Programs & Examples On #Authsmtp

Strip / trim all strings of a dataframe

If you really want to use regex, then

>>> df.replace('(^\s+|\s+$)', '', regex=True, inplace=True)
>>> df
   0   1
0  a  10
1  c   5

But it should be faster to do it like this:

>>> df[0] = df[0].str.strip()

How can I run a function from a script in command line?

Briefly, no.

You can import all of the functions in the script into your environment with source (help source for details), which will then allow you to call them. This also has the effect of executing the script, so take care.

There is no way to call a function from a shell script as if it were a shared library.

(Mac) -bash: __git_ps1: command not found

I was doing the course on Udacity for git hub and was having this same issue. Here is my final code that make is work correctly.

# Change command prompt
alias __git_ps1="git branch 2>/dev/null | grep '*' | sed 's/* \ .   (.*\)/(\1)/'"

if [ -f ~/.git-completion.bash ]; then
  source ~/.git-completion.bash
  export PS1='[\W]$(__git_ps1 "(%s)"): '

source ~/
# '\u' adds the name of the current user to the prompt
# '\$(__git_ps1)' adds git-related stuff
# '\W' adds the name of the current directory
export PS1="$purple\u$green\$(__git_ps1)$blue \W $ $reset"

It works!

Debugging with command-line parameters in Visual Studio

Even if you do start the executable outside Visual Studio, you can still use the "Attach" command to connect Visual Studio to your already-running executable. This can be useful e.g. when your application is run as a plug-in within another application.

How to call on a function found on another file?

Your sprite is created mid way through the playerSprite function... it also goes out of scope and ceases to exist at the end of that same function. The sprite must be created where you can pass it to playerSprite to initialize it and also where you can pass it to your draw function.

Perhaps declare it above your first while?

How do you remove duplicates from a list whilst preserving order?

from itertools import groupby
[ key for key,_ in groupby(sortedList)]

The list doesn't even have to be sorted, the sufficient condition is that equal values are grouped together.

Edit: I assumed that "preserving order" implies that the list is actually ordered. If this is not the case, then the solution from MizardX is the right one.

Community edit: This is however the most elegant way to "compress duplicate consecutive elements into a single element".

Troubleshooting misplaced .git directory (nothing to commit)

I have faced the same issue with git while working with angular CLI 6.1.2. Angular CLI 6.1.2 automatically initializes .git folder when you create a new angular project using Angular CLI. So when I tried git status - it was not detecting the whole working directory.

I have just deleted the hidden .git folder from my angular working directory and then initialized git repository again with git init. And now, I can see all my files with git status.

How to check if a string starts with one of several prefixes?

if(newStr4.startsWith("Mon") || newStr4.startsWith("Tues") || newStr4.startsWith("Weds") .. etc)

You need to include the whole str.startsWith(otherStr) for each item, since || only works with boolean expressions (true or false).

There are other options if you have a lot of things to check, like regular expressions, but they tend to be slower and more complicated regular expressions are generally harder to read.

An example regular expression for detecting day name abbreviations would be:

if(Pattern.matches("Mon|Tues|Wed|Thurs|Fri", stringToCheck)) {

Waiting until the task finishes

Use DispatchGroups to achieve this. You can either get notified when the group's enter() and leave() calls are balanced:

func myFunction() {
    var a: Int?

    let group = DispatchGroup()

    DispatchQueue.main.async {
        a = 1

    // does not wait. But the code in notify() gets run 
    // after enter() and leave() calls are balanced

    group.notify(queue: .main) {

or you can wait:

func myFunction() {
    var a: Int?

    let group = DispatchGroup()

    // avoid deadlocks by not using .main queue here .qosDefault).async {
        a = 1

    // wait ...

    print(a) // you could also `return a` here

Note: group.wait() blocks the current queue (probably the main queue in your case), so you have to dispatch.async on another queue (like in the above sample code) to avoid a deadlock.

Simplest way to detect keypresses in javascript

Don't over complicate.

  document.addEventListener('keydown', logKey);
    function logKey(e) {
      if (`${e.code}` == "ArrowRight") {
        //code here
          if (`${e.code}` == "ArrowLeft") {
        //code here
          if (`${e.code}` == "ArrowDown") {
        //code here
          if (`${e.code}` == "ArrowUp") {
        //code here

How to convert a PIL Image into a numpy array?

You're not saying how exactly putdata() is not behaving. I'm assuming you're doing

>>> pic.putdata(a)
Traceback (most recent call last):
  File "...blablabla.../PIL/", line 1185, in putdata, scale, offset)
SystemError: new style getargs format but argument is not a tuple

This is because putdata expects a sequence of tuples and you're giving it a numpy array. This

>>> data = list(tuple(pixel) for pixel in pix)
>>> pic.putdata(data)

will work but it is very slow.

As of PIL 1.1.6, the "proper" way to convert between images and numpy arrays is simply

>>> pix = numpy.array(pic)

although the resulting array is in a different format than yours (3-d array or rows/columns/rgb in this case).

Then, after you make your changes to the array, you should be able to do either pic.putdata(pix) or create a new image with Image.fromarray(pix).

ASP.NET MVC5/IIS Express unable to debug - Code Not Running

Delete File C:\Users\congt\Documents\IISExpress

I want to vertical-align text in select box

display: flex;
align-items: center;

Understanding Spring @Autowired usage

Nothing in the example says that the "classes implementing the same interface". MovieCatalog is a type and CustomerPreferenceDao is another type. Spring can easily tell them apart.

In Spring 2.x, wiring of beans mostly happened via bean IDs or names. This is still supported by Spring 3.x but often, you will have one instance of a bean with a certain type - most services are singletons. Creating names for those is tedious. So Spring started to support "autowire by type".

What the examples show is various ways that you can use to inject beans into fields, methods and constructors.

The XML already contains all the information that Spring needs since you have to specify the fully qualified class name in each bean. You need to be a bit careful with interfaces, though:

This autowiring will fail:

 public void prepare( Interface1 bean1, Interface1 bean2 ) { ... }

Since Java doesn't keep the parameter names in the byte code, Spring can't distinguish between the two beans anymore. The fix is to use @Qualifier:

 public void prepare( @Qualifier("bean1") Interface1 bean1,
     @Qualifier("bean2")  Interface1 bean2 ) { ... }

How to Remove the last char of String in C#?

If this is something you need to do a lot in your application, or you need to chain different calls, you can create an extension method:

public static String TrimEnd(this String str, int count)
    return str.Substring(0, str.Length - count);

and call it:

string oldString = "...Hello!";
string newString = oldString.Trim(1); //returns "...Hello"

or chained:

string newString = oldString.Substring(3).Trim(1);  //returns "Hello"

Javascript one line If...else...else if statement

Sure, you can do nested ternary operators but they are hard to read.

var variable = (condition) ? (true block) : ((condition2) ? (true block2) : (else block2))

how to cancel/abort ajax request in axios

Typically you want to cancel the previous ajax request and ignore it's coming response, only when a new ajax request of that instance is started, for this purpose, do the following:

Example: getting some comments from API:

// declare an ajax request's cancelToken (globally)
let ajaxRequest = null; 

function getComments() {

    // cancel  previous ajax if exists
    if (ajaxRequest ) {

    // creates a new token for upcomming ajax (overwrite the previous one)
    ajaxRequest = axios.CancelToken.source();  

    return axios.get('/api/get-comments', { cancelToken: ajaxRequest.token }).then((response) => {
    }).catch(function(err) {
        if (axios.isCancel(err)) {
           console.log('Previous request canceled, new request is send', err.message);
        } else {
               // handle error

Spring Data JPA findOne() change to Optional how to use this?

Indeed, in the latest version of Spring Data, findOne returns an optional. If you want to retrieve the object from the Optional, you can simply use get() on the Optional. First of all though, a repository should return the optional to a service, which then handles the case in which the optional is empty. afterwards, the service should return the object to the controller.

How to call a method with a separate thread in Java?

Create a class that implements the Runnable interface. Put the code you want to run in the run() method - that's the method that you must write to comply to the Runnable interface. In your "main" thread, create a new Thread class, passing the constructor an instance of your Runnable, then call start() on it. start tells the JVM to do the magic to create a new thread, and then call your run method in that new thread.

public class MyRunnable implements Runnable {

    private int var;

    public MyRunnable(int var) {
        this.var = var;

    public void run() {
        // code in the other thread, can reference "var" variable

public class MainThreadClass {
    public static void main(String args[]) {
        MyRunnable myRunnable = new MyRunnable(10);
        Thread t = new Thread(myRunnable)

Take a look at Java's concurrency tutorial to get started.

If your method is going to be called frequently, then it may not be worth creating a new thread each time, as this is an expensive operation. It would probably be best to use a thread pool of some sort. Have a look at Future, Callable, Executor classes in the java.util.concurrent package.

Binding ItemsSource of a ComboBoxColumn in WPF DataGrid

Your ComboBox is trying to bind to bind to GridItem[x].CompanyItems, which doesn't exist.

Your RelativeBinding is close, however it needs to bind to DataContext.CompanyItems because Window.CompanyItems does not exist

setContentView(R.layout.main); error


  1. Right click on your project.

  2. Go to properties.

  3. Select android (second option in the Left panel).

  4. Click "add..." (in library), select your project.

  5. Click ok.

  6. And finally, clean your project.

If this doesn't work, make sure that "android-support-v7-appcompat" is in your Project Explorer.

If it isn't there, you can add it by importing a simple project from: C:/android-sdks\extras\android\support\v7\appcompat

Pandas read_csv low_memory and dtype options

It worked for me with low_memory = False while importing a DataFrame. That is all the change that worked for me:

df = pd.read_csv('export4_16.csv',low_memory=False)

Is there a PowerShell "string does not contain" cmdlet or syntax?

To exclude the lines that contain any of the strings in $arrayOfStringsNotInterestedIn, you should use:

(Get-Content $FileName) -notmatch [String]::Join('|',$arrayofStringsNotInterestedIn)

The code proposed by Chris only works if $arrayofStringsNotInterestedIn contains the full lines you want to exclude.

TextView bold via xml file?

just use


The page cannot be displayed because an internal server error has occurred on server

In my case, setting httpErrors and the like in Web.config did not help to identify the issue.

Instead I did:

  1. Activate "Failed Request Tracing" for the website with the error.
  2. Configured a trace for HTTP errors 350-999 (just in case), although I suspected 500.
  3. Called the erroneous URL again.
  4. Watched in the log folder ("%SystemDrive%\inetpub\logs\FailedReqLogFiles" in my case).
  5. Opened one of the XML files in Internet Explorer.

I then saw an entry with a detailed exception information. In my case it was

\?\C:\Websites\\www\web.config ( 592) :Cannot add duplicate collection entry of type 'mimeMap' with unique key attribute 'fileExtension' set to '.json'

I now was able to resolve it and fix the error. After that I deactivated "Failed Request Tracing" again.

Integrating the ZXing library directly into my Android application

Having issues building with ANT? Keep reading

If ant -f core/build.xml says something like:

Unable to locate tools.jar. Expected to find it in
C:\Program Files\Java\jre6\lib\tools.jar

then set your JAVA_HOME environment variable to the proper java folder. I found tools.jar in my (for Windows):

C:\Program Files\Java\jdk1.6.0_21\lib

so I set my JAVA_HOME to:


the reason for the shorter syntax I found at some site which says:

"It is strongly advised that you choose an installation directory that does not include spaces in the path name (e.g., do NOT install in C:\Program Files). If Java is installed in such a directory, it is critical to set the JAVA_HOME environment variable to a path that does not include spaces (e.g., C:\Progra~1); failure to do this will result in exceptions thrown by some programs that depend on the value of JAVA_HOME."

I then relaunched cmd (important because DOS shell only reads env vars upon launching, so changing an env var will require you to use a new shell to get the updated value)

and finally the ant -f core/build.xml worked.

Convert string[] to int[] in one line of code using LINQ

Given an array you can use the Array.ConvertAll method:

int[] myInts = Array.ConvertAll(arr, s => int.Parse(s));

Thanks to Marc Gravell for pointing out that the lambda can be omitted, yielding a shorter version shown below:

int[] myInts = Array.ConvertAll(arr, int.Parse);

A LINQ solution is similar, except you would need the extra ToArray call to get an array:

int[] myInts = arr.Select(int.Parse).ToArray();

How do I concatenate two lists in Python?

You could use the append() method defined on list objects:

mergedlist =[]
for elem in listone:
for elem in listtwo:

How to force file download with PHP

You can stream download too which will consume significantly less resource. example:

$readableStream = fopen('', 'rb');
$writableStream = fopen('php://output', 'wb');

header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename=""');
stream_copy_to_stream($readableStream, $writableStream);

In the above example, I am downloading a (which was actually the android studio zip on my local machine). php://output is a write-only stream (generally used by echo or print). after that, you just need to set the required headers and call stream_copy_to_stream(source, destination). stream_copy_to_stream() method acts as a pipe which takes the input from the source stream (read stream) and pipes it to the destination stream (write stream) and it also avoid the issue of allowed memory exhausted so you can actually download files that are bigger than your PHP memory_limit.

How to add a reference programmatically

Here is how to get the Guid's programmatically! You can then use these guids/filepaths with an above answer to add the reference!


Sub ListReferencePaths()
'Lists path and GUID (Globally Unique Identifier) for each referenced library.
'Select a reference in Tools > References, then run this code to get GUID etc.
    Dim rw As Long, ref
    With ThisWorkbook.Sheets(1)
        rw = 1
        .Range("A" & rw & ":D" & rw) = Array("Reference","Version","GUID","Path")
        For Each ref In ThisWorkbook.VBProject.References
            rw = rw + 1
            .Range("A" & rw & ":D" & rw) = Array(ref.Description, _
                   "v." & ref.Major & "." & ref.Minor, ref.GUID, ref.FullPath)
        Next ref
    End With
End Sub

Here is the same code but printing to the terminal if you don't want to dedicate a worksheet to the output.

Sub ListReferencePaths() 
 'Macro purpose:  To determine full path and Globally Unique Identifier (GUID)
 'to each referenced library.  Select the reference in the Tools\References
 'window, then run this code to get the information on the reference's library

On Error Resume Next 
Dim i As Long 

Debug.Print "Reference name" & " | " & "Full path to reference" & " | " & "Reference GUID" 

For i = 1 To ThisWorkbook.VBProject.References.Count 
  With ThisWorkbook.VBProject.References(i) 
    Debug.Print .Name & " | " & .FullPath  & " | " & .GUID 
  End With 
Next i 
On Error GoTo 0 
End Sub 

How can I concatenate a string and a number in Python?

Since Python is a strongly typed language, concatenating a string and an integer as you may do in Perl makes no sense, because there's no defined way to "add" strings and numbers to each other.

Explicit is better than implicit.

...says "The Zen of Python", so you have to concatenate two string objects. You can do this by creating a string from the integer using the built-in str() function:

>>> "abc" + str(9)

Alternatively use Python's string formatting operations:

>>> 'abc%d' % 9

Perhaps better still, use str.format():

>>> 'abc{0}'.format(9)

The Zen also says:

There should be one-- and preferably only one --obvious way to do it.

Which is why I've given three options. It goes on to say...

Although that way may not be obvious at first unless you're Dutch.

How to run binary file in Linux

The volume it's on is mounted noexec.

How do I overload the square-bracket operator in C#?

That would be the item property:

Maybe something like this would work:

public T Item[int index, int y]
    //Then do whatever you need to return/set here.
    get; set; 

Invalid CSRF Token 'null' was found on the request parameter '_csrf' or header 'X-CSRF-TOKEN'

It looks like the CSRF (Cross Site Request Forgery) protection in your Spring application is enabled. Actually it is enabled by default.

According to

When should you use CSRF protection? Our recommendation is to use CSRF protection for any request that could be processed by a browser by normal users. If you are only creating a service that is used by non-browser clients, you will likely want to disable CSRF protection.

So to disable it:

public class RestSecurityConfig extends WebSecurityConfigurerAdapter {
  protected void configure(HttpSecurity http) throws Exception {

If you want though to keep CSRF protection enabled then you have to include in your form the csrftoken. You can do it like this:

<form .... >
  ....other fields here....
  <input type="hidden"  name="${_csrf.parameterName}"   value="${_csrf.token}"/>

You can even include the CSRF token in the form's action:

<form action="./upload?${_csrf.parameterName}=${_csrf.token}" method="post" enctype="multipart/form-data">

Definitive way to trigger keypress events with jQuery

console.log( String.fromCharCode(event.charCode) );

no need to map character i guess.

How can I update NodeJS and NPM to the next versions?

When it comes to Linux I suggest an Update Node Using a Package Manager:

Node comes with npm pre-installed, but the manager is updated more frequently than Node. Run npm -v to see which version you have, then npm install npm@latest -g to install the newest npm update. Run npm -v again if you want to make sure npm updated correctly.

To update NodeJS, you’ll need npm’s handy n module. Run this code to clear npm’s cache, install n, and install the latest stable version of Node:

sudo npm cache clean -f
sudo npm install -g n
sudo n stable

To install the latest release, use n latest. Alternatively, you can run n #.#.# to get a specific Node version.

When it comes to Windows/ macOS I suggest using Installers on

The Node.js downloads page includes binary packages for Windows and macOS — but why make your life more difficult? The pre-made installers — .msi for Windows and .pkg for macOS — make the installation process unbelievably efficient and understandable. Download and run the file, and let the installation wizard take care of the rest. With each downloaded update, the newer versions of Node and npm will replace the older version.

Alternatively, macOS users can use the npm and n instructions above.

When it comes to updating your node_modules dependencies folder, I suggest skipping all the things that could cause you a headache and just go to your specific project and re-run npm install again.

Before anyone does that, I suggest first checking your package.json file for the following:

As a user of NodeJS packages, you can specify which kinds of updates your app can accept in the package.json file. For example, if you were starting with a package version 1.0.4, this is how you could specify the allowed update version ranges in three basic ways:

To Allow Patch Releases: 1.0 or 1.0.x or ~1.0.4
To Allow Minor Releases: 1 or 1.x or ^1.0.4
To Allow Major Releases: * or x


MAJOR version for when there are incompatible API changes. --> ~

MINOR version for when functionality is added in a backwards compatible manner. --> ^

PATCH version for when backward compatible bug fixes are done. --> *

Sending email with gmail smtp with codeigniter email library

$config = Array(
    'protocol' => 'smtp',
    'smtp_host' => 'ssl://',
    'smtp_port' => 465,
    'smtp_user' => 'xxx',
    'smtp_pass' => 'xxx',
    'mailtype'  => 'html', 
    'charset'   => 'iso-8859-1'
$this->load->library('email', $config);

// Set to, from, message, etc.

$result = $this->email->send();

From the CodeIgniter Forums

How to continue the code on the next line in VBA

(i, j, n + 1) = k * b_xyt(xi, yi, tn) / (4 * hx * hy) * U_matrix(i + 1, j + 1, n) + _
(k * (a_xyt(xi, yi, tn) / hx ^ 2 + d_xyt(xi, yi, tn) / (2 * hx)))

From ms support

To continue a statement from one line to the next, type a space followed by the line-continuation character [the underscore character on your keyboard (_)].

You can break a line at an operator, list separator, or period.

I want to convert std::string into a const wchar_t *

You can use the ATL text conversion macros to convert a narrow (char) string to a wide (wchar_t) one. For example, to convert a std::string:

#include <atlconv.h>
std::string str = "Hello, world!";
CA2W pszWide(str.c_str());

You can also specify a code page, so if your std::string contains UTF-8 chars you can use:

CA2W pszWide(str.c_str(), CP_UTF8);

Very useful but Windows only.

Clear listview content?

I guess you passed a List or an Array to the Adapter. If you keep the instance of this added collection, you can do a


this'll work only if you instantiated the adapter with collection and it's the same instance.

Also, depending on the Adapter you extended, you may not be able to do this. SimpleAdapter is used for static data, thus it can't be updated after creation.

PS. not all Adapters have a clear() method. ArrayAdapter does, but ListAdapter or SimpleAdapter don't

Error in contrasts when defining a linear model in R

If the error happens to be because your data has NAs, then you need to set the glm() function options of how you would like to treat the NA cases. More information on this is found in a relevant post here:

Get all child elements

Another veneration of find_elements_by_xpath(".//*") is:

from import By

find_elements(By.XPATH, ".//*")

chrome : how to turn off user agent stylesheet settings?

  1. Open Chrome dev tools
  2. Click gear icon on bottom right
  3. In General section, check or uncheck "Show user agent styles".

How to compare 2 files fast using .NET?

The slowest possible method is to compare two files byte by byte. The fastest I've been able to come up with is a similar comparison, but instead of one byte at a time, you would use an array of bytes sized to Int64, and then compare the resulting numbers.

Here's what I came up with:

    const int BYTES_TO_READ = sizeof(Int64);

    static bool FilesAreEqual(FileInfo first, FileInfo second)
        if (first.Length != second.Length)
            return false;

        if (string.Equals(first.FullName, second.FullName, StringComparison.OrdinalIgnoreCase))
            return true;

        int iterations = (int)Math.Ceiling((double)first.Length / BYTES_TO_READ);

        using (FileStream fs1 = first.OpenRead())
        using (FileStream fs2 = second.OpenRead())
            byte[] one = new byte[BYTES_TO_READ];
            byte[] two = new byte[BYTES_TO_READ];

            for (int i = 0; i < iterations; i++)
                 fs1.Read(one, 0, BYTES_TO_READ);
                 fs2.Read(two, 0, BYTES_TO_READ);

                if (BitConverter.ToInt64(one,0) != BitConverter.ToInt64(two,0))
                    return false;

        return true;

In my testing, I was able to see this outperform a straightforward ReadByte() scenario by almost 3:1. Averaged over 1000 runs, I got this method at 1063ms, and the method below (straightforward byte by byte comparison) at 3031ms. Hashing always came back sub-second at around an average of 865ms. This testing was with an ~100MB video file.

Here's the ReadByte and hashing methods I used, for comparison purposes:

    static bool FilesAreEqual_OneByte(FileInfo first, FileInfo second)
        if (first.Length != second.Length)
            return false;

        if (string.Equals(first.FullName, second.FullName, StringComparison.OrdinalIgnoreCase))
            return true;

        using (FileStream fs1 = first.OpenRead())
        using (FileStream fs2 = second.OpenRead())
            for (int i = 0; i < first.Length; i++)
                if (fs1.ReadByte() != fs2.ReadByte())
                    return false;

        return true;

    static bool FilesAreEqual_Hash(FileInfo first, FileInfo second)
        byte[] firstHash = MD5.Create().ComputeHash(first.OpenRead());
        byte[] secondHash = MD5.Create().ComputeHash(second.OpenRead());

        for (int i=0; i<firstHash.Length; i++)
            if (firstHash[i] != secondHash[i])
                return false;
        return true;

jQuery checkbox onChange

There is a typo error :

$('#activelist :checkbox')...

Should be :


Setting the Vim background colors

Try adding

set background=dark

to your .gvimrc too. This work well for me.

Retrieve only the queried element in an object array in MongoDB collection

db.test.find( {"shapes.color": "red"}, {_id: 0})

How to really read text file from classpath in Java

I am using webshpere application server and my Web Module is build on Spring MVC. The were located in the resources folder, i tried to load this files using the following:

  1. this.getClass().getClassLoader().getResourceAsStream("");
  2. this.getClass().getResourceAsStream("/");

None of the above code loaded the file.

But with the help of below code the property file was loaded successfully:


Thanks to the user "user1695166".

document.getElementById(id).focus() is not working for firefox or chrome

I know this may be an esoteric use-case but I struggled with getting an input to take focus when using Angular 2 framework. Calling focus() simply did not work not matter what I did.

Ultimately I realized angular was suppressing it because I had not set an [(ngModel)] on the input. Setting one solved it. Hope it helps someone.

How to 'update' or 'overwrite' a python list

I'm learning to code and I found this same problem. I believe the easier way to solve this is literaly overwriting the list like @kerby82 said:

An item in a list in Python can be set to a value using the form

x[n] = v

Where x is the name of the list, n is the index in the array and v is the value you want to set.

In your exemple:

aList = [123, 'xyz', 'zara', 'abc']
aList[0] = 2014
print aList
>>[2014, 'xyz', 'zara', 'abc']

jquery draggable: how to limit the draggable area?

Use the "containment" option:

jQuery UI API - Draggable Widget - containment

The documentation says it only accepts the values: 'parent', 'document', 'window', [x1, y1, x2, y2] but I seem to remember it will accept a selector such as '#container' too.

jquery find closest previous sibling with class

Using prevUntil() will allow us to get a distant sibling without having to get all. I had a particularly long set that was too CPU intensive using prevAll().

var category = $('li.current_sub').prev('li.par_cat');
if (category.length == 0){
  category = $('li.current_sub').prevUntil('li.par_cat').last().prev();

This gets the first preceding sibling if it matches, otherwise it gets the sibling preceding the one that matches, so we just back up one more with prev() to get the desired element.

ES6 export default with multiple functions referring to each other

The export default {...} construction is just a shortcut for something like this:

const funcs = {
    foo() { console.log('foo') }, 
    bar() { console.log('bar') },
    baz() { foo(); bar() }

export default funcs

It must become obvious now that there are no foo, bar or baz functions in the module's scope. But there is an object named funcs (though in reality it has no name) that contains these functions as its properties and which will become the module's default export.

So, to fix your code, re-write it without using the shortcut and refer to foo and bar as properties of funcs:

const funcs = {
    foo() { console.log('foo') }, 
    bar() { console.log('bar') },
    baz() {; } // here is the fix

export default funcs

Another option is to use this keyword to refer to funcs object without having to declare it explicitly, as @pawel has pointed out.

Yet another option (and the one which I generally prefer) is to declare these functions in the module scope. This allows to refer to them directly:

function foo() { console.log('foo') }
function bar() { console.log('bar') }
function baz() { foo(); bar() }

export default {foo, bar, baz}

And if you want the convenience of default export and ability to import items individually, you can also export all functions individually:

// util.js

export function foo() { console.log('foo') }
export function bar() { console.log('bar') }
export function baz() { foo(); bar() }

export default {foo, bar, baz}

// a.js, using default export

import util from './util'

// b.js, using named exports

import {bar} from './util'

Or, as @loganfsmyth suggested, you can do without default export and just use import * as util from './util' to get all named exports in one object.

Export data from R to Excel

Another option is the openxlsx-package. It doesn't depend on and can read, edit and write Excel-files. From the description from the package:

openxlsx simplifies the the process of writing and styling Excel xlsx files from R and removes the dependency on Java

Example usage:


# read data from an Excel file or Workbook object into a data.frame
df <- read.xlsx('name-of-your-excel-file.xlsx')

# for writing a data.frame or list of data.frames to an xlsx file
write.xlsx(df, 'name-of-your-excel-file.xlsx')

Besides these two basic functions, the openxlsx-package has a host of other functions for manipulating Excel-files.

For example, with the writeDataTable-function you can create formatted tables in an Excel-file.

Can I pass an argument to a VBScript (vbs file launched with cscript)?

You can also use named arguments which are optional and can be given in any order.

Set namedArguments = WScript.Arguments.Named

Here's a little helper function:

Function GetNamedArgument(ByVal argumentName, ByVal defaultValue)
  If WScript.Arguments.Named.Exists(argumentName) Then
    GetNamedArgument = WScript.Arguments.Named.Item(argumentName) 
    GetNamedArgument = defaultValue
  End If
End Function

Example VBS:

testArg = GetNamedArgument("testArg", "-unknown-")
wscript.Echo now &": "& testArg

Example Usage:

test.vbs /testArg:123

blur() vs. onblur()

Contrary to what pointy says, the blur() method does exist and is a part of the w3c standard. The following exaple will work in every modern browser (including IE):

        <title>Javascript test</title>
        <script type="text/javascript" language="javascript">
            window.onload = function()
                var field = document.getElementById("field");
                var link = document.getElementById("link");
                var output = document.getElementById("output");

                field.onfocus = function() { output.innerHTML += "<br/>field.onfocus()"; };
                field.onblur = function() { output.innerHTML += "<br/>field.onblur()"; };
                link.onmouseover = function() { field.blur(); };
        <form name="MyForm">
            <input type="text" name="field" id="field" />
            <a href="javascript:void(0);" id="link">Blur field on hover</a>
            <div id="output"></div>

Note that I used link.onmouseover instead of link.onclick, because otherwise the click itself would have removed the focus.

How to detect DIV's dimension changed?

This is pretty much an exact copy of the top answer, but instead of a link, it's just the part of the code that matters, translated to be IMO more readable and easier to understand. A few other small changes include using cloneNode(), and not putting html into a js string. Small stuff, but you can copy and paste this as is and it will work.

The way it works is by making two invisible divs fill the element you're watching, and then putting a trigger in each, and setting a scroll position that will lead to triggering a scroll change if the size changes.

All real credit goes to Marc J, but if you're just looking for the relevant code, here it is:

    window.El = {}

    El.resizeSensorNode = undefined;
    El.initResizeNode = function() {
        var fillParent = "display: block; position: absolute; left: 0; top: 0; right: 0; bottom: 0; overflow: hidden; z-index: -1; visibility: hidden;";
        var triggerStyle = "position: absolute; left: 0; top: 0; transition: 0s;";

        var resizeSensor = El.resizeSensorNode = document.createElement("resizeSensor"); = fillParent;

        var expandSensor = document.createElement("div"); = fillParent;

        var trigger = document.createElement("div"); = triggerStyle;

        var shrinkSensor = expandSensor.cloneNode(true); = triggerStyle + " width: 200%; height: 200%";

    El.onSizeChange = function(domNode, fn) {
        if (!domNode) return;
        if (domNode.resizeListeners) {

        domNode.resizeListeners = [];

        if(El.resizeSensorNode == undefined)

        domNode.resizeSensor = El.resizeSensorNode.cloneNode(true);

        var expand = domNode.resizeSensor.firstChild;
        var expandTrigger = expand.firstChild;
        var shrink = domNode.resizeSensor.childNodes[1];

        var reset = function() {
   = '100000px';
   = '100000px';

            expand.scrollLeft = 100000;
            expand.scrollTop = 100000;

            shrink.scrollLeft = 100000;
            shrink.scrollTop = 100000;


        var hasChanged, frameRequest, newWidth, newHeight;
        var lastWidth = domNode.offsetWidth;
        var lastHeight = domNode.offsetHeight;

        var onResized = function() {
            frameRequest = undefined;

            if (!hasChanged) return;

            lastWidth = newWidth;
            lastHeight = newHeight;

            var listeners = domNode.resizeListeners;
            for(var i = 0; listeners && i < listeners.length; i++) 

        var onScroll = function() {
            newWidth = domNode.offsetWidth;
            newHeight = domNode.offsetHeight;
            hasChanged = newWidth != lastWidth || newHeight != lastHeight;

            if (hasChanged && !frameRequest) {
                frameRequest = requestAnimationFrame(onResized);


        expand.addEventListener("scroll", onScroll);
        shrink.addEventListener("scroll", onScroll);

why are there two different kinds of for loops in java?

The first is the original for loop. You initialize a variable, set a terminating condition, and provide a state incrementing/decrementing counter (There are exceptions, but this is the classic)

For that,

for (int i=0;i<myString.length;i++) { 

is correct.

For Java 5 an alternative was proposed. Any thing that implements iterable can be supported. This is particularly nice in Collections. For example you can iterate the list like this

List<String> list = ....load up with stuff

for (String string : list) {

instead of

for (int i=0; i<list.size();i++) {

So it's just an alternative notation really. Any item that implements Iterable (i.e. can return an iterator) can be written that way.

What's happening behind the scenes is somethig like this: (more efficient, but I'm writing it explicitly)

Iterator<String> it = list.iterator();
while (it.hasNext()) {

In the end it's just syntactic sugar, but rather convenient.

Export data to Excel file with ASP.NET MVC 4 C# is rendering into view

I used a list in my controller class to set data into grid view. The code works fine for me:

public ActionResult ExpExcl()
  List<PersonModel> person= new List<PersonModel>
    new PersonModel() {FirstName= "Jenny", LastName="Mathew", Age= 23},
    new PersonModel() {FirstName= "Paul", LastName="Meehan", Age=25}
   var grid= new GridView();
   grid.DataSource= person;

   Response.AddHeader("content-disposition","attachement; filename=data.xls");
   StringWriter sw= new StringWriter();
   HtmlTextWriter htw= new HtmlTextWriter(sw); 
   return View();

No log4j2 configuration file found. Using default configuration: logging only errors to the console

i had same problem, but i noticed that i have no log4j2.xml in my project after reading on the net about this problem, so i copied the related code in a notepad and reverted the notepad file to xml and add to my project under the folder resources. it works for me.

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
<Console name="Console" target="SYSTEM_OUT">
  <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
<Root level="DEBUG">
  <AppenderRef ref="Console"/>

Visual Studio 2012 Web Publish doesn't copy files

I tried all of these solutions but this is the one that works every time.

We just change the "Publish method:" from "File System" to for example "Web Deploy", and immediately change it back to "File System".

How to set the max size of upload file

I'm using spring-boot-1.3.5.RELEASE and I had the same issue. None of above solutions are not worked for me. But finally adding following property to was fixed the problem.


How do I get elapsed time in milliseconds in Ruby?

I think the answer is incorrectly chosen, that method gives seconds, not milliseconds.

t =­o_f
=> 1382471965.146

Here I suppose the floating value are the milliseconds

Nginx: Job for nginx.service failed because the control process exited

For my case, I need to run

sudo nginx -t

It will check if Nginx configuration is correct or not, if not, it will show you which configuration causes the error.

Then you need to go to /etc/nginx/sites-available to fix the broken configuration.

After that, you can restart Nginx without any problem.

sudo systemctl restart nginx

Single huge .css file vs. multiple smaller specific .css files?

This is a hard one to answer. Both options have their pros and cons in my opinion.

I personally don't love reading through a single HUGE CSS file, and maintaining it is very difficult. On the other hand, splitting it out causes extra http requests which could potentially slow things down.

My opinion would be one of two things.

1) If you know that your CSS will NEVER change once you've built it, I'd build multiple CSS files in the development stage (for readability), and then manually combine them before going live (to reduce http requests)

2) If you know that you're going to change your CSS once in a while, and need to keep it readable, I would build separate files and use code (providing you're using some sort of programming language) to combine them at runtime build time (runtime minification/combination is a resource pig).

With either option I would highly recommend caching on the client side in order to further reduce http requests.

I found this blog that shows how to combine CSS at runtime using nothing but code. Worth taking a look at (though I haven't tested it myself yet).

I've settled on using separate files in my design time, and a build process to minify and combine. This way I can have separate (manageable) css while I develop and a proper monolithic minified file at runtime. And I still have my static files and less system overhead because I'm not doing compression/minification at runtime.

note: for you shoppers out there, I highly suggest using bundler as part of your build process. Whether you're building from within your IDE, or from a build script, bundler can be executed on Windows via the included exe or can be run on any machine that is already running node.js.

How to solve java.lang.OutOfMemoryError trouble in Android

I see only two options:

  1. You have memory leaks in your application.
  2. Devices do not have enough memory when running your application.

"Initializing" variables in python?

Python treats comma on the left hand side of equal sign ( = ) as an input splitter, Very useful for functions that return a tuple.


x,y = (5,2)

What you want to do is:

grade_1 = grade_2 = grade_3 = average = 0.0

though that might not be the most clear way to write it.

Check cell for a specific letter or set of letters

You can use RegExMatch:


How to bind Events on Ajax loaded Content?

If the content is appended after .on() is called, you'll need to create a delegated event on a parent element of the loaded content. This is because event handlers are bound when .on() is called (i.e. usually on page load). If the element doesn't exist when .on() is called, the event will not be bound to it!

Because events propagate up through the DOM, we can solve this by creating a delegated event on a parent element (.parent-element in the example below) that we know exists when the page loads. Here's how:

$('.parent-element').on('click', '.mylink', function(){
  alert ("new link clicked!");

Some more reading on the subject:

You have not accepted the license agreements of the following SDK components

I ran across this error when i ran cordova build android

I solved this issue by firing ./sdkmanager --licenses and accepting all the licenses.

  1. You have a sdkmanager.bat under the android sdk folder in the path: android/sdk/tools/bin
  2. To trigger that open a command prompt in android/sdk/tools/bin
  3. type ./sdkmanager --licenses and enter
  4. Press y to review all licenses and then press y to accept all licenses

How to detect incoming calls, in an Android device?

Here's what I use to do this:


<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.PROCESS_OUTGOING_CALLS"/>

<!--This part is inside the application-->
    <receiver android:name=".CallReceiver" >
            <action android:name="android.intent.action.PHONE_STATE" />
            <action android:name="android.intent.action.NEW_OUTGOING_CALL" />

My base reusable call detector


import java.util.Date;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.telephony.TelephonyManager;

public abstract class PhonecallReceiver extends BroadcastReceiver {

    //The receiver will be recreated whenever android feels like it.  We need a static variable to remember data between instantiations

    private static int lastState = TelephonyManager.CALL_STATE_IDLE;
    private static Date callStartTime;
    private static boolean isIncoming;
    private static String savedNumber;  //because the passed incoming is only valid in ringing

    public void onReceive(Context context, Intent intent) {

        //We listen to two intents.  The new outgoing call only tells us of an outgoing call.  We use it to get the number.
        if (intent.getAction().equals("android.intent.action.NEW_OUTGOING_CALL")) {
            savedNumber = intent.getExtras().getString("android.intent.extra.PHONE_NUMBER");
            String stateStr = intent.getExtras().getString(TelephonyManager.EXTRA_STATE);
            String number = intent.getExtras().getString(TelephonyManager.EXTRA_INCOMING_NUMBER);
            int state = 0;
                state = TelephonyManager.CALL_STATE_IDLE;
            else if(stateStr.equals(TelephonyManager.EXTRA_STATE_OFFHOOK)){
                state = TelephonyManager.CALL_STATE_OFFHOOK;
            else if(stateStr.equals(TelephonyManager.EXTRA_STATE_RINGING)){
                state = TelephonyManager.CALL_STATE_RINGING;

            onCallStateChanged(context, state, number);

    //Derived classes should override these to respond to specific events of interest
    protected abstract void onIncomingCallReceived(Context ctx, String number, Date start);
    protected abstract void onIncomingCallAnswered(Context ctx, String number, Date start);
    protected abstract void onIncomingCallEnded(Context ctx, String number, Date start, Date end);

    protected abstract void onOutgoingCallStarted(Context ctx, String number, Date start);      
    protected abstract void onOutgoingCallEnded(Context ctx, String number, Date start, Date end);

    protected abstract void onMissedCall(Context ctx, String number, Date start);

    //Deals with actual events

    //Incoming call-  goes from IDLE to RINGING when it rings, to OFFHOOK when it's answered, to IDLE when its hung up
    //Outgoing call-  goes from IDLE to OFFHOOK when it dials out, to IDLE when hung up
    public void onCallStateChanged(Context context, int state, String number) {
        if(lastState == state){
            //No change, debounce extras
        switch (state) {
            case TelephonyManager.CALL_STATE_RINGING:
                isIncoming = true;
                callStartTime = new Date();
                savedNumber = number;
                onIncomingCallReceived(context, number, callStartTime);
            case TelephonyManager.CALL_STATE_OFFHOOK:
                //Transition of ringing->offhook are pickups of incoming calls.  Nothing done on them
                if(lastState != TelephonyManager.CALL_STATE_RINGING){
                    isIncoming = false;
                    callStartTime = new Date();
                    onOutgoingCallStarted(context, savedNumber, callStartTime);                     
                    isIncoming = true;
                    callStartTime = new Date();
                    onIncomingCallAnswered(context, savedNumber, callStartTime); 

            case TelephonyManager.CALL_STATE_IDLE:
                //Went to idle-  this is the end of a call.  What type depends on previous state(s)
                if(lastState == TelephonyManager.CALL_STATE_RINGING){
                    //Ring but no pickup-  a miss
                    onMissedCall(context, savedNumber, callStartTime);
                else if(isIncoming){
                    onIncomingCallEnded(context, savedNumber, callStartTime, new Date());                       
                    onOutgoingCallEnded(context, savedNumber, callStartTime, new Date());                                               
        lastState = state;

Then to use it, simply derive a class from it and implement a few easy functions, whichever call types you care about:

public class CallReceiver extends PhonecallReceiver {

    protected void onIncomingCallReceived(Context ctx, String number, Date start)

    protected void onIncomingCallAnswered(Context ctx, String number, Date start)

    protected void onIncomingCallEnded(Context ctx, String number, Date start, Date end)

    protected void onOutgoingCallStarted(Context ctx, String number, Date start)

    protected void onOutgoingCallEnded(Context ctx, String number, Date start, Date end)

    protected void onMissedCall(Context ctx, String number, Date start)


In addition you can see a writeup I did on why the code is like it is on my blog. Gist link:

EDIT: Updated to simpler code, as I've reworked the class for my own use

How to make IPython notebook matplotlib plot inline

If your matplotlib version is above 1.4, it is also possible to use

IPython 3.x and above

%matplotlib notebook

import matplotlib.pyplot as plt

older versions

%matplotlib nbagg

import matplotlib.pyplot as plt

Both will activate the nbagg backend, which enables interactivity.

Example plot with the nbagg backend

Attempt to present UIViewController on UIViewController whose view is not in the window hierarchy

Another potential cause:

I had this issue when I was accidentally presenting the same view controller twice. (Once with performSegueWithIdentifer:sender: which was called when the button was pressed, and a second time with a segue connected directly to the button).

Effectively, two segues were firing at the same time, and I got the error: Attempt to present X on Y whose view is not in the window hierarchy!

About .bash_profile, .bashrc, and where should alias be written in?

Check out for an excellent resource on the topic aside from man bash.


  • You only log in once, and that's when ~/.bash_profile or ~/.profile is read and executed. Since everything you run from your login shell inherits the login shell's environment, you should put all your environment variables in there. Like LESS, PATH, MANPATH, LC_*, ... For an example, see: My .profile
  • Once you log in, you can run several more shells. Imagine logging in, running X, and in X starting a few terminals with bash shells. That means your login shell started X, which inherited your login shell's environment variables, which started your terminals, which started your non-login bash shells. Your environment variables were passed along in the whole chain, so your non-login shells don't need to load them anymore. Non-login shells only execute ~/.bashrc, not /.profile or ~/.bash_profile, for this exact reason, so in there define everything that only applies to bash. That's functions, aliases, bash-only variables like HISTSIZE (this is not an environment variable, don't export it!), shell options with set and shopt, etc. For an example, see: My .bashrc
  • Now, as part of UNIX peculiarity, a login-shell does NOT execute ~/.bashrc but only ~/.profile or ~/.bash_profile, so you should source that one manually from the latter. You'll see me do that in my ~/.profile too: source ~/.bashrc.

function is not defined error in Python

In python functions aren't accessible magically from everywhere (like they are in say, php). They have to be declared first. So this will work:

def pyth_test (x1, x2):
    print x1 + x2

pyth_test(1, 2)

But this won't:

pyth_test(1, 2)

def pyth_test (x1, x2):
    print x1 + x2

Maven- No plugin found for prefix 'spring-boot' in the current project and in the plugin groups

Make sure pom.xml exist in the directory, when using the mvn spring-boot:run command. No need to add any thing in the pom.xml file.

What are some good Python ORM solutions?

We use Elixir alongside SQLAlchemy and have liked it so far. Elixir puts a layer on top of SQLAlchemy that makes it look more like the "ActiveRecord pattern" counter parts.

How do I make a branch point at a specific commit?

git reset --hard 1258f0d0aae

But be careful, if the descendant commits between 1258f0d0aae and HEAD are not referenced in other branches it'll be tedious (but not impossible) to recover them, so you'd better to create a "backup" branch at current HEAD, checkout master, and reset to the commit you want.

Also, be sure that you don't have uncommitted changes before a reset --hard, they will be truly lost (no way to recover).

Passing an array of parameters to a stored procedure

If you are using Sql Server 2008 or better, you can use something called a Table-Valued Parameter (TVP) instead of serializing & deserializing your list data every time you want to pass it to a stored procedure.

Let's start by creating a simple schema to serve as our playground:


USE [TestbedDb]

    /* First, setup the sample program's account & credentials*/

CREATE USER [testbedUser] FOR LOGIN [testbedUser] WITH DEFAULT_SCHEMA=[dbo]

EXEC sp_addrolemember N'db_owner', N'testbedUser'

    /* Now setup the schema */

INSERT INTO dbo.Table1 (t1Id)

With our schema and sample data in place, we are now ready to create our TVP stored procedure:

        t1Id INT

CREATE PROCEDURE dbo.FindMatchingRowsInTable1( @Table1Ids AS T1Ids READONLY )

        SELECT Table1.t1Id FROM dbo.Table1 AS Table1
        JOIN @Table1Ids AS paramTable1Ids ON Table1.t1Id = paramTable1Ids.t1Id;

With both our schema and API in place, we can call the TVP stored procedure from our program like so:

        // Curry the TVP data
        DataTable t1Ids = new DataTable( );
        t1Ids.Columns.Add( "t1Id",
                           typeof( int ) );

        int[] listOfIdsToFind = new[] {1, 5, 9};
        foreach ( int id in listOfIdsToFind )
            t1Ids.Rows.Add( id );
        // Prepare the connection details
        SqlConnection testbedConnection =
                new SqlConnection(
                        @"Data Source=.\SQLExpress;Initial Catalog=TestbedDb;Persist Security Info=True;User ID=testbedUser;Password=letmein12;Connect Timeout=5" );

            testbedConnection.Open( );

            // Prepare a call to the stored procedure
            SqlCommand findMatchingRowsInTable1 = new SqlCommand( "dbo.FindMatchingRowsInTable1",
                                                                  testbedConnection );
            findMatchingRowsInTable1.CommandType = CommandType.StoredProcedure;

            // Curry up the TVP parameter
            SqlParameter sqlParameter = new SqlParameter( "Table1Ids",
                                                          t1Ids );
            findMatchingRowsInTable1.Parameters.Add( sqlParameter );

            // Execute the stored procedure
            SqlDataReader sqlDataReader = findMatchingRowsInTable1.ExecuteReader( );

            while ( sqlDataReader.Read( ) )
                Console.WriteLine( "Matching t1ID: {0}",
                                   sqlDataReader[ "t1Id" ] );
        catch ( Exception e )
            Console.WriteLine( e.ToString( ) );
  /* Output:
   * Matching t1ID: 1
   * Matching t1ID: 5
   * Matching t1ID: 9

There is probably a less painful way to do this using a more abstract API, such as Entity Framework. However, I do not have the time to see for myself at this time.

How can the Euclidean distance be calculated with NumPy?

Having a and b as you defined them, you can use also:

distance = np.sqrt(np.sum((a-b)**2))

How to uninstall jupyter

For python 3.7:

  1. On windows command prompt, type: "py -m pip install pip-autoremove". You will get a successful message.
  2. Change directory, if you didn't add the following as your PATH: cd C:\Users{user_name}\AppData\Local\Programs\Python\Python37-32\Scripts To know where your package/application has been installed/located, type: "where program_name" like> where jupyter If you didn't find a location, you need to add the location in PATH.

  3. Type: pip-autoremove jupyter It will ask to type y/n to confirm the action.

release Selenium chromedriver.exe from memory

This answer is how to properly dispose of the driver in C#

If you want to use a 'proper' mechanism that should be used to 'tidy up' after running ChromeDriver you should use IWebDriver.Dispose();

Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources. (Inherited from IDisposable.)

I usually implement IDisposable on class that is dealing with IWebDriver

public class WebDriverController : IDisposable
    public IWebDriver Driver;

    public void Dispose()

and use it like:

using (var controller = new WebDriverController())
  //code goes here

Hope this saves you some time

Git conflict markers

The line (or lines) between the lines beginning <<<<<<< and ====== here:

<<<<<<< HEAD:file.txt
Hello world

... is what you already had locally - you can tell because HEAD points to your current branch or commit. The line (or lines) between the lines beginning ======= and >>>>>>>:

>>>>>>> 77976da35a11db4580b80ae27e8d65caf5208086:file.txt

... is what was introduced by the other (pulled) commit, in this case 77976da35a11. That is the object name (or "hash", "SHA1sum", etc.) of the commit that was merged into HEAD. All objects in git, whether they're commits (version), blobs (files), trees (directories) or tags have such an object name, which identifies them uniquely based on their content.

Leaflet changing Marker color

In R, use the addAwesomeMarkers() function. Sample code producing red marker:

leaflet() %>%
addTiles() %>%
addAwesomeMarkers(lng = -77.03654, lat = 38.8973, icon = awesomeIcons(icon = 'ion-ionic', library = 'ion', markerColor = 'red'))

Link for ion icons:

Can I access a form in the controller?

Bit late for an answer but came with following option. It is working for me but not sure if it is the correct way or not.

In my view I'm doing this:

<form name="formName">
    <div ng-init="setForm(formName);"></div>

And in the controller:

$scope.setForm = function (form) {
    $scope.myForm = form;

Now after doing this I have got my form in my controller variable which is $scope.myForm

What is the difference between RTP or RTSP in a streaming server?

AFAIK, RTSP does not transmit streams at all, it is just an out-of-band control protocol with functions like PLAY and STOP.

Raw UDP or RTP over UDP are transmission protocols for streams just like raw TCP or HTTP over TCP.

To be able to stream a certain program over the given transmission protocol, an encapsulation method has to be defined for your container format. For example TS container can be transmitted over UDP but Matroska can not.

Pretty much everything can be transported through TCP though.

(The fact that which codec do you use also matters indirectly as it restricts the container formats you can use.)

Parsing string as JSON with single quotes?

I know it's an old post, but you can use JSON5 for this purpose.

<script src="json5.js"></script>

function to remove duplicate characters in a string

Yet another solution, seems to be the most concise so far:

private static String removeDuplicates(String s)
        String x = new String(s);

        for(int i=0;i<x.length()-1;i++)
            x = x.substring(0,i+1) + (x.substring(i+1)).replace(String.valueOf(x.charAt(i)), "");

        return x;

How to get a parent element to appear above child

Set a negative z-index for the child, and remove the one set on the parent.

.parent {_x000D_
    position: relative;_x000D_
    width: 350px;_x000D_
    height: 150px;_x000D_
    background: red;_x000D_
    border: solid 1px #000;_x000D_
.parent2 {_x000D_
    position: relative;_x000D_
    width: 350px;_x000D_
    height: 40px;_x000D_
    background: red;_x000D_
    border: solid 1px #000;_x000D_
.child {_x000D_
    position: relative;_x000D_
    background-color: blue;_x000D_
    height: 200px;_x000D_
.wrapper {_x000D_
    position: relative;_x000D_
    background: green;_x000D_
    height: 350px;_x000D_
<div class="wrapper">_x000D_
    <div class="parent">parent 1 parent 1_x000D_
        <div class="child">child child child</div>_x000D_
    <div class="parent2">parent 2 parent 2_x000D_

import dat file into R

The dat file has some lines of extra information before the actual data. Skip them with the skip argument:

           header=TRUE, skip=3)

An easy way to check this if you are unfamiliar with the dataset is to first use readLines to check a few lines, as below:

# [1] "Ozone data from CZ03 2009"   "Local time: GMT + 0"        
# [3] ""                            "Date        Hour      Value"
# [5] "01.01.2009 00:00       34.3" "01.01.2009 01:00       31.9"
# [7] "01.01.2009 02:00       29.9" "01.01.2009 03:00       28.5"
# [9] "01.01.2009 04:00       32.9" "01.01.2009 05:00       20.5"

Here, we can see that the actual data starts at [4], so we know to skip the first three lines.


If you really only wanted the Value column, you could do that by:

               header=TRUE, skip=3)$Value)

Again, readLines is useful for helping us figure out the actual name of the columns we will be importing.

But I don't see much advantage to doing that over reading the whole dataset in and extracting later.

Does uninstalling a package with "pip" also remove the dependent packages?

i've successfully removed dependencies of a package using this bash line:

for dep in $(pip show somepackage | grep Requires | sed 's/Requires: //g; s/,//g') ; do pip uninstall -y $dep ; done

this worked on pip 1.5.4

How do I download a file from the internet to my linux server with Bash

You can use the command wget to download from command line. Specifically, you could use


However because Oracle requires you to accept a license agreement this may not work (and I am currently unable to test it).

How to add a new audio (not mixing) into a video using ffmpeg?

If you are using an old version of FFMPEG and you cant upgrade you can do the following:


Notice that I used -vcodec

Simpler way to create dictionary of separate variables?

In reading the thread, I saw an awful lot of friction. It's easy enough to give a bad answer, then let someone give the correct answer. Anyway, here is what I found.

From: [] (

The names are a bit different — they’re not really properties of the object, and the object itself doesn't know what it’s called.

An object can have any number of names, or no name at all.

Names live in namespaces (such as a module namespace, an instance namespace, a function’s local namespace).

Note: that it says the object itself doesn’t know what it’s called, so that was the clue. Python objects are not self-referential. Then it says, Names live in namespaces. We have this in TCL/TK. So maybe my answer will help (but it did help me)

    jj = 123
    print eval("'" + str(id(jj)) + "'")
    print dir()

['__builtins__', '__doc__', '__file__', '__name__', '__package__', 'jj']

So there is 'jj' at the end of the list.

Rewrite the code as:

    jj = 123
    print eval("'" + str(id(jj)) + "'")
    for x in dir():
        print id(eval(x))

['__builtins__', '__doc__', '__file__', '__name__', '__package__', 'jj']

This nasty bit of code id's the name of variable/object/whatever-you-pedantics-call-it.

So, there it is. The memory address of 'jj' is the same when we look for it directly, as when we do the dictionary look up in global name space. I'm sure you can make a function to do this. Just remember which namespace your variable/object/wypci is in.


What is an Endpoint?

API stands for Application Programming Interface. It is a way for your application to interact with other applications via an endpoint. Conversely, you can build out an API for your application that is available for other developers to utilize/connect to via HTTP methods, which are RESTful. Representational State Transfer (REST):

  • GET: Retrieve data from an API endpoint.
  • PUT: Update data via an API - similar to POST but more about updating info.
  • POST: Send data to an API.
  • DELETE: Remove data from given API.

Git command to show which specific files are ignored by .gitignore

Another option that's pretty clean (No pun intended.):

git clean -ndX


$ git help clean

git-clean - Remove untracked files from the working tree
-n, --dry-run - Don't actually remove anything, just show what would be done.
-d - Remove untracked directories in addition to untracked files.
-X - Remove only files ignored by Git.

Note: This solution will not show ignored files that have already been removed.

What is the easiest way to clear a database from the CLI with in Django?

Quickest (drops and creates all tables including data):

./ reset appname | ./ dbshell


  • Might not work on Windows correctly.
  • Might keep some old tables in the db

Python decorators in classes

You can decorate the decorator:

import decorator

class Test(object):
    def _decorator(foo, self):

    def bar(self):

What is an abstract class in PHP?

An abstract class is a class that is only partially implemented by the programmer. It may contain one or more abstract methods. An abstract method is simply a function definition that serves to tell the programmer that the method must be implemented in a child class.

There is good explanation of that here.

What is String pool in Java?

When the JVM loads classes, or otherwise sees a literal string, or some code interns a string, it adds the string to a mostly-hidden lookup table that has one copy of each such string. If another copy is added, the runtime arranges it so that all the literals refer to the same string object. This is called "interning". If you say something like

String s = "test";
return (s == "test");

it'll return true, because the first and second "test" are actually the same object. Comparing interned strings this way can be much, much faster than String.equals, as there's a single reference comparison rather than a bunch of char comparisons.

You can add a string to the pool by calling String.intern(), which will give you back the pooled version of the string (which could be the same string you're interning, but you'd be crazy to rely on that -- you often can't be sure exactly what code has been loaded and run up til now and interned the same string). The pooled version (the string returned from intern) will be equal to any identical literal. For example:

String s1 = "test";
String s2 = new String("test");  // "new String" guarantees a different object

System.out.println(s1 == s2);  // should print "false"

s2 = s2.intern();
System.out.println(s1 == s2);  // should print "true"

"NOT IN" clause in LINQ to Entities

If you are using an in-memory collection as your filter, it's probably best to use the negation of Contains(). Note that this can fail if the list is too long, in which case you will need to choose another strategy (see below for using a strategy for a fully DB-oriented query).

   var exceptionList = new List<string> { "exception1", "exception2" };

   var query = myEntities.MyEntity
                         .Select(e => e.Name)
                         .Where(e => !exceptionList.Contains(e.Name));

If you're excluding based on another database query using Except might be a better choice. (Here is a link to the supported Set extensions in LINQ to Entities)

   var exceptionList = myEntities.MyOtherEntity
                                 .Select(e => e.Name);

   var query = myEntities.MyEntity
                         .Select(e => e.Name)

This assumes a complex entity in which you are excluding certain ones depending some property of another table and want the names of the entities that are not excluded. If you wanted the entire entity, then you'd need to construct the exceptions as instances of the entity class such that they would satisfy the default equality operator (see docs).

Android lollipop change navigation bar color

It can be done inside styles.xml using

<item name="android:navigationBarColor">@color/theme_color</item>


window.setNavigationBarColor(@ColorInt int color)

Note that the method was introduced in Android Lollipop and won't work on API version < 21.

The second method (works on KitKat) is to set windowTranslucentNavigation to true in the manifest and place a colored view beneath the navigation bar.

How can I run NUnit tests in Visual Studio 2017?

You need to install NUnitTestAdapter. The latest version of NUnit is 3.x.y (3.6.1) and you should install NUnit3TestAdapter along with NUnit 3.x.y

To install NUnit3TestAdapter in Visual Studio 2017, follow the steps below:

  1. Right click on menu Project ? click "Manage NuGet Packages..." from the context menu
  2. Go to the Browse tab and search for NUnit
  3. Select NUnit3TestAdapter ? click Install at the right side ? click OK from the Preview pop up

Enter image description here

How to write :hover using inline style?

Not gonna happen with CSS only

Inline javascript

<a href='index.html' 
    Click Me

In a working draft of the CSS2 spec it was declared that you could use pseudo-classes inline like this:

<a href=""
   style="{color: blue; background: white}  /* a+=0 b+=0 c+=0 */
      :visited {color: green}           /* a+=0 b+=1 c+=0 */
      :hover {background: yellow}       /* a+=0 b+=1 c+=0 */
      :visited:hover {color: purple}    /* a+=0 b+=2 c+=0 */

but it was never implemented in the release of the spec as far as I know.

Get the value of bootstrap Datetimepicker in JavaScript

This is working for me using this Bootsrap Datetimepiker, it returns the value as it is shown in the datepicker input, e.g. 2019-04-11

$('#myDateTimePicker').on('click,focusout', function (){
    var myDate = $("#myDateTimePicker").val();

Why do I get an error instantiating an interface?

It is what it says, you just cannot instantiate an abstract class. You need to implement it first, then instantiate that class.

IUser user = new User();

Differences in string compare methods in C#

with .Equals, you also gain the StringComparison options. very handy for ignoring case and other things.

btw, this will evaluate to false

string a = "myString";
string b = "myString";

return a==b

Since == compares the values of a and b (which are pointers) this will only evaluate to true if the pointers point to the same object in memory. .Equals dereferences the pointers and compares the values stored at the pointers. a.Equals(b) would be true here.

and if you change b to:


then a.Equals(b) is false, but

a.Equals(b, StringComparison.OrdinalIgnoreCase) 

would be true

a.CompareTo(b) calls the string's CompareTo function which compares the values at the pointers and returns <0 if the value stored at a is less than the value stored at b, returns 0 if a.Equals(b) is true, and >0 otherwise. However, this is case sensitive, I think there are possibly options for CompareTo to ignore case and such, but don't have time to look now. As others have already stated, this would be done for sorting. Comparing for equality in this manner would result in unecessary overhead.

I'm sure I'm leaving stuff out, but I think this should be enough info to start experimenting if you need more details.

Creating PHP class instance with a string

Lets say ClassOne is defined as:

public class ClassOne
    protected $arg1;
    protected $arg2;

    public function __construct($arg1, $arg2)
        $this->arg1 = $arg1;
        $this->arg2 = $arg2;

    public function echoArgOne
        echo $this->arg1;


Using PHP Reflection;

$str = "One";
$className = "Class".$str;
$class = new \ReflectionClass($className);

Create a new Instance:

$instance = $class->newInstanceArgs(["Banana", "Apple")]);

Call a method:

//prints "Banana"

Use a variable as a method:

$method = "echoArgOne";

//prints "Banana"

Using Reflection instead of just using the raw string to create an object gives you better control over your object and easier testability (PHPUnit relies heavily on Reflection)

Searching for UUIDs in text with regex

For UUID generated on OS X with uuidgen, the regex pattern is


Verify with

uuidgen | grep -E "[A-F0-9]{8}-[A-F0-9]{4}-4[A-F0-9]{3}-[89AB][A-F0-9]{3}-[A-F0-9]{12}"

Simple and clean way to convert JSON string to Object in Swift

It might be help someone. Similar example.

This is our Codable class to bind data. You can easily create this class using SwiftyJsonAccelerator

 class ModelPushNotificationFilesFile: Codable {

  enum CodingKeys: String, CodingKey {
    case url
    case id
    case fileExtension = "file_extension"
    case name

  var url: String?
  var id: Int?
  var fileExtension: String?
  var name: String?

  init (url: String?, id: Int?, fileExtension: String?, name: String?) {
    self.url = url = id
    self.fileExtension = fileExtension = name

  required init(from decoder: Decoder) throws {
    let container = try decoder.container(keyedBy: CodingKeys.self)
    url = try container.decodeIfPresent(String.self, forKey: .url)
    id = try container.decodeIfPresent(Int.self, forKey: .id)
    fileExtension = try container.decodeIfPresent(String.self, forKey: .fileExtension)
    name = try container.decodeIfPresent(String.self, forKey: .name)


This is Json String

    let jsonString = "[{\"name\":\"\",\"file_extension\":\"\",\"id\":10684,\"url\":\"https:\\/\\/\\/~ece533\\/images\\/tulips.png\"},





Here we convert to swift object.

   let jsonData = Data(jsonString.utf8)

        let decoder = JSONDecoder()

        do {
            let fileArray = try decoder.decode([ModelPushNotificationFilesFile].self, from: jsonData)
        } catch {

AngularJS- Login and Authentication in each route and controller

All have suggested big solution why you are worrying of session on client side. I mean when state/url changes I suppose you are doing an ajax call to load the data for tempelate.

Note :- To Save user's data you may use `resolve` feature of `ui-router`.
 Check cookie if it exist load template , if even cookies doesn't exist than 
there is no chance of logged in , simply redirect to login template/page.

Now the ajax data is returned by server using any api. Now the point came into play , return standard return types using server according to logged in status of user. Check those return codes and process your request in controller. Note:- For controller which doesn't require an ajax call natively , you can call a blank request to server like this server.location/api/checkSession.php and this is checkSession.php

session_start();//You may use your language specific function if required
set_header("200 OK");//this is not right syntax , it is just to hint
set_header("-1 NOT LOGGED_IN");//you may set any code but compare that same       
//code on client side to check if user is logged in or not.

On client side inside controller or through any service as shown in other answers

    .success(function (data){
        $scope.templateData = data;
    .error(function (error, status){
        $ = { message: error, status: status};
//redirect to login

Note :- I will update more tomorrow or in future

Css transition from display none to display block, navigation with subnav

As you know the display property cannot be animated BUT just by having it in your CSS it overrides the visibility and opacity transitions.

The solution...just removed the display properties.

nav.main ul ul {_x000D_
  position: absolute;_x000D_
  list-style: none;_x000D_
  opacity: 0;_x000D_
  visibility: hidden;_x000D_
  padding: 10px;_x000D_
  background-color: rgba(92, 91, 87, 0.9);_x000D_
  -webkit-transition: opacity 600ms, visibility 600ms;_x000D_
  transition: opacity 600ms, visibility 600ms;_x000D_
nav.main ul li:hover ul {_x000D_
  visibility: visible;_x000D_
  opacity: 1;_x000D_
<nav class="main">_x000D_
      <a href="">Lorem</a>_x000D_
        <li><a href="">Ipsum</a>_x000D_
        <li><a href="">Dolor</a>_x000D_
        <li><a href="">Sit</a>_x000D_
        <li><a href="">Amet</a>_x000D_

Creating a UITableView Programmatically

You might be do that its works 100% .

- (void)viewDidLoad
    [super viewDidLoad];
    // init table view
    tableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];

    // must set delegate & dataSource, otherwise the the table will be empty and not responsive
    tableView.delegate = self;
    tableView.dataSource = self;

    tableView.backgroundColor = [UIColor cyanColor];

    // add to canvas
    [self.view addSubview:tableView];

#pragma mark - UITableViewDataSource
// number of section(s), now I assume there is only 1 section
- (NSInteger)numberOfSectionsInTableView:(UITableView *)theTableView
    return 1;

// number of row in the section, I assume there is only 1 row
- (NSInteger)tableView:(UITableView *)theTableView numberOfRowsInSection:(NSInteger)section
    return 1;

// the cell will be returned to the tableView
- (UITableViewCell *)tableView:(UITableView *)theTableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    static NSString *cellIdentifier = @"HistoryCell";

    // Similar to UITableViewCell, but 
    JSCustomCell *cell = (JSCustomCell *)[theTableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (cell == nil) {
        cell = [[JSCustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
    // Just want to test, so I hardcode the data
    cell.descriptionLabel.text = @"Testing";

    return cell;

#pragma mark - UITableViewDelegate
// when user tap the row, what action you want to perform
- (void)tableView:(UITableView *)theTableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    NSLog(@"selected %d row", indexPath.row);


How do you perform address validation?

In the course of developing an in-house address verification service at a German company I used to work for I've come across a number of ways to tackle this issue. I'll do my best to sum up my findings below:

Free, Open Source Software

Clearly, the first approach anyone would take is an open-source one (like, which is never a bad idea. But whether or not you can really put this to good and reliable use depends very much on how much you need to rely on the results.

Addresses are an incredibly variable thing. Verifying U.S. addresses is not an easy task, but bearable, but once you're going for Europe, especially the U.K. with their extensive Postal Code system, the open-source approach will simply lack data.

Web Services / APIs

Enterprise-Class Software

Money gets it done, obviously. But not every business or developer can spend ~$0.15 per address lookup (that's $150 for 1,000 API requests) - a very expensive business model the vast majority of address validation APIs have implemented.

What I ended up integrating: streetlayer API

Since I was not willing to take on the programmatic approach of verifying address data manually I finally came to the conclusion that I was in need of an API with a price tag that would not make my boss want to fire me and still deliver solid and reliable international verification results.

Long story short, I ended up integrating an API built by apilayer, called "streetlayer API". I was easily convinced by a simple JSON integration, surprisingly accurate validation results and their developer-friendly pricing. Also, 100 requests/month are entirely free.

Hope this helps!

Combine Date and Time columns using python pandas

I don't have enough reputation to comment on so:

I had to amend's line for it to work:

df.apply(lambda r : pd.datetime.combine(r['date_column_name'],r['time_column_name']).time(),1)

This might help others.

Also, I have tested a different approach, using replace instead of combine:

def combine_date_time(df, datecol, timecol):
    return df.apply(lambda row: row[datecol].replace(

which in the OP's case would be:

combine_date_time(df, 'Date', 'Time')

I have timed both approaches for a relatively large dataset (>500.000 rows), and they both have similar runtimes, but using combine is faster (59s for replace vs 50s for combine).

What is the difference between Spring, Struts, Hibernate, JavaServer Faces, Tapestry?


Hibernate is used for handling database operations. There is a rich set of database utility functionality, which reduces your number of lines of code. Especially you have to read @Annotation of hibernate. It is an ORM framework and persistence layer.

Spring provides a rich set of the Injection based working mechanism. Currently, Spring is well-known. You have to also read about Spring AOP. There is a bridge between Struts and Hibernate. Mainly Spring provides this kind of utility.

Struts2 provides action based programming. There are a rich set of Struts tags. Struts prove action based programming so you have to maintain all the relevant control of your view.

In Addition, Tapestry is a different framework for Java. In which you have to handle only .tml (template file). You have to create two main files for any class. One is JAVA class and another one is its template. Both names are same. Tapestry automatically calls related classes.

How to install pip for Python 3 on Mac OS X?

Here is my simple solution:

If you have python2 and python3 both installed in your system, the pip upgrade will point to python2 by default. Hence, we must specify the version of python(python3) and use the below command:

python3 -m pip install --upgrade pip

This command will uninstall the previously installed pip and install the new version- upgrading your pip.

This will save memory and declutter your system.

Image - How the upgrading of pip in Python3 works on MacOS

Open File Dialog, One Filter for Multiple Excel Extensions?

Use a semicolon

OpenFileDialog of = new OpenFileDialog();
of.Filter = "Excel Files|*.xls;*.xlsx;*.xlsm";

Differences between JDK and Java SDK

The JDK (Java Development Kit) is an SDK (Software Dev Kit).

It is used to build software/applications on Java and of course it includes the JRE (Java Runtime Edition) to execute that software. If you just want to execute a Java application, download only the JRE.

By the way, Java EE (Enterprise Edition) contains libraries of packages of classes "with methods (functions)" to build apps for the WEB environment and Java ME (Micro Edition) for mobile devices. If you are interested in it (Java ME) I would recommend to take a look at Google's Android DevKit and API.

Take a look here: it's gonna explain bit more..

What's the fastest way to convert String to Number in JavaScript?

A fast way to convert strings to an integer is to use a bitwise or, like so:

x | 0

While it depends on how it is implemented, in theory it should be relatively fast (at least as fast as +x) since it will first cast x to a number and then perform a very efficient or.

Decimal precision and scale in EF Code First

In EF6

    .Where(x => x.GetCustomAttributes(false).OfType<DecimalPrecisionAttribute>().Any())
    .Configure(c => {
        var attr = (DecimalPrecisionAttribute)c.ClrPropertyInfo.GetCustomAttributes(typeof (DecimalPrecisionAttribute), true).FirstOrDefault();

        c.HasPrecision(attr.Precision, attr.Scale);

How can I set size of a button?

Try with setPreferredSize instead of setSize.

UPDATE: GridLayout take up all space in its container, and BoxLayout seams to take up all the width in its container, so I added some glue-panels that are invisible and just take up space when the user stretches the window. I have just done this horizontally, and not vertically, but you could implement that in the same way if you want it.

Since GridLayout make all cells in the same size, it doesn't matter if they have a specified size. You have to specify a size for its container instead, as I have done.

import javax.swing.*;
import java.awt.*;

public class PanelModel {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Colored Trails");

        JPanel mainPanel = new JPanel();
        mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));

        JPanel firstPanel = new JPanel(new GridLayout(4, 4));
        firstPanel.setPreferredSize(new Dimension(4*100, 4*100));
        for (int i=1; i<=4; i++) {
            for (int j=1; j<=4; j++) {
                firstPanel.add(new JButton());

        JPanel firstGluePanel = new JPanel(new BorderLayout());
        firstGluePanel.add(firstPanel, BorderLayout.WEST);
        firstGluePanel.add(Box.createHorizontalGlue(), BorderLayout.CENTER);
        firstGluePanel.add(Box.createVerticalGlue(), BorderLayout.SOUTH);

        JPanel secondPanel = new JPanel(new GridLayout(13, 5));
        secondPanel.setPreferredSize(new Dimension(5*40, 13*40));
        for (int i=1; i<=5; i++) {
            for (int j=1; j<=13; j++) {
                secondPanel.add(new JButton());

        JPanel secondGluePanel = new JPanel(new BorderLayout());
        secondGluePanel.add(secondPanel, BorderLayout.WEST);
        secondGluePanel.add(Box.createHorizontalGlue(), BorderLayout.CENTER);
        secondGluePanel.add(Box.createVerticalGlue(), BorderLayout.SOUTH);



Arduino Nano - "avrdude: ser_open():system can't open device "\\.\COM1": the system cannot find the file specified"

This is how I solved the problem. In Device Manager you will find the Arduino COM port.

Enter image description here

Go to the Advanced properties of the port

Enter image description here

Set the COM port number to COM1.

Enter image description here

Then replug the USB.

Extract data from log file in specified range of time

I used this command to find last 5 minutes logs for particular event "DHCPACK", try below:

$ grep "DHCPACK" /var/log/messages | grep "$(date +%h\ %d) [$(date --date='5 min ago' %H)-$(date +%H)]:*:*"

pandas: find percentile stats of a given column

I figured out below would work:

my_df.dropna().quantile([0.0, .9])

Using 'starts with' selector on individual class names

Try this:

$("div[class]").filter(function() {
    var classNames = this.className.split(/\s+/);
    for (var i=0; i<classNames.length; ++i) {
        if (classNames[i].substr(0, 6) === "apple-") {
            return true;
    return false;

What type of hash does WordPress use?

MD5 worked for me changing my database manually. See: Resetting Your Password

Child element click event trigger the parent click event

You need to use event.stopPropagation()

Live Demo



Description: Prevents the event from bubbling up the DOM tree, preventing any parent handlers from being notified of the event.

How do I resolve a HTTP 414 "Request URI too long" error?

I have a simple workaround.

Suppose your URI has a string stringdata that is too long. You can simply break it into a number of parts depending on the limits of your server. Then submit the first one, in my case to write a file. Then submit the next ones to append to previously added data.

Laravel Eloquent get results grouped by days

this way work properly and I used it in many projects! for example I get data of views the last 30 days:

$viewsData = DB::table('page_views')
    ->where('page_id', $page->id)
    ->whereDate('created_at', '>=', now()->subDays(30))
    ->select(DB::raw('DATE(created_at) as data'), DB::raw('count(*) as views'))

If you want to get the number of views based on different IPs, you can use the DISTINCT like below :

$viewsData = DB::table('page_views')
    ->where('page_id', $page->id)
    ->whereDate('created_at', '>=', now()->subDays(30))
    ->select(DB::raw('DATE(created_at) as data'), DB::raw('count(DISTINCT user_ip) as visitors'))

You can easily customize it by manipulating the columns name

How to append elements into a dictionary in Swift?

In Swift, if you are using NSDictionary, you can use setValue:

dict.setValue("value", forKey: "key")

Maven not found in Mac OSX mavericks

Maven is not installed any more by default on Mac OS X 10.9. You need to install it yourself, for example using Homebrew.

The command to install Maven using Homebrew is brew install maven

How to specify a editor to open crontab file? "export EDITOR=vi" does not work

Very probable that your VISUAL environment variable is set to something else. Try:

export VISUAL=vi

How do I get a consistent byte representation of strings in C# without manually specifying an encoding?

The closest approach to the OP's question is Tom Blodget's, which actually goes into the object and extracts the bytes. I say closest because it depends on implementation of the String Object.

"Can't I simply get what bytes the string has been stored in?"

Sure, but that's where the fundamental error in the question arises. The String is an object which could have an interesting data structure. We already know it does, because it allows unpaired surrogates to be stored. It might store the length. It might keep a pointer to each of the 'paired' surrogates allowing quick counting. Etc. All of these extra bytes are not part of the character data.

What you want is each character's bytes in an array. And that is where 'encoding' comes in. By default you will get UTF-16LE. If you don't care about the bytes themselves except for the round trip then you can choose any encoding including the 'default', and convert it back later (assuming the same parameters such as what the default encoding was, code points, bug fixes, things allowed such as unpaired surrogates, etc.

But why leave the 'encoding' up to magic? Why not specify the encoding so that you know what bytes you are gonna get?

"Why is there a dependency on character encodings?"

Encoding (in this context) simply means the bytes that represent your string. Not the bytes of the string object. You wanted the bytes the string has been stored in -- this is where the question was asked naively. You wanted the bytes of string in a contiguous array that represent the string, and not all of the other binary data that a string object may contain.

Which means how a string is stored is irrelevant. You want a string "Encoded" into bytes in a byte array.

I like Tom Bloget's answer because he took you towards the 'bytes of the string object' direction. It's implementation dependent though, and because he's peeking at internals it might be difficult to reconstitute a copy of the string.

Mehrdad's response is wrong because it is misleading at the conceptual level. You still have a list of bytes, encoded. His particular solution allows for unpaired surrogates to be preserved -- this is implementation dependent. His particular solution would not produce the string's bytes accurately if GetBytes returned the string in UTF-8 by default.

I've changed my mind about this (Mehrdad's solution) -- this isn't getting the bytes of the string; rather it is getting the bytes of the character array that was created from the string. Regardless of encoding, the char datatype in c# is a fixed size. This allows a consistent length byte array to be produced, and it allows the character array to be reproduced based on the size of the byte array. So if the encoding were UTF-8, but each char was 6 bytes to accommodate the largest utf8 value, it would still work. So indeed -- encoding of the character does not matter.

But a conversion was used -- each character was placed into a fixed size box (c#'s character type). However what that representation is does not matter, which is technically the answer to the OP. So -- if you are going to convert anyway... Why not 'encode'?

Is it better to use NOT or <> when comparing values?

Agreed, code readability is very important for others, but more importantly yourself. Imagine how difficult it would be to understand the first example in comparison to the second.

If code takes more than a few seconds to read (understand), perhaps there is a better way to write it. In this case, the second way.

git add only modified changes and ignore untracked files

Not sure if this is a feature or a bug but this worked for us:

git commit '' -m "Message"

Note the empty file list ''. Git interprets this to commit all modified tracked files, even if they are not staged, and ignore untracked files.

Insert data into table with result from another select query

If table_2 is empty, then try the following insert statement:

insert into table_2 (itemid,location1) 
select itemid,quantity from table_1 where locationid=1

If table_2 already contains the itemid values, then try this update statement:

update table_2 set location1=
(select quantity from table_1 where locationid=1 and table_1.itemid = table_2.itemid)

Open directory dialog

I created a UserControl which is used like this:

  <UtilitiesWPF:FolderEntry Text="{Binding Path=LogFolder}" Description="Folder for log files"/>

The xaml source looks like this:

<UserControl x:Class="Utilities.WPF.FolderEntry"
        <Button Margin="0" Padding="0" DockPanel.Dock="Right" Width="Auto" Click="BrowseFolder">...</Button>
        <TextBox Height="Auto" HorizontalAlignment="Stretch" DockPanel.Dock="Right" 
           Text="{Binding Text, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}" />

and the code-behind

public partial class FolderEntry {
    public static DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof(string), typeof(FolderEntry), new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
    public static DependencyProperty DescriptionProperty = DependencyProperty.Register("Description", typeof(string), typeof(FolderEntry), new PropertyMetadata(null));

    public string Text { get { return GetValue(TextProperty) as string; } set { SetValue(TextProperty, value); }}

    public string Description { get { return GetValue(DescriptionProperty) as string; } set { SetValue(DescriptionProperty, value); } }

    public FolderEntry() { InitializeComponent(); }

    private void BrowseFolder(object sender, RoutedEventArgs e) {
        using (FolderBrowserDialog dlg = new FolderBrowserDialog()) {
            dlg.Description = Description;
            dlg.SelectedPath = Text;
            dlg.ShowNewFolderButton = true;
            DialogResult result = dlg.ShowDialog();
            if (result == System.Windows.Forms.DialogResult.OK) {
                Text = dlg.SelectedPath;
                BindingExpression be = GetBindingExpression(TextProperty);
                if (be != null)

Adding a collaborator to my free GitHub account?

In the repository, click Admin, then go to the Collaborators tab.

YouTube Autoplay not working

You can use embed player with opacity over on a cover photo with a right positioned play icon. After this you can check the activeElement of your document.

Of course I know this is not an optimal solution, but works on mobile devices too.

<div style="position: relative;">
   <img src="" style="position:absolute;top:0;left:0;opacity:1;" id="cover">
   <iframe width="560" height="315" src="" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in- picture" allowfullscreen style="position: absolute;top:0;left:0;opacity:0;" id="player"></iframe>
      if(document.activeElement instanceof HTMLIFrameElement){
    } , 50);

Try it on codepen:

How do I mock a REST template exchange?

If you are using RestTemplateBuilder may be the usual thing wouldn't work. You need to add this in your test class along with when(condition).

public void setup() {        
     ReflectionTestUtils.setField(service, "restTemplate", restTemplate);    

Make div fill remaining space along the main axis in flexbox

Use the flex-grow property to make a flex item consume free space on the main axis.

This property will expand the item as much as possible, adjusting the length to dynamic environments, such as screen re-sizing or the addition / removal of other items.

A common example is flex-grow: 1 or, using the shorthand property, flex: 1.

Hence, instead of width: 96% on your div, use flex: 1.

You wrote:

So at the moment, it's set to 96% which looks OK until you really squash the screen - then the right hand div gets a bit starved of the space it needs.

The squashing of the fixed-width div is related to another flex property: flex-shrink

By default, flex items are set to flex-shrink: 1 which enables them to shrink in order to prevent overflow of the container.

To disable this feature use flex-shrink: 0.

For more details see The flex-shrink factor section in the answer here:

Learn more about flex alignment along the main axis here:

Learn more about flex alignment along the cross axis here:

How can I get session id in php and show it?

I would not recommend you to start session just to get some unique id. Instead, use such things as uniqid() because it's intended to return unique id.

However, if you already have session, then, of course, use session_id() to get your session id - but do not rely on that, because "unique id" isn't same as "session id" in common sense: for example, multiple tabs in most browsers will use same process, thus, use same session identifier in result - and, therefore, different connections will have same id. It's your decision about desired behavior, I've mentioned this just to show the difference between session id and unique id.

Compilation error - missing zlib.h

In openSUSE 19.2 installing the patterns-hpc-development_node package fixed this issue for me.

setTimeout in for-loop does not print consecutive values

You can use an immediately-invoked function expression (IIFE) to create a closure around setTimeout:

for (var i = 1; i <= 3; i++) {_x000D_
    (function(index) {_x000D_
        setTimeout(function() { alert(index); }, i * 1000);_x000D_

Change arrow colors in Bootstraps carousel

This worked for me:

.carousel-control-prev-icon {
        background-image: url("data:image/svg+xml,%3csvg xmlns='' fill='%23000' width='8' height='8' viewBox='0 0 8 8'%3e%3cpath d='M5.25 0l-4 4 4 4 1.5-1.5L4.25 4l2.5-2.5L5.25 0z'/%3e%3c/svg%3e");
      .carousel-control-next-icon {
        background-image: url("data:image/svg+xml,%3csvg xmlns='' fill='%23000' width='8' height='8' viewBox='0 0 8 8'%3e%3cpath d='M2.75 0l-1.5 1.5L3.75 4l-2.5 2.5L2.75 8l4-4-4-4z'/%3e%3c/svg%3e");

I changed the color in the url of the icon. Thats the original that is used in the bootstrap page but with this section in black:


Get first element in PHP stdObject

Update PHP 7.4

Curly brace access syntax is deprecated since PHP 7.4

Update 2019

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

Simply iterate its using {}



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

For PHP 5.6 and below use this


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

So, if your object looks like

object(stdClass)#19 (3) {
  object(stdClass)#20 (22) {
    string(1) "123"

Then you can just do;

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

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

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

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

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

In newer versions of PHP, use the ArrayIterator class:

$objIterator = new ArrayIterator($obj);

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

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

Popup window in PHP?

PHP runs on the server-side thus you have to use a client-side technology which is capable of showing popup windows: JavaScript.

So you should output a specific JS block via PHP if your form contains errors and you want to show that popup.

remove inner shadow of text input

Set border: 1px solid black to make all sides equals and remove any kind of custom border (other than solid). Also, set box-shadow: none to remove any inset shadow applied to it.

'pip install' fails for every package ("Could not find a version that satisfies the requirement")

Support for TLS 1.0 and 1.1 was dropped for PyPI. If your system does not use a more recent version, it could explain your error.

Could you try reinstalling pip system-wide, to update your system dependencies to a newer version of TLS?

This seems to be related to Unable to install Python libraries

See Dominique Barton's answer:

Apparently pip is trying to access PyPI via HTTPS (which is encrypted and fine), but with an old (insecure) SSL version. Your system seems to be out of date. It might help if you update your packages.

On Debian-based systems I'd try:

apt-get update && apt-get upgrade python-pip

On Red Hat Linux-based systems:

yum update python-pip # (or python2-pip, at least on Red Hat Linux 7)

On Mac:

sudo easy_install -U pip

You can also try to update openssl separately.

How to sort an ArrayList?

For example I have a class Person: String name, int age ==>Constructor new Person(name,age)

import java.util.Collections;
import java.util.ArrayList;
import java.util.Arrays;

public void main(String[] args){
    Person ibrahima=new Person("Timera",40);
    Person toto=new Person("Toto",35);
    Person alex=new Person("Alex",50);
    ArrayList<Person> myList=new ArrayList<Person>
    Collections.sort(myList, new Comparator<Person>() {
        public int compare(Person p1, Person p2) {
            // return p1.age+"".compareTo(p2.age+""); //sort by age
            return; // if you want to short by name
    //[Person [name=Alex, age=50], Person [name=Timera, age=40], Person [name=Toto, age=35]]
    //[Person [name=Toto, age=35], Person [name=Timera, age=40], Person [name=Alex, age=50]]


How do I remove/delete a folder that is not empty?

import shutil


Standard Library Reference: shutil.rmtree.

By design, rmtree fails on folder trees containing read-only files. If you want the folder to be deleted regardless of whether it contains read-only files, then use

shutil.rmtree('/folder_name', ignore_errors=True)

Check if element found in array c++

One wants this to be done tersely. Nothing makes code more unreadable then spending 10 lines to achieve something elementary. In C++ (and other languages) we have all and any which help us to achieve terseness in this case. I want to check whether a function parameter is valid, meaning equal to one of a number of values. Naively and wrongly, I would first write

if (!any_of({ DNS_TYPE_A, DNS_TYPE_MX }, wtype) return false;

a second attempt could be

if (!any_of({ DNS_TYPE_A, DNS_TYPE_MX }, [&wtype](const int elem) { return elem == wtype; })) return false;

Less incorrect, but looses some terseness. However, this is still not correct because C++ insists in this case (and many others) that I specify both start and end iterators and cannot use the whole container as a default for both. So, in the end:

const vector validvalues{ DNS_TYPE_A, DNS_TYPE_MX };
if (!any_of(validvalues.cbegin(),  validvalues.cend(), [&wtype](const int elem) { return elem == wtype; })) return false;

which sort of defeats the terseness, but I don't know a better alternative... Thank you for not pointing out that in the case of 2 values I could just have just if ( || ). The best approach here (if possible) is to use a case structure with a default where not only the values are checked, but also the appropriate actions are done. The default case can be used for signalling an invalid value.

How to replace all special character into a string using C#

Assume you want to replace symbols which are not digits or letters (and _ character as @Guffa correctly pointed):

string input = "Hello@Hello&Hello(Hello)";
string result = Regex.Replace(input, @"[^\w\d]", ",");
// Hello,Hello,Hello,Hello,

You can add another symbols which should not be replaced. E.g. if you want white space symbols to stay, then just add \s to pattern: \[^\w\d\s]

What exactly is \r in C language?

' \r ' means carriage return.

The \r means nothing special as a consequence.For character-mode terminals (typically emulating even-older printing ones as above), in raw mode, \r and \n act similarly (except both in terms of the cursor, as there is no carriage or roller . Historically a \n was used to move the carriage down, while the \r was used to move the carriage back to the left side of the screen.

How can I prevent the backspace key from navigating back?


I was worried about performance and made a fiddle:

var stresstest = function(e, method, index){...

I have analyzed the most promising methods i found in this thread. It turns out, they were all very fast and most probably do not cause a problem in terms of "sluggishness" when typing. The slowest Method i looked at was about 125 ms for 10.000 Calls in IE8. Which is 0.0125ms per Stroke.

I found the methods posted by Codenepal and Robin Maben to be fastest ~ 0.001ms (IE8) but beware of the different semantics.

Perhaps this is a relief to someone introducing this kind of functionality to his code.

Genymotion, "Unable to load VirtualBox engine." on Mavericks. VBox is setup correctly

Eventually, you might not have anything in your /Library/StartupItems.

Using the following command helps :

sudo /Library/Application\ Support/VirtualBox/LaunchDaemons/ restart

It worked for me on two different Mavericks installs.

Git error: "Please make sure you have the correct access rights and the repository exists"

  1. The first thing you may want to confirm is the internet connection. Though, internet issues mostly will say that the repo cannot be accessed.

  2. Ensure you have set up ssh both locally and on your github. See how

  3. Ensure you are using the ssh git remote. If you had cloned the https, just set the url to the ssh url, with this git command git remote set-url origin [email protected]:your-username/your-repo-name.git

  4. If you have set up ssh properly but it just stopped working, do the following:

    • eval "$(ssh-agent -s)"
    • ssh-add

    If you are still having the issue, check to ensure that you have not deleted the ssh from your github. In a case where the ssh has been deleted from github, you can add it back. Use pbcopy < ~/.ssh/ to copy the ssh key and then go to your github ssh setting and add it.

I will recommend you always use ssh. For most teams I've worked with, you can't access the repo (which are mostly private) except you use ssh. For a beginner, it may appear to be harder but later you'll find it quite easier and more secured.

How do I verify/check/test/validate my SSH passphrase?

You can verify your SSH key passphrase by attempting to load it into your SSH agent. With OpenSSH this is done via ssh-add.

Once you're done, remember to unload your SSH passphrase from the terminal by running ssh-add -d.

MongoDB relationships: embed or reference?

MongoDB gives freedom to be schema-less and this feature can result in pain in the long term if not thought or planned well,

There are 2 options either Embed or Reference. I will not go through definitions as the above answers have well defined them.

When embedding you should answer one question is your embedded document going to grow, if yes then how much (remember there is a limit of 16 MB per document) So if you have something like a comment on a post, what is the limit of comment count, if that post goes viral and people start adding comments. In such cases, reference could be a better option (but even reference can grow and reach 16 MB limit).

So how to balance it, the answer is a combination of different patterns, check these links, and create your own mix and match based on your use case.

What is the best way to access redux store outside a react component?

Found a solution. So I import the store in my api util and subscribe to it there. And in that listener function I set the axios' global defaults with my newly fetched token.

This is what my new api.js looks like:

// tooling modules
import axios from 'axios'

// store
import store from '../store'

function select(state) {
  return state.auth.tokens.authentication_token

function listener() {
  let token = select(store.getState())
  axios.defaults.headers.common['Authorization'] = token;

// configuration
const api = axios.create({
  baseURL: 'http://localhost:5001/api/v1',
  headers: {
    'Content-Type': 'application/json',

export default api

Maybe it can be further improved, cause currently it seems a bit inelegant. What I could do later is add a middleware to my store and set the token then and there.

Using BigDecimal to work with currencies

There is an extensive example of how to do this on See in particular the Money class, which is meant to make monetary calculations simpler than using BigDecimal directly.

The design of this Money class is intended to make expressions more natural. For example:

if ( ) {
 cost = amount.times(price); 

The WEB4J tool has a similar class, called Decimal, which is a bit more polished than the Money class.

Sending mail from Python using SMTP

Based on this example I made following function:

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

def send_email(host, port, user, pwd, recipients, subject, body, html=None, from_=None):
    """ copied and adapted from
    returns None if all ok, but if problem then returns exception object

    PORT_LIST = (25, 587, 465)

    FROM = from_ if from_ else user 
    TO = recipients if isinstance(recipients, (list, tuple)) else [recipients]
    SUBJECT = subject
    TEXT = body.encode("utf8") if isinstance(body, unicode) else body
    HTML = html.encode("utf8") if isinstance(html, unicode) else html

    if not html:
        # Prepare actual message
        message = """From: %s\nTo: %s\nSubject: %s\n\n%s
        """ % (FROM, ", ".join(TO), SUBJECT, TEXT)
        msg = MIMEMultipart('alternative')
        msg['Subject'] = SUBJECT
        msg['From'] = FROM
        msg['To'] = ", ".join(TO)

        # Record the MIME types of both parts - text/plain and text/html.
        # utf-8 ->
        part1 = MIMEText(TEXT, 'plain', "utf-8")
        part2 = MIMEText(HTML, 'html', "utf-8")

        # Attach parts into message container.
        # According to RFC 2046, the last part of a multipart message, in this case
        # the HTML message, is best and preferred.

        message = msg.as_string()

        if port not in PORT_LIST: 
            raise Exception("Port %s not one of %s" % (port, PORT_LIST))

        if port in (465,):
            server = smtplib.SMTP_SSL(host, port)
            server = smtplib.SMTP(host, port)

        # optional

        if port in (587,): 

        server.login(user, pwd)
        server.sendmail(FROM, TO, message)
        #"SENT_EMAIL to %s: %s" % (recipients, subject))
    except Exception, ex:
        return ex

    return None

if you pass only body then plain text mail will be sent, but if you pass html argument along with body argument, html email will be sent (with fallback to text content for email clients that don't support html/mime types).

Example usage:

ex = send_email(
      host        = ''
   #, port        = 465 # OK
    , port        = 587  #OK
    , user        = "[email protected]"
    , pwd         = "xxx"
    , from_       = '[email protected]'
    , recipients  = ['[email protected]']
    , subject     = "Test from python"
    , body        = "Test from python - body"
if ex: 
    print("Mail sending failed: %s" % ex)
    print("OK - mail sent"

Btw. If you want to use gmail as testing or production SMTP server, enable temp or permanent access to less secured apps:

What is the meaning of ToString("X2")?

ToString("X2") prints the input in Hexadecimal

Compilation fails with "relocation R_X86_64_32 against `.rodata.str1.8' can not be used when making a shared object"

It is not always about the compilation flags, I have the same error on gentoo when using distcc.

The reason is that on distcc server is using a not-hardened profile and on client the profile is hardened. Check this discussion:

How to install XNA game studio on Visual Studio 2012?

On codeplex was released new XNA Extension for Visual Studio 2012/2013. You can download it from:

Is it possible to change the radio button icon in an android radio button group

The easier way to only change the radio button is simply set selector for drawable right

    android:drawableRight="@drawable/radio_button_selector" />

And the selector is:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="">
    <item android:drawable="@drawable/ic_checkbox_checked" android:state_checked="true" />
    <item android:drawable="@drawable/ic_checkbox_unchecked" android:state_checked="false" /></selector>

That's all

How to install beautiful soup 4 with python 2.7 on windows

easy_install BeautifulSoup4


easy_install BeautifulSoup 

to install easy_install

How to get text from EditText?

Well, it depends on your needs. Very often I keep my references to widgets in activity (as a class fields) - and set them in onCreate method. I think that is a good idea
Probably the reason for your nulls is that you are trying to call findViewById() before you set contentView() in your onCreate() method - please check that.

How to update ruby on linux (ubuntu)?

Ruby is v2.0 now. Programs like Jekyll (and I am sure many others) require it. I just ran:

sudo apt-get install ruby2.0

check version

ruby --version

Hope that helps

How do you set the Content-Type header for an HttpClient request?

try to use TryAddWithoutValidation

  var client = new HttpClient();
  client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/json; charset=utf-8");

How to clear variables in ipython?

Adding the following lines to a new script will clear all variables each time you rerun the script:

from IPython import get_ipython
get_ipython().magic('reset -sf') 

To make life easy, you can add them to your default template.

In Spyder: Tools>Preferences>Editor>Edit template

Jquery Open in new Tab (_blank)

window.location always refers to the location of the current window. Changing it will affect only the current window.

One thing that can be done is forcing a click on the link after setting its target attribute to _blank:

Check this:

Disclaimer: Its my blog.

Batch files: List all files in a directory with relative paths

Of course, you may write a recursive algorithm in Batch that gives you exact control of what you do in every nested subdirectory:

@echo off
set mypath=
call :treeProcess
goto :eof

for %%f in (*.txt) do echo %mypath%%%f
for /D %%d in (*) do (
    set mypath=%mypath%%%d\
    cd %%d
    call :treeProcess
    cd ..
exit /b

How do I auto size columns through the Excel interop objects?

This method opens already created excel file, Autofit all columns of all sheets based on 3rd Row. As you can see Range is selected From "A3 to K3" in excel.

 public static void AutoFitExcelSheets()
        Microsoft.Office.Interop.Excel.Application _excel = null;
        Microsoft.Office.Interop.Excel.Workbook excelWorkbook = null;
            string ExcelPath = ApplicationData.PATH_EXCEL_FILE;
            _excel = new Microsoft.Office.Interop.Excel.Application();
            _excel.Visible = false;
            object readOnly = false;
            object isVisible = true;
            object missing = System.Reflection.Missing.Value;

            excelWorkbook = _excel.Workbooks.Open(ExcelPath,
                   0, false, 5, "", "", false, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "",
                   true, false, 0, true, false, false);
            Microsoft.Office.Interop.Excel.Sheets excelSheets = excelWorkbook.Worksheets;
            foreach (Microsoft.Office.Interop.Excel.Worksheet currentSheet in excelSheets)
                string Name = currentSheet.Name;
                Microsoft.Office.Interop.Excel.Worksheet excelWorksheet = (Microsoft.Office.Interop.Excel.Worksheet)excelSheets.get_Item(Name);
                Microsoft.Office.Interop.Excel.Range excelCells =
(Microsoft.Office.Interop.Excel.Range)excelWorksheet.get_Range("A3", "K3");
        catch (Exception ex)
            ProjectLog.AddError("EXCEL ERROR: Can not AutoFit: " + ex.Message);
            excelWorkbook.Close(true, Type.Missing, Type.Missing);

Merge Two Lists in R

This is a very simple adaptation of the modifyList function by Sarkar. Because it is recursive, it will handle more complex situations than mapply would, and it will handle mismatched name situations by ignoring the items in 'second' that are not in 'first'.

appendList <- function (x, val) 
    stopifnot(is.list(x), is.list(val))
    xnames <- names(x)
    for (v in names(val)) {
        x[[v]] <- if (v %in% xnames && is.list(x[[v]]) && is.list(val[[v]])) 
            appendList(x[[v]], val[[v]])
        else c(x[[v]], val[[v]])

> appendList(first,second)
[1] 1 2

[1] 2 3

[1] 3 4

How do I rotate the Android emulator display?

You can use Numpad-9 and Numpad-7 to rotate on Windows and Ubuntu.

regex with space and letters only?

$('#input').on('keyup', function() {
     var RegExpression = /^[a-zA-Z\s]*$/;  


\s will allow the space

Install NuGet via PowerShell script

  1. Run Powershell with Admin rights
  2. Type the below PowerShell security protocol command for TLS12:
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

Why doesn't java.util.Set have get(int index)?

To get element in a Set, i use to following one:

public T getElement(Set<T> set, T element) {
T result = null;
if (set instanceof TreeSet<?>) {
    T floor = ((TreeSet<T>) set).floor(element);
    if (floor != null && floor.equals(element))
    result = floor;
} else {
    boolean found = false;
    for (Iterator<T> it = set.iterator(); !found && it.hasNext();) {
    if (true) {
        T current =;
        if (current.equals(element)) {
        result = current;
        found = true;
return result;

Python dict how to create key or append an element to key?

You can use a defaultdict for this.

from collections import defaultdict
d = defaultdict(list)

This is slightly more efficient than setdefault since you don't end up creating new lists that you don't end up using. Every call to setdefault is going to create a new list, even if the item already exists in the dictionary.

String comparison using '==' vs. 'strcmp()'

The reason to use it is because strcmp

returns < 0 if str1 is less than str2; > 0 if str1 is greater than str2, and 0 if they are equal.

=== only returns true or false, it doesn't tell you which is the "greater" string.

How can I resize an image dynamically with CSS as the browser width/height changes?


   width:100vw; /* Matches to the Viewport Width */
   max-width:100% !important;

Only works with display block and inline block, this has no effect on flex items as I've just spent ages trying to find out.

Mythical man month 10 lines per developer day - how close on large projects?

One suspects this perennial bit of manager-candy was coined when everything was a sys app written in C because if nothing else the magic number would vary by orders of magnitude depending on the language, scale and nature of the application. And then you have to discount comments and attributes. And ultimately who cares about the number of lines of code written? Are you supposed to be finished when you've reach 10K lines? 100K? So arbitrary.

It's useless.

Proper use cases for Android UserManager.isUserAGoat()?

There's a funny named method/constant/whatever in each version of Android.

The only practical use I ever saw was in the Last Call for Google I/O Contest where they asked what it was for a particular version, to see if contestants read the API diff report for each release. The contest had programming problems too, but generally some trivia that could be graded automatically first to get the number of submissions down to reasonable amounts that would be easier to check.

How to compare DateTime in C#?

//Time compare.
private int CompareTime(string t1, string t2)
    TimeSpan s1 = TimeSpan.Parse(t1);
    TimeSpan s2 = TimeSpan.Parse(t2);
    return s2.CompareTo(s1);

Attempt to set a non-property-list object as an NSUserDefaults

A default object must be a property list—that is, an instance of (or for collections, a combination of instances of): NSData, NSString, NSNumber, NSDate, NSArray, or NSDictionary.

If you want to store any other type of object, you should typically archive it to create an instance of NSData. For more details, see Preferences and Settings Programming Guide.

csv.Error: iterator should return strings, not bytes

The reason it is throwing that exception is because you have the argument rb, which opens the file in binary mode. Change that to r, which will by default open the file in text mode.

Your code:

import csv
ifile  = open('sample.csv', "rb")
read = csv.reader(ifile)
for row in read :
    print (row) 

New code:

import csv
ifile  = open('sample.csv', "r")
read = csv.reader(ifile)
for row in read :
    print (row)

How to get resources directory path programmatically

Just use class. Example:

 URL url = Resources.getResource("file name")

After that you have methods like: .getContent(), .getFile(), .getPath() etc

Check if object value exists within a Javascript array of objects and if not add a new object to array

Let's assume we have an array of objects and you want to check if value of name is defined like this,

let persons = [ {"name" : "test1"},{"name": "test2"}];

if(persons.some(person => == 'test1')) {
    ... here your code in case is defined and available

How to round up a number to nearest 10?

floor() will go down.

ceil() will go up.

round() will go to nearest by default.

Divide by 10, do the ceil, then multiply by 10 to reduce the significant digits.

$number = ceil($input / 10) * 10;

Edit: I've been doing it this way for so long.. but TallGreenTree's answer is cleaner.

Counting the number of files in a directory using Java

Since Java 8, you can do that in three lines:

try (Stream<Path> files = Files.list(Paths.get("your/path/here"))) {
    long count = files.count();

Regarding the 5000 child nodes and inode aspects:

This method will iterate over the entries but as Varkhan suggested you probably can't do better besides playing with JNI or direct system commands calls, but even then, you can never be sure these methods don't do the same thing!

However, let's dig into this a little:

Looking at JDK8 source, Files.list exposes a stream that uses an Iterable from Files.newDirectoryStream that delegates to FileSystemProvider.newDirectoryStream.

On UNIX systems (decompiled sun.nio.fs.UnixFileSystemProvider.class), it loads an iterator: A sun.nio.fs.UnixSecureDirectoryStream is used (with file locks while iterating through the directory).

So, there is an iterator that will loop through the entries here.

Now, let's look to the counting mechanism.

The actual count is performed by the count/sum reducing API exposed by Java 8 streams. In theory, this API can perform parallel operations without much effort (with multihtreading). However the stream is created with parallelism disabled so it's a no go...

The good side of this approach is that it won't load the array in memory as the entries will be counted by an iterator as they are read by the underlying (Filesystem) API.

Finally, for the information, conceptually in a filesystem, a directory node is not required to hold the number of the files that it contains, it can just contain the list of it's child nodes (list of inodes). I'm not an expert on filesystems, but I believe that UNIX filesystems work just like that. So you can't assume there is a way to have this information directly (i.e: there can always be some list of child nodes hidden somewhere).

jQuery Datepicker localization

You can do like this

 $.datepicker.regional['fr'] = {clearText: 'Effacer', clearStatus: '',
    closeText: 'Fermer', closeStatus: 'Fermer sans modifier',
    prevText: '&lt;Préc', prevStatus: 'Voir le mois précédent',
    nextText: 'Suiv&gt;', nextStatus: 'Voir le mois suivant',
    currentText: 'Courant', currentStatus: 'Voir le mois courant',
    monthNames: ['Janvier','Février','Mars','Avril','Mai','Juin',
    monthNamesShort: ['Jan','Fév','Mar','Avr','Mai','Jun',
    monthStatus: 'Voir un autre mois', yearStatus: 'Voir un autre année',
    weekHeader: 'Sm', weekStatus: '',
    dayNames: ['Dimanche','Lundi','Mardi','Mercredi','Jeudi','Vendredi','Samedi'],
    dayNamesShort: ['Dim','Lun','Mar','Mer','Jeu','Ven','Sam'],
    dayNamesMin: ['Di','Lu','Ma','Me','Je','Ve','Sa'],
    dayStatus: 'Utiliser DD comme premier jour de la semaine', dateStatus: 'Choisir le DD, MM d',
    dateFormat: 'dd/mm/yy', firstDay: 0, 
    initStatus: 'Choisir la date', isRTL: false};

HRESULT: 0x80131040: The located assembly's manifest definition does not match the assembly reference

In my particular situation, I got this as a result of a CreateObject done in VBScript. The cause in my case was a version of the assembly that resided in the GAC, that was older than the one I had compiled. (trying to solve an earlier problem, I installed the assembly in the GAC).

So, if you're working with COM visible classes, then be sure you remove older versions of your assembly from the GAC, before registering your new assembly with RegASM.

Find the PID of a process that uses a port on Windows

PowerShell (Core-compatible) one-liner to ease copypaste scenarios:

netstat -aon | Select-String 8080 | ForEach-Object { $_ -replace '\s+', ',' } | ConvertFrom-Csv -Header @('Empty', 'Protocol', 'AddressLocal', 'AddressForeign', 'State', 'PID') | ForEach-Object { $portProcess = Get-Process | Where-Object Id -eq $_.PID; $_ | Add-Member -NotePropertyName 'ProcessName' -NotePropertyValue $portProcess.ProcessName; Write-Output $_ } | Sort-Object ProcessName, State, Protocol, AddressLocal, AddressForeign | Select-Object  ProcessName, State, Protocol, AddressLocal, AddressForeign | Format-Table


ProcessName State     Protocol AddressLocal AddressForeign
----------- -----     -------- ------------ --------------
System      LISTENING TCP      [::]:8080    [::]:0

Same code, developer-friendly:

$Port = 8080

# Get PID's listening to $Port, as PSObject
$PidsAtPortString = netstat -aon `
  | Select-String $Port
$PidsAtPort = $PidsAtPortString `
  | ForEach-Object { `
      $_ -replace '\s+', ',' `
  } `
  | ConvertFrom-Csv -Header @('Empty', 'Protocol', 'AddressLocal', 'AddressForeign', 'State', 'PID')

# Enrich port's list with ProcessName data
$ProcessesAtPort = $PidsAtPort `
  | ForEach-Object { `
    $portProcess = Get-Process `
      | Where-Object Id -eq $_.PID; `
    $_ | Add-Member -NotePropertyName 'ProcessName' -NotePropertyValue $portProcess.ProcessName; `
    Write-Output $_;

# Show output
$ProcessesAtPort `
  | Sort-Object    ProcessName, State, Protocol, AddressLocal, AddressForeign `
  | Select-Object  ProcessName, State, Protocol, AddressLocal, AddressForeign `
  | Format-Table

What is the difference between a Relational and Non-Relational Database?

The relational database uses a formal system of predicates to address data. The underlying physical implementation is of no substance and can vary to optimize for certain operations, but it must always assume the relational model. In layman's terms, that's just saying I know exactly how many values (attributes) each row (tuple) in my table (relation) has and now I want to exploit the fact accordingly, thoroughly and to it's extreme. That's the true nature of the beast. 

Since we're obviously the generation that has had a relational upbringing, if you look at NoSQL database models from the perspective of the relational model, again in layman's terms, the first obvious difference is that no assumptions about the number of values a row can contain is ever made. This is really oversimplifying the matter and does not cleanly apply to the intricacies of the physical models of every NoSQL database, but it's the pinnacle of the relational model and the first assumption we have to leave behind or, if you'd rather, the biggest leap we have to make.

We can agree to two things that are true for every DBMS: it can store any kind of data and has enough mathematical underpinnings to make it possible to manage the data in any way imaginable. The reality is that you'll never want to make the mistake of putting any of the two points to the test, but rather just stick with what the actual DBMS was really made for. In layman's terms: respect the beast within!

(Please note that I've avoided comparing the (obviously) well founded standards revolving around the relational model against the many flavors provided by NoSQL databases. If you'd like, consider NoSQL databases as an umbrella term for any DBMS that does not completely assume the relational model, in exclusion to everything else. The differences are too many, but that's the principal difference and the one I think would be of most use to you to understand the two.)

Error sending json in POST to web API service

another tip...where to add "content-type: application/json" the textbox field on the Composer/Parsed tab. There are 3 lines already filled in there, so I added this Content-type as the 4th line. That made the Post work.

Construct a manual legend for a complicated plot

In case you were struggling to change linetypes, the following answer should be helpful. (This is an addition to the solution by Andy W.)

We will try to extend the learned pattern:

cols <- c("LINE1"="#f04546","LINE2"="#3591d1","BAR"="#62c76b")
line_types <- c("LINE1"=1,"LINE2"=3)
ggplot(data=data,aes(x=a)) + 
  geom_bar(stat="identity", aes(y=h,fill = "BAR"))+ #green
  geom_line(aes(y=b,group=1, colour="LINE1", linetype="LINE1"),size=0.5) +   #red
  geom_point(aes(y=b, colour="LINE1", fill="LINE1"),size=2) +           #red
  geom_line(aes(y=c,group=1,colour="LINE2", linetype="LINE2"),size=0.5) +   #blue 
  geom_point(aes(y=c,colour="LINE2", fill="LINE2"),size=2) +           #blue
  scale_colour_manual(name="Error Bars",values=cols, 
                  guide = guide_legend(override.aes=aes(fill=NA))) + 
  scale_fill_manual(name="Bar",values=cols, guide="none") +
  ylab("Symptom severity") + xlab("PHQ-9 symptoms") +
  ylim(0,1.6) +
  theme_bw() +
  theme(axis.title.x = element_text(size = 15, vjust=-.2)) +
  theme(axis.title.y = element_text(size = 15, vjust=0.3))

However, what we get is the following result: manual without name

The problem is that the linetype is not merged in the main legend. Note that we did not give any name to the method scale_linetype_manual. The trick which works here is to give it the same name as what you used for naming scale_colour_manual. More specifically, if we change the corresponding line to the following we get the desired result:

scale_linetype_manual(name="Error Bars",values=line_types)

manual with the same name

Now, it is easy to change the size of the line with the same idea.

Note that the geom_bar has not colour property anymore. (I did not try to fix this issue.) Also, adding geom_errorbar with colour attribute spoils the result. It would be great if somebody can come up with a better solution which resolves these two issues as well.