned when using LIMIT with OFFSET in MySQL?

OFFSET is nothing but a keyword to indicate starting cursor in table

SELECT column FROM table LIMIT 18 OFFSET 8 -- fetch 18 records, begin with record 9 (OFFSET 8)

you would get the same result form

SELECT column FROM table LIMIT 8, 18

visual representation (R is one record in the table in some order)

 OFFSET        LIMIT          rest of the table
 __||__   _______||_______   __||__
/      \ /                \ /
             your result

c# Image resizing to different size while preserving aspect ratio

I'm going to add my code here too. This code will allow you resize an image with or without the aspect ratio being enforced or to resize with padding. This is a modified version of egrunin's code.

using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;

namespace ConsoleApplication1
    public class Program
        public static void Main(string[] args)
            var path = Directory.GetParent(Directory.GetCurrentDirectory()).Parent.FullName;
            ResizeImage(path, "large.jpg", path, "new.jpg", 100, 100, true, true);

        /// <summary>Resizes an image to a new width and height.</summary>
        /// <param name="originalPath">The folder which holds the original image.</param>
        /// <param name="originalFileName">The file name of the original image.</param>
        /// <param name="newPath">The folder which will hold the resized image.</param>
        /// <param name="newFileName">The file name of the resized image.</param>
        /// <param name="maximumWidth">When resizing the image, this is the maximum width to resize the image to.</param>
        /// <param name="maximumHeight">When resizing the image, this is the maximum height to resize the image to.</param>
        /// <param name="enforceRatio">Indicates whether to keep the width/height ratio aspect or not. If set to false, images with an unequal width and height will be distorted and padding is disregarded. If set to true, the width/height ratio aspect is maintained and distortion does not occur.</param>
        /// <param name="addPadding">Indicates whether fill the smaller dimension of the image with a white background. If set to true, the white padding fills the smaller dimension until it reach the specified max width or height. This is used for maintaining a 1:1 ratio if the max width and height are the same.</param>
        private static void ResizeImage(string originalPath, string originalFileName, string newPath, string newFileName, int maximumWidth, int maximumHeight, bool enforceRatio, bool addPadding)
            var image = Image.FromFile(originalPath + "\\" + originalFileName);
            var imageEncoders = ImageCodecInfo.GetImageEncoders();
            EncoderParameters encoderParameters = new EncoderParameters(1);
            encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality, 100L);
            var canvasWidth = maximumWidth;
            var canvasHeight = maximumHeight;
            var newImageWidth = maximumWidth;
            var newImageHeight = maximumHeight;
            var xPosition = 0;
            var yPosition = 0;

            if (enforceRatio)
                var ratioX = maximumWidth / (double)image.Width;
                var ratioY = maximumHeight / (double)image.Height;
                var ratio = ratioX < ratioY ? ratioX : ratioY;
                newImageHeight = (int)(image.Height * ratio);
                newImageWidth = (int)(image.Width * ratio);

                if (addPadding)
                    xPosition = (int)((maximumWidth - (image.Width * ratio)) / 2);
                    yPosition = (int)((maximumHeight - (image.Height * ratio)) / 2);
                    canvasWidth = newImageWidth;
                    canvasHeight = newImageHeight;                  

            var thumbnail = new Bitmap(canvasWidth, canvasHeight);
            var graphic = Graphics.FromImage(thumbnail);

            if (enforceRatio && addPadding)

            graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
            graphic.SmoothingMode = SmoothingMode.HighQuality;
            graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
            graphic.CompositingQuality = CompositingQuality.HighQuality;
            graphic.DrawImage(image, xPosition, yPosition, newImageWidth, newImageHeight);

            thumbnail.Save(newPath + "\\" + newFileName, imageEncoders[1], encoderParameters);

What is the correct wget command syntax for HTTPS with username and password?

You could try the same address with HTTP instead of HTTPS. Be aware that this does use HTTP instead of HTTPS and only some sites might support this method.

Example address:


*notice the http:// instead of https://.

This is probably not recommended though :)

If you can, try use curl.


FYI an example with username (and prompt for password) would be:

curl --user $USERNAME -O

Where -O is

 -O, --remote-name
              Write output to a local file named like the remote file we get. (Only the file part of the remote file is used, the path is cut off.)

Excel formula to display ONLY month and year?

Try the formula


How to use enums as flags in C++?

@Xaqq has provided a really nice type-safe way to use enum flags here by a flag_set class.

I published the code in GitHub, usage is as follows:

#include "flag_set.hpp"

enum class AnimalFlags : uint8_t {

int main()
    flag_set<AnimalFlags> seahawkFlags(AnimalFlags::HAS_CLAWS
                                       | AnimalFlags::EATS_FISH
                                       | AnimalFlags::ENDANGERED);

    if (seahawkFlags & AnimalFlags::ENDANGERED)
        cout << "Seahawk is endangered";

What does upstream mean in nginx?

It's used for proxying requests to other servers.

An example from is:

http {
  upstream myproject {
    server weight=3;

  server {
    listen 80;
    location / {
      proxy_pass http://myproject;

This means all requests for / go to the any of the servers listed under upstream XXX, with a preference for port 8000.

Remove Backslashes from Json Data in JavaScript

tl;dr: You don't have to remove the slashes, you have nested JSON, and hence have to decode the JSON twice: DEMO (note I used double slashes in the example, because the JSON is inside a JS string literal).

I assume that your actual JSON looks like

{"data":"{\n \"taskNames\" : [\n \"01 Jan\",\n \"02 Jan\",\n \"03 Jan\",\n \"04 Jan\",\n \"05 Jan\",\n \"06 Jan\",\n \"07 Jan\",\n \"08 Jan\",\n \"09 Jan\",\n \"10 Jan\",\n \"11 Jan\",\n \"12 Jan\",\n \"13 Jan\",\n \"14 Jan\",\n \"15 Jan\",\n \"16 Jan\",\n \"17 Jan\",\n \"18 Jan\",\n \"19 Jan\",\n \"20 Jan\",\n \"21 Jan\",\n \"22 Jan\",\n \"23 Jan\",\n \"24 Jan\",\n \"25 Jan\",\n \"26 Jan\",\n \"27 Jan\"]}"}

I.e. you have a top level object with one key, data. The value of that key is a string containing JSON itself. This is usually because the server side code didn't properly create the JSON. That's why you see the \" inside the string. This lets the parser know that " is to be treated literally and doesn't terminate the string.

So you can either fix the server side code, so that you don't double encode the data, or you have to decode the JSON twice, e.g.

var data = JSON.parse(JSON.parse(json).data));

How can I create a dynamic button click event on a dynamic button?

Let's say you have 25 objects and want one process to handle any one objects click event. You could write 25 delegates or use a loop to handle the click event.

public form1()
    foreach (Panel pl  in Container.Components)
        pl.Click += Panel_Click;

private void Panel_Click(object sender, EventArgs e)
    // Process the panel clicks here
    int index = Panels.FindIndex(a => a == sender);

GridView sorting: SortDirection always Ascending

All that answer not fully correct. I use That:

protected void SetPageSort(GridViewSortEventArgs e) 
            if (e.SortExpression == SortExpression) 
                if (SortDirection == "ASC") 
                    SortDirection = "DESC"; 
                    SortDirection = "ASC"; 
                if (SortDirection == "ASC")
                    SortDirection = "DESC";
                    SortDirection = "ASC";
                SortExpression = e.SortExpression; 
  protected void gridView_Sorting(object sender, GridViewSortEventArgs e)

in gridView_Sorting...

What are allowed characters in cookies?

One more consideration. I recently implemented a scheme in which some sensitive data posted to a PHP script needed to convert and return it as an encrypted cookie, that used all base64 values I thought were guaranteed 'safe". So I dutifully encrypted the data items using RC4, ran the output through base64_encode, and happily returned the cookie to the site. Testing seemed to go well until a base64 encoded string contained a "+" symbol. The string was written to the page cookie with no trouble. Using the browser diagnostics I could also verify the cookies was written unchanged. Then when a subsequent page called my PHP and obtained the cookie via the $_COOKIE array, I was stammered to find the string was now missing the "+" sign. Every occurrence of that character was replaced with an ASCII space.

Considering how many similar unresolved complaints I've read describing this scenario since then, often siting numerous references to using base64 to "safely" store arbitrary data in cookies, I thought I'd point out the problem and offer my admittedly kludgy solution.

After you've done whatever encryption you want to do on a piece of data, and then used base64_encode to make it "cookie-safe", run the output string through this...

// from browser to PHP. substitute troublesome chars with 
// other cookie safe chars, or vis-versa.  

function fix64($inp) {
    $out =$inp;
    for($i = 0; $i < strlen($inp); $i++) {
        $c = $inp[$i];
        switch ($c) {
            case '+':  $c = '*'; break; // definitly won't transfer!
            case '*':  $c = '+'; break;

            case '=':  $c = ':'; break; // = symbol seems like a bad idea
            case ':':  $c = '='; break;

            default: continue;
        $out[$i] = $c;
    return $out;

Here I'm simply substituting "+" (and I decided "=" as well) with other "cookie safe" characters, before returning the encoded value to the page, for use as a cookie. Note that the length of the string being processed doesn't change. When the same (or another page on the site) runs my PHP script again, I'll be able to recover this cookie without missing characters. I just have to remember to pass the cookie back through the same fix64() call I created, and from there I can decode it with the usual base64_decode(), followed by whatever other decryption in your scheme.

There may be some setting I could make in PHP that allows base64 strings used in cookies to be transferred back to to PHP without corruption. In the mean time this works. The "+" may be a "legal" cookie value, but if you have any desire to be able to transmit such a string back to PHP (in my case via the $_COOKIE array), I'm suggesting re-processing to remove offending characters, and restore them after recovery. There are plenty of other "cookie safe" characters to choose from.

swift 3.0 Data to String?

According to the Apple doc below, device token can not be decoded. So, I think the best thing to do is just leave it be.

Security Architecture

A device token is an opaque NSData instance that contains a unique identifier assigned by Apple to a specific app on a specific device. Only APNs can decode and read the contents of a device token. Each app instance receives its unique device token when it registers with APNs, and must then forward the token to its provider, as described in Configuring Remote Notification Support. The provider must include the device token in each push notification request that targets the associated device; APNs uses the device token to ensure the notification is delivered only to the unique app-device combination for which it is intended.

How to resize a custom view programmatically?

This works for me:

ViewGroup.LayoutParams params = layout.getLayoutParams();
params.height = customHeight;

How do I format a number in Java?

Be aware that classes that descend from NumberFormat (and most other Format descendants) are not synchronized. It is a common (but dangerous) practice to create format objects and store them in static variables in a util class. In practice, it will pretty much always work until it starts experiencing significant load.

Convert HTML to NSAttributedString in iOS

honoring font family, dynamic font I've concocted this abomination:

extension NSAttributedString
    convenience fileprivate init?(html: String, font: UIFont? = Font.dynamic(style: .subheadline))
        guard let data = String.Encoding.utf8, allowLossyConversion: true) else {
        var totalString = html
            .AppleSystemUIFont I get in font.familyName does not work
         while -apple-system does:
        var ffamily = "-apple-system"
        if let font = font {
            let lLDBsucks = font.familyName
            if !lLDBsucks.hasPrefix(".appleSystem") {
                ffamily = font.familyName
            totalString = "<style>\nhtml * {font-family: \(ffamily) !important;}\n            </style>\n" + html
        guard let data = String.Encoding.utf8, allowLossyConversion: true) else {
            return nil
        guard let attributedText = try?  NSAttributedString(data: data, options: [.documentType: NSAttributedString.DocumentType.html, .characterEncoding: String.Encoding.utf8.rawValue], documentAttributes: nil) else {
            return nil
        let mutable = NSMutableAttributedString(attributedString: attributedText)
        if let font = font {
        do {
            var found = false
            mutable.enumerateAttribute(NSAttributedString.Key.font, in: NSMakeRange(0, attributedText.length), options: NSAttributedString.EnumerationOptions(rawValue: 0)) { (value, range, stop) in
                    if let oldFont = value as? UIFont {
                        let newsize = oldFont.pointSize * 15 * Font.scaleHeruistic / 12
                        let newFont = oldFont.withSize(newsize)
                        mutable.addAttribute(NSAttributedString.Key.font, value: newFont, range: range)
                        found = true
                if !found {
                    // No font was found - do something else?

//            mutable.addAttribute(.font, value: font, range: NSRange(location: 0, length: mutable.length))
        self.init(attributedString: mutable)


alternatively you can use the versions this was derived from and set font on UILabel after setting attributedString

this will clobber the size and boldness encapsulated in the attributestring though

kudos for reading through all the answers up to here. You are a very patient man woman or child.

Sending a JSON HTTP POST request from Android

try some thing like blow:

SString otherParametersUrServiceNeed =  "Company=acompany&Lng=test&MainPeriod=test&UserID=123&CourseDate=8:10:10";
String request = "";

URL url = new URL(request); 
HttpURLConnection connection = (HttpURLConnection) url.openConnection();   
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); 
connection.setRequestProperty("charset", "utf-8");
connection.setRequestProperty("Content-Length", "" + Integer.toString(otherParametersUrServiceNeed.getBytes().length));
connection.setUseCaches (false);

DataOutputStream wr = new DataOutputStream(connection.getOutputStream ());

   JSONObject jsonParam = new JSONObject();
jsonParam.put("ID", "25");
jsonParam.put("description", "Real");
jsonParam.put("enable", "true");



References :

  2. Java - sending HTTP parameters via POST method easily

How can I update npm on Windows?

This might help someone. Neither "npm-windows-upgrade" nor the installer alone did it for me. Powershell was still using an older version of node and npm.

So this is what I did (worked for me): 1. Download the latest installer from Install node. It will update your node; everywhere (Powershell, cmd etc.). 2. Install the npm-windows-upgrade package (npm install -g npm-windows-upgrade) and run npm-windows-upgrade.

I didn't uninstall anything and didn't set any paths.

how do I set height of container DIV to 100% of window height?

Add this to your css:

html, body {

If you say height:100%, you mean '100% of the parent element'. If the parent element has no specified height, nothing will happen. You only set 100% on body, but you also need to add it to html.

Bootstrap 3, 4 and 5 .container-fluid with grid adding unwanted padding

You only need these CSS properties in .container class of Bootstrap and you can put inside him the normal grid system without someone content of the container will be out of him (without scroll-x in the viewport).


<div class="container">
    <div class="row">
        <div class="col-xs-12">
            Your content here!
    ... more rows


/* Bootstrap custom */
    padding-left: 0rem;
    padding-right: 0rem;
    overflow: hidden;

What is 'Context' on Android?

Just putting it out there for newbies;

So First understand Word Context :

In english-lib. it means:

"The circumstances that form the setting for an event, statement, or idea, and in terms of which it can be fully understood and assessed."

"The parts of something written or spoken that immediately precede and follow a word or passage and clarify its meaning."

Now take the same understanding to programming world:

context of current state of the application/object. It lets newly created objects understand what has been going on. Typically you call it to get information regarding another part of your program (activity, package/application)

You can get the context by invoking getApplicationContext(), getContext(), getBaseContext() or this (when in the activity class).

To Get Context Anywhere in application use following code:

Create new class AppContext inside your android application

public class AppContext extends Application {

    private static Context context;

    public void onCreate(){
        AppContext.context = getApplicationContext();

    public static Context getAppContext() {
        return AppContext.context;

Now any time you want application context in non-activity class, call this method and you have application context.

Hope this help ;)

Entity framework left join

If UserGroups has a one to many relationship with UserGroupPrices table, then in EF, once the relationship is defined in code like:

//In UserGroups Model
public List<UserGroupPrices> UserGrpPriceList {get;set;}

//In UserGroupPrices model
public UserGroups UserGrps {get;set;}

You can pull the left joined result set by simply this:

var list = db.UserGroupDbSet.ToList();

assuming your DbSet for the left table is UserGroupDbSet, which will include the UserGrpPriceList, which is a list of all associated records from the right table.

How to properly add include directories with CMake

CMake is more like a script language if comparing it with other ways to create Makefile (e.g. make or qmake). It is not very cool like Python, but still.

There are no such thing like a "proper way" if looking in various opensource projects how people include directories. But there are two ways to do it.

  1. Crude include_directories will append a directory to the current project and all other descendant projects which you will append via a series of add_subdirectory commands. Sometimes people say that such approach is legacy.

  2. A more elegant way is with target_include_directories. It allows to append a directory for a specific project/target without (maybe) unnecessary inheritance or clashing of various include directories. Also allow to perform even a subtle configuration and append one of the following markers for this command.

PRIVATE - use only for this specified build target

PUBLIC - use it for specified target and for targets which links with this project

INTERFACE -- use it only for targets which links with the current project


  1. Both commands allow to mark a directory as SYSTEM to give a hint that it is not your business that specified directories will contain warnings.

  2. A similar answer is with other pairs of commands target_compile_definitions/add_definitions, target_compile_options/CMAKE_C_FLAGS

How to compare dates in datetime fields in Postgresql?

Use the range type. If the user enter a date:

select *
from table
    tsrange('2013-05-03', '2013-05-03'::date + 1, '[)');

If the user enters timestamps then you don't need the ::date + 1 part

Import text file as single character string

readChar doesn't have much flexibility so I combined your solutions (readLines and paste).

I have also added a space between each line:

con <- file("/Users/YourtextFile.txt", "r", blocking = FALSE)
singleString <- readLines(con) # empty
singleString <- paste(singleString, sep = " ", collapse = " ")

Multiprocessing vs Threading Python

Process may have multiple threads. These threads may share memory and are the units of execution within a process.

Processes run on the CPU, so threads are residing under each process. Processes are individual entities which run independently. If you want to share data or state between each process, you may use a memory-storage tool such as Cache(redis, memcache), Files, or a Database.

How do I open phone settings when a button is clicked?

I have seen this line of code

UIApplication.sharedApplication() .openURL(NSURL(string:"prefs:root=General")!)

is not working, it didn't work for me in ios10/ Xcode 8, just a small code difference, please replace this with




Replace with


Hope it helps. Cheers.

How can I pass a list as a command-line argument with argparse?

I prefer passing a delimited string which I parse later in the script. The reasons for this are; the list can be of any type int or str, and sometimes using nargs I run into problems if there are multiple optional arguments and positional arguments.

parser = ArgumentParser()
parser.add_argument('-l', '--list', help='delimited list input', type=str)
args = parser.parse_args()
my_list = [int(item) for item in args.list.split(',')]


python -l "265340,268738,270774,270817" [other arguments]


python -l 265340,268738,270774,270817 [other arguments]

will work fine. The delimiter can be a space, too, which would though enforce quotes around the argument value like in the example in the question.

Or you can use a lambda type as suggested in the comments by Chepner:

parser.add_argument('-l', '--list', help='delimited list input', 
    type=lambda s: [int(item) for item in s.split(',')])

Modifying a file inside a jar

You can use Vim:

vim my.jar

Vim is able to edit compressed text files, given you have unzip in your environment.

JavaScript: Create and save file

setTimeout("create('Hello world!', 'myfile.txt', 'text/plain')");_x000D_
function create(text, name, type) {_x000D_
  var dlbtn = document.getElementById("dlbtn");_x000D_
  var file = new Blob([text], {type: type});_x000D_
  dlbtn.href = URL.createObjectURL(file);_x000D_ = name;_x000D_
<a href="javascript:void(0)" id="dlbtn"><button>click here to download your file</button></a>

Index Error: list index out of range (Python)

Generally it means that you are providing an index for which a list element does not exist.

E.g, if your list was [1, 3, 5, 7], and you asked for the element at index 10, you would be well out of bounds and receive an error, as only elements 0 through 3 exist.

json_decode() expects parameter 1 to be string, array given

Ok I was running into the same issue. What I failed to notice is that I was using json_decode() instead of using json_encode() so for those who are going to come here please make sure you are using the right function, which is json_encode()

Note: Depends on what you are working on but make sure you are using the right function.

How can I format a number into a string with leading zeros?

int num=1;
string number=num.ToString().PadLeft(4, '0')


EDIT: Changed to match the PadLeft amount

How should I read a file line-by-line in Python?


with open('filename.txt') as fp:
    for line in fp:
        print line

is the way to go.

It is not more verbose. It is more safe.

How to select an item in a ListView programmatically?

if (listView1.Items.Count > 0)
    listView1.Items[0].Selected = true;

list items do not appear selected unless the control has the focus (or you set the HideSelection property to false)

Javascript setInterval not working

That's because you should pass a function, not a string:

function funcName() {

setInterval(funcName, 10000);

Your code has two problems:

  • var func = funcName(); calls the function immediately and assigns the return value.
  • Just "func" is invalid even if you use the bad and deprecated eval-like syntax of setInterval. It would be setInterval("func()", 10000) to call the function eval-like.

Running code in main thread from another thread

So most handy is to do sort of:

import android.os.AsyncTask
import android.os.Handler
import android.os.Looper

object Dispatch {
    fun asyncOnBackground(call: ()->Unit) {
        AsyncTask.execute {

    fun asyncOnMain(call: ()->Unit) {
        Handler(Looper.getMainLooper()).post {

And after:

Dispatch.asyncOnBackground {
    val value = ...// super processing
    Dispatch.asyncOnMain { completion(value)}

How to get last N records with activerecord?

Add an :order parameter to the query

MVC 4 Razor adding input type date

If you want to use @Html.EditorFor() you have to use jQuery ui and update your Mvc to with NuGet Package Manager.

@Html.EditorFor(m => m.EntryDate, new { htmlAttributes = new { @class = "datepicker" } })

@section Scripts {








How can I add a background thread to flask?

First, you should use any WebSocket or polling mechanics to notify the frontend part about changes that happened. I use Flask-SocketIO wrapper, and very happy with async messaging for my tiny apps.

Nest, you can do all logic which you need in a separate thread(s), and notify the frontend via SocketIO object (Flask holds continuous open connection with every frontend client).

As an example, I just implemented page reload on backend file modifications:

<!doctype html>
    sio = io()

class App(Web, Module):

    def __init__(self, V):
        ## flask module instance
        self.flask = flask
        ## wrapped application instance = flask.Flask(self.value)['SECRET_KEY'] = config.SECRET_KEY
        ## `flask-socketio`
        self.sio = SocketIO(

    ## inotify reload files after change via `sio(reload)``
    def watchfiles(self):
        from watchdog.observers import Observer
        from import FileSystemEventHandler
        class Handler(FileSystemEventHandler):
            def __init__(self,sio):
                self.sio = sio
            def on_modified(self, event):
                self.sio.emit('reload',[event.src_path,event.event_type,event.is_directory]) = Observer(),path='static',recursive=True),path='templates',recursive=True)

Getting started with Haskell

I'd suggest joining the #haskell irc channel and asking questions there. That's how I learned Haskell. If you go through Real World Haskell as suggested above, real time answers to your questions will help greatly. Lots of smart people on #haskell write Haskell for fun and for profit, so you'll get lots of good input. Try it!

How do I get the size of a java.sql.ResultSet?

ResultSet rs = ps.executeQuery();
int rowcount = 0;
if (rs.last()) {
  rowcount = rs.getRow();
  rs.beforeFirst(); // not rs.first() because the below will move on, missing the first element
while ( {
  // do your standard per row stuff

How to emulate GPS location in the Android Emulator?

No one here mentioned the built in solution of the emulator itself, so for future visitors, I'd like to share it with visuals.

First, run your Android Emulator and click on the menu button (3 dots) shown below:

emulator with menu button

Then from the left pane, select Location and change the coordinates according to your needs. After pressing Send button, changes will immediately take effect (I recommend you to open up Google Maps for better understanding).

enter image description here

Android Studio Version: 2.3.3

In addition, to make your different locations coming to your application in real time, you can use GPX file. It's very easy to create this file from Google Map direction link:

  1. Go to google map, choose a location, then press "Directions" and enter the second location.
  2. After route is created, copy a link from the browser
  3. Go to this website: and paste the link to "Let's Go" box
  4. Press the "Let's Go" button and GPX file will be downloaded

Use "Load GPS/KML" button to load the created file to your emulator, choose speed, and press green play button on the bottom. Locations will be sent in real time as shown on the picture below.

enter image description here

Custom "confirm" dialog in JavaScript?

var confirmBox = '<div class="modal fade confirm-modal">' +_x000D_
    '<div class="modal-dialog modal-sm" role="document">' +_x000D_
    '<div class="modal-content">' +_x000D_
    '<button type="button" class="close m-4 c-pointer" data-dismiss="modal" aria-label="Close">' +_x000D_
    '<span aria-hidden="true">&times;</span>' +_x000D_
    '</button>' +_x000D_
    '<div class="modal-body pb-5"></div>' +_x000D_
    '<div class="modal-footer pt-3 pb-3">' +_x000D_
    '<a href="#" class="btn btn-primary yesBtn btn-sm">OK</a>' +_x000D_
    '<button type="button" class="btn btn-secondary abortBtn btn-sm" data-dismiss="modal">Abbrechen</button>' +_x000D_
    '</div>' +_x000D_
    '</div>' +_x000D_
    '</div>' +_x000D_
var dialog = function(el, text, trueCallback, abortCallback) {_x000D_
_x000D_ {_x000D_
        var thisConfirm = $(confirmBox).clone();_x000D_
        if (abortCallback) {_x000D_
            $(thisConfirm).find('.abortBtn').click(function(e) {_x000D_
        if (trueCallback) {_x000D_
            $(thisConfirm).find('.yesBtn').click(function(e) {_x000D_
        } else {_x000D_
            if (el.prop('nodeName') == 'A') {_x000D_
                $(thisConfirm).find('.yesBtn').attr('href', el.attr('href'));_x000D_
            if (el.attr('type') == 'submit') {_x000D_
                $(thisConfirm).find('.yesBtn').click(function(e) {_x000D_
        $(thisConfirm).on('', function(e) {_x000D_
// custom confirm_x000D_
$(function() {_x000D_
    $('[data-confirm]').each(function() {_x000D_
        dialog($(this), $(this).attr('data-confirm'));_x000D_
    dialog($('#customCallback'), "dialog with custom callback", function() {_x000D_
        alert("hi there");_x000D_
.test {_x000D_
  padding: 5p 10px;_x000D_
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<link href="" rel="stylesheet"/>_x000D_
example 1_x000D_
<a class="test" href="http://example" data-confirm="do you want really leave the website?">leave website</a><br><br>_x000D_
example 2_x000D_
<form action="">_x000D_
<button class="test" type="submit" data-confirm="send form to delete some files?">delete some files</button>_x000D_
example 3_x000D_
<span class="test"  id="customCallback">with callback</span>

Why does MSBuild look in C:\ for Microsoft.Cpp.Default.props instead of c:\Program Files (x86)\MSBuild? ( error MSB4019)

EDIT: This applies to older versions of Visual Studio / MSBuild (specifically MSVC2015?). With more modern versions, MSBuild is included in Visual Studio Build Tools 2019, and compilers are located in different places and detected in different ways.

This is due to a mismatch of installed MSBuild toolsets and registry settings. It can happen if you did one or more of the following:

  • Install multiple Visual Studio versions in the wrong order
  • Uninstall one or more versions of Visual Studio
  • Manually make registry changes or modifications to the Visual Studio installation

The only safe and reliable solution I know of is to reinstall your OS. If your project needs multiple versions of Visual Studio to build, install the oldest version first. Then fix your code so you can use one single tool to build it, or you or your colleagues will be in the same mess again soon.

If this is not an option for you, first read for a better understanding of the problem and what the various "solutions" actually do. Then, depending on your Visual Studio version and setup, one of the other answers or variations of them may eventually help.

Some more hints:

I want my android application to be only run in portrait mode?

in the manifest:

<activity android:name=".activity.MainActivity"
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />

or : in the MainActivity

protected void onCreate(Bundle savedInstanceState) {

Truncating all tables in a Postgres database

If I have to do this, I will simply create a schema sql of current db, then drop & create db, then load db with schema sql.

Below are the steps involved:

1) Create Schema dump of database (--schema-only)

pg_dump mydb -s > schema.sql

2) Drop database

drop database mydb;

3) Create Database

create database mydb;

4) Import Schema

psql mydb < schema.sql

UNIX export command

export is used to set environment variables. For example:

export EDITOR=pico

Will set your default text editor to be the pico command.

What are the applications of binary trees?

your programs syntax, or for that matter many other things such as natural languages can be parsed using binary tree (though not necessarily).

What are the differences between "git commit" and "git push"?

in layman terms, git commit is the step before git push you run them in that order to successfully git your file to github.

Log4j, configuring a Web App to use a relative path

My suggestion is the log file should always be logged above the root context of the webApp, so in case we redeploy the webApp, we don't want to override the existing log files.

Live search through table rows

$("#search").on("keyup", function() {
        var value = $(this).val().toLowerCase();
        $("tbody tr").filter(function() {
            $(this).toggle($(this).text().toLowerCase().indexOf(value) > -1)

Assumption there is a one table with a tbody. you can also search with find or if the table has an ID you can use the id

Remove or uninstall library previously added : cocoapods

Remove pod name from Podfile then Open Terminal, set project folder path and Run pod update command.

NOTE: pod update will update all the libraries to the latest version and will also remove those libraries whose name have been removed from podfile.

Java 8 NullPointerException in Collectors.toMap

I have slightly modified Emmanuel Touzery's implementation.

This version;

  • Allows null keys
  • Allows null values
  • Detects duplicate keys (even if they are null) and throws IllegalStateException as in the original JDK implementation.
  • Detects duplicate keys also when the key already mapped to the null value. In other words, separates a mapping with null-value from no-mapping.
public static <T, K, U> Collector<T, ?, Map<K, U>> toMapOfNullables(Function<? super T, ? extends K> keyMapper, Function<? super T, ? extends U> valueMapper) {
    return Collectors.collectingAndThen(
        list -> {
            Map<K, U> map = new LinkedHashMap<>();
            list.forEach(item -> {
                K key = keyMapper.apply(item);
                if (map.containsKey(key)) {
                    throw new IllegalStateException(String.format("Duplicate key %s", key));
                map.put(key, valueMapper.apply(item));
            return map;

Unit tests:

public void toMapOfNullables_WhenHasNullKey() {
    assertEquals(singletonMap(null, "value"),
        Stream.of("ignored").collect(Utils.toMapOfNullables(i -> null, i -> "value"))

public void toMapOfNullables_WhenHasNullValue() {
    assertEquals(singletonMap("key", null),
        Stream.of("ignored").collect(Utils.toMapOfNullables(i -> "key", i -> null))

public void toMapOfNullables_WhenHasDuplicateNullKeys() {
    assertThrows(new IllegalStateException("Duplicate key null"),
        () -> Stream.of(1, 2, 3).collect(Utils.toMapOfNullables(i -> null, i -> i))

public void toMapOfNullables_WhenHasDuplicateKeys_NoneHasNullValue() {
    assertThrows(new IllegalStateException("Duplicate key duplicated-key"),
        () -> Stream.of(1, 2, 3).collect(Utils.toMapOfNullables(i -> "duplicated-key", i -> i))

public void toMapOfNullables_WhenHasDuplicateKeys_OneHasNullValue() {
    assertThrows(new IllegalStateException("Duplicate key duplicated-key"),
        () -> Stream.of(1, null, 3).collect(Utils.toMapOfNullables(i -> "duplicated-key", i -> i))

public void toMapOfNullables_WhenHasDuplicateKeys_AllHasNullValue() {
    assertThrows(new IllegalStateException("Duplicate key duplicated-key"),
        () -> Stream.of(null, null, null).collect(Utils.toMapOfNullables(i -> "duplicated-key", i -> i))

How do you save/store objects in SharedPreferences on Android?

Here's a take on using Kotlin Delegated Properties that I picked up from here, but expanded on and allows for a simple mechanism for getting/setting SharedPreference properties.

For String, Int, Long, Float or Boolean, it uses the standard SharePreference getter(s) and setter(s). However, for all other data classes, it uses GSON to serialize to a String, for the setter. Then deserializes to the data object, for the getter.

Similar to other solutions, this requires adding GSON as a dependency in your gradle file:

implementation ''

Here's an example of a simple data class that we would want to be able to save and store to SharedPreferences:

data class User(val first: String, val last: String)

Here is the one class that implements the property delegates:

object UserPreferenceProperty : PreferenceProperty<User>(
    key = "USER_OBJECT",
    defaultValue = User(first = "Jane", last = "Doe"),
    clazz =

object NullableUserPreferenceProperty : NullablePreferenceProperty<User?, User>(
    defaultValue = null,
    clazz =

object FirstTimeUser : PreferenceProperty<Boolean>(
        key = "FIRST_TIME_USER",
        defaultValue = false,
        clazz =

sealed class PreferenceProperty<T : Any>(key: String,
                                         defaultValue: T,
                                         clazz: Class<T>) : NullablePreferenceProperty<T, T>(key, defaultValue, clazz)

sealed class NullablePreferenceProperty<T : Any?, U : Any>(private val key: String,
                                                           private val defaultValue: T,
                                                           private val clazz: Class<U>) : ReadWriteProperty<Any, T> {

    override fun getValue(thisRef: Any, property: KProperty<*>): T = HandstandApplication.appContext().getPreferences()
            .run {
                when {
                    clazz.isAssignableFrom( -> getString(key, defaultValue as String?) as T
                    clazz.isAssignableFrom( -> getInt(key, defaultValue as Int) as T
                    clazz.isAssignableFrom( -> getLong(key, defaultValue as Long) as T
                    clazz.isAssignableFrom( -> getFloat(key, defaultValue as Float) as T
                    clazz.isAssignableFrom( -> getBoolean(key, defaultValue as Boolean) as T
                    else -> getObject(key, defaultValue, clazz)

    override fun setValue(thisRef: Any, property: KProperty<*>, value: T) = HandstandApplication.appContext().getPreferences()
            .apply {
                when {
                    clazz.isAssignableFrom( -> putString(key, value as String?) as T
                    clazz.isAssignableFrom( -> putInt(key, value as Int) as T
                    clazz.isAssignableFrom( -> putLong(key, value as Long) as T
                    clazz.isAssignableFrom( -> putFloat(key, value as Float) as T
                    clazz.isAssignableFrom( -> putBoolean(key, value as Boolean) as T
                    else -> putObject(key, value)

    private fun Context.getPreferences(): SharedPreferences = getSharedPreferences(APP_PREF_NAME, Context.MODE_PRIVATE)

    private fun <T, U> SharedPreferences.getObject(key: String, defValue: T, clazz: Class<U>): T =
            Gson().fromJson(getString(key, null), clazz) as T ?: defValue

    private fun <T> SharedPreferences.Editor.putObject(key: String, value: T) = putString(key, Gson().toJson(value))

    companion object {
        private const val APP_PREF_NAME = "APP_PREF"

Note: you shouldn't need to update anything in the sealed class. The delegated properties are the Object/Singletons UserPreferenceProperty, NullableUserPreferenceProperty and FirstTimeUser.

To setup a new data object for saving/getting from SharedPreferences, it's now as easy as adding four lines:

object NewPreferenceProperty : PreferenceProperty<String>(
        key = "NEW_PROPERTY",
        defaultValue = "",
        clazz =

Finally, you can read/write values to SharedPreferences by just using the by keyword:

private var user: User by UserPreferenceProperty
private var nullableUser: User? by NullableUserPreferenceProperty
private var isFirstTimeUser: Boolean by 

Log.d("TAG", user) // outputs the `defaultValue` for User the first time
user = User(first = "John", last = "Doe") // saves this User to the Shared Preferences
Log.d("TAG", user) // outputs the newly retrieved User (John Doe) from Shared Preferences

Entity Framework code first unique column

From your code it becomes apparent that you use POCO. Having another key is unnecessary: you can add an index as suggested by juFo.
If you use Fluent API instead of attributing UserName property your column annotation should look like this:

this.Property(p => p.UserName)
    .HasColumnAnnotation("Index", new IndexAnnotation(new[] { 
        new IndexAttribute("Index") { IsUnique = true } 

This will create the following SQL script:

    [UserName] ASC
    ONLINE = OFF, 

If you attempt to insert multiple Users having the same UserName you'll get a DbUpdateException with the following message:

Cannot insert duplicate key row in object 'dbo.Users' with unique index 'Index'. 
The duplicate key value is (...).
The statement has been terminated.

Again, column annotations are not available in Entity Framework prior to version 6.1.

How can I get onclick event on webview in android?

You can implement an OnClickListener via OnTouchListener:

webView.setOnTouchListener(new View.OnTouchListener() {

        public final static int FINGER_RELEASED = 0;
        public final static int FINGER_TOUCHED = 1;
        public final static int FINGER_DRAGGING = 2;
        public final static int FINGER_UNDEFINED = 3;

        private int fingerState = FINGER_RELEASED;

        public boolean onTouch(View view, MotionEvent motionEvent) {

            switch (motionEvent.getAction()) {

                case MotionEvent.ACTION_DOWN:
                    if (fingerState == FINGER_RELEASED) fingerState = FINGER_TOUCHED;
                    else fingerState = FINGER_UNDEFINED;

                case MotionEvent.ACTION_UP:
                    if(fingerState != FINGER_DRAGGING) {
                        fingerState = FINGER_RELEASED;

                        // Your onClick codes

                    else if (fingerState == FINGER_DRAGGING) fingerState = FINGER_RELEASED;
                    else fingerState = FINGER_UNDEFINED;

                case MotionEvent.ACTION_MOVE:
                    if (fingerState == FINGER_TOUCHED || fingerState == FINGER_DRAGGING) fingerState = FINGER_DRAGGING;
                    else fingerState = FINGER_UNDEFINED;

                    fingerState = FINGER_UNDEFINED;


            return false;

Remove an item from array using UnderscoreJS

Underscore has a _without() method perfect for removing an item from an array, especially if you have the object to remove.

Returns a copy of the array with all instances of the values removed.

_.without(["bob", "sam", "fred"], "sam");

=> ["bob", "fred"]

Works with more complex objects too.

var bob = { Name: "Bob", Age: 35 };
var sam = { Name: "Sam", Age: 19 };
var fred = { Name: "Fred", Age: 50 };

var people = [bob, sam, fred]

_.without(people, sam);

=> [{ Name: "Bob", Age: 35 }, { Name: "Fred", Age: 50 }];

If you don't have the item to remove, just a property of it, you can use _.findWhere and then _.without.

Polynomial time and exponential time

polynomial time O(n)^k means Number of operations are proportional to power k of the size of input

exponential time O(k)^n means Number of operations are proportional to the exponent of the size of input

Export MySQL data to Excel in PHP

Just Try With The Following :

PHP Part :

/*******EDIT LINES 3-8*******/
$DB_Server = "localhost"; //MySQL Server    
$DB_Username = "username"; //MySQL Username     
$DB_Password = "password";             //MySQL Password     
$DB_DBName = "databasename";         //MySQL Database Name  
$DB_TBLName = "tablename"; //MySQL Table Name   
$filename = "excelfilename";         //File Name
//create MySQL connection   
$sql = "Select * from $DB_TBLName";
$Connect = @mysql_connect($DB_Server, $DB_Username, $DB_Password) or die("Couldn't connect to MySQL:<br>" . mysql_error() . "<br>" . mysql_errno());
//select database   
$Db = @mysql_select_db($DB_DBName, $Connect) or die("Couldn't select database:<br>" . mysql_error(). "<br>" . mysql_errno());   
//execute query 
$result = @mysql_query($sql,$Connect) or die("Couldn't execute query:<br>" . mysql_error(). "<br>" . mysql_errno());    
$file_ending = "xls";
//header info for browser
header("Content-Type: application/xls");    
header("Content-Disposition: attachment; filename=$filename.xls");  
header("Pragma: no-cache"); 
header("Expires: 0");
/*******Start of Formatting for Excel*******/   
//define separator (defines columns in excel & tabs in word)
$sep = "\t"; //tabbed character
//start of printing column names as names of MySQL fields
for ($i = 0; $i < mysql_num_fields($result); $i++) {
echo mysql_field_name($result,$i) . "\t";
//end of printing column names  
//start while loop to get data
    while($row = mysql_fetch_row($result))
        $schema_insert = "";
        for($j=0; $j<mysql_num_fields($result);$j++)
                $schema_insert .= "NULL".$sep;
            elseif ($row[$j] != "")
                $schema_insert .= "$row[$j]".$sep;
                $schema_insert .= "".$sep;
        $schema_insert = str_replace($sep."$", "", $schema_insert);
        $schema_insert = preg_replace("/\r\n|\n\r|\n|\r/", " ", $schema_insert);
        $schema_insert .= "\t";
        print "\n";

I think this may help you to resolve your problem.

How to write an XPath query to match two attributes?

//div[@id='..' and @class='...]

should do the trick. That's selecting the div operators that have both attributes of the required value.

It's worth using one of the online XPath testbeds to try stuff out.

How to get current route in Symfony 2?

With Symfony 3.3, I have used this method and working fine.

I have 4 routes like

admin_category_index, admin_category_detail, admin_category_create, admin_category_update

And just one line make an active class for all routes.

<li  {% if app.request.get('_route') starts with 'admin_category' %} class="active"{% endif %}>
 <a href="{{ path('admin_category_index') }}">Product Categoires</a>

Java equivalent of unsigned long long?

Java 8 provides a set of unsigned long operations that allows you to directly treat those Long variables as unsigned Long, here're some commonly used ones:

And additions, subtractions, and multiplications are the same for signed and unsigned longs.

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

On Linux.

Add function to ~/.bashrc:

function killTcpListen () {
  kill -9 $(lsof -sTCP:LISTEN -i:$1 -t)

Pull changes: source ~/.bashrc

And use it: killTcpListen 3000

Display label text with line breaks in c#

You can also use <br/> where you want to break the text.

Why can't I initialize non-const static member or static array in class?

I think it's to prevent you from mixing declarations and definitions. (Think about the problems that could occur if you include the file in multiple places.)

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

Implements Parcelable and send arraylist as putParcelableArrayListExtra and get it from next activity getParcelableArrayListExtra


Implement parcelable on your custom class -(Alt +enter) Implement its methods

public class Model implements Parcelable {

private String Id;

public Model() {


protected Model(Parcel in) {
    Id= in.readString();       

public static final Creator<Model> CREATOR = new Creator<Model>() {
    public ModelcreateFromParcel(Parcel in) {
        return new Model(in);

    public Model[] newArray(int size) {
        return new Model[size];

public String getId() {
    return Id;

public void setId(String Id) {
    this.Id = Id;

public int describeContents() {
    return 0;

public void writeToParcel(Parcel dest, int flags) {

Pass class object from activity 1

 Intent intent = new Intent(Activity1.this, Activity2.class);
            intent.putParcelableArrayListExtra("model", modelArrayList);

Get extra from Activity2

if (getIntent().hasExtra("model")) {
        Intent intent = getIntent();
        cartArrayList = intent.getParcelableArrayListExtra("model");


How to cast an object in Objective-C

((SelectionListViewController *)myEditController).list

More examples:

int i = (int)19.5f; // (precision is lost)
id someObject = [NSMutableArray new]; // you don't need to cast id explicitly

Changing SqlConnection timeout

You can set the connection timeout to the connection level and command level.

Add "Connection Timeout=10" to the connection string. Now connection timeout is 10 seconds.

var connectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;Connection Timeout=10";
using (var con = new SqlConnection(connectionString))


Set the of CommandTimeout property to SqlCommand

var connectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword";
using (var con = new SqlConnection(connectionString))

    using (var cmd =new SqlCommand())
        cmd.CommandTimeout = 10;


How to identify which columns are not "NA" per row in a matrix?


which( !, arr.ind=TRUE)

Which I think is just as informative and probably more useful than the output you specified, But if you really wanted the list version, then this could be used:

> apply(p, 1, function(x) which(! )
[1] 2 3

[1] 4 7


[1] 5


Or even with smushing together with paste:

lapply(apply(p, 1, function(x) which(! ) , paste, collapse=", ")

The output from which function the suggested method delivers the row and column of non-zero (TRUE) locations of logical tests:

> which( !, arr.ind=TRUE)
     row col
[1,]   1   2
[2,]   1   3
[3,]   2   4
[4,]   4   5
[5,]   2   7

Without the arr.ind parameter set to non-default TRUE, you only get the "vector location" determined using the column major ordering the R has as its convention. R-matrices are just "folded vectors".

> which( ! )
[1]  6 11 17 24 32

how to change directory using Windows command line

Just type your desired drive initial in the command line and press enter

Like if you want to go L:\\ drive, Just type L: or l:

Excel data validation with suggestions/autocomplete

If you don't want to go down the VBA path, there is this trick from a previous question.

Excel 2010: how to use autocomplete in validation list

It does add some annoying bulk to the top of your sheets, and potential maintenance (should you need more options, adding names of people from a staff list, new projects etc.) but works all the same.

Get a particular cell value from HTML table using JavaScript

You can also use the DOM way to obtain the cell value: Cells[0]

Read more on that in my post at

Mix Razor and Javascript code

Wrap your Razor code in @{ } when inside JS script and be aware of using just @ Sometimes it doesn't work:

function hideSurveyReminder() {
       @Session["_isSurveyPassed"] = true;

This will produce

function hideSurveyReminder() {
       False = true;

in browser =(

How to refresh app upon shaking the device?

Here is an example code. Put this into your activity class:

  /* put this into your activity class */
  private SensorManager mSensorManager;
  private float mAccel; // acceleration apart from gravity
  private float mAccelCurrent; // current acceleration including gravity
  private float mAccelLast; // last acceleration including gravity

  private final SensorEventListener mSensorListener = new SensorEventListener() {

    public void onSensorChanged(SensorEvent se) {
      float x = se.values[0];
      float y = se.values[1];
      float z = se.values[2];
      mAccelLast = mAccelCurrent;
      mAccelCurrent = (float) Math.sqrt((double) (x*x + y*y + z*z));
      float delta = mAccelCurrent - mAccelLast;
      mAccel = mAccel * 0.9f + delta; // perform low-cut filter

    public void onAccuracyChanged(Sensor sensor, int accuracy) {

  protected void onResume() {
    mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);

  protected void onPause() {

And add this to your onCreate method:

    /* do this in onCreate */
    mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
    mAccel = 0.00f;
    mAccelCurrent = SensorManager.GRAVITY_EARTH;
    mAccelLast = SensorManager.GRAVITY_EARTH;

You can then ask "mAccel" wherever you want in your application for the current acceleration, independent from the axis and cleaned from static acceleration such as gravity. It will be approx. 0 if there is no movement, and, lets say >2 if the device is shaked.

Based on the comments - to test this:

if (mAccel > 12) {
    Toast toast = Toast.makeText(getApplicationContext(), "Device has shaken.", Toast.LENGTH_LONG);;


The accelometer should be deactivated onPause and activated onResume to save resources (CPU, Battery). The code assumes we are on planet Earth ;-) and initializes the acceleration to earth gravity. Otherwise you would get a strong "shake" when the application starts and "hits" the ground from free-fall. However, the code gets used to the gravitation due to the low-cut filter and would work also on other planets or in free space, once it is initialized. (you never know how long your application will be in use...;-)

Is there an opposite to display:none?

A true opposite to display: none there is not (yet).

But display: unset is very close and works in most cases.

From MDN (Mozilla Developer Network):

The unset CSS keyword is the combination of the initial and inherit keywords. Like these two other CSS-wide keywords, it can be applied to any CSS property, including the CSS shorthand all. This keyword resets the property to its inherited value if it inherits from its parent or to its initial value if not. In other words, it behaves like the inherit keyword in the first case and like the initial keyword in the second case.


Note also that display: revert is currently being developed. See MDN for details.

Refresh (reload) a page once using jQuery?

You may need to use this reference along with location.reload() check this, it will work.


Use JAXB to create Object from XML String

There is no unmarshal(String) method. You should use a Reader:

Person person = (Person) unmarshaller.unmarshal(new StringReader("xml string"));

But usually you are getting that string from somewhere, for example a file. If that's the case, better pass the FileReader itself.

Hexadecimal value 0x00 is a invalid character

To add to Sonz's answer above, following worked for us.

//Instead of 
XmlString.Replace("&#x0;", "[0x00]");
// use this
XmlString.Replace("\x00", "[0x00]");

release Selenium chromedriver.exe from memory

For Ubuntu/Linux users: - the command is either pkill or killall . pkill is generally recommended, since on some systems, killall will actually kill all processes.

UICollectionView - dynamic cell height?

We can maintain dynamic height for collection view cell without xib(only using storyboard).

- (CGSize)collectionView:(UICollectionView *)collectionView
  sizeForItemAtIndexPath:(NSIndexPath *)indexPath {

        NSAttributedString* labelString = [[NSAttributedString alloc] initWithString:@"Your long string goes here" attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:17.0]}];
        CGRect cellRect = [labelString boundingRectWithSize:CGSizeMake(cellWidth, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin context:nil];

        return CGSizeMake(cellWidth, cellRect.size.height);

Make sure that numberOfLines in IB should be 0.

Add JVM options in Tomcat

if you want to set jvm args on eclipse you can use below:

see below two links to accomplish it:

  1. eclipse setting to pass jvm args to java
  2. eclipse setting to pass jvm args to java and adding to run config on eclipse

And for Tomcat you can create a setenv.bat file in bin folder of Tomcat and add below lines to it :

echo "hello im starting setenv"
set CATALINA_OPTS=-DNLP.home=${NLP.home} -Dhostname=${hostname}

Is there a way in Pandas to use previous row value in dataframe.apply when previous value is also calculated in the apply?


For recursive calculations which are not vectorisable, numba, which uses JIT-compilation and works with lower level objects, often yields large performance improvements. You need only define a regular for loop and use the decorator @njit or (for older versions) @jit(nopython=True):

For a reasonable size dataframe, this gives a ~30x performance improvement versus a regular for loop:

from numba import jit

def calculator_nb(a, b, d):
    res = np.empty(d.shape)
    res[0] = d[0]
    for i in range(1, res.shape[0]):
        res[i] = res[i-1] * a[i] + b[i]
    return res

df['C'] = calculator_nb(*df[list('ABD')].values.T)

n = 10**5
df = pd.concat([df]*n, ignore_index=True)

# benchmarking on Python 3.6.0, Pandas 0.19.2, NumPy 1.11.3, Numba 0.30.1
# calculator() is same as calculator_nb() but without @jit decorator
%timeit calculator_nb(*df[list('ABD')].values.T)  # 14.1 ms per loop
%timeit calculator(*df[list('ABD')].values.T)     # 444 ms per loop

Using LINQ to remove elements from a List<T>

Below is the example to remove the element from the list.

 List<int> items = new List<int>() { 2, 2, 3, 4, 2, 7, 3,3,3};

 var result = items.Remove(2);//Remove the first ocurence of matched elements and returns boolean value
 var result1 = items.RemoveAll(lst => lst == 3);// Remove all the matched elements and returns count of removed element
 items.RemoveAt(3);//Removes the elements at the specified index

Open Windows Explorer and select a file

Check out this snippet:

Private Sub openDialog()
    Dim fd As Office.FileDialog

    Set fd = Application.FileDialog(msoFileDialogFilePicker)

   With fd

      .AllowMultiSelect = False

      ' Set the title of the dialog box.
      .Title = "Please select the file."

      ' Clear out the current filters, and add our own.
      .Filters.Add "Excel 2003", "*.xls"
      .Filters.Add "All Files", "*.*"

      ' Show the dialog box. If the .Show method returns True, the
      ' user picked at least one file. If the .Show method returns
      ' False, the user clicked Cancel.
      If .Show = True Then
        txtFileName = .SelectedItems(1) 'replace txtFileName with your textbox

      End If
   End With
End Sub

I think this is what you are asking for.

How to import cv2 in python3?

Use '!' before the pip:

! pip install opencv-python

Convert boolean to int in Java

public static int convBool(boolean b)
int convBool = 0;
if(b) convBool = 1;
return convBool;

Then use :


How many threads is too many?

In most cases you should allow the thread pool to handle this. If you post some code or give more details it might be easier to see if there is some reason the default behavior of the thread pool would not be best.

You can find more information on how this should work here:

Android button with icon and text

Try this one.


Correct way to load a Nib for a UIView subclass

In Swift:

For example, name of your custom class is InfoView

At first, you create files InfoView.xib and InfoView.swiftlike this:

import Foundation
import UIKit

class InfoView: UIView {
    class func instanceFromNib() -> UIView {
    return UINib(nibName: "InfoView", bundle: nil).instantiateWithOwner(nil, options: nil)[0] as! UIView

Then set File's Owner to UIViewController like this:

enter image description here

Rename your View to InfoView:

enter image description here

Right-click to File's Owner and connect your view field with your InfoView:

enter image description here

Make sure that class name is InfoView:

enter image description here

And after this you can add the action to button in your custom class without any problem:

enter image description here

And usage of this custom class in your MainViewController:

func someMethod() {
    var v = InfoView.instanceFromNib()
    v.frame = self.view.bounds

ImportError: No module named 'encodings'

Look at /lib/python3.5 and you will see broken links to python libraries. Recreate it to working directory.

Next error -

Failed to import the site module
Traceback (most recent call last):
  File "/home/script/script/lib/python3.5/", line 703, in <module>
  File "/home/script/script/lib/python3.5/", line 683, in main
    paths_in_sys = addsitepackages(paths_in_sys)
  File "/home/script/script/lib/python3.5/", line 282, in addsitepackages
    addsitedir(sitedir, known_paths)
  File "/home/script/script/lib/python3.5/", line 204, in addsitedir
    addpackage(sitedir, name, known_paths)
  File "/home/script/script/lib/python3.5/", line 173, in addpackage
  File "<string>", line 1, in <module>
  File "/home/script/script/lib/python3.5/", line 166, in <module>
    import functools as _functools
  File "/home/script/script/lib/python3.5/", line 23, in <module>
    from weakref import WeakKeyDictionary
  File "/home/script/script/lib/python3.5/", line 12, in <module>
    from _weakref import (
ImportError: cannot import name '_remove_dead_weakref'

fixed like this -

cd my-virtualenv-directory
virtualenv . --system-site-packages

PHP how to get the base domain/url?

Please try this:

$uri = $_SERVER['REQUEST_URI']; // $uri ==
$exploded_uri = explode('/', $uri); //$exploded_uri == array('','sub')
$domain_name = $exploded_uri[1]; //$domain_name = ''

I hope this will help you.

How can I save application settings in a Windows Forms application?

public static class SettingsExtensions
    public static bool TryGetValue<T>(this Settings settings, string key, out T value)
        if (settings.Properties[key] != null)
            value = (T) settings[key];
            return true;

        value = default(T);
        return false;

    public static bool ContainsKey(this Settings settings, string key)
        return settings.Properties[key] != null;

    public static void SetValue<T>(this Settings settings, string key, T value)
        if (settings.Properties[key] == null)
            var p = new SettingsProperty(key)
                PropertyType = typeof(T),
                Provider = settings.Providers["LocalFileSettingsProvider"],
                SerializeAs = SettingsSerializeAs.Xml
            p.Attributes.Add(typeof(UserScopedSettingAttribute), new UserScopedSettingAttribute());
            var v = new SettingsPropertyValue(p);
        settings[key] = value;

How do I pass variables and data from PHP to JavaScript?

I'm going to try a simpler answer:

Explanation of the problem

First, let's understand the flow of events when a page is served from our server:

  • First PHP is run, it generates the HTML that is served to the client.
  • Then, the HTML is delivered to the client, after PHP is done with it, I'd like to emphasize that once the code leaves the server - PHP is done with it and can no longer access it.
  • Then, the HTML with JavaScript reaches the client, which can execute JavaScript on that HTML.

So really, the core thing to remember here is that HTTP is stateless. Once a request left the server, the server can not touch it. So, that leaves our options to:

  1. Send more requests from the client after the initial request is done.
  2. Encode what the server had to say in the initial request.


That's the core question you should be asking yourself is:

Am I writing a website or an application?

Websites are mainly page based, and the page load times needs to be as fast as possible (for example - Wikipedia). Web applications are more AJAX heavy and perform a lot of round trips to get the client fast information (for example - a stock dashboard).


Sending more requests from the client after the initial request is done is slow as it requires more HTTP requests which have significant overhead. Moreover, it requires asynchronousity as making an AJAX request requires a handler for when it's complete.

I would not recommend making another request unless your site is an application for getting that information from the server.

You want fast response times which have a huge impact on conversion and load times. Making Ajax requests is slow for the initial uptime in this case and unneeded.

You have two ways to tackle the issue

  • Set a cookie - cookies are headers sent in HTTP requests that both the server and client can read.
  • Encode the variable as JSON - JSON looks very close to JavaScript objects and most JSON objects are valid JavaScript variables.

Setting a cookie is really not very difficult, you just assign it a value:

setcookie("MyCookie", $value); // Sets the cookie to the value, remember, do not
                               // Set it with HTTP only to true.

Then, you can read it with JavaScript using document.cookie:

Here is a short hand rolled parser, but the answer I linked to right above this has better tested ones:

var cookies = document.cookie.split(";").
    map(function(el){ return el.split("="); }).
    reduce(function(prev,cur){ prev[cur[0]] = cur[1];return prev },{});

cookies["MyCookie"] // Value set with PHP.

Cookies are good for a little data. This is what tracking services often do.

Once we have more data, we can encode it with JSON inside a JavaScript variable instead:

    var myServerData = <?=json_encode($value)?>; // Don't forget to sanitize
                                                 //server data

Assuming $value is json_encodeable on the PHP side (it usually is). This technique is what Stack Overflow does with its chat for example (only using .NET instead of PHP).


If you're writing an application - suddenly the initial load time isn't always as important as the ongoing performance of the application, and it starts to pay off to load data and code separately.

My answer here explains how to load data using AJAX in JavaScript:

function callback(data){
    // What do I do with the response?

var httpRequest = new XMLHttpRequest;
httpRequest.onreadystatechange = function(){
    if (httpRequest.readyState === 4) { // Request is done
        if (httpRequest.status === 200) { // successfully
            callback(httpRequest.responseText); // We're calling our method
};'GET', "/echo/json");

Or with jQuery:

    // What do I do with the data?

Now, the server just needs to contain a /your/url route/file that contains code that grabs the data and does something with it, in your case:

     $val = myService->getValue(); // Makes an API and database call
     echo json_encode($val); // Write it to the output

This way, our JavaScript file asks for the data and shows it rather than asking for code or for layout. This is cleaner and starts to pay off as the application gets higher. It's also better separation of concerns and it allows testing the client side code without any server side technology involved which is another plus.

Postscript: You have to be very aware of XSS attack vectors when you inject anything from PHP to JavaScript. It's very hard to escape values properly and it's context sensitive. If you're unsure how to deal with XSS, or unaware of it - please read this OWASP article, this one and this question.

Chrome hangs after certain amount of data transfered - waiting for available socket

simple and correct solution is put off preload your audio and video file from setting and recheck your page your problem of waiting for available socket will resolved ...

if you use jplayer then replace preload:"metadata" to preload:"none" from jplayer JS file ...

preload:"metadata" is the default value which play your audio/video file on page load thats why google chrome showing "waiting for available socket" error

How do you uninstall the package manager "pip", if installed from source?

I was using above command but it was not working. This command worked for me:

python -m pip uninstall pip setuptools

How to create query parameters in Javascript?

ES2017 (ES8)

Making use of Object.entries(), which returns an array of object's [key, value] pairs. For example, for {a: 1, b: 2} it would return [['a', 1], ['b', 2]]. It is not supported (and won't be) only by IE.


const buildURLQuery = obj =>
            .map(pair =>'='))


buildURLQuery({name: 'John', gender: 'male'});



How to differentiate single click event and double click event?

I know this is old, but below is a JS only example of a basic loop counter with a single timer to determine a single vs double click. Hopefully this helps someone.

var count = 0;
var ele = document.getElementById("my_id");
ele.addEventListener('click', handleSingleDoubleClick, false); 

function handleSingleDoubleClick()
  if(!count) setTimeout(TimerFcn, 400); // 400 ms click delay
  count += 1;
function TimerFcn() 
  if(count > 1) console.log('you double clicked!')
  else console.log('you single clicked')
  count = 0;

Targeting .NET Framework 4.5 via Visual Studio 2010

I have been struggling with VS2010/DNFW 4.5 integration and have finally got this working. Starting in VS 2008, a cache of assemblies was introduced that is used by Visual Studio called the "Referenced Assemblies". This file cache for VS 2010 is located at \Reference Assemblies\Microsoft\Framework.NetFramework\v4.0. Visual Studio loads framework assemblies from this location instead of from the framework installation directory. When Microsoft says that VS 2010 does not support DNFW 4.5 what they mean is that this directory does not get updated when DNFW 4.5 is installed. Once you have replace the files in this location with the updated DNFW 4.5 files, you will find that VS 2010 will happily function with DNFW 4.5.

How to select an element with 2 classes

Just chain them together:

.a.b {
  color: #666;

Calling constructors in c++ without new

I played a bit with it and the syntax seems to get quite strange when a constructor takes no arguments. Let me give an example:

#include <iostream> 

using namespace std;

class Thing

    cout << "Hi" << endl;

int main()
    //Thing myThing(); // Does not work
    Thing myThing; // Works


so just writing Thing myThing w/o brackets actually calls the constructor, while Thing myThing() makes the compiler thing you want to create a function pointer or something ??!!

Format numbers in thousands (K) in Excel

Non-Americans take note! If you use Excel with "." as 1000 separator, you need to replace the "," with a "." in the formula, such as:

[>=1000]€ #.##0." K";[<=-1000]-€ #.##0." K";0

The code above will display € 62.123 as "€ 62 K".

How to call a asp:Button OnClick event using JavaScript?

Set style= "display:none;". By setting visible=false, it will not render button in the browser. Thus,client side script wont execute.

<asp:Button ID="savebtn" runat="server" OnClick="savebtn_Click" style="display:none" />

html markup should be

<button id="btnsave" onclick="fncsave()">Save</button>

Change javascript to

<script type="text/javascript">
     function fncsave()
        document.getElementById('<%= savebtn.ClientID %>').click();

Python, add items from txt file into a list

The pythonic way to read a file and put every lines in a list:

from __future__ import with_statement #for python 2.5
Names = []
with open('C:/path/txtfile.txt', 'r') as f:
    lines = f.readlines()

How to draw a line with matplotlib?

As of matplotlib 3.3, you can do this with plt.axline((x1, y1), (x2, y2)).

Best way to integrate Python and JavaScript?

PyExecJS is able to use each of PyV8, Node, JavaScriptCore, SpiderMonkey, JScript.

>>> import execjs
>>> execjs.eval("'red yellow blue'.split(' ')")
['red', 'yellow', 'blue']
>>> execjs.get().name
'Node.js (V8)'

How to create a sticky footer that plays well with Bootstrap 3

Not sure what you have tried so far, but its pretty simple. Just do this:

html, body {
  height: 100%;

footer {
  position: absolute;
  bottom: 0;

How to download a Nuget package without nuget.exe or Visual Studio extension?

Either make an account on the website, then log in, browse to the package you want and click on the Download link on the left menu.

Or guess the URL. They have the following format:{packageID}/{packageVersion}

Then simply unzip the .nupkg file and extract the contents you need.

How to remove certain characters from a string in C++?

remove_if() has already been mentioned. But, with C++0x, you can specify the predicate for it with a lambda instead.

Below is an example of that with 3 different ways of doing the filtering. "copy" versions of the functions are included too for cases when you're working with a const or don't want to modify the original.

#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>
using namespace std;

string& remove_chars(string& s, const string& chars) {
    s.erase(remove_if(s.begin(), s.end(), [&chars](const char& c) {
        return chars.find(c) != string::npos;
    }), s.end());
    return s;
string remove_chars_copy(string s, const string& chars) {
    return remove_chars(s, chars);

string& remove_nondigit(string& s) {
    s.erase(remove_if(s.begin(), s.end(), [](const char& c) {
        return !isdigit(c);
    }), s.end());
    return s;
string remove_nondigit_copy(string s) {
    return remove_nondigit(s);

string& remove_chars_if_not(string& s, const string& allowed) {
    s.erase(remove_if(s.begin(), s.end(), [&allowed](const char& c) {
        return allowed.find(c) == string::npos;
    }), s.end());
    return s;
string remove_chars_if_not_copy(string s, const string& allowed) {
    return remove_chars_if_not(s, allowed);

int main() {
    const string test1("(555) 555-5555");
    string test2(test1);
    string test3(test1);
    string test4(test1);
    cout << remove_chars_copy(test1, "()- ") << endl;
    cout << remove_chars(test2, "()- ") << endl;
    cout << remove_nondigit_copy(test1) << endl;
    cout << remove_nondigit(test3) << endl;
    cout << remove_chars_if_not_copy(test1, "0123456789") << endl;
    cout << remove_chars_if_not(test4, "0123456789") << endl;

How can I perform a reverse string search in Excel without using VBA?

This is very clean and compact, and works well.

{=RIGHT(A1,LEN(A1)-MAX(IF(MID(A1,ROW(1:999),1)=" ",ROW(1:999),0)))}

It does not error trap for no spaces or one word, but that's easy to add.

This handles trailing spaces, single word, and empty cell scenarios. I have not found a way to break it.

{=RIGHT(TRIM(A1),LEN(TRIM(A1))-MAX(IF(MID(TRIM(A1),ROW($1:$999),1)=" ",ROW($1:$999),0)))}

How to create major and minor gridlines with different linestyles in Python

A simple DIY way would be to make the grid yourself:

import matplotlib.pyplot as plt

fig = plt.figure()
ax = fig.add_subplot(111)

ax.plot([1,2,3], [2,3,4], 'ro')

for xmaj in ax.xaxis.get_majorticklocs():
  ax.axvline(x=xmaj, ls='-')
for xmin in ax.xaxis.get_minorticklocs():
  ax.axvline(x=xmin, ls='--')

for ymaj in ax.yaxis.get_majorticklocs():
  ax.axhline(y=ymaj, ls='-')
for ymin in ax.yaxis.get_minorticklocs():
  ax.axhline(y=ymin, ls='--')

android listview get selected item

final ListView lv = (ListView) findViewById(;

lv.setOnItemClickListener(new OnItemClickListener() {
      public void onItemClick(AdapterView<?> myAdapter, View myView, int myItemInt, long mylng) {
        String selectedFromList =(String) (lv.getItemAtPosition(myItemInt));


I hope this fixes your problem.

Using C++ base class constructors?

Here is a good discussion about superclass constructor calling rules. You always want the base class constructor to be called before the derived class constructor in order to form an object properly. Which is why this form is used

  B( int v) : A( v )

Returning value from Thread

With small modifications to your code, you can achieve it in a more generic way.

 final Handler responseHandler = new Handler(Looper.getMainLooper()){
            public void handleMessage(Message msg) {
                //txtView.setText((String) msg.obj);
                        "Result from UIHandlerThread:"+(int)msg.obj,

        HandlerThread handlerThread = new HandlerThread("UIHandlerThread"){
            public void run(){
                Integer a = 2;
                Message msg = new Message();
                msg.obj = a;

Solution :

  1. Create a Handler in UI Thread,which is called as responseHandler
  2. Initialize this Handler from Looper of UI Thread.
  3. In HandlerThread, post message on this responseHandler
  4. handleMessgae shows a Toast with value received from message. This Message object is generic and you can send different type of attributes.

With this approach, you can send multiple values to UI thread at different point of times. You can run (post) many Runnable objects on this HandlerThread and each Runnable can set value in Message object, which can be received by UI Thread.

Is there a stopwatch in Java?

Performetrics provides a convenient Stopwatch class, just the way you need. It can measure wall-clock time and more: it also measures CPU time (user time and system time) if you need. It's small, free and you can download from Maven Central. More information and examples can be found here:

Stopwatch sw = new Stopwatch();

// Your code


// Sample output:
// +-----------------+----------------------+--------------+
// | Counter         |         Elapsed time | Time unit    |
// +-----------------+----------------------+--------------+
// | Wall clock time |             85605718 | nanoseconds  |
// | CPU time        |             78000500 | nanoseconds  |
// | User time       |             62400400 | nanoseconds  |
// | System time     |             15600100 | nanoseconds  |
// +-----------------+----------------------+--------------+

You can convert the metrics to any time unit (nanoseconds, milliseconds, seconds, etc...)

PS: I am the author of the tool.

How to preserve request url with nginx proxy_pass

Note to other people finding this: The heart of the solution to make nginx not manipulate the URL, is to remove the slash at the end of the Copy: proxy_pass directive. http://my_app_upstream vs http://my_app_upstream/ – Hugo Josefson

I found this above in the comments but I think it really should be an answer.

How to view UTF-8 Characters in VIM or Gvim

Did you try

:set encoding=utf-8
:set fileencoding=utf-8


Angular error: "Can't bind to 'ngModel' since it isn't a known property of 'input'"

This is a right answer. you need to import FormsMoudle

first in app.module.ts


import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { NgModule  } from '@angular/core';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
  declarations: [
  imports: [
    ReactiveFormsModule ,
  providers: [],
  bootstrap: [AppComponent]
export class AppModule { }

** second in app.component.spec.ts

import { TestBed, async } from '@angular/core/testing';
import { RouterTestingModule } from '@angular/router/testing';
import { AppComponent } from './app.component';
import { FormsModule } from '@angular/forms';
describe('AppComponent', () => {
  beforeEach(async(() => {
      imports: [
      declarations: [

Best regards and hope will be helpfull

jQuery find() method not working in AngularJS directive

From the docs on angular.element:

find() - Limited to lookups by tag name

So if you're not using jQuery with Angular, but relying upon its jqlite implementation, you can't do elm.find('#someid').

You do have access to children(), contents(), and data() implementations, so you can usually find a way around it.

remove inner shadow of text input

here is a small snippet that might be cool to try out:

input {
border-radius: 10px;
border-color: violet;
border-style: solid;

note that: border-style removes the inner shadow.

input {_x000D_
    border-radius: 10px;_x000D_
    border-color: violet;_x000D_
    border-style: solid;_x000D_
<input type="text"/>

Set Date in a single line

This is yet another reason to use Joda Time

new DateMidnight(2010, 3, 5)

DateMidnight is now deprecated but the same effect can be achieved with Joda Time DateTime

DateTime dt = new DateTime(2010, 3, 5, 0, 0);

How to create a Java / Maven project that works in Visual Studio Code?

This is not a particularly good answer as it explains how to run your java code n VS Code and not necessarily a Maven project, but it worked for me because I could not get around to doing the manual configuration myself. I decided to use this method instead since it is easier and faster.

Install VSCode (and for windows, set your environment variables), then install vscode:extension/vscjava.vscode-java-pack as detailed above, and then install the code runner extension pack, which basically sets up the whole process (in the background) as explained in the accepted answer above and then provides a play button to run your java code when you're ready.

This was all explained in this video.

Again, this is not the best solution, but if you want to cut to the chase, you may find this answer useful.

How to read appSettings section in the web.config file?

Here's the easy way to get access to the web.config settings anywhere in your C# project.


Use case:

litBodyText.Text = Properties.Settings.Default.BodyText;
litFootText.Text = Properties.Settings.Default.FooterText;
litHeadText.Text = Properties.Settings.Default.HeaderText;

Web.config file:

      <setting name="BodyText" serializeAs="String">
          &lt;h1&gt;Hello World&lt;/h1&gt;
      Ipsum Lorem
      <setting name="HeaderText" serializeAs="String">
      My header text
        <value />
      <setting name="FooterText" serializeAs="String">
      My footer text
        <value />

No need for special routines - everything is right there already. I'm surprised that no one has this answer for the best way to read settings from your web.config file.

How to find all duplicate from a List<string>?

For what it's worth, here is my way:

List<string> list = new List<string>(new string[] { "cat", "Dog", "parrot", "dog", "parrot", "goat", "parrot", "horse", "goat" });
Dictionary<string, int> wordCount = new Dictionary<string, int>();

//count them all:
list.ForEach(word =>
    string key = word.ToLower();
    if (!wordCount.ContainsKey(key))
        wordCount.Add(key, 0);

//remove words appearing only once:
wordCount.Keys.ToList().FindAll(word => wordCount[word] == 1).ForEach(key => wordCount.Remove(key));

Console.WriteLine(string.Format("Found {0} duplicates in the list:", wordCount.Count));
wordCount.Keys.ToList().ForEach(key => Console.WriteLine(string.Format("{0} appears {1} times", key, wordCount[key])));

How to initialize all members of an array to the same value?

Back in the day (and I'm not saying it's a good idea), we'd set the first element and then:

memcpy (&element [1], &element [0], sizeof (element)-sizeof (element [0]);

Not even sure it would work any more (that would depend on the implementation of memcpy) but it works by repeatedly copying the initial element to the next - even works for arrays of structures.

Why the switch statement cannot be applied on strings?

More functional workaround to the switch problem:

class APIHandlerImpl

// define map of "cases"
std::map<string, std::function<void(server*, websocketpp::connection_hdl, string)>> in_events;

        // bind handler method in constructor
        in_events["/hello"] = std::bind(&APIHandlerImpl::handleHello, this, _1, _2, _3);
        in_events["/bye"] = std::bind(&APIHandlerImpl::handleBye, this, _1, _2, _3);

    void onEvent(string event = "/hello", string data = "{}")
        // execute event based on incomming event
        in_events[event](s, hdl, data);

    void APIHandlerImpl::handleHello(server* s, websocketpp::connection_hdl hdl, string data)
        // ...

    void APIHandlerImpl::handleBye(server* s, websocketpp::connection_hdl hdl, string data)
        // ...

Set Google Maps Container DIV width and height 100%

I just added inline style .
<div id="map_canvas" style="width:750px;height:484px;"></div>
And it worked for me .

How to make a page redirect using JavaScript?

You can call a JavaScript function and use window.location = 'url';:

How do I kill a VMware virtual machine that won't die?

see the following from VMware's webpage

Powering off a virtual machine on an ESXi host (1014165) Symptoms

You are experiencing these issues:

You cannot power off an ESXi hosted virtual machine.
A virtual machine is not responsive and cannot be stopped or killed.

"Using the ESXi 5.x esxcli command to power off a virtual machine

The esxcli command can be used locally or remotely to power off a virtual machine running on ESXi 5.x. For more information, see the esxcli vm Commands section of the vSphere Command-Line Interface Reference.

Open a console session where the esxcli tool is available, either in the ESXi Shell, the vSphere Management Assistant (vMA), or the location where the vSphere Command-Line Interface (vCLI) is installed.

Get a list of running virtual machines, identified by World ID, UUID, Display Name, and path to the .vmx configuration file, using this command:

esxcli vm process list

Power off one of the virtual machines from the list using this command:

esxcli vm process kill --type=[soft,hard,force] --world-id=WorldNumber

Three power-off methods are available. Soft is the most graceful, hard performs an immediate shutdown, and force should be used as a last resort.
Alternate power off command syntax is: esxcli vm process kill -t [soft,hard,force] -w WorldNumber

Repeat Step 2 and validate that the virtual machine is no longer running.

For ESXi 4.1:

Get a list of running virtual machines, identified by World ID, UUID, Display Name, and path to the .vmx configuration file, using this command:

esxcli vms vm list

Power off one of the virtual machines from the list using this command:

esxcli vms vm kill --type=[soft,hard,force] --world-id=WorldNumber"

Selecting multiple columns/fields in MySQL subquery

Yes, you can do this. The knack you need is the concept that there are two ways of getting tables out of the table server. One way is ..


The other way is

FROM (SELECT col as name1, col2 as name2 FROM ...) B

Notice that the select clause and the parentheses around it are a table, a virtual table.

So, using your second code example (I am guessing at the columns you are hoping to retrieve here):

SELECT a.attr,, b.trans, b.lang
FROM attribute a
 SELECT AS id, at.translation AS trans, at.language AS lang, a.attribute
 FROM attributeTranslation at
) b ON ( = b.attribute AND b.lang = 1)

Notice that your real table attribute is the first table in this join, and that this virtual table I've called b is the second table.

This technique comes in especially handy when the virtual table is a summary table of some kind. e.g.

SELECT a.attr,, b.trans, b.lang, c.langcount
FROM attribute a
 SELECT AS id, at.translation AS trans, at.language AS lang, at.attribute
 FROM attributeTranslation at
) b ON ( = b.attribute AND b.lang = 1)
 SELECT count(*) AS langcount,  at.attribute
 FROM attributeTranslation at
 GROUP BY at.attribute
) c ON ( = c.attribute)

See how that goes? You've generated a virtual table c containing two columns, joined it to the other two, used one of the columns for the ON clause, and returned the other as a column in your result set.

round a single column in pandas

No need to use for loop. It can be directly applied to a column of a dataframe

sleepstudy['Reaction'] = sleepstudy['Reaction'].round(1)

Automatic creation date for Django model form objects?

Well, the above answer is correct, auto_now_add and auto_now would do it, but it would be better to make an abstract class and use it in any model where you require created_at and updated_at fields.

class TimeStampMixin(models.Model):
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True

Now anywhere you want to use it you can do a simple inherit and you can use timestamp in any model you make like.

class Posts(TimeStampMixin):
    name = models.CharField(max_length=50)

In this way, you can leverage object-oriented reusability, in Django DRY(don't repeat yourself)

How can I increment a char?

Check this: USING FOR LOOP

for a in range(5):
    val=chr(ord(x) + a)


Convert list into a pandas data frame

You need convert list to numpy array and then reshape:

df = pd.DataFrame(np.array(my_list).reshape(3,3), columns = list("abc"))
print (df)
   a  b  c
0  1  2  3
1  4  5  6
2  7  8  9

linux script to kill java process

pkill -f for whatever reason does not work for me. Whatever that does, it seems very finicky about actually grepping through what ps aux shows me clearly is there.

After an afternoon of swearing I went for putting the following in my start script:

(ps aux | grep -v -e 'grep ' | grep MainApp | tr -s " " | cut -d " " -f 2 | xargs kill -9 ) || true

ASP.NET Web Site or ASP.NET Web Application?

One of the key differences is that Websites compile dynamically and create on-the-fly assemblies. Web applicaitons compile into one large assembly.

The distinction between the two has been done away with in Visual Studio 2008.

How to check python anaconda version installed on Windows 10 PC?

The folder containing your Anaconda installation contains a subfolder called conda-meta with json files for all installed packages, including one for Anaconda itself. Look for anaconda-<version>-<build>.json.

My file is called anaconda-5.0.1-py27hdb50712_1.json, and at the bottom is more info about the version:

"installed_by": "Anaconda2-5.0.1-Windows-x86_64.exe", 
"link": { "source": "C:\\ProgramData\\Anaconda2\\pkgs\\anaconda-5.0.1-py27hdb50712_1" }, 
"name": "anaconda", 
"platform": "win", 
"subdir": "win-64", 
"url": "", 
"version": "5.0.1"

(Slightly edited for brevity.)

The output from conda -V is the conda version.

Changing three.js background to transparent or other color

I found that when I created a scene via the three.js editor, I not only had to use the correct answer's code (above), to set up the renderer with an alpha value and the clear color, I had to go into the app.json file and find the "Scene" Object's "background" attribute and set it to: "background: null".

The export from Three.js editor had it originally set to "background": 0

UL list style not applying

In IE I just use a class "normal_ol" for styling an ol list and made some modifications shown below:

previous code: ol.normal_ol { float:left; padding:0 0 0 25px; margin:0; width:500px;} ol.normal_ol li{ font:normal 13px/20px Arial; color:#4D4E53; float:left; width:100%;}

modified code: ol.normal_ol { float:left; padding:0 0 0 25px; margin:0;} ol.normal_ol li{ font:normal 13px/20px Arial; color:#4D4E53; }

How to pass a single object[] to a params object[]

One option is you can wrap it into another array:

Foo(new object[]{ new object[]{ (object)"1", (object)"2" } });

Kind of ugly, but since each item is an array, you can't just cast it to make the problem go away... such as if it were Foo(params object items), then you could just do:

Foo((object) new object[]{ (object)"1", (object)"2" });

Alternatively, you could try defining another overloaded instance of Foo which takes just a single array:

void Foo(object[] item)
    // Somehow don't duplicate Foo(object[]) and
    // Foo(params object[]) without making an infinite
    // recursive call... maybe something like
    // FooImpl(params object[] items) and then this
    // could invoke it via:
    // FooImpl(new object[] { item });

How can I set selected option selected in vue.js 2?

<select v-model="challan.warehouse_id">
<option value="">Select Warehouse</option>
<option v-for="warehouse in warehouses" v-bind:value=""  >
   {{ }}

Here "challan.warehouse_id" come from "challan" object you get from:

editChallan: function() {
    let that = this;'/api/challan_list/get_challan_data', {
    challan_id: that.challan_id
 .then(function (response) {
    that.challan =;
 .catch(function (error) {
    that.errors = error;

Why does 2 mod 4 = 2?


2 mod 4

We can use this little formula I came up with after thinking a bit, maybe it's already defined somewhere I don't know but works for me, and its really useful.

A mod B = C where C is the answer

K * B - A = |C| where K is how many times B fits in A

2 mod 4 would be:

0 * 4 - 2 = |C|

C = |-2| => 2

Hope it works for you :)

Add column in dataframe from list

Old question; but I always try to use fastest code!

I had a huge list with 69 millions of uint64. np.array() was fastest for me.

df['hashes'] = hashes
Time spent: 17.034842014312744

df['hashes'] = pd.Series(hashes).values
Time spent: 17.141014337539673

df['key'] = np.array(hashes)
Time spent: 10.724546194076538

Batch command date and time in file name

So you want to generate date in format YYYYMMDD_hhmmss. As %date% and %time% formats are locale dependant you might need more robust ways to get a formatted date.

Here's one option:

@if (@X)==(@Y) @end /*
    @cscript //E:JScript //nologo "%~f0"
    @exit /b %errorlevel%
var todayDate = new Date();
todayDate = "" + 
    todayDate.getFullYear() + 
    ("0" + (todayDate.getMonth() + 1)).slice(-2) +
    ("0" + todayDate.getDate()).slice(-2) + 
    "_" + 
    ("0" + todayDate.getHours()).slice(-2) +
    ("0" + todayDate.getMinutes()).slice(-2) +
    ("0" + todayDate.getSeconds()).slice(-2) ;

and if you save the script as jsdate.bat you can assign it as a value :

for /f %%a in ('jsdate.bat') do @set "fdate=%%a"
echo %fdate%

or directly from command prompt:

for /f %a in ('jsdate.bat') do @set "fdate=%a"

Or you can use powershell which probably is the way that requires the less code:

for /f %%# in ('powershell Get-Date -Format "yyyyMMdd_HHmmss"') do set "fdate=%%#"

How to select first child with jQuery?

As @Roko mentioned you can do this in multiple ways.

1.Using the jQuery first-child selector - SnoopCode

    $(".alldivs onediv:first-child").css("background-color","yellow");
  1. Using jQuery eq Selector - SnoopCode

     $( "body" ).find( "onediv" ).eq(1).addClass( "red" );
  2. Using jQuery Id Selector - SnoopCode

         $("#div1").css("background-color: red;");

How to fix this Error: #include <gl/glut.h> "Cannot open source file gl/glut.h"

Visual Studio Community 2017

Go here : C:\Program Files (x86)\Windows Kits\10

and do whatever you were supposed to go in the given directory for VS 13.

in the lib folder, you will find some versions, I copied the 32-bit glut.lib files in amd and x86 and 64-bit glut.lib in arm64 and x64 directories in um folder for every version that I could find.

That worked for me.

EDIT : I tried this in windows 10, maybe you need to go to C:\Program Files (x86)\Windows Kits\8.1 folder for windows 8/8.1.

How to access the contents of a vector from a pointer to the vector in C++?

vector <int> numbers {10,20,30,40};
vector <int> *ptr {nullptr};

ptr = &numbers;

for(auto num: *ptr){
 cout << num << endl;

cout << (*ptr).at(2) << endl; // 20

cout << "-------" << endl;

cout << ptr -> at(2) << endl; // 20

How to initialize an array in Java?

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

WCF change endpoint address at runtime

So your endpoint address defined in your first example is incomplete. You must also define endpoint identity as shown in client configuration. In code you can try this:

EndpointIdentity spn = EndpointIdentity.CreateSpnIdentity("host/mikev-ws");
var address = new EndpointAddress("http://id.web/Services/EchoService.svc", spn);   
var client = new EchoServiceClient(address); 
litResponse.Text = client.SendEcho("Hello World"); 

Actual working final version by valamas

EndpointIdentity spn = EndpointIdentity.CreateSpnIdentity("host/mikev-ws");
Uri uri = new Uri("http://id.web/Services/EchoService.svc");
var address = new EndpointAddress(uri, spn);
var client = new EchoServiceClient("WSHttpBinding_IEchoService", address);
client.SendEcho("Hello World");

Entity Framework Join 3 Tables

I think it will be easier using syntax-based query:

var entryPoint = (from ep in dbContext.tbl_EntryPoint
                 join e in dbContext.tbl_Entry on ep.EID equals e.EID
                 join t in dbContext.tbl_Title on e.TID equals t.TID
                 where e.OwnerID == user.UID
                 select new {
                     UID = e.OwnerID,
                     TID = e.TID,
                     Title = t.Title,
                     EID = e.EID

And you should probably add orderby clause, to make sure Top(10) returns correct top ten items.

Add all files to a commit except a single file?

We can add all the files and exclude the file which has to be removed by git reset.

git add .
git reset -- <file_name_to_exclude>

How to wrap text using CSS?

This will work everywhere.

  <table style="table-layout:fixed;">
    <td><div style="word-wrap: break-word; width: 100px" > gdfggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg</div></td>

The absolute uri: cannot be resolved in either web.xml or the jar files deployed with this application

I have removed the scope and then used a maven update to solve this problem.

    **<!-- <scope>provided</scope> -->**

The jstl lib is not present in the tomcat lib folder.So we have to include it. I don't understand why we are told to keep both servlet-api and jstl's scope as provided.

A html space is showing as %2520 instead of %20

A bit of explaining as to what that %2520 is :

The common space character is encoded as %20 as you noted yourself. The % character is encoded as %25.

The way you get %2520 is when your url already has a %20 in it, and gets urlencoded again, which transforms the %20 to %2520.

Are you (or any framework you might be using) double encoding characters?

Edit: Expanding a bit on this, especially for LOCAL links. Assuming you want to link to the resource C:\my path\my file.html:

  • if you provide a local file path only, the browser is expected to encode and protect all characters given (in the above, you should give it with spaces as shown, since % is a valid filename character and as such it will be encoded) when converting to a proper URL (see next point).
  • if you provide a URL with the file:// protocol, you are basically stating that you have taken all precautions and encoded what needs encoding, the rest should be treated as special characters. In the above example, you should thus provide file:///c:/my%20path/my%20file.html. Aside from fixing slashes, clients should not encode characters here.


  • Slash direction - forward slashes / are used in URLs, reverse slashes \ in Windows paths, but most clients will work with both by converting them to the proper forward slash.
  • In addition, there are 3 slashes after the protocol name, since you are silently referring to the current machine instead of a remote host ( the full unabbreviated path would be file://localhost/c:/my%20path/my%file.html ), but again most clients will work without the host part (ie two slashes only) by assuming you mean the local machine and adding the third slash.

How to count the number of letters in a string without the spaces?

For another one-liner solution:

def count_letters(word):  return len(filter(lambda x: x not in " ", word))

This works by using the filter function, which lets you pick the elements of a list that return true when passed to a boolean-valued function that you pass as the first argument. I'm using a lambda function to make a quick, throwaway function for that purpose.

>>> count_letters("This is a test")

You could easily extend this to exclude any selection of characters you like:

def count_letters(word, exclude):  return len(filter(lambda x: x not in exclude, word))

>>> count_letters ("This is a test", "aeiou ")

Edit: However, you wanted to get your own code to work, so here are some thoughts. The first problem is that you weren't setting a list for the Counter object to count. However, since you're looking for the total number of letters, you need to join the words back together again rather than counting each word individually. Looping to add up the number of each letter isn't really necessary because you can pull out the list of values and use "sum" to add them.

Here's a version that's as close to your code as I could make it, without the loop:

from collections import Counter
import string

def count_letters(word):
   wordsList = string.split(word)
   count = Counter("".join(wordsList))
   return sum(dict(count).values())

word = "The grey old fox is an idiot"
print count_letters(word)

Edit: In response to a comment asking why not to use a for loop, it's because it's not necessary, and in many cases using the many implicit ways to perform repetitive tasks in Python can be faster, simpler to read, and more memory-efficient.

For example, I could have written

joined_words = []
for curr_word in wordsList:
count = Counter(joined_words)

but in doing this I wind up allocating an extra array and executing a loop through the Python interpreter that my solution:

count = Counter("".join(wordsList))

would execute in a chunk of optimized, compiled C code. My solution isn't the only way to simplify that loop, but it's one way.

How to add smooth scrolling to Bootstrap's scroll spy function

Do you really need that plugin? You can just animate the scrollTop property:

$("#nav ul li a[href^='#']").on('click', function(e) {

   // prevent default anchor click behavior

   // store hash
   var hash = this.hash;

   // animate
   $('html, body').animate({
       scrollTop: $(hash).offset().top
     }, 300, function(){

       // when done, add hash to url
       // (default click behaviour)
       window.location.hash = hash;



Call to undefined function oci_connect()

You need to enable that extension in your php.ini file. See Oracle Installation:

CSS: Set Div height to 100% - Pixels

The best way to do this is to use view port styles. It just does the work and no other techniques needed.



How do I select text nodes with jQuery?

I had the same problem and solved it with:


$.fn.nextNode = function(){
  var contents = $(this).parent().contents();
  return contents.get(contents.index(this)+1);



Is like next() but also returns the text nodes.

How do I check in SQLite whether a table exists?

You could try:

SELECT name FROM sqlite_master WHERE name='table_name'

"CASE" statement within "WHERE" clause in SQL Server 2008

Thanks for this question, actually I am looking for something else which is in below query. this may helps someone.


above query is to fill in dropdown which blank values shows as "(blank)". Also if we pass this value into sql where clause to get blank values with other values I don't know how to handle that. And finally came up with below solution this may helps to somebody.

here it is ,


Restore a deleted file in the Visual Studio Code Recycle Bin

  1. Go to your computer's Recycle Bin.
  2. Search for the specific file that got deleted.
  3. Right click on that file. Go to Restore in the drop-down list.

Voila! The file is restored and is back in your folder. Happy Coding!

MySQL query finding values in a comma separated string

If the set of colors is more or less fixed, the most efficient and also most readable way would be to use string constants in your app and then use MySQL's SET type with FIND_IN_SET('red',colors) in your queries. When using the SET type with FIND_IN_SET, MySQL uses one integer to store all values and uses binary "and" operation to check for presence of values which is way more efficient than scanning a comma-separated string.

In SET('red','blue','green'), 'red' would be stored internally as 1, 'blue' would be stored internally as 2 and 'green' would be stored internally as 4. The value 'red,blue' would be stored as 3 (1|2) and 'red,green' as 5 (1|4).

How to best display in Terminal a MySQL SELECT returning too many fields?

You can use the --table or -t option, which will output a nice looking set of results

echo 'desc table_name' | mysql -uroot database -t

or some other method to pass a query to mysql, like:

mysql -uroot table_name --table < /tmp/somequery.sql


| Field        | Type         | Null | Key | Default | Extra          |
| id           | int(11)      | NO   | PRI | NULL    | auto_increment |
| username     | varchar(30)  | NO   | UNI | NULL    |                |
| first_name   | varchar(30)  | NO   |     | NULL    |                |
| last_name    | varchar(30)  | NO   |     | NULL    |                |
| email        | varchar(75)  | NO   |     | NULL    |                |
| password     | varchar(128) | NO   |     | NULL    |                |
| is_staff     | tinyint(1)   | NO   |     | NULL    |                |
| is_active    | tinyint(1)   | NO   |     | NULL    |                |
| is_superuser | tinyint(1)   | NO   |     | NULL    |                |
| last_login   | datetime     | NO   |     | NULL    |                |
| date_joined  | datetime     | NO   |     | NULL    |                |

Requery a subform from another form?

By closing and opening, the main form usually runs all related queries (including the subform related ones). I had a similar problem and resolved it by adding the following to Save Command button on click event.

DoCmd.Close acForm, "formname", acSaveYes
DoCmd.OpenForm "formname"