Programs & Examples On #Groovy console

The Groovy Console is a Java Swing based graphical user interface that is packaged with the Groovy distribution. It provides a simple but elegant way of executing interactive groovy scripts, with Groovy script entered in the top window, and the output of the script appearing in the lower window.

Check date between two other dates spring data jpa

You can also write a custom query using @Query

@Query(value = "from EntityClassTable t where yourDate BETWEEN :startDate AND :endDate")
public List<EntityClassTable> getAllBetweenDates(@Param("startDate")Date startDate,@Param("endDate")Date endDate);

How to solve "sign_and_send_pubkey: signing failed: agent refused operation"?

Run ssh-add on the client machine, that will add the SSH key to the agent.

Confirm with ssh-add -l (again on the client) that it was indeed added.

Angular2 Exception: Can't bind to 'routerLink' since it isn't a known native property

For >= V5

import { RouterModule, Routes } from '@angular/router';

const appRoutes: Routes = [
    {path:'routing-test', component: RoutingTestComponent}

    imports: [
    // other imports here


    selector: 'my-app',
    template: `
        <h1>Component Router</h1>
        <a routerLink="/routing-test" routerLinkActive="active">Routing Test</a>

For < V5

Also can use RouterLink as a directives ie. directives: [RouterLink]. that worked for me

import {Router, RouteParams, RouterLink} from 'angular2/router';

    selector: 'my-app',
    directives: [RouterLink],
    template: `
        <h1>Component Router</h1>
        <a [routerLink]="['RoutingTest']">Routing Test</a>

    {path:'/routing-test', name: 'RoutingTest', component: RoutingTestComponent, useAsDefault: true},

How to process images of a video, frame by frame, in video streaming using OpenCV and Python

The only solution I have found is not to set the index to a previous frame and wait (then OpenCV stops reading frames, anyway), but to initialize the capture one more time. So, it looks like this:

cap = cv2.VideoCapture(camera_url)
while True:
    ret, frame =

    if not ret:
        cap = cv.VideoCapture(camera_url)

    # do your processing here

And it works perfectly!

C++11 thread-safe queue

I would rewrite your dequeue function as:

std::string FileQueue::dequeue(const std::chrono::milliseconds& timeout)
    std::unique_lock<std::mutex> lock(qMutex);
    while(q.empty()) {
        if (populatedNotifier.wait_for(lock, timeout) == std::cv_status::timeout ) 
           return std::string();
    std::string ret = q.front();
    return ret;

It is shorter and does not have duplicate code like your did. Only issue it may wait longer that timeout. To prevent that you would need to remember start time before loop, check for timeout and adjust wait time accordingly. Or specify absolute time on wait condition.

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

In many environments (e.g. Heroku), and as a convention, you can set the environment variable PORT to tell your web server what port to listen on.

So process.env.PORT || 3000 means: whatever is in the environment variable PORT, or 3000 if there's nothing there.

So you pass that to app.listen, or to app.set('port', ...), and that makes your server able to accept a "what port to listen on" parameter from the environment.

If you pass 3000 hard-coded to app.listen(), you're always listening on port 3000, which might be just for you, or not, depending on your requirements and the requirements of the environment in which you're running your server.

How to rename JSON key

In this case it would be easiest to use string replace. Serializing the JSON won't work well because _id will become the property name of the object and changing a property name is no simple task (at least not in most langauges, it's not so bad in javascript). Instead just do;

jsonString = jsonString.replace("\"_id\":", "\"id\":");

Creating a search form in PHP to search a database?

You're getting errors 'table liam does not exist' because the table's name is Liam which is not the same as liam. MySQL table names are case sensitive.

How to name and retrieve a stash by name in git?

You can turn a stash into a branch if you feel it's important enough:

git stash branch <branchname> [<stash>]

from the man page:

This creates and checks out a new branch named <branchname> starting from the commit at which the <stash> was originally created, applies the changes recorded in <stash> to the new working tree and index, then drops the <stash> if that completes successfully. When no <stash> is given, applies the latest one.

This is useful if the branch on which you ran git stash save has changed enough that git stash apply fails due to conflicts. Since the stash is applied on top of the commit that was HEAD at the time git stash was run, it restores the originally stashed state with no conflicts.

You can later rebase this new branch to some other place that's a descendent of where you were when you stashed.

Codeigniter $this->db->get(), how do I return values for a specific row?


$this->db->where('id', '3');
// here we select every column of the table
$q = $this->db->get('my_users_table');
$data = $q->result_array();



// here we select just the age column
$this->db->where('id', '3');
$q = $this->db->get('my_users_table');
$data = $q->result_array();



$this->db->where('id', '3');
$q = $this->db->get('my_users_table');
// if id is unique, we want to return just one row
$data = array_shift($q->result_array());



$q = $this->db->query('SELECT age FROM my_users_table WHERE id = ?',array(3));
$data = array_shift($q->result_array());

E: Unable to locate package mongodb-org

This worked on Ubuntu 17.04

sudo apt-key adv --keyserver hkp:// --recv 2930ADAE8CAF5059EE73BB4B58712A2291FA4AD5

echo "deb [ arch=amd64,arm64 ] xenial/mongodb-org/3.6 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.6.list

sudo apt-get update

sudo apt-get install -y mongodb-org

If you see a failure like:

dpkg: error processing archive /var/cache/apt/archives/mongodb-org-tools_3.6.2_amd64.deb (--unpack):
trying to overwrite '/usr/bin/bsondump', which is also in package mongo-tools 3.2.11-1
dpkg-deb: error: subprocess paste was killed by signal (Broken pipe)

Then run this command:

echo "deb [ arch=amd64,arm64 ] xenial/mongodb-org/3.6 multiverse" |

sudo tee /etc/apt/sources.list.d/mongodb-org-3.6.list


sudo apt update
sudo apt install mongodb-org


Using app.config in .Net Core

It is possible to use your usual System.Configuration even in .NET Core 2.0 on Linux. Try this test example:

  1. Created a .NET Standard 2.0 Library (say MyLib.dll)
  2. Added the NuGet package System.Configuration.ConfigurationManager v4.4.0. This is needed since this package isn't covered by the meta-package NetStandard.Library v2.0.0 (I hope that changes)
  3. All your C# classes derived from ConfigurationSection or ConfigurationElement go into MyLib.dll. For example MyClass.cs derives from ConfigurationSection and MyAccount.cs derives from ConfigurationElement. Implementation details are out of scope here but Google is your friend.
  4. Create a .NET Core 2.0 app (e.g. a console app, MyApp.dll). .NET Core apps end with .dll rather than .exe in Framework.
  5. Create an app.config in MyApp with your custom configuration sections. This should obviously match your class designs in #3 above. For example:

<?xml version="1.0" encoding="utf-8"?>
    <section name="myCustomConfig" type="MyNamespace.MyClass, MyLib" />
    <myAccount id="007" />

That's it - you'll find that the app.config is parsed properly within MyApp and your existing code within MyLib works just fine. Don't forget to run dotnet restore if you switch platforms from Windows (dev) to Linux (test).

Additional workaround for test projects

If you're finding that your App.config is not working in your test projects, you might need this snippet in your test project's .csproj (e.g. just before the ending </Project>). It basically copies App.config into your output folder as testhost.dll.config so dotnet test picks it up.

  <!-- START: This is a buildtime work around for -->
  <Target Name="CopyCustomContent" AfterTargets="AfterBuild">
    <Copy SourceFiles="App.config" DestinationFiles="$(OutDir)\testhost.dll.config" />
  <!-- END: This is a buildtime work around for -->

Excel Date to String conversion

Here is a VBA approach:

Sub change()
    toText Sheets(1).Range("A1:F20")
End Sub

Sub toText(target As Range)
Dim cell As Range
    For Each cell In target
        cell.Value = cell.Text
        cell.NumberFormat = "@"
    Next cell
End Sub

If you are looking for a solution without programming, the Question should be moved to SuperUser.

ExecuteReader: Connection property has not been initialized

After SqlCommand cmd=new SqlCommand ("insert into time(project,iteration)values('.... Add

cmd.Connection = conn;

Hope this help

How to find my php-fpm.sock?

I encounter this issue when I first run LEMP on centos7 refer to this post.

I restart nginx to test the phpinfo page, but get this is not unreachable now.

Then I use tail -f /var/log/nginx/error.log to see more info. I find is the php-fpm.sock file not exist. Then I reboot the system, everything is OK.

Here may not need to reboot the system as Fath's post, just reload nginx and php-fpm.

restart php-fpm

reload nginx config

Go To Definition: "Cannot navigate to the symbol under the caret."

After I read that this particular issue was fixed in the roslyn compiler (see this issue at GitHub), I updated Visual Studio from version 15.0.x to 15.3.1. It works like a charm now.

How to use session in JSP pages to get information?

You can directly use (String)session.getAttribute("username"); inside scriptlet tag ie <% %>.

Java Command line arguments

Try to pass value a and compare using the equals method like this:

public static void main(String str[]) {

    boolean b = str[0].equals("a");



Follow this link to know more about Command line argument in Java

Easier way to create circle div than using an image?

There's also [the bad idea of] using several (20+) horizontal or vertical 1px divs to construct a circle. This jQuery plugin uses this method to construct different shapes.

Named tuple and default values for optional keyword arguments

Python 3.7: introduction of defaults param in namedtuple definition.

Example as shown in the documentation:

>>> Account = namedtuple('Account', ['type', 'balance'], defaults=[0])
>>> Account._fields_defaults
{'balance': 0}
>>> Account('premium')
Account(type='premium', balance=0)

Read more here.

Eclipse - no Java (JRE) / (JDK) ... no virtual machine

It turned out that all I needed to do was change the 'path' to:

"C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem; C:\Program Files (x86)\Java; C:\Program Files (x86)\Java\jdk1.6.0_14\bin"

that did it :)

How to set character limit on the_content() and the_excerpt() in wordpress

wp_trim_words() This function trims text to a certain number of words and returns the trimmed text.

$excerpt = wp_trim_words( get_the_content(), 40, '<a href="'.get_the_permalink().'">More Link</a>');

Get truncated string with specified width using mb_strimwidth() php function.

$excerpt = mb_strimwidth( strip_tags(get_the_content()), 0, 100, '...' );

Using add_filter() method of WordPress on the_content filter hook.

add_filter( "the_content", "limit_content_chr" );
function limit_content_chr( $content ){
    if ( 'post' == get_post_type() ) {
        return mb_strimwidth( strip_tags($content), 0, 100, '...' );
    } else {
        return $content;

Using custom php function to limit content characters.

function limit_content_chr( $content, $limit=100 ) {
    return mb_strimwidth( strip_tags($content), 0, $limit, '...' );

// using above function in template tags
echo limit_content_chr( get_the_content(), 50 );

bower proxy configuration

The key for me was adding an extra line, "strict-ssl": false

Create .bowerrc on root folder, and add the following,

  "directory": "bower_components", // If you change this, your folder named will change within dependecies. EX) Vendors instead of bower_components.
  "proxy": "http://yourProxy:yourPort",
  "strict-ssl": false 

Best of luck for the people still stuck on this.

How can I check if a directory exists?

Use the following code to check if a folder exists. It works on both Windows & Linux platforms.

#include <stdio.h>
#include <sys/stat.h>

int main(int argc, char* argv[])
    const char* folder;
    //folder = "C:\\Users\\SaMaN\\Desktop\\Ppln";
    folder = "/tmp";
    struct stat sb;

    if (stat(folder, &sb) == 0 && S_ISDIR(sb.st_mode)) {
    } else {

Format in kotlin string templates

Since String.format is only an extension function (see here) which internally calls java.lang.String.format you could write your own extension function using Java's DecimalFormat if you need more flexibility:

fun Double.format(fracDigits: Int): String {
    val df = DecimalFormat()
    return df.format(this)

println(3.14159.format(2)) // 3.14

Why is processing a sorted array faster than processing an unsorted array?

Bjarne Stroustrup's Answer to this question:

That sounds like an interview question. Is it true? How would you know? It is a bad idea to answer questions about efficiency without first doing some measurements, so it is important to know how to measure.

So, I tried with a vector of a million integers and got:

Already sorted    32995 milliseconds
Shuffled          125944 milliseconds

Already sorted    18610 milliseconds
Shuffled          133304 milliseconds

Already sorted    17942 milliseconds
Shuffled          107858 milliseconds

I ran that a few times to be sure. Yes, the phenomenon is real. My key code was:

void run(vector<int>& v, const string& label)
    auto t0 = system_clock::now();
    sort(v.begin(), v.end());
    auto t1 = system_clock::now();
    cout << label
         << duration_cast<microseconds>(t1 — t0).count()
         << " milliseconds\n";

void tst()
    vector<int> v(1'000'000);
    iota(v.begin(), v.end(), 0);
    run(v, "already sorted ");
    std::shuffle(v.begin(), v.end(), std::mt19937{ std::random_device{}() });
    run(v, "shuffled    ");

At least the phenomenon is real with this compiler, standard library, and optimizer settings. Different implementations can and do give different answers. In fact, someone did do a more systematic study (a quick web search will find it) and most implementations show that effect.

One reason is branch prediction: the key operation in the sort algorithm is “if(v[i] < pivot]) …” or equivalent. For a sorted sequence that test is always true whereas, for a random sequence, the branch chosen varies randomly.

Another reason is that when the vector is already sorted, we never need to move elements to their correct position. The effect of these little details is the factor of five or six that we saw.

Quicksort (and sorting in general) is a complex study that has attracted some of the greatest minds of computer science. A good sort function is a result of both choosing a good algorithm and paying attention to hardware performance in its implementation.

If you want to write efficient code, you need to know a bit about machine architecture.

Parsing huge logfiles in Node.js - read in line-by-line

I searched for a solution to parse very large files (gbs) line by line using a stream. All the third-party libraries and examples did not suit my needs since they processed the files not line by line (like 1 , 2 , 3 , 4 ..) or read the entire file to memory

The following solution can parse very large files, line by line using stream & pipe. For testing I used a 2.1 gb file with 17.000.000 records. Ram usage did not exceed 60 mb.

First, install the event-stream package:

npm install event-stream


var fs = require('fs')
    , es = require('event-stream');

var lineNr = 0;

var s = fs.createReadStream('very-large-file.csv')

        // pause the readstream

        lineNr += 1;

        // process line here and call s.resume() when rdy
        // function below was for logging memory usage

        // resume the readstream, possibly from a callback
    .on('error', function(err){
        console.log('Error while reading file.', err);
    .on('end', function(){
        console.log('Read entire file.')

enter image description here

Please let me know how it goes!

Asynchronous Process inside a javascript for loop

Any recommendation on how to fix this?

Several. You can use bind:

for (i = 0; i < j; i++) {
    asycronouseProcess(function (i) {
    }.bind(null, i));

Or, if your browser supports let (it will be in the next ECMAScript version, however Firefox already supports it since a while) you could have:

for (i = 0; i < j; i++) {
    let k = i;
    asycronouseProcess(function() {

Or, you could do the job of bind manually (in case the browser doesn't support it, but I would say you can implement a shim in that case, it should be in the link above):

for (i = 0; i < j; i++) {
    asycronouseProcess(function(i) {
        return function () {

I usually prefer let when I can use it (e.g. for Firefox add-on); otherwise bind or a custom currying function (that doesn't need a context object).

How do I get the parent directory in Python?

import os
SITE_ROOT = os.path.dirname(os.path.realpath(__file__))
print("example 1: "+SITE_ROOT)
PARENT_ROOT=os.path.abspath(os.path.join(SITE_ROOT, os.pardir))
print("example 2: "+PARENT_ROOT)
GRANDPAPA_ROOT=os.path.abspath(os.path.join(PARENT_ROOT, os.pardir))
print("example 3: "+GRANDPAPA_ROOT)
print "------------------------------------------------------------"

How to deny access to a file in .htaccess

Place the below line in your .htaccess file and replace the file name as you wish

RewriteRule ^(test\.php) - [F,L,NC]

how to get current month and year

Like this:

DateTime.Now.ToString("MMMM yyyy")

For more information, see DateTime Format Strings.

Schedule automatic daily upload with FileZilla

FileZilla does not have any command line arguments (nor any other way) that allow an automatic transfer.

Some references:

Though you can use any other client that allows automation.

You have not specified, what protocol you are using. FTP or SFTP? You will definitely be able to use WinSCP, as it supports all protocols that FileZilla does (and more).

Combine WinSCP scripting capabilities with Windows Scheduler:

A typical WinSCP script for upload (with SFTP) looks like:

open sftp://user:[email protected]/ -hostkey="ssh-rsa 2048 xxxxxxxxxxx...="
put c:\mypdfs\*.pdf /home/user/

With FTP, just replace the sftp:// with the ftp:// and remove the -hostkey="..." switch.

Similarly for download: How to schedule an automatic FTP download on Windows?

WinSCP can even generate a script from an imported FileZilla session.

For details, see the guide to FileZilla automation.

(I'm the author of WinSCP)

Another option, if you are using SFTP, is the psftp.exe client from PuTTY suite.

How to gracefully handle the SIGKILL signal in Java

You can use Runtime.getRuntime().addShutdownHook(...), but you cannot be guaranteed that it will be called in any case.

How to import an existing X.509 certificate and private key in Java keystore to use in SSL?

And one more:


# We have:
# 1) $KEY : Secret key in PEM format ("-----BEGIN RSA PRIVATE KEY-----") 
# 2) $LEAFCERT : Certificate for secret key obtained from some
#    certification outfit, also in PEM format ("-----BEGIN CERTIFICATE-----")   
# 3) $CHAINCERT : Intermediate certificate linking $LEAFCERT to a trusted
#    Self-Signed Root CA Certificate 
# We want to create a fresh Java "keystore" $TARGET_KEYSTORE with the
# password $TARGET_STOREPW, to be used by Tomcat for HTTPS Connector.
# The keystore must contain: $KEY, $LEAFCERT, $CHAINCERT
# The Self-Signed Root CA Certificate is obtained by Tomcat from the
# JDK's truststore in /etc/pki/java/cacerts

# The non-APR HTTPS connector (APR uses OpenSSL-like configuration, much
# easier than this) in server.xml looks like this 
# (See:
#  <Connector port="8443" protocol="org.apache.coyote.http11.Http11Protocol"
#                SSLEnabled="true"
#                maxThreads="150" scheme="https" secure="true"
#                clientAuth="false" sslProtocol="TLS"
#                keystoreFile="/etc/tomcat6/etl-web.keystore.jks"
#                keystorePass="changeit" />

# Let's roll:    




# ----
# Create PKCS#12 file to import using keytool later
# ----

# From
# The PKCS#12 or PFX format is a binary format for storing the server certificate,
# any intermediate certificates, and the private key in one encryptable file. PFX
# files usually have extensions such as .pfx and .p12. PFX files are typically used 
# on Windows machines to import and export certificates and private keys.

TMPPW=$$ # Some random password


if [[ $? != 0 ]]; then
  echo "Creation of temporary PKCS12 file failed -- exiting" >&2; exit 1


if [[ $? != 0 ]]; then
  echo "Creation of temporary transit file failed -- exiting" >&2; exit 1


openssl pkcs12 -export -passout "pass:$TMPPW" -in "$TRANSITFILE" -name etl-web > "$PKCS12FILE"

/bin/rm "$TRANSITFILE"

# Print out result for fun! Bug in doc (I think): "-pass " arg does not work, need "-passin"

openssl pkcs12 -passin "pass:$TMPPW" -passout "pass:$TMPPW" -in "$PKCS12FILE" -info

# ----
# Import contents of PKCS12FILE into a Java keystore. WTF, Sun, what were you thinking?
# ----

if [[ -f "$TARGET_KEYSTORE" ]]; then
  /bin/rm "$TARGET_KEYSTORE"

keytool -importkeystore \
   -deststorepass  "$TARGET_STOREPW" \
   -destkeypass    "$TARGET_STOREPW" \
   -destkeystore   "$TARGET_KEYSTORE" \
   -srckeystore    "$PKCS12FILE" \
   -srcstoretype  PKCS12 \
   -srcstorepass  "$TMPPW" \
   -alias foo-the-server

/bin/rm "$PKCS12FILE"

# ----
# Import the chain certificate. This works empirically, it is not at all clear from the doc whether this is correct
# ----

echo "Importing chain"


keytool -import $TT -storepass "$TARGET_STOREPW" -file "$CHAINCERT" -keystore "$TARGET_KEYSTORE" -alias chain

# ----
# Print contents
# ----

echo "Listing result"

keytool -list -storepass "$TARGET_STOREPW" -keystore "$TARGET_KEYSTORE"

IE11 prevents ActiveX from running

We started finding some machines with IE 11 not playing video (via flash) after we set the emulation mode of our app (web browser control) to 110001. Adding the meta tag to our htm files worked for us.

pass JSON to HTTP POST Request

I think the following should work:

// fire request
    url: url,
    method: "POST",
    json: requestData
}, ...

In this case, the Content-type: application/json header is automatically added.

Pandas merge two dataframes with different columns

I had this problem today using any of concat, append or merge, and I got around it by adding a helper column sequentially numbered and then doing an outer join

for i in df1.index:
for i in df2.index:

How can I check if my python object is a number?

Use Number from the numbers module to test isinstance(n, Number) (available since 2.6).

isinstance(n, numbers.Number)

Here it is in action with various kinds of numbers and one non-number:

>>> from numbers import Number
... from decimal import Decimal
... from fractions import Fraction
... for n in [2, 2.0, Decimal('2.0'), complex(2,0), Fraction(2,1), '2']:
...     print '%15s %s' % (n.__repr__(), isinstance(n, Number))
              2 True
            2.0 True
 Decimal('2.0') True
         (2+0j) True
 Fraction(2, 1) True
            '2' False

This is, of course, contrary to duck typing. If you are more concerned about how an object acts rather than what it is, perform your operations as if you have a number and use exceptions to tell you otherwise.

How to create a circular ImageView in Android?

I too needed a rounded ImageView, I used the below code, you can modify it accordingly:

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageView;

public class RoundedImageView extends ImageView {

    public RoundedImageView(Context context) {

    public RoundedImageView(Context context, AttributeSet attrs) {
        super(context, attrs);

    public RoundedImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

    protected void onDraw(Canvas canvas) {

        Drawable drawable = getDrawable();

        if (drawable == null) {

        if (getWidth() == 0 || getHeight() == 0) {
        Bitmap b = ((BitmapDrawable) drawable).getBitmap();
        Bitmap bitmap = b.copy(Bitmap.Config.ARGB_8888, true);

        int w = getWidth();
        int h = getHeight();

        Bitmap roundBitmap = getCroppedBitmap(bitmap, w);
        canvas.drawBitmap(roundBitmap, 0, 0, null);


    public static Bitmap getCroppedBitmap(Bitmap bmp, int radius) {
        Bitmap sbmp;

        if (bmp.getWidth() != radius || bmp.getHeight() != radius) {
            float smallest = Math.min(bmp.getWidth(), bmp.getHeight());
            float factor = smallest / radius;
            sbmp = Bitmap.createScaledBitmap(bmp,
                    (int) (bmp.getWidth() / factor),
                    (int) (bmp.getHeight() / factor), false);
        } else {
            sbmp = bmp;

        Bitmap output = Bitmap.createBitmap(radius, radius, Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

        final String color = "#BAB399";
        final Paint paint = new Paint();
        final Rect rect = new Rect(0, 0, radius, radius);

        canvas.drawARGB(0, 0, 0, 0);
        canvas.drawCircle(radius / 2 + 0.7f, radius / 2 + 0.7f,
                radius / 2 + 0.1f, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(sbmp, rect, rect, paint);

        return output;


What is the order of precedence for CSS?

First of all, based on your @extend directive, it seems you're not using pure CSS, but a preprocessor such as SASS os Stylus.

Now, when we talk about "order of precedence" in CSS, there is a general rule involved: whatever rules set after other rules (in a top-down fashion) are applied. In your case, just by specifying .smallbox after .smallbox-paysummary you would be able to change the precedence of your rules.

However, if you wanna go a bit further, I suggest this reading: CSS cascade W3C specification. You will find that the precedence of a rule is based on:

  1. The current media type;
  2. Importance;
  3. Origin;
  4. Specificity of the selector, and finally our well-known rule:
  5. Which one is latter specified.

What is the difference between a static method and a non-static method?

Static methods are useful if you have only one instance (situation, circumstance) where you're going to use the method, and you don't need multiple copies (objects). For example, if you're writing a method that logs onto one and only one web site, downloads the weather data, and then returns the values, you could write it as static because you can hard code all the necessary data within the method and you're not going to have multiple instances or copies. You can then access the method statically using one of the following:


Non-static methods are used if you're going to use your method to create multiple copies. For example, if you want to download the weather data from Boston, Miami, and Los Angeles, and if you can do so from within your method without having to individually customize the code for each separate location, you then access the method non-statically:

MyClass boston = new MyClassConstructor(); 

MyClass miami = new MyClassConstructor(); 

MyClass losAngeles = new MyClassConstructor();

In the above example, Java creates three separate objects and memory locations from the same method that you can individually access with the "boston", "miami", or "losAngeles" reference. You can't access any of the above statically, because MyClass.myMethod(); is a generic reference to the method, not to the individual objects that the non-static reference created.

If you run into a situation where the way you access each location, or the way the data is returned, is sufficiently different that you can't write a "one size fits all" method without jumping through a lot of hoops, you can better accomplish your goal by writing three separate static methods, one for each location.

Checking on a thread / remove from list

As TokenMacGuy says, you should use thread.is_alive() to check if a thread is still running. To remove no longer running threads from your list you can use a list comprehension:

for t in my_threads:
    if not t.is_alive():
        # get results from thread
        t.handled = True
my_threads = [t for t in my_threads if not t.handled]

This avoids the problem of removing items from a list while iterating over it.

Variables within app.config/web.config

You can accomplish using my library Expansive. Also available on nuget here.

It was designed with this as a primary use-case.

Moderate Example (using AppSettings as default source for token expansion)

In app.config:

        <add key="Domain" value=""/>
        <add key="ServerName" value="db01.{Domain}"/>
        <add name="Default" connectionString="server={ServerName};uid=uid;pwd=pwd;Initial Catalog=master;" provider="System.Data.SqlClient" />

Use the .Expand() extension method on the string to be expanded:

var connectionString = ConfigurationManager.ConnectionStrings["Default"].ConnectionString;
connectionString.Expand() // returns ";uid=uid;pwd=pwd;Initial Catalog=master;"


Use the Dynamic ConfigurationManager wrapper "Config" as follows (Explicit call to Expand() not necessary):

var serverName = Config.AppSettings.ServerName;
// returns ""

var connectionString = Config.ConnectionStrings.Default;
// returns ";uid=uid;pwd=pwd;Initial Catalog=master;"

Advanced Example 1 (using AppSettings as default source for token expansion)

In app.config:

        <add key="Environment" value="dev"/>
        <add key="Domain" value=""/>
        <add key="UserId" value="uid"/>
        <add key="Password" value="pwd"/>
        <add key="ServerName" value="db01-{Environment}.{Domain}"/>
        <add key="ReportPath" value="\\{ServerName}\SomeFileShare"/>
        <add name="Default" connectionString="server={ServerName};uid={UserId};pwd={Password};Initial Catalog=master;" provider="System.Data.SqlClient" />

Use the .Expand() extension method on the string to be expanded:

var connectionString = ConfigurationManager.ConnectionStrings["Default"].ConnectionString;
connectionString.Expand() // returns ";uid=uid;pwd=pwd;Initial Catalog=master;"

How do I free memory in C?

You have to free() the allocated memory in exact reverse order of how it was allocated using malloc().

Note that You should free the memory only after you are done with your usage of the allocated pointers.

memory allocation for 1D arrays:

    buffer = malloc(num_items*sizeof(double));

memory deallocation for 1D arrays:


memory allocation for 2D arrays:

    double **cross_norm=(double**)malloc(150 * sizeof(double *));
    for(i=0; i<150;i++)

memory deallocation for 2D arrays:

    for(i=0; i<150;i++)


(XML) The markup in the document following the root element must be well-formed. Start location: 6:2

In XML there can be only one root element - you have two - heading and song.

If you restructure to something like:

<?xml version="1.0" encoding="UTF-8"?>
 The Twelve Days of Christmas

The error about well-formed XML on the root level should disappear (though there may be other issues).

Compute row average in pandas

If you are looking to average column wise. Try this,

df.drop('Region', axis=1).apply(lambda x: x.mean())

# it drops the Region column
df.drop('Region', axis=1,inplace=True)

Python requests library how to pass Authorization header with single token

In python:


is equivalent to


And requests interprets

('TOK', '<MY_TOKEN>')

As you wanting requests to use Basic Authentication and craft an authorization header like so:


Which is the base64 representation of 'TOK:<MY_TOKEN>'

To pass your own header you pass in a dictionary like so:

r = requests.get('<MY_URI>', headers={'Authorization': 'TOK:<MY_TOKEN>'})

How to convert seconds to HH:mm:ss in moment.js

From this post I would try this to avoid leap issues


I did not run jsPerf, but I would think this is faster than creating new date objects a million times

function pad(num) {
    return ("0"+num).slice(-2);
function hhmmss(secs) {
  var minutes = Math.floor(secs / 60);
  secs = secs%60;
  var hours = Math.floor(minutes/60)
  minutes = minutes%60;
  return `${pad(hours)}:${pad(minutes)}:${pad(secs)}`;
  // return pad(hours)+":"+pad(minutes)+":"+pad(secs); for old browsers

function pad(num) {_x000D_
    return ("0"+num).slice(-2);_x000D_
function hhmmss(secs) {_x000D_
  var minutes = Math.floor(secs / 60);_x000D_
  secs = secs%60;_x000D_
  var hours = Math.floor(minutes/60)_x000D_
  minutes = minutes%60;_x000D_
  return `${pad(hours)}:${pad(minutes)}:${pad(secs)}`;_x000D_
  // return pad(hours)+":"+pad(minutes)+":"+pad(secs); for old browsers_x000D_
for (var i=60;i<=60*60*5;i++) {_x000D_
/* _x000D_
function show(s) {_x000D_
  var d = new Date();_x000D_
  var d1 = new Date(d.getTime()+s*1000);_x000D_
  var  hms = hhmmss(s);_x000D_
  return (s+"s = "+ hms + " - "+ Math.floor((d1-d)/1000)+"\n"+d.toString().split("GMT")[0]+"\n"+d1.toString().split("GMT")[0]);_x000D_
}    _x000D_

Explanation of 'String args[]' and static in 'public static void main(String[] args)'

The normal usage of static is to access the function directly with out any object creation. Same as in java main we could not create any object for that class to invoke the main method. It will execute automatically. If we want to execute manually we can call by using main() inside the class and ClassName.main from outside the class.

Error: Unable to run mksdcard SDK tool

For UBUNTU 15.04,15.10,16.04 LTS, Debian 8 & Debian 9 Try this command:

sudo apt-get install lib32stdc++6

What is two way binding?

Worth mentioning that there are many different solutions which offer two way binding and play really nicely.

I have had a pleasant experience with this model binder - which gives sensible defaults yet a lot of custom jquery selector mapping of model attributes to input elements.

There is a more extended list of backbone extensions/plugins on github

How to convert JSON object to JavaScript array?

Suppose you have:

var j = {0: "1", 1: "2", 2: "3", 3: "4"};

You could get the values with (supported in practically all browser versions):

Object.keys(j).map(function(_) { return j[_]; })

or simply:



["1", "2", "3", "4"]

How to insert tab character when expandtab option is on in Vim

You can disable expandtab option from within Vim as below:

:set expandtab!


:set noet

PS: And set it back when you are done with inserting tab, with "set expandtab" or "set et"

PS: If you have tab set equivalent to 4 spaces in .vimrc (softtabstop), you may also like to set it to 8 spaces in order to be able to insert a tab by pressing tab key once instead of twice (set softtabstop=8).

How do you get the index of the current iteration of a foreach loop?

C# 7 finally gives us an elegant way to do this:

static class Extensions
    public static IEnumerable<(int, T)> Enumerate<T>(
        this IEnumerable<T> input,
        int start = 0
        int i = start;
        foreach (var t in input)
            yield return (i++, t);

class Program
    static void Main(string[] args)
        var s = new string[]

        foreach (var (i, t) in s.Enumerate())
            Console.WriteLine($"{i}: {t}");

How to set xampp open localhost:8080 instead of just localhost

The port that the Admin button references is configurable. In the XAMPP install folder there is a xampp-control.ini file. Changing the Apache entry under [ServicePorts] will affect the url the Admin button opens.


Check if table exists in SQL Server

If this is to be the 'ultimate' discussion, then it should be noted that Larry Leonard's script can query a remote server as well if the servers are linked.

if exists (select * from REMOTE_SERVER.MyOtherDatabase.sys.tables where name = 'MyTable')
    print 'Exists'

ASP.NET MVC - Set custom IIdentity or IPrincipal

Here's how I do it.

I decided to use IPrincipal instead of IIdentity because it means I don't have to implement both IIdentity and IPrincipal.

  1. Create the interface

    interface ICustomPrincipal : IPrincipal
        int Id { get; set; }
        string FirstName { get; set; }
        string LastName { get; set; }
  2. CustomPrincipal

    public class CustomPrincipal : ICustomPrincipal
        public IIdentity Identity { get; private set; }
        public bool IsInRole(string role) { return false; }
        public CustomPrincipal(string email)
            this.Identity = new GenericIdentity(email);
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
  3. CustomPrincipalSerializeModel - for serializing custom information into userdata field in FormsAuthenticationTicket object.

    public class CustomPrincipalSerializeModel
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
  4. LogIn method - setting up a cookie with custom information

    if (Membership.ValidateUser(viewModel.Email, viewModel.Password))
        var user = userRepository.Users.Where(u => u.Email == viewModel.Email).First();
        CustomPrincipalSerializeModel serializeModel = new CustomPrincipalSerializeModel();
        serializeModel.Id = user.Id;
        serializeModel.FirstName = user.FirstName;
        serializeModel.LastName = user.LastName;
        JavaScriptSerializer serializer = new JavaScriptSerializer();
        string userData = serializer.Serialize(serializeModel);
        FormsAuthenticationTicket authTicket = new FormsAuthenticationTicket(
        string encTicket = FormsAuthentication.Encrypt(authTicket);
        HttpCookie faCookie = new HttpCookie(FormsAuthentication.FormsCookieName, encTicket);
        return RedirectToAction("Index", "Home");
  5. Global.asax.cs - Reading cookie and replacing HttpContext.User object, this is done by overriding PostAuthenticateRequest

    protected void Application_PostAuthenticateRequest(Object sender, EventArgs e)
        HttpCookie authCookie = Request.Cookies[FormsAuthentication.FormsCookieName];
        if (authCookie != null)
            FormsAuthenticationTicket authTicket = FormsAuthentication.Decrypt(authCookie.Value);
            JavaScriptSerializer serializer = new JavaScriptSerializer();
            CustomPrincipalSerializeModel serializeModel = serializer.Deserialize<CustomPrincipalSerializeModel>(authTicket.UserData);
            CustomPrincipal newUser = new CustomPrincipal(authTicket.Name);
            newUser.Id = serializeModel.Id;
            newUser.FirstName = serializeModel.FirstName;
            newUser.LastName = serializeModel.LastName;
            HttpContext.Current.User = newUser;
  6. Access in Razor views

    @((User as CustomPrincipal).Id)
    @((User as CustomPrincipal).FirstName)
    @((User as CustomPrincipal).LastName)

and in code:

    (User as CustomPrincipal).Id
    (User as CustomPrincipal).FirstName
    (User as CustomPrincipal).LastName

I think the code is self-explanatory. If it isn't, let me know.

Additionally to make the access even easier you can create a base controller and override the returned User object (HttpContext.User):

public class BaseController : Controller
    protected virtual new CustomPrincipal User
        get { return HttpContext.User as CustomPrincipal; }

and then, for each controller:

public class AccountController : BaseController
    // ...

which will allow you to access custom fields in code like this:


But this will not work inside views. For that you would need to create a custom WebViewPage implementation:

public abstract class BaseViewPage : WebViewPage
    public virtual new CustomPrincipal User
        get { return base.User as CustomPrincipal; }

public abstract class BaseViewPage<TModel> : WebViewPage<TModel>
    public virtual new CustomPrincipal User
        get { return base.User as CustomPrincipal; }

Make it a default page type in Views/web.config:

<pages pageBaseType="Your.Namespace.BaseViewPage">
    <add namespace="System.Web.Mvc" />
    <add namespace="System.Web.Mvc.Ajax" />
    <add namespace="System.Web.Mvc.Html" />
    <add namespace="System.Web.Routing" />

and in views, you can access it like this:


How to use PHP OPCache?

OPcache replaces APC

Because OPcache is designed to replace the APC module, it is not possible to run them in parallel in PHP. This is fine for caching PHP opcode as neither affects how you write code.

However it means that if you are currently using APC to store other data (through the apc_store() function) you will not be able to do that if you decide to use OPCache.

You will need to use another library such as either APCu or Yac which both store data in shared PHP memory, or switch to use something like memcached, which stores data in memory in a separate process to PHP.

Also, OPcache has no equivalent of the upload progress meter present in APC. Instead you should use the Session Upload Progress.

Settings for OPcache

The documentation for OPcache can be found here with all of the configuration options listed here. The recommended settings are:

; Sets how much memory to use

;Sets how much memory should be used by OPcache for storing internal strings 
;(e.g. classnames and the files they are contained in)

; The maximum number of files OPcache will cache

;How often (in seconds) to check file timestamps for changes to the shared
;memory storage allocation.

;If enabled, a fast shutdown sequence is used for the accelerated code
;The fast shutdown sequence doesn't free each allocated block, but lets
;the Zend Engine Memory Manager do the work.

;Enables the OPcache for the CLI version of PHP.

If you use any library or code that uses code annotations you must enable save comments:


If disabled, all PHPDoc comments are dropped from the code to reduce the size of the optimized code. Disabling "Doc Comments" may break some existing applications and frameworks (e.g. Doctrine, ZF2, PHPUnit)

How to change an Android app's name?

If you are here because when you tried to upload your fresh/brand new application using the play console it displayed this error: "You must use another package name because "" already exists in Google Play."

You just need to go to your build.gradle file (your application) and change

applicationId ""


applicationId "some.package.different-unique-name"

Other answers here didn't fix this error.

Python MYSQL update statement

It should be:

cursor.execute ("""
   UPDATE tblTableName
   SET Year=%s, Month=%s, Day=%s, Hour=%s, Minute=%s
   WHERE Server=%s
""", (Year, Month, Day, Hour, Minute, ServerID))

You can also do it with basic string manipulation,

cursor.execute ("UPDATE tblTableName SET Year=%s, Month=%s, Day=%s, Hour=%s, Minute=%s WHERE Server='%s' " % (Year, Month, Day, Hour, Minute, ServerID))

but this way is discouraged because it leaves you open for SQL Injection. As it's so easy (and similar) to do it the right waytm. Do it correctly.

The only thing you should be careful, is that some database backends don't follow the same convention for string replacement (SQLite comes to mind).

Why use $_SERVER['PHP_SELF'] instead of ""

I know that the question is two years old, but it was the first result of what I am looking for. I found a good answers and I hope I can help other users.

Look at this

I will make this brief:

  • use the $_SERVER["PHP_SELF"] Variable with htmlspecialchars():

  • PHP_SELF returns the filename of the currently executing script.

  • The htmlspecialchars() function converts special characters to HTML entities. --> NO XSS

How to delete migration files in Rails 3

We can use,

$ rails d migration table_name  

Which will delete the migration.

Comparing strings by their alphabetical order

String a = "..."; 
String b = "...";  

int compare = a.compareTo(b);  

if (compare < 0) {  
    //a is smaller
else if (compare > 0) {
    //a is larger 
else {  
    //a is equal to b

Reload browser window after POST without prompting user to resend POST data

This worked for me.

window.location = window.location.pathname;

Tested on

  • Chrome 44.0.2403
  • IE edge
  • Firefox 39.0

Getting full URL of action in ASP.NET MVC

This may be just me being really, really picky, but I like to only define constants once. If you use any of the approaches defined above, your action constant will be defines multiple times.

To avoid this, you can do the following:

    public class Url
        public string LocalUrl { get; }

        public Url(string localUrl)
            LocalUrl = localUrl;

        public override string ToString()
            return LocalUrl;

    public abstract class Controller
        public Url RootAction => new Url(GetUrl());

        protected abstract string Root { get; }

        public Url BuildAction(string actionName)
            var localUrl = GetUrl() + "/" + actionName;
            return new Url(localUrl);

        private string GetUrl()
            if (Root == "")
                return "";

            return "/" + Root;

        public override string ToString()
            return GetUrl();

Then create your controllers, say for example the DataController:

    public static readonly DataController Data = new DataController();
    public class DataController : Controller
        public const string DogAction = "dog";
        public const string CatAction = "cat";
        public const string TurtleAction = "turtle";

        protected override string Root => "data";

        public Url Dog => BuildAction(DogAction);
        public Url Cat => BuildAction(CatAction);
        public Url Turtle => BuildAction(TurtleAction);

Then just use it like:

    // GET: Data/Cat
    public ActionResult Etisys()
        return View();

And from your .cshtml (or any code)

    <li><a href="@ControllerRoutes.Data.Dog">Dog</a></li>
    <li><a href="@ControllerRoutes.Data.Cat">Cat</a></li>

This is definitely a lot more work, but I rest easy knowing compile time validation is on my side.

Laravel form html with PUT method for PUT routes

Is very easy, you just need to use method_field('PUT') like this:


<form action="{{ route('route_name') }}" method="post">
    {{ method_field('PUT') }}
    {{ csrf_field() }}


<form action="{{ route('route_name') }}" method="post">
    <input type="hidden" name="_method" value="PUT">
    <input type="hidden" name="_token" value="{{ csrf_token() }}">


What is float in Java?

In Java, when you type a decimal number as 3.6, its interpreted as a double. double is a 64-bit precision IEEE 754 floating point, while floatis a 32-bit precision IEEE 754 floating point. As a float is less precise than a double, the conversion cannot be performed implicitly.

If you want to create a float, you should end your number with f (i.e.: 3.6f).

For more explanation, see the primitive data types definition of the Java tutorial.


9.5 and newer:

PostgreSQL 9.5 and newer support INSERT ... ON CONFLICT (key) DO UPDATE (and ON CONFLICT (key) DO NOTHING), i.e. upsert.


Quick explanation.

For usage see the manual - specifically the conflict_action clause in the syntax diagram, and the explanatory text.

Unlike the solutions for 9.4 and older that are given below, this feature works with multiple conflicting rows and it doesn't require exclusive locking or a retry loop.

The commit adding the feature is here and the discussion around its development is here.

If you're on 9.5 and don't need to be backward-compatible you can stop reading now.

9.4 and older:

PostgreSQL doesn't have any built-in UPSERT (or MERGE) facility, and doing it efficiently in the face of concurrent use is very difficult.

This article discusses the problem in useful detail.

In general you must choose between two options:

  • Individual insert/update operations in a retry loop; or
  • Locking the table and doing batch merge

Individual row retry loop

Using individual row upserts in a retry loop is the reasonable option if you want many connections concurrently trying to perform inserts.

The PostgreSQL documentation contains a useful procedure that'll let you do this in a loop inside the database. It guards against lost updates and insert races, unlike most naive solutions. It will only work in READ COMMITTED mode and is only safe if it's the only thing you do in the transaction, though. The function won't work correctly if triggers or secondary unique keys cause unique violations.

This strategy is very inefficient. Whenever practical you should queue up work and do a bulk upsert as described below instead.

Many attempted solutions to this problem fail to consider rollbacks, so they result in incomplete updates. Two transactions race with each other; one of them successfully INSERTs; the other gets a duplicate key error and does an UPDATE instead. The UPDATE blocks waiting for the INSERT to rollback or commit. When it rolls back, the UPDATE condition re-check matches zero rows, so even though the UPDATE commits it hasn't actually done the upsert you expected. You have to check the result row counts and re-try where necessary.

Some attempted solutions also fail to consider SELECT races. If you try the obvious and simple:



UPDATE testtable
SET somedata = 'blah'
WHERE id = 2;

-- Remember, this is WRONG. Do NOT COPY IT.

INSERT INTO testtable (id, somedata)
SELECT 2, 'blah'


then when two run at once there are several failure modes. One is the already discussed issue with an update re-check. Another is where both UPDATE at the same time, matching zero rows and continuing. Then they both do the EXISTS test, which happens before the INSERT. Both get zero rows, so both do the INSERT. One fails with a duplicate key error.

This is why you need a re-try loop. You might think that you can prevent duplicate key errors or lost updates with clever SQL, but you can't. You need to check row counts or handle duplicate key errors (depending on the chosen approach) and re-try.

Please don't roll your own solution for this. Like with message queuing, it's probably wrong.

Bulk upsert with lock

Sometimes you want to do a bulk upsert, where you have a new data set that you want to merge into an older existing data set. This is vastly more efficient than individual row upserts and should be preferred whenever practical.

In this case, you typically follow the following process:


  • COPY or bulk-insert the new data into the temp table

  • LOCK the target table IN EXCLUSIVE MODE. This permits other transactions to SELECT, but not make any changes to the table.

  • Do an UPDATE ... FROM of existing records using the values in the temp table;

  • Do an INSERT of rows that don't already exist in the target table;

  • COMMIT, releasing the lock.

For example, for the example given in the question, using multi-valued INSERT to populate the temp table:


CREATE TEMPORARY TABLE newvals(id integer, somedata text);

INSERT INTO newvals(id, somedata) VALUES (2, 'Joe'), (3, 'Alan');


UPDATE testtable
SET somedata = newvals.somedata
FROM newvals

INSERT INTO testtable
SELECT, newvals.somedata
FROM newvals
LEFT OUTER JOIN testtable ON ( =


Related reading

What about MERGE?

SQL-standard MERGE actually has poorly defined concurrency semantics and is not suitable for upserting without locking a table first.

It's a really useful OLAP statement for data merging, but it's not actually a useful solution for concurrency-safe upsert. There's lots of advice to people using other DBMSes to use MERGE for upserts, but it's actually wrong.

Other DBs:

CSS performance relative to translateZ(0)

I can attest to the fact that -webkit-transform: translate3d(0, 0, 0); will mess with the new position: -webkit-sticky; property. With a left drawer navigation pattern that I was working on, the hardware acceleration I wanted with the transform property was messing with the fixed positioning of my top nav bar. I turned off the transform and the positioning worked fine.

Luckily, I seem to have had hardware acceleration on already, because I had -webkit-font-smoothing: antialiased on the html element. I was testing this behavior in iOS7 and Android.

ParseError: not well-formed (invalid token) using cElementTree

The only thing that worked for me is I had to add mode and encoding while opening the file like below:

with open(filenames[0], mode='r',encoding='utf-8') as f:

Otherwise it was failing every time with invalid token error if I simply do this:

 f = open(filenames[0], 'r')

How to select a value in dropdown javascript?

function setSelectedIndex(s, v) {
    for ( var i = 0; i < s.options.length; i++ ) {
        if ( s.options[i].value == v ) {
            s.options[i].selected = true;

Where s is the dropdown and v is the value

Replacing values from a column using a condition in R

I arrived here from a google search, since my other code is 'tidy' so leaving the 'tidy' way for anyone who else who may find it useful

iris %>% 
  mutate(Species = ifelse(as.character(Species) == "virginica", "newValue", as.character(Species)))

Shortcuts in Objective-C to concatenate NSStrings

An option:

[NSString stringWithFormat:@"%@/%@/%@", one, two, three];

Another option:

I'm guessing you're not happy with multiple appends (a+b+c+d), in which case you could do:

NSLog(@"%@", [Util append:one, @" ", two, nil]); // "one two"
NSLog(@"%@", [Util append:three, @"/", two, @"/", one, nil]); // three/two/one

using something like

+ (NSString *) append:(id) first, ...
    NSString * result = @"";
    id eachArg;
    va_list alist;
        result = [result stringByAppendingString:first];
        va_start(alist, first);
        while (eachArg = va_arg(alist, id)) 
        result = [result stringByAppendingString:eachArg];
    return result;

Query to list all stored procedures

Select All Stored Procedures and Views

select name,type,type_desc
from sys.objects
where type in ('V','P')
order by name,type

How to find day of week in php in a specific timezone

I think this is the correct answer, just change Europe/Stockholm to the users time-zone.

$dateTime = new \DateTime(
    new \DateTimeZone('Europe/Stockholm')
$day = $dateTime->format('N');

ISO-8601 numeric representation of the day of the week (added in PHP 5.1.0) 1 (for Monday) through 7 (for Sunday)

For a list of supported time-zones, see

Trigger insert old values- values that was updated

ALTER trigger ETU on Employee FOR UPDATE AS insert into Log (EmployeeId, LogDate, OldName) select EmployeeId, getdate(), name from deleted go

INSERT INTO from two different server database

The answer given by Simon works fine for me but you have to do it in the right sequence: First you have to be in the server that you want to insert data into which is [DATABASE.WINDOWS.NET].[basecampdev] in your case.

You can try to see if you can select some data out of the Invoice table to make sure you have access.

Select top 10 * from [DATABASE.WINDOWS.NET].[basecampdev].[dbo].[invoice]

Secondly, execute the query given by Simon in order to link to a different server. This time use the other server:

EXEC sp_addlinkedserver [BC1-PC]; -- this will create a link tempdb that you can access from where you are
USE tempdb;
    [BC1-PC].testdabse.dbo.invoice; -- Make a copy of the table and data that you can use

Now just do your insert statement.

INSERT INTO [DATABASE.WINDOWS.NET].[basecampdev].[dbo].[invoice]
SELECT [InvoiceNumber]
       ,[Remarks] FROM MyInvoice

Hope this helps!

Angular 4: How to include Bootstrap?

In Angular4 as you deal with @types system, you should do following things,


1) npm install --save @types/jquery
2) npm install --save @types/bootstrap


look for types array and add jquery and bootstrap entries,

"types": [


in head section add following entries,

  <link href="node_modules/bootstrap/dist/css/bootstrap.min.css" rel="stylesheet">
  <script src="node_modules/jquery/dist/jquery.min.js "></script>
  <script src="node_modules/bootstrap/dist/js/bootstrap.js "></script>

And start using jquery and bootstrap both.

Is there a way to programmatically scroll a scroll view to a specific edit text?

private final void focusOnView(){ Runnable() {
            public void run() {
                your_scrollview.scrollTo(0, your_EditBox.getBottom());

Is it possible to install iOS 6 SDK on Xcode 5?

Find and download old SDK. Older SDKs are found here.

I have copied the directory as

Now you can test and debug in both xcode versions. You have to run them from the corresponding folders or create shortcuts in your desktop. When building from command line give the parameter as iPhoneOS6.1 instead of iPhoneOS7.0

This worked great for me in Xcode5 and iOS.

Go to into Xcode5's SDK dir. Its usually located at:


Add a symbolic link to the old SDK like this:

sudo ln -s /Applications/ iPhoneOS6.1.sdk

Or more accurately from anywhere in the command line,

sudo ln -s /Applications/  /Applications/

How to embed new Youtube's live video permanent URL?

Here's how to do it in Squarespace using the embed block classes to create responsiveness.

Put this into a code block:

<div class="sqs-block embed-block sqs-block-embed" data-block-type="22" >
    <div class="sqs-block-content"><div class="intrinsic" style="max-width:100%">
        <div class="embed-block-wrapper embed-block-provider-YouTube" style="padding-bottom:56.20609%;">
            <iframe allow="autoplay; fullscreen" scrolling="no" data-image-dimensions="854x480" allowfullscreen="true" src="" width="854" data-embed="true" frameborder="0" title="YouTube embed" class="embedly-embed" height="480">

Tweak however you'd like!

CSS to make HTML page footer stay at bottom of the page with a minimum height, but not overlap the page

What about that:

<div style="min-height: 100vh;"> 

 copyright blah blah

diff current working copy of a file with another branch's committed copy

git diff mybranch master -- file

should also work

How to make popup look at the centre of the screen?

In order to get the popup exactly centered, it's a simple matter of applying a negative top margin of half the div height, and a negative left margin of half the div width. For this example, like so:

.div {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 50%;

JavaScript: How to find out if the user browser is Chrome?

all answers are wrong. "Opera" and "Chrome" are same in all cases.

(edited part)

here is the right answer

if ( && {
    // this is Chrome

What does the keyword "transient" mean in Java?

It means that trackDAO should not be serialized.

How to set selected value on select using selectpicker plugin from bootstrap

Well another way to do it is, with this keyword, you can simply get the object in this and manipulate it's value. Eg :

    function() {

Multiline TextBox multiple newline

You need to set the textbox to be multiline, this can be done two ways:

In the control:

<asp:TextBox runat="server" ID="MyBox" TextMode="MultiLine" Rows="10" />

Code Behind:

MyBox.TextMode = TextBoxMode.MultiLine;
MyBox.Rows = 10;

This will render as a <textarea>

Why use 'virtual' for class properties in Entity Framework model definitions?

It allows the Entity Framework to create a proxy around the virtual property so that the property can support lazy loading and more efficient change tracking. See What effect(s) can the virtual keyword have in Entity Framework 4.1 POCO Code First? for a more thorough discussion.

Edit to clarify "create a proxy around": By "create a proxy around" I'm referring specifically to what the Entity Framework does. The Entity Framework requires your navigation properties to be marked as virtual so that lazy loading and efficient change tracking are supported. See Requirements for Creating POCO Proxies.
The Entity Framework uses inheritance to support this functionality, which is why it requires certain properties to be marked virtual in your base class POCOs. It literally creates new types that derive from your POCO types. So your POCO is acting as a base type for the Entity Framework's dynamically created subclasses. That's what I meant by "create a proxy around".

The dynamically created subclasses that the Entity Framework creates become apparent when using the Entity Framework at runtime, not at static compilation time. And only if you enable the Entity Framework's lazy loading or change tracking features. If you opt to never use the lazy loading or change tracking features of the Entity Framework (which is not the default) then you needn't declare any of your navigation properties as virtual. You are then responsible for loading those navigation properties yourself, either using what the Entity Framework refers to as "eager loading", or manually retrieving related types across multiple database queries. You can and should use lazy loading and change tracking features for your navigation properties in many scenarios though.

If you were to create a standalone class and mark properties as virtual, and simply construct and use instances of those classes in your own application, completely outside of the scope of the Entity Framework, then your virtual properties wouldn't gain you anything on their own.

Edit to describe why properties would be marked as virtual

Properties such as:

 public ICollection<RSVP> RSVPs { get; set; }

Are not fields and should not be thought of as such. These are called getters and setters and at compilation time, they are converted into methods.

//Internally the code looks more like this:
public ICollection<RSVP> get_RSVPs()
    return _RSVPs;

public void set_RSVPs(RSVP value)
    _RSVPs = value;

private RSVP _RSVPs;

That's why they're marked as virtual for use in the Entity Framework, it allows the dynamically created classes to override the internally generated get and set functions. If your navigation property getter/setters are working for you in your Entity Framework usage, try revising them to just properties, recompile, and see if the Entity Framework is able to still function properly:

 public virtual ICollection<RSVP> RSVPs;

iPhone/iPad browser simulator?

EDIT 2020: Most of these are basically just to test resolution stuff, some of them even outdated, sadly, mobile browser development went sideways with desktop (especially in Apple), therefore one can't really "emulate" a real phone with these as mentioned with comment.

To emulate real phones, often the best choice is to download a desktop app which, for Windows, is usually paid/freemium, on Mac just use the Xcode one (but I doubt Mac people are looking for this Q/A).

Freemium online easy to use that I found recently is it seems to really render the screen according to network, but honestly I didn't really dig into whether it also has identical features and indentically missing features as real iOS.

Online simulators / emulators I use

1) recombu

Fine simulator which - unlike resizing browser window to mobile phone dimensions - acts same as a smart phone. Don't be confused that you can't edit address bar in safari - just open deveolper tools (usually F12) and rewrite iframe's source URL to yours.

2) responsimulator

Seems to work like recombu, but you can open url directly by text input and you can zoom in/out.

3) transmog

This one seems to process the webpage, but it emulates old iPhone - still handy sometimes.

X) google it / internet search for it

Always use google (or other internet searchers) to check for other simulators/emulators and new versions.
Link with example google search for this one:

Browser device mode

If you open your browser's developer's tools (in Chrome F12), there will probably be an option to toggle device mode (in Chrome it is the little smartphone icon at top-left).
chrome device mode icon

After choosing this option GUI will change and will provide option to select device to simulate (in Chrome it is at the top - select option "Device"), after selecting device, refreshing the page is often adviced to ensure simulator's accuracy.
chrome device mode - device select option

How to make a local variable (inside a function) global

If you need access to the internal states of a function, you're possibly better off using a class. You can make a class instance behave like a function by making it a callable, which is done by defining __call__:

class StatefulFunction( object ):
    def __init__( self ):
        self.public_value = 'foo'

    def __call__( self ):
        return self.public_value

>> f = StatefulFunction()
>> f()
>> f.public_value = 'bar'
>> f()

What determines the monitor my app runs on?

Important note: If you remember the position of your application and shutdown and then start up again at that position, keep in mind that the user's monitor configuration may have changed while your application was closed.

Laptop users, for example, frequently change their display configuration. When docked there may be a 2nd monitor that disappears when undocked. If the user closes an application that was running on the 2nd monitor and the re-opens the application when the monitor is disconnected, restoring the window to the previous coordinates will leave it completely off-screen.

To figure out how big the display really is, check out GetSystemMetrics.

XSLT - How to select XML Attribute by Attribute?

Note: using // at the beginning of the xpath is a bit CPU intensitve -- it will search every node for a match. Using a more specific path, such as /root/DataSet will create a faster query.

How to prevent user from typing in text field without disabling the field?

if you don't want the field to look "disabled" or smth, just use this:

onkeydown="return false;"

it's basically the same that greengit and Derek said but a little shorter

How to print a dictionary's key?

key_name = '...'
print "the key name is %s and its value is %s"%(key_name, mydic[key_name])

Why should I use a pointer rather than the object itself?

One reason for using pointers is to interface with C functions. Another reason is to save memory; for example: instead of passing an object which contains a lot of data and has a processor-intensive copy-constructor to a function, just pass a pointer to the object, saving memory and speed especially if you're in a loop, however a reference would be better in that case, unless you're using an C-style array.

How to kill zombie process

A zombie is already dead, so you cannot kill it. To clean up a zombie, it must be waited on by its parent, so killing the parent should work to eliminate the zombie. (After the parent dies, the zombie will be inherited by pid 1, which will wait on it and clear its entry in the process table.) If your daemon is spawning children that become zombies, you have a bug. Your daemon should notice when its children die and wait on them to determine their exit status.

An example of how you might send a signal to every process that is the parent of a zombie (note that this is extremely crude and might kill processes that you do not intend. I do not recommend using this sort of sledge hammer):

# Don't do this.  Incredibly risky sledge hammer!
kill $(ps -A -ostat,ppid | awk '/[zZ]/ && !a[$2]++ {print $2}')

Tree data structure in C#

In case you need a rooted tree data structure implementation that uses less memory, you can write your Node class as follows (C++ implementation):

class Node {
       Node* parent;
       int item; // depending on your needs

       Node* firstChild; //pointer to left most child of node
       Node* nextSibling; //pointer to the sibling to the right

How to configure CORS in a Spring Boot + Spring Security application?

For properties configuration

endpoints.cors.allow-credentials= # Set whether credentials are supported. When not set, credentials are not supported.
endpoints.cors.allowed-headers= # Comma-separated list of headers to allow in a request. '*' allows all headers.
endpoints.cors.allowed-methods=GET # Comma-separated list of methods to allow. '*' allows all methods.
endpoints.cors.allowed-origins= # Comma-separated list of origins to allow. '*' allows all origins. When not set, CORS support is disabled. # Comma-separated list of headers to include in a response.
endpoints.cors.max-age=1800 # How long, in seconds, the response from a pre-flight request can be cached by clients.

Calculate date from week number

The easiest way is probably to find the first Monday of the year, and then add the relevant number of weeks. Here's some sample code. It assumes a week number starting at 1, by the way:

using System;

class Test
    static void Main()
        // Show the third Tuesday in 2009. Should be January 20th
        Console.WriteLine(YearWeekDayToDateTime(2009, DayOfWeek.Tuesday, 3));

    static DateTime YearWeekDayToDateTime(int year, DayOfWeek day, int week)
        DateTime startOfYear = new DateTime (year, 1, 1);

        // The +7 and %7 stuff is to avoid negative numbers etc.
        int daysToFirstCorrectDay = (((int)day - (int)startOfYear.DayOfWeek) + 7) % 7;

        return startOfYear.AddDays(7 * (week-1) + daysToFirstCorrectDay);

Converting HTML to XML

I did found a way to convert (even bad) html into well formed XML. I started to base this on the DOM loadHTML function. However during time several issues occurred and I optimized and added patches to correct side effects.

  function tryToXml($dom,$content) {
    if(!$content) return false;

    // xml well formed content can be loaded as xml node tree
    $fragment = $dom->createDocumentFragment();
    // wonderfull appendXML to add an XML string directly into the node tree!

    // aappendxml will fail on a xml declaration so manually skip this when occurred
    if( substr( $content,0, 5) == '<?xml' ) {
      $content = substr($content,strpos($content,'>')+1);
      if( strpos($content,'<') ) {
        $content = substr($content,strpos($content,'<'));

    // if appendXML is not working then use below htmlToXml() for nasty html correction
    if(!@$fragment->appendXML( $content )) {
      return $this->htmlToXml($dom,$content);

    return $fragment;

  // convert content into xml
  // dom is only needed to prepare the xml which will be returned
  function htmlToXml($dom, $content, $needEncoding=false, $bodyOnly=true) {

    // no xml when html is empty
    if(!$content) return false;

    // real content and possibly it needs encoding
    if( $needEncoding ) {
      // no need to convert character encoding as loadHTML will respect the content-type (only)
      $content =  '<meta http-equiv="Content-Type" content="text/html;charset='.$this->encoding.'">' . $content;

    // return a dom from the content
    $domInject = new DOMDocument("1.0", "UTF-8");
    $domInject->preserveWhiteSpace = false;
    $domInject->formatOutput = true;

    // html type
    try {
      @$domInject->loadHTML( $content );
    } catch(Exception $e){
      // do nothing and continue as it's normal that warnings will occur on nasty HTML content
        // to check encoding: echo $dom->encoding
        $this->reworkDom( $domInject );

    if( $bodyOnly ) {
      $fragment = $dom->createDocumentFragment();

      // retrieve nodes within /html/body
      foreach( $domInject->documentElement->childNodes as $elementLevel1 ) {
       if( $elementLevel1->nodeName == 'body' and $elementLevel1->nodeType == XML_ELEMENT_NODE ) {
         foreach( $elementLevel1->childNodes as $elementInject ) {
           $fragment->insertBefore( $dom->importNode($elementInject, true) );
    } else {
      $fragment = $dom->importNode($domInject->documentElement, true);

    return $fragment;

    protected function reworkDom( $node, $level = 0 ) {

        // start with the first child node to iterate
        $nodeChild = $node->firstChild;

        while ( $nodeChild )  {
            $nodeNextChild = $nodeChild->nextSibling;

            switch ( $nodeChild->nodeType ) {
                case XML_ELEMENT_NODE:
                    // iterate through children element nodes
                    $this->reworkDom( $nodeChild, $level + 1);
                case XML_TEXT_NODE:
                case XML_CDATA_SECTION_NODE:
                    // do nothing with text, cdata
                case XML_COMMENT_NODE:
                    // ensure comments to remove - sign also follows the w3c guideline
                    $nodeChild->nodeValue = str_replace("-","_",$nodeChild->nodeValue);
                case XML_DOCUMENT_TYPE_NODE:  // 10: needs to be removed
                case XML_PI_NODE: // 7: remove PI
                    $node->removeChild( $nodeChild );
                    $nodeChild = null; // make null to test later
                case XML_DOCUMENT_NODE:
                    // should not appear as it's always the root, just to be complete
                    // however generate exception!
                case XML_HTML_DOCUMENT_NODE:
                    // should not appear as it's always the root, just to be complete
                    // however generate exception!
                    throw new exception("Engine: reworkDom type not declared [".$nodeChild->nodeType. "]");
            $nodeChild = $nodeNextChild;
        } ;

Now this also allows to add more html pieces into one XML which I needed to use myself. In general it can be used like this:

    $dom=new DOMDocument('1.0', 'UTF-8');

$n=$dom->appendChild($dom->createElement('info')); // make a root element

if( $valueXml=tryToXml($dom,$c) ) {
    echo '<pre/>'. htmlentities($dom->saveXml($n)). '</pre>';

In this example '<p>test<font>two</p>' will nicely be outputed in well formed XML as '<info><p>test<font>two</font></p></info>'. The info root tag is added as it will also allow to convert '<p>one</p><p>two</p>' which is not XML as it has not one root element. However if you html does for sure have one root element then the extra root <info> tag can be skipped.

With this I'm getting real nice XML out of unstructured and even corrupted HTML!

I hope it's a bit clear and might contribute to other people to use it.

Using ResourceManager

The quick and dirty way to check what string you need it to look at the generated .resources files.

Your .resources are generated in the resources projects obj/Debug directory. (if not right click on .resx file in solution explorer and hit 'Run Custom Tool' to generate the .resources files)

Navigate to this directory and have a look at the filenames. You should see a file ending in XYZ.resources. Copy that filename and remove the trailing .resources and that is the file you should be loading.

For example in my obj/Bin directory I have the file:


If the resource files are in the same Class library/Application I would use the following C#

ResourceManager RM = new ResourceManager("MyLocalisation.Properties.Resources", Assembly.GetExecutingAssembly());

However, as it sounds like you are using the resources file from a separate Class library/Application you probably want

Assembly localisationAssembly = Assembly.Load("MyLocalisation");
ResourceManager RM =  new ResourceManager("MyLocalisation.Properties.Resources", localisationAssembly);

UIScrollView scroll to bottom programmatically

I found that contentSize doesn't really reflect the actual size of the text, so when trying to scroll to the bottom, it will be a little bit off. The best way to determine the actual content size is actually to use the NSLayoutManager's usedRectForTextContainer: method:

UITextView *textView;
CGSize textSize = [textView.layoutManager usedRectForTextContainer:textView.textContainer].size;

To determine how much text actually is shown in the UITextView, you can calculate it by subtracting the text container insets from the frame height.

UITextView *textView;
UIEdgeInsets textInsets = textView.textContainerInset;
CGFloat textViewHeight = textView.frame.size.height - - textInsets.bottom;

Then it becomes easy to scroll:

// if you want scroll animation, use contentOffset
UITextView *textView;
textView.contentOffset = CGPointMake(textView.contentOffset.x, textSize - textViewHeight);

// if you don't want scroll animation
CGRect scrollBounds = textView.bounds;
scrollBounds.origin = CGPointMake(textView.contentOffset.x, textSize - textViewHeight);
textView.bounds = scrollBounds;

Some numbers for reference on what the different sizes represent for an empty UITextView.

textView.frame.size = (width=246, height=50)
textSize = (width=10, height=16.701999999999998)
textView.contentSize = (width=246, height=33)
textView.textContainerInset = (top=8, left=0, bottom=8, right=0)

Android Emulator: Installation error: INSTALL_FAILED_VERSION_DOWNGRADE

First uninstall your application from the emulator:

adb -e uninstall

Then try to install the application again.

Best HTML5 markup for sidebar

Based on this HTML5 Doctor diagram, I'm thinking this may be the best markup:

<aside class="sidebar">
    <article id="widget_1" class="widget">...</article>
    <article id="widget_2" class="widget">...</article>
    <article id="widget_3" class="widget">...</article>
</aside> <!-- end .sidebar -->

I think it's clear that <aside> is the appropriate element as long as it's outside the main <article> element.

Now, I'm thinking that <article> is also appropriate for each widget in the aside. In the words of the W3C:

The article element represents a self-contained composition in a document, page, application, or site and that is, in principle, independently distributable or reusable, e.g. in syndication. This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content.

Android and Facebook share intent

In Lollipop (21), you can use Intent.EXTRA_REPLACEMENT_EXTRAS to override the intent for Facebook specifically (and specify a link only)

private void doShareLink(String text, String link) {
  Intent shareIntent = new Intent(Intent.ACTION_SEND);
  Intent chooserIntent = Intent.createChooser(shareIntent, getString(R.string.share_via));

  // for 21+, we can use EXTRA_REPLACEMENT_EXTRAS to support the specific case of Facebook
  // (only supports a link)
  // >=21: facebook=link, other=text+link
  // <=20: all=link
    shareIntent.putExtra(Intent.EXTRA_TEXT, text + " " + link);
    Bundle facebookBundle = new Bundle();
    facebookBundle.putString(Intent.EXTRA_TEXT, link);
    Bundle replacement = new Bundle();
    replacement.putBundle("com.facebook.katana", facebookBundle);
    chooserIntent.putExtra(Intent.EXTRA_REPLACEMENT_EXTRAS, replacement);
  } else {
    shareIntent.putExtra(Intent.EXTRA_TEXT, link);


Where does application data file actually stored on android device?

This is a simple way to identify the application related storage paths of a particular app.


  1. Have the android device connected to your mac or android emulator open
  2. Open the terminal
  3. adb shell
  4. find .

The "find ." command will list all the files with their paths in the terminal.

./apex/[email protected]
./apex/[email protected]
./apex/[email protected]

After this, just search for your app with the bundle identifier and you can use adb pull command to download the files to your local directory.

Python __call__ special method practical example

I just stumbled upon a usage of __call__() in concert with __getattr__() which I think is beautiful. It allows you to hide multiple levels of a JSON/HTTP/(however_serialized) API inside an object.

The __getattr__() part takes care of iteratively returning a modified instance of the same class, filling in one more attribute at a time. Then, after all information has been exhausted, __call__() takes over with whatever arguments you passed in.

Using this model, you can for example make a call like api.v2.volumes.ssd.update(size=20), which ends up in a PUT request to https://some.tld/api/v2/volumes/ssd/update.

The particular code is a block storage driver for a certain volume backend in OpenStack, you can check it out here:

EDIT: Updated the link to point to master revision.

iOS: UIButton resize according to text length

Swift 4.2

Thank god, this solved. After setting a text to the button, you can retrieve intrinsicContentSize which is the natural size from an UIView (the official document is here). For UIButton, you can use it like below.


For your information, I adjusted the width to make it look properly.

button.frame = CGRect(fx: xOffset, y: 0.0, width: button.intrinsicContentSize.width + 18, height: 40)


UIButtons with intrinsicContentSize


How to get first item from a java.util.Set?

As, you mentioned pContext.getParent().getPropertyValue return Set. You can convert Set to List to get the first element. Just change your code like:

 Set<String> siteIdSet = (Set<String>) pContext.getParent().getPropertyValue(..);
 List<String> siteIdList=new ArrayList<>(siteIdSet);

 String firstItem=siteIdList.get(0);

Split (explode) pandas dataframe string entry to separate rows


import pandas as pd
import numpy as np

def explode_str(df, col, sep):
    s = df[col]
    i = np.arange(len(s)).repeat(s.str.count(sep) + 1)
    return df.iloc[i].assign(**{col: sep.join(s).split(sep)})

def explode_list(df, col):
    s = df[col]
    i = np.arange(len(s)).repeat(s.str.len())
    return df.iloc[i].assign(**{col: np.concatenate(s)})


explode_str(a, 'var1', ',')

  var1  var2
0    a     1
0    b     1
0    c     1
1    d     2
1    e     2
1    f     2

Let's create a new dataframe d that has lists

d = a.assign(var1=lambda d: d.var1.str.split(','))

explode_list(d, 'var1')

  var1  var2
0    a     1
0    b     1
0    c     1
1    d     2
1    e     2
1    f     2

General Comments

I'll use np.arange with repeat to produce dataframe index positions that I can use with iloc.


Why don't I use loc?

Because the index may not be unique and using loc will return every row that matches a queried index.

Why don't you use the values attribute and slice that?

When calling values, if the entirety of the the dataframe is in one cohesive "block", Pandas will return a view of the array that is the "block". Otherwise Pandas will have to cobble together a new array. When cobbling, that array must be of a uniform dtype. Often that means returning an array with dtype that is object. By using iloc instead of slicing the values attribute, I alleviate myself from having to deal with that.

Why do you use assign?

When I use assign using the same column name that I'm exploding, I overwrite the existing column and maintain its position in the dataframe.

Why are the index values repeat?

By virtue of using iloc on repeated positions, the resulting index shows the same repeated pattern. One repeat for each element the list or string.
This can be reset with reset_index(drop=True)

For Strings

I don't want to have to split the strings prematurely. So instead I count the occurrences of the sep argument assuming that if I were to split, the length of the resulting list would be one more than the number of separators.

I then use that sep to join the strings then split.

def explode_str(df, col, sep):
    s = df[col]
    i = np.arange(len(s)).repeat(s.str.count(sep) + 1)
    return df.iloc[i].assign(**{col: sep.join(s).split(sep)})

For Lists

Similar as for strings except I don't need to count occurrences of sep because its already split.

I use Numpy's concatenate to jam the lists together.

import pandas as pd
import numpy as np

def explode_list(df, col):
    s = df[col]
    i = np.arange(len(s)).repeat(s.str.len())
    return df.iloc[i].assign(**{col: np.concatenate(s)})

How to manually install a pypi module without pip/easy_install?

To further explain Sheena's answer, I needed to have setup-tools installed as a dependency of another tool e.g. more-itertools.


Click the Clone or download button and choose your method. I placed these into a dev/py/libs directory in my user home directory. It does not matter where they are saved, because they will not be installed there.

Installing setup-tools

You will need to run the following inside the setup-tools directory.

python install

General dependencies installation

Now you can navigate to the more-itertools direcotry and install it as normal.

  1. Download the package
  2. Unpackage it if it's an archive
  3. Navigate (cd ...) into the directory containing
  4. If there are any installation instructions contained in the documentation contained herein, read and follow the instructions OTHERWISE
  5. Type in: python install

Getting current date and time in JavaScript

Its simple and superb

 $(document).ready(function () { _x000D_
            var fpsOut = document.getElementById('myTime');_x000D_
            setInterval(function () {_x000D_
                var d = new Date(); _x000D_
                fpsOut.innerHTML = d;_x000D_
            }, 1000);_x000D_
<script src=""></script>_x000D_
<div id="myTime"></div>

please find the below fiddler for the example

How to correctly get image from 'Resources' folder in NetBeans

Thanks, Valter Henrique, with your tip i managed to realise, that i simply entered incorrect path to this image. In one of my tries i use

    String pathToImageSortBy = "resources/testDataIcons/filling.png";
    ImageIcon SortByIcon = new ImageIcon(getClass().getClassLoader().getResource(pathToImageSortBy));

But correct way was use name of my project in path to resource

String pathToImageSortBy = "nameOfProject/resources/testDataIcons/filling.png";
ImageIcon SortByIcon = new ImageIcon(getClass().getClassLoader().getResource(pathToImageSortBy));

Error message Strict standards: Non-static method should not be called statically in php

use className->function(); instead className::function() ;

Check if a varchar is a number (TSQL)

Do not forget to exclude carriage returns from your data !!!

as in:

  , CASE WHEN TRIM(REPLACE([MyVal], char(13) + char(10), '')) not like '%[^0-9]%' and RTRIM(REPLACE([MyVal], char(13) + char(10), '')) not like '.' and isnumeric(REPLACE([MyVal], char(13) + char(10), '')) = 1 THEN 'my number: ' +  [MyVal]
             ELSE ISNULL(Cast([MyVal] AS VARCHAR(8000)), '')
        END AS 'MyVal'
FROM MyTable

Inserting data into a MySQL table using VB.NET

After instantiating the connection, open it.

  SQLConnection = New MySqlConnection()
  SQLConnection.ConnectionString = connectionString

Also, avoid building SQL statements by just appending strings. It's better if you use parameters, that way you win on performance, your program is not prone to SQL injection attacks and your program is more stable. For example:

 str_carSql = "insert into members_car 
               (car_id, member_id, model, color, chassis_id, plate_number, code) 

And then you do this:

' And so on... 

Then you call:


Sort array of objects by single key with date value

Just another, more mathematical, way of doing the same thing but shorter:

arr.sort(function(a, b){
    var diff = new Date(a.updated_at) - new Date(b.updated_at);
    return diff/(Math.abs(diff)||1);

or in the slick lambda arrow style:

arr.sort((a, b) => {
    var diff = new Date(a.updated_at) - new Date(b.updated_at);
    return diff/(Math.abs(diff)||1);

This method can be done with any numeric input

How to set background color in jquery

$(this).css('background-color', 'red');

Create HTML table using Javascript

This beautiful code here creates a table with each td having array values. Not my code, but it helped me!

var rows = 6, cols = 7;

for(var i = 0; i < rows; i++) {
  for(var j = 0; j < cols; j++) {
    $('table').find('tr').eq(i).find('td').eq(j).attr('data-row', i).attr('data-col', j);

Unable to import path from django.urls

As error shows that path can not be imported.

enter image description here

So here we will use the url instead of path as shown below:-

first import the url package then replace the path with url

from django.conf.urls import url
urlpatterns = [

for more information you can take the reference of this link.

Pass in an array of Deferreds to $.when()

You can apply the when method to your array:

var arr = [ /* Deferred objects */ ];

$.when.apply($, arr);

How do you work with an array of jQuery Deferreds?

Java 8 forEach with index

Since you are iterating over an indexable collection (lists, etc.), I presume that you can then just iterate with the indices of the elements:

IntStream.range(0, params.size())
  .forEach(idx ->

The resulting code is similar to iterating a list with the classic i++-style for loop, except with easier parallelizability (assuming, of course, that concurrent read-only access to params is safe).

Android - how to replace part of a string by another string?


I noticed that you commented in 2011 but i thought i should post this answer anyway, in case anyone needs to "replace the original string" and runs into this answer ..

Im using a EditText as an example


 EditText textbox = (EditText) findViewById(;


 String oldText = "hello"
 String newText = "Hi";      
 String textBoxText = textbox.getText().toString();


String returnedString = textBoxText.replace( oldText, newText );



This is untested, but it's just an example of using the returned string to replace the original layouts string with setText() !

Obviously this example requires that you have a EditText with the ID set to your_textboxID

Convert an integer to an array of digits

You can just do:

char[] digits = string.toCharArray();

And then you can evaluate the chars as integers.

For example:

char[] digits = "12345".toCharArray();
int digit = Character.getNumericValue(digits[0]);
System.out.println(digit); // Prints 1

AngularJS view not updating on model change

setTimout executes outside of angular. You need to use $timeout service for this to work:

var app = angular.module('test', []);

    app.controller('TestCtrl', function ($scope, $timeout) {
       $scope.testValue = 0;

        $timeout(function() {
        }, 500);

The reason is that two-way binding in angular uses dirty checking. This is a good article to read about angular's dirty checking. $scope.$apply() kicks off a $digest cycle. This will apply the binding. $timeout handles the $apply for you so it is the recommended service to use when using timeouts.

Essentially, binding happens during the $digest cycle (if the value is seen to be different).

Perform Button click event when user press Enter key in Textbox

Codeproject has a complete solution for this:

and like the article says: "decide which solution best fits your needs"

=================== EDITED ANSWER ============================

The link mentioned above, talks about two ways of capturing the "Enter Key" event:

Javascript (bind the onKeyPress event to the object and create a javascript function to check which key was pressed and do your logic)

_Page_Load in code behind:_

 //Add the javascript so we know where we want the enter key press to go
if (!IsPostBack)
                   "doClick('" + btnSearch.ClientID + "',event)");
                  "doClick('" + btnSearch.ClientID + "',event)");

Javascript code:

<SCRIPT type=text/javascript>
    function doClick(buttonName,e)
        //the purpose of this function is to allow the enter key to 
        //point to the correct button to click.
        var key;

              key = window.event.keyCode;     //IE
              key = e.which;     //firefox

        if (key == 13)
            //Get the button the user wants to have clicked
            var btn = document.getElementById(buttonName);
            if (btn != null)
            { //If we find the button click it
                event.keyCode = 0

Panel Control

<asp:Panel ID="panSearch" runat="server" DefaultButton="btnSearch2" Width="100%" >
    <asp:TextBox ID="txtboxFirstName2" runat="server" ></asp:TextBox>


Notice that the Panel tag has a property called DefaultButton. You set this property to the button ID of the button you want to be clicked on an Enter key press event. So any text box inside of the Panel will direct its Enter key press to the button set in the DefaultButton property of the Panel

Search for value in DataGridView in a column

Why don't you build a DataTable first then assign it to the DataGridView as DataSource:

DataTable table4DataSource=new DataTable();



(add your rows, manually, in a circle or via a DataReader from a database table) (assign the datasource)

dtGrdViewGrid.DataSource = table4DataSource;

and then use:

(dtGrdViewGrid.DataSource as DataTable).DefaultView.RowFilter = "col00 = '" + textBoxSearch.Text+ "'";

You can even put this piece of code within your textbox_textchange event and your filtered values will be showing as you write.

Cannot read property 'getContext' of null, using canvas

Put your JavaScript code after your tag <canvas></canvas>

TypeError: 'DataFrame' object is not callable

It seems you need DataFrame.var:

Normalized by N-1 by default. This can be changed using the ddof argument

var1 = credit_card.var()


#random dataframe
credit_card = pd.DataFrame(np.random.randint(10, size=(5,5)), columns=list('ABCDE'))
print (credit_card)
   A  B  C  D  E
0  8  8  3  7  7
1  0  4  2  5  2
2  2  2  1  0  8
3  4  0  9  6  2
4  4  1  5  3  4

var1 = credit_card.var()
print (var1)
A     8.8
B    10.0
C    10.0
D     7.7
E     7.8
dtype: float64

var2 = credit_card.var(axis=1)
print (var2)
0     4.3
1     3.8
2     9.8
3    12.2
4     2.3
dtype: float64

If need numpy solutions with numpy.var:

print (np.var(credit_card.values, axis=0))
[ 7.04  8.    8.    6.16  6.24]

print (np.var(credit_card.values, axis=1))
[ 3.44  3.04  7.84  9.76  1.84]

Differences are because by default ddof=1 in pandas, but you can change it to 0:

var1 = credit_card.var(ddof=0)
print (var1)
A    7.04
B    8.00
C    8.00
D    6.16
E    6.24
dtype: float64

var2 = credit_card.var(ddof=0, axis=1)
print (var2)
0    3.44
1    3.04
2    7.84
3    9.76
4    1.84
dtype: float64

What is the best way to use a HashMap in C++?

Here's a more complete and flexible example that doesn't omit necessary includes to generate compilation errors:

#include <iostream>
#include <unordered_map>

class Hashtable {
    std::unordered_map<const void *, const void *> htmap;

    void put(const void *key, const void *value) {
            htmap[key] = value;

    const void *get(const void *key) {
            return htmap[key];


int main() {
    Hashtable ht;
    ht.put("Bob", "Dylan");
    int one = 1;
    ht.put("one", &one);
    std::cout << (char *)ht.get("Bob") << "; " << *(int *)ht.get("one");

Still not particularly useful for keys, unless they are predefined as pointers, because a matching value won't do! (However, since I normally use strings for keys, substituting "string" for "const void *" in the declaration of the key should resolve this problem.)

"Could not find acceptable representation" using spring-boot-starter-web

I had the same exception. The problem was, that I used the annotation


instead of


jQuery Ajax error handling, show custom exception messages

This is probably caused by the JSON field names not having quotation marks.

Change the JSON structure from:




Pandas "Can only compare identically-labeled DataFrame objects" error

Here's a small example to demonstrate this (which only applied to DataFrames, not Series, until Pandas 0.19 where it applies to both):

In [1]: df1 = pd.DataFrame([[1, 2], [3, 4]])

In [2]: df2 = pd.DataFrame([[3, 4], [1, 2]], index=[1, 0])

In [3]: df1 == df2
Exception: Can only compare identically-labeled DataFrame objects

One solution is to sort the index first (Note: some functions require sorted indexes):

In [4]: df2.sort_index(inplace=True)

In [5]: df1 == df2
      0     1
0  True  True
1  True  True

Note: == is also sensitive to the order of columns, so you may have to use sort_index(axis=1):

In [11]: df1.sort_index().sort_index(axis=1) == df2.sort_index().sort_index(axis=1)
      0     1
0  True  True
1  True  True

Note: This can still raise (if the index/columns aren't identically labelled after sorting).

Undefined behavior and sequence points

C++98 and C++03

This answer is for the older versions of the C++ standard. The C++11 and C++14 versions of the standard do not formally contain 'sequence points'; operations are 'sequenced before' or 'unsequenced' or 'indeterminately sequenced' instead. The net effect is essentially the same, but the terminology is different.

Disclaimer : Okay. This answer is a bit long. So have patience while reading it. If you already know these things, reading them again won't make you crazy.

Pre-requisites : An elementary knowledge of C++ Standard

What are Sequence Points?

The Standard says

At certain specified points in the execution sequence called sequence points, all side effects of previous evaluations shall be complete and no side effects of subsequent evaluations shall have taken place. (§1.9/7)

Side effects? What are side effects?

Evaluation of an expression produces something and if in addition there is a change in the state of the execution environment it is said that the expression (its evaluation) has some side effect(s).

For example:

int x = y++; //where y is also an int

In addition to the initialization operation the value of y gets changed due to the side effect of ++ operator.

So far so good. Moving on to sequence points. An alternation definition of seq-points given by the comp.lang.c author Steve Summit:

Sequence point is a point in time at which the dust has settled and all side effects which have been seen so far are guaranteed to be complete.

What are the common sequence points listed in the C++ Standard ?

Those are:

  • at the end of the evaluation of full expression (§1.9/16) (A full-expression is an expression that is not a subexpression of another expression.)1

    Example :

    int a = 5; // ; is a sequence point here
  • in the evaluation of each of the following expressions after the evaluation of the first expression (§1.9/18) 2

    • a && b (§5.14)
    • a || b (§5.15)
    • a ? b : c (§5.16)
    • a , b (§5.18) (here a , b is a comma operator; in func(a,a++) , is not a comma operator, it's merely a separator between the arguments a and a++. Thus the behaviour is undefined in that case (if a is considered to be a primitive type))
  • at a function call (whether or not the function is inline), after the evaluation of all function arguments (if any) which takes place before execution of any expressions or statements in the function body (§1.9/17).

1 : Note : the evaluation of a full-expression can include the evaluation of subexpressions that are not lexically part of the full-expression. For example, subexpressions involved in evaluating default argument expressions (8.3.6) are considered to be created in the expression that calls the function, not the expression that defines the default argument

2 : The operators indicated are the built-in operators, as described in clause 5. When one of these operators is overloaded (clause 13) in a valid context, thus designating a user-defined operator function, the expression designates a function invocation and the operands form an argument list, without an implied sequence point between them.

What is Undefined Behaviour?

The Standard defines Undefined Behaviour in Section §1.3.12 as

behavior, such as might arise upon use of an erroneous program construct or erroneous data, for which this International Standard imposes no requirements 3.

Undefined behavior may also be expected when this International Standard omits the description of any explicit definition of behavior.

3 : permissible undefined behavior ranges from ignoring the situation completely with unpredictable results, to behaving during translation or program execution in a documented manner characteristic of the environment (with or with- out the issuance of a diagnostic message), to terminating a translation or execution (with the issuance of a diagnostic message).

In short, undefined behaviour means anything can happen from daemons flying out of your nose to your girlfriend getting pregnant.

What is the relation between Undefined Behaviour and Sequence Points?

Before I get into that you must know the difference(s) between Undefined Behaviour, Unspecified Behaviour and Implementation Defined Behaviour.

You must also know that the order of evaluation of operands of individual operators and subexpressions of individual expressions, and the order in which side effects take place, is unspecified.

For example:

int x = 5, y = 6;

int z = x++ + y++; //it is unspecified whether x++ or y++ will be evaluated first.

Another example here.

Now the Standard in §5/4 says

  • 1) Between the previous and next sequence point a scalar object shall have its stored value modified at most once by the evaluation of an expression.

What does it mean?

Informally it means that between two sequence points a variable must not be modified more than once. In an expression statement, the next sequence point is usually at the terminating semicolon, and the previous sequence point is at the end of the previous statement. An expression may also contain intermediate sequence points.

From the above sentence the following expressions invoke Undefined Behaviour:

i++ * ++i;   // UB, i is modified more than once btw two SPs
i = ++i;     // UB, same as above
++i = 2;     // UB, same as above
i = ++i + 1; // UB, same as above
++++++i;     // UB, parsed as (++(++(++i)))

i = (i, ++i, ++i); // UB, there's no SP between `++i` (right most) and assignment to `i` (`i` is modified more than once btw two SPs)

But the following expressions are fine:

i = (i, ++i, 1) + 1; // well defined (AFAIK)
i = (++i, i++, i);   // well defined 
int j = i;
j = (++i, i++, j*i); // well defined

  • 2) Furthermore, the prior value shall be accessed only to determine the value to be stored.

What does it mean? It means if an object is written to within a full expression, any and all accesses to it within the same expression must be directly involved in the computation of the value to be written.

For example in i = i + 1 all the access of i (in L.H.S and in R.H.S) are directly involved in computation of the value to be written. So it is fine.

This rule effectively constrains legal expressions to those in which the accesses demonstrably precede the modification.

Example 1:

std::printf("%d %d", i,++i); // invokes Undefined Behaviour because of Rule no 2

Example 2:

a[i] = i++ // or a[++i] = i or a[i++] = ++i etc

is disallowed because one of the accesses of i (the one in a[i]) has nothing to do with the value which ends up being stored in i (which happens over in i++), and so there's no good way to define--either for our understanding or the compiler's--whether the access should take place before or after the incremented value is stored. So the behaviour is undefined.

Example 3 :

int x = i + i++ ;// Similar to above

Follow up answer for C++11 here.

How much data / information can we save / store in a QR code?

QR codes have three parameters: Datatype, size (number of 'pixels') and error correction level. How much information can be stored there also depends on these parameters. For example the lower the error correction level, the more information that can be stored, but the harder the code is to recognize for readers.

The maximum size and the lowest error correction give the following values:
Numeric only Max. 7,089 characters
Alphanumeric Max. 4,296 characters
Binary/byte Max. 2,953 characters (8-bit bytes)

Log.INFO vs. Log.DEBUG

Also remember that all info(), error(), and debug() logging calls provide internal documentation within any application.

Image steganography that could survive jpeg compression

Quite a few applications seem to implement Steganography on JPEG, so it's feasible:

Here's an article regarding a relevant algorithm (PM1) to get you started:

Transactions in .net

There are 2 main kinds of transactions; connection transactions and ambient transactions. A connection transaction (such as SqlTransaction) is tied directly to the db connection (such as SqlConnection), which means that you have to keep passing the connection around - OK in some cases, but doesn't allow "create/use/release" usage, and doesn't allow cross-db work. An example (formatted for space):

using (IDbTransaction tran = conn.BeginTransaction()) {
    try {
        // your code
    }  catch {

Not too messy, but limited to our connection "conn". If we want to call out to different methods, we now need to pass "conn" around.

The alternative is an ambient transaction; new in .NET 2.0, the TransactionScope object (System.Transactions.dll) allows use over a range of operations (suitable providers will automatically enlist in the ambient transaction). This makes it easy to retro-fit into existing (non-transactional) code, and to talk to multiple providers (although DTC will get involved if you talk to more than one).

For example:

using(TransactionScope tran = new TransactionScope()) {

Note here that the two methods can handle their own connections (open/use/close/dispose), yet they will silently become part of the ambient transaction without us having to pass anything in.

If your code errors, Dispose() will be called without Complete(), so it will be rolled back. The expected nesting etc is supported, although you can't roll-back an inner transaction yet complete the outer transaction: if anybody is unhappy, the transaction is aborted.

The other advantage of TransactionScope is that it isn't tied just to databases; any transaction-aware provider can use it. WCF, for example. Or there are even some TransactionScope-compatible object models around (i.e. .NET classes with rollback capability - perhaps easier than a memento, although I've never used this approach myself).

All in all, a very, very useful object.

Some caveats:

  • On SQL Server 2000, a TransactionScope will go to DTC immediately; this is fixed in SQL Server 2005 and above, it can use the LTM (much less overhead) until you talk to 2 sources etc, when it is elevated to DTC.
  • There is a glitch that means you might need to tweak your connection string

What is key=lambda

In Python, lambda is a keyword used to define anonymous functions(functions with no name) and that's why they are known as lambda functions.

Basically it is used for defining anonymous functions that can/can't take argument(s) and returns value of data/expression. Let's see an example.

>>> # Defining a lambda function that takes 2 parameters(as integer) and returns their sum
>>> lambda num1, num2: num1 + num2 
<function <lambda> at 0x1004b5de8>
>>> # Let's store the returned value in variable & call it(1st way to call)
>>> addition = lambda num1, num2: num1 + num2
>>> addition(62, 5)
>>> addition(1700, 29)
>>> # Let's call it in other way(2nd way to call, one line call )
>>> (lambda num1, num2: num1 + num2)(120, 1)
>>> (lambda num1, num2: num1 + num2)(-68, 2)
>>> (lambda num1, num2: num1 + num2)(-68, 2**3)

Now let me give an answer of your 2nd question. The 1st answer is also great. This is my own way to explain with another example.

Suppose we have a list of items(integers and strings with numeric contents) as follows,

nums = ["2", 1, 3, 4, "5", "8", "-1", "-10"]

and I want to sort it using sorted() function, lets see what happens.

>>> nums = ["2", 1, 3, 4, "5", "8", "-1", "-10"]
>>> sorted(nums)
[1, 3, 4, '-1', '-10', '2', '5', '8']

It didn't give me what I expected as I wanted like below,

['-10', '-1', 1, '2', 3, 4, '5', '8']

It means we need some strategy(so that sorted could treat our string items as an ints) to achieve this. This is why the key keyword argument is used. Please look at the below one.

>>> nums = ["2", 1, 3, 4, "5", "8", "-1", "-10"]
>>> sorted(nums, key=int)
['-10', '-1', 1, '2', 3, 4, '5', '8']

Lets use lambda function as a value of key

>>> names = ["Rishikesh", "aman", "Ajay", "Hemkesh", "sandeep", "Darshan", "Virendra", "Shwetabh"]
>>> names2 = sorted(names)
>>> names2
['Ajay', 'Darshan', 'Hemkesh', 'Rishikesh', 'Shwetabh', 'Virendra', 'aman', 'sandeep']
>>> # But I don't want this o/p(here our intention is to treat 'a' same as 'A')
>>> names3 = sorted(names, key=lambda name:name.lower())
>>> names3
['Ajay', 'aman', 'Darshan', 'Hemkesh', 'Rishikesh', 'sandeep', 'Shwetabh', 'Virendra']

You can define your own function(callable) and provide it as value of key.

Dear programers, I have written the below code for you, just try to understand it and comment your explanation. I would be glad to see your explanation(it's simple).

>>> def validator(item):
...     try:
...         return int(item)
...     except:
...         return 0
>>> sorted(['gurmit', "0", 5, 2, 1, "front", -2, "great"], key=validator)
[-2, 'gurmit', '0', 'front', 'great', 1, 2, 5]

I hope it would be useful.

How to parse/format dates with LocalDateTime? (Java 8)

All the answers are good. The java8+ have these patterns for parsing and formatting timezone: V, z, O, X, x, Z.

Here's they are, for parsing, according to rules from the documentation :

   Symbol  Meaning                     Presentation      Examples
   ------  -------                     ------------      -------
   V       time-zone ID                zone-id           America/Los_Angeles; Z; -08:30
   z       time-zone name              zone-name         Pacific Standard Time; PST
   O       localized zone-offset       offset-O          GMT+8; GMT+08:00; UTC-08:00;
   X       zone-offset 'Z' for zero    offset-X          Z; -08; -0830; -08:30; -083015; -08:30:15;
   x       zone-offset                 offset-x          +0000; -08; -0830; -08:30; -083015; -08:30:15;
   Z       zone-offset                 offset-Z          +0000; -0800; -08:00;

But how about formatting? Here's a sample for a date (assuming ZonedDateTime) that show these patters behavior for different formatting patters:

// The helper function:
static void printInPattern(ZonedDateTime dt, String pattern) {
    System.out.println(pattern + ": " + dt.format(DateTimeFormatter.ofPattern(pattern)));

// The date:
String strDate = "2020-11-03 16:40:44 America/Los_Angeles";
DateTimeFormatter format = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss zzzz");
ZonedDateTime dt = ZonedDateTime.parse(strDate, format);
// 2020-11-03T16:40:44-08:00[America/Los_Angeles]

// Rules:
// printInPattern(dt, "V");     // exception!
printInPattern(dt, "VV");       // America/Los_Angeles
// printInPattern(dt, "VVV");   // exception!
// printInPattern(dt, "VVVV");  // exception!
printInPattern(dt, "z");        // PST
printInPattern(dt, "zz");       // PST
printInPattern(dt, "zzz");      // PST
printInPattern(dt, "zzzz");     // Pacific Standard Time
printInPattern(dt, "O");        // GMT-8
// printInPattern(dt, "OO");    // exception!
// printInPattern(dt, "OO0");   // exception!
printInPattern(dt, "OOOO");     // GMT-08:00
printInPattern(dt, "X");        // -08
printInPattern(dt, "XX");       // -0800
printInPattern(dt, "XXX");      // -08:00
printInPattern(dt, "XXXX");     // -0800
printInPattern(dt, "XXXXX");    // -08:00
printInPattern(dt, "x");        // -08
printInPattern(dt, "xx");       // -0800
printInPattern(dt, "xxx");      // -08:00
printInPattern(dt, "xxxx");     // -0800
printInPattern(dt, "xxxxx");    // -08:00
printInPattern(dt, "Z");        // -0800
printInPattern(dt, "ZZ");       // -0800
printInPattern(dt, "ZZZ");      // -0800
printInPattern(dt, "ZZZZ");     // GMT-08:00
printInPattern(dt, "ZZZZZ");    // -08:00

In the case of positive offset the + sign character is used everywhere(where there is - now) and never omitted.

This well works for new java.time types. If you're about to use these for java.util.Date or java.util.Calendar - not all going to work as those types are broken(and so marked as deprecated, please don't use them)

How do I make a Docker container start automatically on system boot?

1) First of all, you must enable docker service on boot

$ sudo systemctl enable docker

2) Then if you have docker-compose .yml file add restart: always or if you have docker container add restart=always like this:

docker run --restart=always and run docker container

Make sure

If you manually stop a container, its restart policy is ignored until the Docker daemon restarts or the container is manually restarted.

see this restart policy on Docker official page

3) If you want start docker-compose, all of the services run when you reboot your system So you run below command only once

$ docker-compose up -d

Make a div fill up the remaining width

Although a bit late in posting an answer, here is an alternative approach without using margins.

    #divMain { width: 500px; }
    #div1 { width: 100px; float: left; background-color: #fcc; }
    #div2 { overflow:hidden; background-color: #cfc; }
    #div3 { width: 100px; float: right; background-color: #ccf; }

<div id="divMain">
    <div id="div1">
        div 1
    <div id="div3">
        div 3
    <div id="div2">
        div 2<br />bit taller

This method works like magic, but here is an explanation :)\

Fiddle with a similar sample here.

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

A way that I have done this is as follows:

At the python shell:

>>> from cryptography.fernet import Fernet
>>> key = Fernet.generate_key()
>>> print(key)
>>> cipher = Fernet(key)
>>> password = "thepassword".encode('utf-8')
>>> token = cipher.encrypt(password)
>>> print(token)

Then, create a module with the following code:

from cryptography.fernet import Fernet

# you store the key and the token
key = b'B8XBLJDiroM3N2nCBuUlzPL06AmfV4XkPJ5OKsPZbC4='
token = b'gAAAAABe_TUP82q1zMR9SZw1LpawRLHjgNLdUOmW31RApwASzeo4qWSZ52ZBYpSrb1kUeXNFoX0tyhe7kWuudNs2Iy7vUwaY7Q=='

# create a cipher and decrypt when you need your password
cipher = Fernet(key)

mypassword = cipher.decrypt(token).decode('utf-8')

Once you've done this, you can either import mypassword directly or you can import the token and cipher to decrypt as needed.

Obviously, there are some shortcomings to this approach. If someone has both the token and the key (as they would if they have the script), they can decrypt easily. However it does obfuscate, and if you compile the code (with something like Nuitka) at least your password won't appear as plain text in a hex editor.

Error : java.lang.NoSuchMethodError: org.objectweb.asm.ClassWriter.<init>(I)V

You have an incompatibility between the version of ASM required by Hibernate (asm-1.5.3.jar) and the one required by Spring. But, actually, I wonder why you have asm-2.2.3.jar on your classpath (ASM is bundled in spring.jar and spring-core.jar to avoid such problems AFAIK). See HHH-2222.

What's the best three-way merge tool?

Diffuse is an easy to use three-way merge tool. It supports all of the platforms and version control systems you mentioned, and it can compare more than three files at the same time.

enter image description here

How can I inspect element in an Android browser?

Had to debug a site for native Android browser and came here. So I tried weinre on an OS X 10.9 (as weinre server) with Firefox 30.0 (weinre client) and an Android 4.1.2 (target). I'm really, really surprised of the result.

  1. Download and install node runtime from
  2. Install weinre: sudo npm -g install weinre
  3. Find out your current IP address at Settings > Network
  4. Setup a weinre server on your machine: weinre --boundHost YOUR.IP.ADDRESS.HERE
  5. In your browser call: http://YOUR.IP.ADRESS.HERE:8080
  6. You'll see a script snippet, place it into your site: <script src="http://YOUR.IP.ADDRESS.HERE:8080/target/target-script-min.js"></script>
  7. Open the debug client in your local browser: http://YOUR.IP.ADDRESS.HERE:8080/client
  8. Finally on your Android: call the site you want to inspect (the one with the script inside) and see how it appears as "Target" in your local browser. Now you can open "Elements" or whatever you want.

Maybe 8080 isn't your default port. Then in step 4 you have to call weinre --httpPort YOURPORT --boundHost YOUR.IP.ADRESS.HERE.

And I don't remember exactly when it was, maybe somewhere after step 5, I had to accept incoming connections prompt, of course.

Happy debugging

P.S. I'm still overwhelmed how good that works. Even elements-highlighting work

How to use a variable for a key in a JavaScript object literal?

This way also you can achieve desired output

var jsonobj={};_x000D_
var count=0;_x000D_
$(document).on('click','#btnadd', function() {_x000D_
    jsonobj[count]=new Array({ "1"  : $("#txtone").val()},{ "2"  : $("#txttwo").val()});_x000D_
<script src=""></script>_x000D_
<span>value 1</span><input id="txtone" type="text"/>_x000D_
<span>value 2</span><input id="txttwo" type="text"/>_x000D_
<button id="btnadd">Add</button>

How to sort a list of strings numerically?

Try this, it’ll sort the list in-place in descending order (there’s no need to specify a key in this case):


listB = [24, 13, -15, -36, 8, 22, 48, 25, 46, -9]
listC = sorted(listB, reverse=True) # listB remains untouched
print listC


 [48, 46, 25, 24, 22, 13, 8, -9, -15, -36]

How to hide column of DataGridView when using custom DataSource?

I had the same problem

Here is the Solution that might work for you. It worked for me

if (GridView1.Columns.Count > 0)
    GridView1.Columns[0].Visible = false;
    GridView1.HeaderRow.Cells[0].Visible = false;
    foreach (GridViewRow gvr in GridView1.Rows)
        gvr.Cells[0].Visible = false;

How to check empty object in angular 2 template using *ngIf

This worked for me:

Check the length property and use ? to avoid undefined errors.

So your example would be:

<div class="comeBack_up" *ngIf="previous_info?.length">


The length property only exists on arrays. Since the question was about objects, use Object.getOwnPropertyNames(obj) to get an array of properties from the object. The example becomes:

<div class="comeBack_up" *ngIf="previous_info  && Object.getOwnPropertyNames(previous_info).length > 0">

The previous_info && is added to check if the object exists. If it evaluates to true the next statement checks if the object has at least on proporty. It does not check whether the property has a value.

SQL Bulk Insert with FIRSTROW parameter skips the following line

Maybe check that the header has the same line-ending as the actual data rows (as specified in ROWTERMINATOR)?

Update: from MSDN:

The FIRSTROW attribute is not intended to skip column headers. Skipping headers is not supported by the BULK INSERT statement. When skipping rows, the SQL Server Database Engine looks only at the field terminators, and does not validate the data in the fields of skipped rows.

AngularJS : Custom filters and ng-repeat

You can call more of 1 function filters in the same ng-repeat filter

<article data-ng-repeat="result in results | filter:search() | filter:filterFn()" class="result">

jquery stop child triggering parent event

Or, rather than having an extra event handler to prevent another handler, you can use the Event Object argument passed to your click event handler to determine whether a child was clicked. target will be the clicked element and currentTarget will be the .header div:

     //Do nothing if .header was not directly clicked
     if( !== e.currentTarget) return;


If REST applications are supposed to be stateless, how do you manage sessions?

The whole concept is different... You don't need to manage sessions if you are trying to implement RESTFul protocol. In that case it is better to do authentication procedure on every request (whereas there is an extra cost to it in terms of performance - hashing password would be a good example. not a big deal...). If you use sessions - how can you distribute load across multiple servers? I bet RESTFul protocol is meant to eliminate sessions whatsoever - you don't really need them... That's why it is called "stateless". Sessions are only required when you cannot store anything other than Cookie on a client side after a reqest has been made (take old, non Javascript/HTML5-supporting browser as an example). In case of "full-featured" RESTFul client it is usually safe to store base64(login:password) on a client side (in memory) until the applictation is still loaded - the application is used to access to the only host and the cookie cannot be compromised by the third party scripts...

I would stronly recommend to disable cookie authentication for RESTFul sevices... check out Basic/Digest Auth - that should be enough for RESTFul based services.

JavaScript code to stop form submission

Use prevent default

Dojo Toolkit

dojo.connect(form, "onsubmit", function(evt) {


$('#form').submit(function (evt) {

Vanilla JavaScript

if (element.addEventListener) {
    element.addEventListener("submit", function(evt) {
    }, true);
else {
    element.attachEvent('onsubmit', function(evt){

Display Yes and No buttons instead of OK and Cancel in Confirm box?

If you switch to the jQuery UI Dialog box, you can initialize the buttons array with the appropriate names like:

  buttons: {
    "Yes": function() {},
    "No": function() {}

Composer Update Laravel

write this command in your terminal :

composer update

Android device is not connected to USB for debugging (Android studio)

I had tried restart the device, and it's work, popup and ask want to trust the mac for debug mode.

How to change Toolbar home icon color

Well there is a more easy way to do this

drawerToggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.open_drawer, R.string.close_drawer);
arrow = drawerToggle.getDrawerArrowDrawable();

And then


PostgreSQL 'NOT IN' and subquery

You could also use a LEFT JOIN and IS NULL condition:

    LEFT JOIN consols ON logs.mac = consols.mac
  consols.mac IS NULL;

An index on the "mac" columns might improve performance.

Git Push error: refusing to update checked out branch

Maybe your remote repo is in the branch which you want to push. You can try to checkout another branch in your remote machine. I did this, than these error disappeared, and I pushed success to my remote repo. Notice that I use ssh to connect my own server instead of

How to append data to a json file?

import jsonlines

object1 = {
               "name": "name1",
               "url": "url1"

object2 = {
               "name": "name2",
               "url": "url2"

# filename.jsonl is the name of the file
with"filename.jsonl", "a") as writer:   # for writing

with'filename.jsonl') as reader:      # for reading
    for obj in reader:

visit for more info

VB.NET: how to prevent user input in a ComboBox

Set the DropDownStyle property of the combobox to DropDownList. This will allow only items in the list to be selected and will not allow any free-form user input.

How to pass arguments within docker-compose?

This can now be done as of docker-compose v2+ as part of the build object;


version: '2'
            context: . #current dir as build context
                var1: 1
                var2: c

See the docker compose docs.

In the above example "var1" and "var2" will be sent to the build environment.

Note: any env variables (specified by using the environment block) which have the same name as args variable(s) will override that variable.

How to call a function within class?

Since these are member functions, call it as a member function on the instance, self.

def isNear(self, p):

Intersect Two Lists in C#

From performance point of view if two lists contain number of elements that differ significantly, you can try such approach (using conditional operator ?:):

1.First you need to declare a converter:

Converter<string, int> del = delegate(string s) { return Int32.Parse(s); };

2.Then you use a conditional operator:

var r = data1.Count > data2.Count ?
 data2.ConvertAll<int>(del).Intersect(data1) :
 data1.Select(v => v.ToString()).Intersect(data2).ToList<string>().ConvertAll<int>(del);

You convert elements of shorter list to match the type of longer list. Imagine an execution speed if your first set contains 1000 elements and second only 10 (or opposite as it doesn't matter) ;-)

As you want to have a result as List, in a last line you convert the result (only result) back to int.

Create Pandas DataFrame from a string

In one line, but first import IO

import pandas as pd
import io   


df = pd.read_csv(  io.StringIO(TESTDATA)  , sep=";")
print ( df )

What event handler to use for ComboBox Item Selected (Selected Item not necessarily changed)

private void OnDropDownClosed(object sender, EventArgs e)
     if (combobox.SelectedItem == null) return;
     // Do actions

Convert time fields to strings in Excel

If you want to show those number values as a time then change the format of the cell to Time.

And if you want to transform it to a text in another cell:


Can I add and remove elements of enumeration at runtime in Java

I needed to do something like this (for unit testing purposes), and I came across this - the EnumBuster:

It allows enum values to be added, removed and restored.

Edit: I've only just started using this, and found that there's some slight changes needed for java 1.5, which I'm currently stuck with:

  • Add array copyOf static helper methods (e.g. take these 1.6 versions:
  • Change EnumBuster.undoStack to a Stack<Memento>
    • In undo(), change undoStack.poll() to undoStack.isEmpty() ? null : undoStack.pop();
  • The string VALUES_FIELD needs to be "ENUM$VALUES" for the java 1.5 enums I've tried so far

CSS rotation cross browser with jquery.animate()

jQuery transit will probably make your life easier if you are dealing with CSS3 animations through jQuery.

EDIT March 2014 (because my advice has constantly been up and down voted since I posted it)

Let me explain why I was initially hinting towards the plugin above:

Updating the DOM on each step (i.e. $.animate ) is not ideal in terms of performance. It works, but will most probably be slower than pure CSS3 transitions or CSS3 animations.

This is mainly because the browser gets a chance to think ahead if you indicate what the transition is going to look like from start to end.

To do so, you can for example create a CSS class for each state of the transition and only use jQuery to toggle the animation state.

This is generally quite neat as you can tweak you animations alongside the rest of your CSS instead of mixing it up with your business logic:

// initial state
.eye {
   -webkit-transform: rotate(45deg);
   -moz-transform: rotate(45deg);
   transform: rotate(45deg);
   // etc.

   // transition settings
   -webkit-transition: -webkit-transform 1s linear 0.2s;
   -moz-transition: -moz-transform 1s linear 0.2s;
   transition: transform 1s linear 0.2s;
   // etc.

// open state {

   transform: rotate(90deg);

// Javascript
$('.eye').on('click', function () { $(this).addClass('open'); });

If any of the transform parameters is dynamic you can of course use the style attribute instead:

$('.eye').on('click', function () { 
        -webkit-transition: '-webkit-transform 1s ease-in',
        -moz-transition: '-moz-transform 1s ease-in',
        // ...

        // note that jQuery will vendor prefix the transform property automatically
        transform: 'rotate(' + (Math.random()*45+45).toFixed(3) + 'deg)'

A lot more detailed information on CSS3 transitions on MDN.

HOWEVER There are a few other things to keep in mind and all this can get a bit tricky if you have complex animations, chaining etc. and jQuery Transit just does all the tricky bits under the hood:

$('.eye').transit({ rotate: '90deg'}); // easy huh ?

How to save and extract session data in codeigniter

First you have load session library.


You can load it in auto load, which I think is better.

To set session


To extract Data


jquery how to use multiple ajax calls one after the end of the other

Place them inside of the success: of the one it relies on.

    url: 'http://www.xxxxxxxxxxxxx',
    data: {name: 'xxxxxx'},
    dataType: 'jsonp',
    success: function(data){

        // do stuff

        // call next ajax function
        $.ajax({ xxx });

How do I check out a remote Git branch?



Other answers do not work with modern Git in my benign case. You might need to pull first if the remote branch is new, but I haven't checked that case.

Does --disable-web-security Work In Chrome Anymore?

If you want to automate this: Kill chrome from task Manager First. In Windows - Right Click (or Shift+right click, in-case of taskbar) on Chrome Icon. Select Properties. In "Target" text-box, add --disable-web-security flag.

So text in text-box should look like

C:\Users\njadhav\AppData\Local\Google\Chrome SxS\Application\chrome.exe" --disable-web-security

Click Ok and launch chrome.

TypeError: 'module' object is not callable

When configuring an console_scripts entrypoint in I found this issue existed when the endpoint was a module or package rather than a function within the module.

Traceback (most recent call last):
   File "/Users/ubuntu/.virtualenvs/virtualenv/bin/mycli", line 11, in <module>
load_entry_point('my-package', 'console_scripts', 'mycli')()
TypeError: 'module' object is not callable

For example

from setuptools import setup
setup (
# ...
    entry_points = {
        'console_scripts': [mycli=package.module.submodule]
# ...

Should have been

from setuptools import setup
setup (
# ...
    entry_points = {
        'console_scripts': [mycli=package.module.submodule:main]
# ...

So that it would refer to a callable function rather than the module itself. It seems to make no difference if the module has a if __name__ == '__main__': block. This will not make the module callable.

Early exit from function?

if you are looking for a script to avoid submitting form when some errors found, this method should work

function verifyData(){
     if (document.MyForm.FormInput.value.length == "") {
          alert("Write something!");
     else {

change the Submit Button type to "button"

<input value="Save" type="button" onClick="verifyData()">

hope this help.

How to get current moment in ISO 8601 format with date, hour, and minute?

I did it in Android using Calendar and SimpleDateFormat. The following method returns a Calendar with the "GMT" TimeZone (This is the universal time zone). Then you can use the Calendar class to set the hour between differents time zones, using the method setTimeZone() of the Calendar class.

private static final String GMT = "GMT";
private static final String DATE_FORMAT_ISO = "yyyyMMdd'T'HHmmss";

public static Calendar isoToCalendar(final String inputDate) {
    Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone(GMT));
    try {
        SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT_ISO, Locale.US);
        Date date = dateFormat.parse(inputDate);
    } catch (ParseException e) {
    return calendar;

REMEMBER: The Date class doesn't know about the TimeZone existence. By this reason, if you debug one date,you always see the date for your current timezone.

PHP check whether property exists in object or class

To check if something exits, you can use the PHP function isset() see This function will check if the variable is set and is not NULL.


  //do something

If you need to check if a property exists in a class, then you can use the build in function property_exists()


if (property_exists('class', $property)) {
    //do something

JQuery - $ is not defined

In my case I was pointing to Google hosted JQuery. It was included properly, but I was on an HTTPS page and calling it via HTTP. Once I fixed the problem (or allowed insecure content), it fired right up.

Creating a very simple 1 username/password login in php

Here is a simple php script for login and a page that can only be accessed by logged in users.


    echo isset($_SESSION['login']);
    if(isset($_SESSION['login'])) {
      header('LOCATION:index.php'); die();
<!DOCTYPE html>
     <meta http-equiv='content-type' content='text/html;charset=utf-8' />
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <link rel="stylesheet" href="">
  <div class="container">
    <h3 class="text-center">Login</h3>
        $username = $_POST['username']; $password = $_POST['password'];
        if($username === 'admin' && $password === 'password'){
          $_SESSION['login'] = true; header('LOCATION:admin.php'); die();
        } {
          echo "<div class='alert alert-danger'>Username and Password do not match.</div>";

    <form action="" method="post">
      <div class="form-group">
        <label for="username">Username:</label>
        <input type="text" class="form-control" id="username" name="username" required>
      <div class="form-group">
        <label for="pwd">Password:</label>
        <input type="password" class="form-control" id="pwd" name="password" required>
      <button type="submit" name="submit" class="btn btn-default">Login</button>

admin.php ( only logged in users can access it )

    if(!isset($_SESSION['login'])) {
        header('LOCATION:login.php'); die();
        <title>Admin Page</title>
        This is admin page view able only by logged in users.

How do I set vertical space between list items?

To apply to an entire list, use

ul.space_list li { margin-bottom: 1em; }

Then, in the html:

<ul class=space_list>

Put search icon near textbox using bootstrap

You can do it in pure CSS using the :after pseudo-element and getting creative with the margins.

Here's an example, using Font Awesome for the search icon:

.search-box-container input {_x000D_
  padding: 5px 20px 5px 5px;_x000D_
.search-box-container:after {_x000D_
    content: "\f002";_x000D_
    font-family: FontAwesome;_x000D_
    margin-left: -25px;_x000D_
    margin-right: 25px;_x000D_
<!-- font awesome -->_x000D_
<link href="" rel="stylesheet"/>_x000D_
<div class="search-box-container">_x000D_
  <input type="text" placeholder="Search..."  />_x000D_

Is there a CSS selector for text nodes?

Text nodes cannot have margins or any other style applied to them, so anything you need style applied to must be in an element. If you want some of the text inside of your element to be styled differently, wrap it in a span or div, for example.

Should you always favor xrange() over range()?

range() returns a list, xrange() returns an xrange object.

xrange() is a bit faster, and a bit more memory efficient. But the gain is not very large.

The extra memory used by a list is of course not just wasted, lists have more functionality (slice, repeat, insert, ...). Exact differences can be found in the documentation. There is no bonehard rule, use what is needed.

Python 3.0 is still in development, but IIRC range() will very similar to xrange() of 2.X and list(range()) can be used to generate lists.

Maven Error: Could not find or load main class

Unless you need the 'maven-assembly-plugin' for reasons other than setting the mainClass, you could use the 'maven-jar-plugin' plugin.


You can see the plugin in practise in the ATLauncher.

The 'mainClass' element should be set to the class that you have the entry point to your program in eg:

package your.package.yourprogram;

public class YourMainClass {

    public static void main(String[] args) {
        System.out.println("Hello World");

Join between tables in two different databases?

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

Just make sure that in the SELECT line you specify which table columns you are using, either by full reference, or by alias. Any of the following will work:

SELECT t1.*,t2.column2
SELECT A.table1.column1, t2.*

Pass C# ASP.NET array to Javascript array

Here is another alternative solution. You can use ClientScriptManager Page.ClientScript.RegisterArrayDeclaration. Here is an example for chart data.

var page = HttpContext.Current.CurrentHandler as Page;

_data = "[Date.UTC(2018, 9, 29, 0, 3), parseFloat(21.84)]
         ,[Date.UTC(2018, 9, 29, 0, 13), parseFloat(21.84)]
         ,[Date.UTC(2018, 9, 29, 0, 23), parseFloat(21.83)]
         ,[Date.UTC(2018, 9, 29, 0, 33), parseFloat(21.83)]";
page.ClientScript.RegisterArrayDeclaration("chartdata0", _data);

This code creates an array on the client side

var chartdata0 = new Array([Date.UTC(2018, 9, 29, 0, 3), parseFloat(21.84)]
             ,[Date.UTC(2018, 9, 29, 0, 13), parseFloat(21.84)]
             ,[Date.UTC(2018, 9, 29, 0, 23), parseFloat(21.83)]
             ,[Date.UTC(2018, 9, 29, 0, 33), parseFloat(21.83)]);

See the following article

This solution has an issue with bigger arrays on chrome 64 browser including "Version 78.0.3904.70 (Official Build) (64-bit)". You may get "Uncaught RangeError: Maximum call stack size exceeded". However it is working with IE11, Microsoft Edge, and FireFox.

Fixed digits after decimal with f-strings

Include the type specifier in your format expression:

>>> a = 10.1234
>>> f'{a:.2f}'

Return JSON response from Flask view

To return a JSON response and set a status code you can use make_response:

from flask import jsonify, make_response

def summary():
    d = make_summary()
    return make_response(jsonify(d), 200)

Inspiration taken from this comment in the Flask issue tracker.

Setting environment variables in Linux using Bash

export VAR=value will set VAR to value. Enclose it in single quotes if you want spaces, like export VAR='my val'. If you want the variable to be interpolated, use double quotes, like export VAR="$MY_OTHER_VAR".

How to check that Request.QueryString has a specific value or not in ASP.NET?

To check for an empty QueryString you should use Request.QueryString.HasKeys property.

To check if the key is present: Request.QueryString.AllKeys.Contains()

Then you can get ist's Value and do any other check you want, such as isNullOrEmpty, etc.