Programs & Examples On #Encryption symmetric

A type of encryption where the same key is used to encrypt and decrypt the message.

PHP AES encrypt / decrypt

Please use an existing secure PHP encryption library

It's generally a bad idea to write your own cryptography unless you have experience breaking other peoples' cryptography implementations.

None of the examples here authenticate the ciphertext, which leaves them vulnerable to bit-rewriting attacks.

If you can install PECL extensions, libsodium is even better

<?php
// PECL libsodium 0.2.1 and newer

/**
 * Encrypt a message
 * 
 * @param string $message - message to encrypt
 * @param string $key - encryption key
 * @return string
 */
function safeEncrypt($message, $key)
{
    $nonce = \Sodium\randombytes_buf(
        \Sodium\CRYPTO_SECRETBOX_NONCEBYTES
    );

    return base64_encode(
        $nonce.
        \Sodium\crypto_secretbox(
            $message,
            $nonce,
            $key
        )
    );
}

/**
 * Decrypt a message
 * 
 * @param string $encrypted - message encrypted with safeEncrypt()
 * @param string $key - encryption key
 * @return string
 */
function safeDecrypt($encrypted, $key)
{   
    $decoded = base64_decode($encrypted);
    $nonce = mb_substr($decoded, 0, \Sodium\CRYPTO_SECRETBOX_NONCEBYTES, '8bit');
    $ciphertext = mb_substr($decoded, \Sodium\CRYPTO_SECRETBOX_NONCEBYTES, null, '8bit');

    return \Sodium\crypto_secretbox_open(
        $ciphertext,
        $nonce,
        $key
    );
}    

Then to test it out:

<?php
// This refers to the previous code block.
require "safeCrypto.php"; 

// Do this once then store it somehow:
$key = \Sodium\randombytes_buf(\Sodium\CRYPTO_SECRETBOX_KEYBYTES);
$message = 'We are all living in a yellow submarine';

$ciphertext = safeEncrypt($message, $key);
$plaintext = safeDecrypt($ciphertext, $key);

var_dump($ciphertext);
var_dump($plaintext);

This can be used in any situation where you are passing data to the client (e.g. encrypted cookies for sessions without server-side storage, encrypted URL parameters, etc.) with a reasonably high degree of certainty that the end user cannot decipher or reliably tamper with it.

Since libsodium is cross-platform, this also makes it easier to communicate with PHP from, e.g. Java applets or native mobile apps.


Note: If you specifically need to add encrypted cookies powered by libsodium to your app, my employer Paragon Initiative Enterprises is developing a library called Halite that does all of this for you.

Simplest two-way encryption using PHP

PHP 7.2 moved completely away from Mcrypt and the encryption now is based on the maintainable Libsodium library.

All your encryption needs can be basically resolved through Libsodium library.

// On Alice's computer:
$msg = 'This comes from Alice.';
$signed_msg = sodium_crypto_sign($msg, $secret_sign_key);


// On Bob's computer:
$original_msg = sodium_crypto_sign_open($signed_msg, $alice_sign_publickey);
if ($original_msg === false) {
    throw new Exception('Invalid signature');
} else {
    echo $original_msg; // Displays "This comes from Alice."
}

Libsodium documentation: https://github.com/paragonie/pecl-libsodium-doc

How to encrypt/decrypt data in php?

Answer Background and Explanation

To understand this question, you must first understand what SHA256 is. SHA256 is a Cryptographic Hash Function. A Cryptographic Hash Function is a one-way function, whose output is cryptographically secure. This means it is easy to compute a hash (equivalent to encrypting data), but hard to get the original input using the hash (equivalent to decrypting the data). Since using a Cryptographic hash function means decrypting is computationally infeasible, so therefore you cannot perform decryption with SHA256.

What you want to use is a two-way function, but more specifically, a Block Cipher. A function that allows for both encryption and decryption of data. The functions mcrypt_encrypt and mcrypt_decrypt by default use the Blowfish algorithm. PHP's use of mcrypt can be found in this manual. A list of cipher definitions to select the cipher mcrypt uses also exists. A wiki on Blowfish can be found at Wikipedia. A block cipher encrypts the input in blocks of known size and position with a known key, so that the data can later be decrypted using the key. This is what SHA256 cannot provide you.

Code

$key = 'ThisIsTheCipherKey';

$ciphertext = mcrypt_encrypt(MCRYPT_BLOWFISH, $key, 'This is plaintext.', MCRYPT_MODE_CFB);

$plaintext = mcrypt_decrypt(MCRYPT_BLOWFISH, $key, $encrypted, MCRYPT_MODE_CFB);

How do you Encrypt and Decrypt a PHP String?

If you don't want to use library (which you should) then use something like this (PHP 7):

function sign($message, $key) {
    return hash_hmac('sha256', $message, $key) . $message;
}

function verify($bundle, $key) {
    return hash_equals(
      hash_hmac('sha256', mb_substr($bundle, 64, null, '8bit'), $key),
      mb_substr($bundle, 0, 64, '8bit')
    );
}

function getKey($password, $keysize = 16) {
    return hash_pbkdf2('sha256',$password,'some_token',100000,$keysize,true);
}

function encrypt($message, $password) {
    $iv = random_bytes(16);
    $key = getKey($password);
    $result = sign(openssl_encrypt($message,'aes-256-ctr',$key,OPENSSL_RAW_DATA,$iv), $key);
    return bin2hex($iv).bin2hex($result);
}

function decrypt($hash, $password) {
    $iv = hex2bin(substr($hash, 0, 32));
    $data = hex2bin(substr($hash, 32));
    $key = getKey($password);
    if (!verify($data, $key)) {
      return null;
    }
    return openssl_decrypt(mb_substr($data, 64, null, '8bit'),'aes-256-ctr',$key,OPENSSL_RAW_DATA,$iv);
}

$string_to_encrypt='John Smith';
$password='password';
$encrypted_string=encrypt($string_to_encrypt, $password);
$decrypted_string=decrypt($encrypted_string, $password);

Javascript - Regex to validate date format

You can use regular multiple expressions with the use of OR (|) operator.

function validateDate(date){
    var regex=new RegExp("([0-9]{4}[-](0[1-9]|1[0-2])[-]([0-2]{1}[0-9]{1}|3[0-1]{1})|([0-2]{1}[0-9]{1}|3[0-1]{1})[-](0[1-9]|1[0-2])[-][0-9]{4})");
    var dateOk=regex.test(date);
    if(dateOk){
        alert("Ok");
    }else{
        alert("not Ok");
    }
}

Above function can validate YYYY-MM-DD, DD-MM-YYYY date formats. You can simply extend the regular expression to validate any date format. Assume you want to validate YYYY/MM/DD, just replace "[-]" with "[-|/]". This expression can validate dates to 31, months to 12. But leap years and months ends with 30 days are not validated.

What is the best way to conditionally apply attributes in AngularJS?

Edit: This answer is related to Angular2+! Sorry, I missed the tag!

Original answer:

As for the very simple case when you only want to apply (or set) an attribute if a certain Input value was set, it's as easy as

<my-element [conditionalAttr]="optionalValue || false">

It's the same as:

<my-element [conditionalAttr]="optionalValue ? optionalValue : false">

(So optionalValue is applied if given otherwise the expression is false and attribute is not applied.)

Example: I had the case, where I let apply a color but also arbitrary styles, where the color attribute didn't work as it was already set (even if the @Input() color wasn't given):

@Component({
  selector: "rb-icon",
  styleUrls: ["icon.component.scss"],
  template: "<span class="ic-{{icon}}" [style.color]="color==color" [ngStyle]="styleObj" ></span>",
})
export class IconComponent {
   @Input() icon: string;
   @Input() color: string;
   @Input() styles: string;

   private styleObj: object;
...
}

So, "style.color" was only set, when the color attribute was there, otherwise the color attribute in the "styles" string could be used.

Of course, this could also be achieved with

[style.color]="color" 

and

@Input color: (string | boolean) = false;

How to create an android app using HTML 5

The WebIntoApp.com V.2 allows you to convert HTML5 / JS / CSS into a mobile app for Android APK (free) and iOS.

(I'm the author)

Add 2 hours to current time in MySQL?

SELECT * FROM courses WHERE (NOW() + INTERVAL 2 HOUR) > start_time

Git merge reports "Already up-to-date" though there is a difference

Say you have a branch master with the following commit history:

A -- B -- C -- D

Now, you create a branch test, work on it, and do 4 commits:


                 E -- F -- G -- H
                /
A -- B -- C -- D

master's head points to D, and test's head points to H.

The "Already up-to-date" message shows up when the HEAD of the branch you are merging into is a parent of the chain of commits of the branch you want to merge. That's the case, here: D is a parent of E.

There is nothing to merge from test to master, since nothing has changed on master since then. What you want to do here is literally to tell Git to have master's head to point to H, so master's branch has the following commits history:

A -- B -- C -- D -- E -- F -- G -- H

This is a job for Git command reset. You also want the working directory to reflect this change, so you'll do a hard reset:

git reset --hard H

JSON.Net Self referencing loop detected

Sometimes you have loops becouse your type class have references to other classes and that classes have references to your type class, thus you have to select the parameters that you need exactly in the json string, like this code.

List<ROficina> oficinas = new List<ROficina>();
oficinas = /*list content*/;
var x = JsonConvert.SerializeObject(oficinas.Select(o => new
            {
                o.IdOficina,
                o.Nombre
            }));

How To Create Table with Identity Column

[id] [int] IDENTITY(1,1) NOT NULL,

of course since you're creating the table in SQL Server Management Studio you could use the table designer to set the Identity Specification.

enter image description here

Extract MSI from EXE

Launch the installer, but don't press the Install > button. Then

cd "%AppData%\..\LocalLow\Sun\Java"

and find your MSI file in one of sub-directories (e.g., jre1.7.0_25).

Note that Data1.cab from that sub-directory will be required as well.

How do you 'redo' changes after 'undo' with Emacs?

Emacs 28 adds a redo command (called undo-redo).

If you want to have more typical undo/redo, the following commands can be used.

(global-set-key (kbd "C-z") 'undo-only)
(global-set-key (kbd "C-S-z") 'undo-redo)

How to keep one variable constant with other one changing with row in excel

You put it as =(B0+4)/($A$0)

You can also go across WorkSheets with Sheet1!$a$0

Installation of VB6 on Windows 7 / 8 / 10

VB6 Installs just fine on Windows 7 (and Windows 8 / Windows 10) with a few caveats.

Here is how to install it:

  • Before proceeding with the installation process below, create a zero-byte file in C:\Windows called MSJAVA.DLL. The setup process will look for this file, and if it doesn't find it, will force an installation of old, old Java, and require a reboot. By creating the zero-byte file, the installation of moldy Java is bypassed, and no reboot will be required.
  • Turn off UAC.
  • Insert Visual Studio 6 CD.
  • Exit from the Autorun setup.
  • Browse to the root folder of the VS6 CD.
  • Right-click SETUP.EXE, select Run As Administrator.
  • On this and other Program Compatibility Assistant warnings, click Run Program.
  • Click Next.
  • Click "I accept agreement", then Next.
  • Enter name and company information, click Next.
  • Select Custom Setup, click Next.
  • Click Continue, then Ok.
  • Setup will "think to itself" for about 2 minutes. Processing can be verified by starting Task Manager, and checking the CPU usage of ACMSETUP.EXE.
  • On the options list, select the following:
    • Microsoft Visual Basic 6.0
    • ActiveX
    • Data Access
    • Graphics
    • All other options should be unchecked.
  • Click Continue, setup will continue.
  • Finally, a successful completion dialog will appear, at which click Ok. At this point, Visual Basic 6 is installed.
  • If you do not have the MSDN CD, clear the checkbox on the next dialog, and click next. You'll be warned of the lack of MSDN, but just click Yes to accept.
  • Click Next to skip the installation of Installshield. This is a really old version you don't want anyway.
  • Click Next again to skip the installation of BackOffice, VSS, and SNA Server. Not needed!
  • On the next dialog, clear the checkbox for "Register Now", and click Finish.
  • The wizard will exit, and you're done. You can find VB6 under Start, All Programs, Microsoft Visual Studio 6. Enjoy!
  • Turn On UAC again

  • You might notice after successfully installing VB6 on Windows 7 that working in the IDE is a bit, well, sluggish. For example, resizing objects on a form is a real pain.
  • After installing VB6, you'll want to change the compatibility settings for the IDE executable.
  • Using Windows Explorer, browse the location where you installed VB6. By default, the path is C:\Program Files\Microsoft Visual Studio\VB98\
  • Right click the VB6.exe program file, and select properties from the context menu.
  • Click on the Compatibility tab.
  • Place a check in each of these checkboxes:
  • Run this program in compatibility mode for Windows XP (Service Pack 3)
    • Disable Visual Themes
    • Disable Desktop Composition
    • Disable display scaling on high DPI settings
    • If you have UAC turned on, it is probably advisable to check the 'Run this program as an Administrator' box

After changing these settings, fire up the IDE, and things should be back to normal, and the IDE is no longer sluggish.

Edit: Updated dead link to point to a different page with the same instructions

Edit: Updated the answer with the actual instructions in the post as the link kept dying

Table Height 100% inside Div element

to set height of table to its container I must do:

1) set "position: absolute"

2) remove redundant contents of cells (!)

nodejs vs node on ubuntu 12.04

Apparently the solution differs between Ubuntu versions. Following worked for me on Ubuntu 13.10:

sudo apt-get install nodejs-legacy

HTH

Edit: Rule of thumb:

If you have installed nodejs but are missing the /usr/bin/node binary, then also install nodejs-legacy. This just creates the missing softlink.

According to my tests, Ubuntu 17.10 and above already have the compatibility-softlink /usr/bin/node in place after nodejs is installed, so nodejs-legacy is missing from these releases as it is no more needed.

Spring Boot and how to configure connection details to MongoDB?

Just to quote Boot Docs:

You can set spring.data.mongodb.uri property to change the url, or alternatively specify a host/port. For example, you might declare the following in your application.properties:

spring.data.mongodb.host=mongoserver
spring.data.mongodb.port=27017

All available options for spring.data.mongodb prefix are fields of MongoProperties:

private String host;

private int port = DBPort.PORT;

private String uri = "mongodb://localhost/test";

private String database;

private String gridFsDatabase;

private String username;

private char[] password;

How to make a machine trust a self-signed Java application

I was having the same issue. So I went to the Java options through Control Panel. Copied the web address that I was having an issue with to the exceptions and it was fixed.

CreateProcess error=206, The filename or extension is too long when running main() method

To solve it:

If you are using Eclipse:

Move .m2 repository to

c:\ Go to Eclipse > Windows/Preferences/Maven/User Settings -> Create your own setting.xml with its content:

<settings>
  <localRepository>c:/.m2/repository</localRepository>
</settings>

If you are using IntelliJ: Go to IntelliJ > clicking the right mouse button on "pom.xml" > maven > create "settings.xml"

with its content:

<settings>
      xmlns="yourcontent"
      xmlns:xsi="yourcontent"
      xsi:schemaLocation="yourcontent.xsd">
  <localRepository>c:/.m2/repository</localRepository>
</settings>

How to use wait and notify in Java without IllegalMonitorStateException?

This looks like a situation for producer-consumer pattern. If you’re using java 5 or up, you may consider using blocking queue(java.util.concurrent.BlockingQueue) and leave the thread coordination work to the underlying framework/api implementation. See the example from java 5: http://docs.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/BlockingQueue.html or java 7 (same example): http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingQueue.html

How to execute a .sql script from bash

If you want to run a script to a database:

mysql -u user -p data_base_name_here < db.sql

How to concatenate a std::string and an int?

If you have C++11, you can use std::to_string.

Example:

std::string name = "John";
int age = 21;

name += std::to_string(age);

std::cout << name;

Output:

John21

set initial viewcontroller in appdelegate - swift

Open a viewcontroller with SWRevealViewController From App delegate.

 self.window = UIWindow(frame: UIScreen.main.bounds)
 let storyboard = UIStoryboard(name: "StoryboardName", bundle: nil)
 let swrevealviewcontroller:SWRevealViewController = storyboard.instantiateInitialViewController() as! SWRevealViewController 
 self.window?.rootViewController = swrevealviewcontroller
 self.window?.makeKeyAndVisible()

python tuple to dict

>>> dict([('hi','goodbye')])
{'hi': 'goodbye'}

Or:

>>> [ dict([i]) for i in (('CSCO', 21.14), ('CSCO', 21.14), ('CSCO', 21.14), ('CSCO', 21.14)) ]
[{'CSCO': 21.14}, {'CSCO': 21.14}, {'CSCO': 21.14}, {'CSCO': 21.14}]

C: What is the difference between ++i and i++?

i++: In this scenario first the value is assigned and then increment happens.

++i: In this scenario first the increment is done and then value is assigned

Below is the image visualization and also here is a nice practical video which demonstrates the same.

enter image description here

How can I pass a parameter to a Java Thread?

You can derive a class from Runnable, and during the construction (say) pass the parameter in.

Then launch it using Thread.start(Runnable r);

If you mean whilst the thread is running, then simply hold a reference to your derived object in the calling thread, and call the appropriate setter methods (synchronising where appropriate)

What's the difference between ViewData and ViewBag?

public ActionResult Index()
{
    ViewBag.Name = "Monjurul Habib";
    return View();
}

public ActionResult Index()
{
    ViewData["Name"] = "Monjurul Habib";
    return View();
} 

In View:

@ViewBag.Name 
@ViewData["Name"] 

CentOS 7 and Puppet unable to install nc

yum install nmap-ncat.x86_64

resolved my problem

PHP: How to send HTTP response code?

If your version of PHP does not include this function:

<?php

function http_response_code($code = NULL) {
        if ($code !== NULL) {
            switch ($code) {
                case 100: $text = 'Continue';
                    break;
                case 101: $text = 'Switching Protocols';
                    break;
                case 200: $text = 'OK';
                    break;
                case 201: $text = 'Created';
                    break;
                case 202: $text = 'Accepted';
                    break;
                case 203: $text = 'Non-Authoritative Information';
                    break;
                case 204: $text = 'No Content';
                    break;
                case 205: $text = 'Reset Content';
                    break;
                case 206: $text = 'Partial Content';
                    break;
                case 300: $text = 'Multiple Choices';
                    break;
                case 301: $text = 'Moved Permanently';
                    break;
                case 302: $text = 'Moved Temporarily';
                    break;
                case 303: $text = 'See Other';
                    break;
                case 304: $text = 'Not Modified';
                    break;
                case 305: $text = 'Use Proxy';
                    break;
                case 400: $text = 'Bad Request';
                    break;
                case 401: $text = 'Unauthorized';
                    break;
                case 402: $text = 'Payment Required';
                    break;
                case 403: $text = 'Forbidden';
                    break;
                case 404: $text = 'Not Found';
                    break;
                case 405: $text = 'Method Not Allowed';
                    break;
                case 406: $text = 'Not Acceptable';
                    break;
                case 407: $text = 'Proxy Authentication Required';
                    break;
                case 408: $text = 'Request Time-out';
                    break;
                case 409: $text = 'Conflict';
                    break;
                case 410: $text = 'Gone';
                    break;
                case 411: $text = 'Length Required';
                    break;
                case 412: $text = 'Precondition Failed';
                    break;
                case 413: $text = 'Request Entity Too Large';
                    break;
                case 414: $text = 'Request-URI Too Large';
                    break;
                case 415: $text = 'Unsupported Media Type';
                    break;
                case 500: $text = 'Internal Server Error';
                    break;
                case 501: $text = 'Not Implemented';
                    break;
                case 502: $text = 'Bad Gateway';
                    break;
                case 503: $text = 'Service Unavailable';
                    break;
                case 504: $text = 'Gateway Time-out';
                    break;
                case 505: $text = 'HTTP Version not supported';
                    break;
                default:
                    exit('Unknown http status code "' . htmlentities($code) . '"');
                    break;
            }
            $protocol = (isset($_SERVER['SERVER_PROTOCOL']) ? $_SERVER['SERVER_PROTOCOL'] : 'HTTP/1.0');
            header($protocol . ' ' . $code . ' ' . $text);
            $GLOBALS['http_response_code'] = $code;
        } else {
            $code = (isset($GLOBALS['http_response_code']) ? $GLOBALS['http_response_code'] : 200);
        }
        return $code;
    }

Dropdown select with images

I am a little to late on this, but you can do this using a simple bootstrap drop down and then do your code on select change event in any language or framework. (This is just a very basic solution, for other people like me who are just starting out and looking for a solution for a small simple project.)

<div class="dropdown">
    <button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="true">
        Select Image
        <span class="caret"></span>
    </button>
    <ul class="dropdown-menu" aria-labelledby="dropdownMenu1">
        <li> <a style="background-image: url(../Content/Images/Backgrounds/background.png);height:100px;width:300px" class="img-thumbnail" href=""> </a></li>
        <li role="separator" class="divider"></li>
        <li> <a style="background-image: url(../Content/Images/Backgrounds/background.png);height:100px;width:300px" class="img-thumbnail" href=""> </a></li>
    </ul>
</div>

Bad Request, Your browser sent a request that this server could not understand

in my magento2 website ,show exactly the same error when click a product,

my solution is to go to edit the value of Search Engine Optimization - URL Key of this product,

make sure that there are only alphabet,number and - in URL Key, such as 100-washed-cotton-duvet-cover-set, deleting all other special characters ,such as % .

Maven: add a dependency to a jar by relative path

You can use eclipse to generate a runnable Jar : Export/Runable Jar file

Python: import cx_Oracle ImportError: No module named cx_Oracle error is thown

To access Oracle from python you need (additionally) the cx_Oracle module. The module must be located either in the system python path or you have to set the PYTHONPATH appropriate.

SQL Server String Concatenation with Null

I had a lot of trouble with this too. Couldn't get it working using the case examples above, but this does the job for me:

Replace(rtrim(ltrim(ISNULL(Flat_no, '') + 
' ' + ISNULL(House_no, '') + 
' ' + ISNULL(Street, '') + 
' ' + ISNULL(Town, '') + 
' ' + ISNULL(City, ''))),'  ',' ')

Replace corrects the double spaces caused by concatenating single spaces with nothing between them. r/ltrim gets rid of any spaces at the ends.

Simple Pivot Table to Count Unique Values

If you have the data sorted.. i suggest using the following formula

=IF(OR(A2<>A3,B2<>B3),1,0)

This is faster as it uses less cells to calculate.

Why am I getting this error: No mapping specified for the following EntitySet/AssociationSet - Entity1?

Had this error when I had deleted a table from the database. Solved it by right clicking on EDMX diagram, going to Properties, selecting the table from the list in the Properties window, and deleting it (using delete key) from the diagram.

Firing events on CSS class changes in jQuery

Whenever you change a class in your script, you could use a trigger to raise your own event.

$(this).addClass('someClass');
$(mySelector).trigger('cssClassChanged')
....
$(otherSelector).bind('cssClassChanged', data, function(){ do stuff });

but otherwise, no, there's no baked-in way to fire an event when a class changes. change() only fires after focus leaves an input whose input has been altered.

_x000D_
_x000D_
$(function() {_x000D_
  var button = $('.clickme')_x000D_
      , box = $('.box')_x000D_
  ;_x000D_
  _x000D_
  button.on('click', function() { _x000D_
    box.removeClass('box');_x000D_
    $(document).trigger('buttonClick');_x000D_
  });_x000D_
            _x000D_
  $(document).on('buttonClick', function() {_x000D_
    box.text('Clicked!');_x000D_
  });_x000D_
});
_x000D_
.box { background-color: red; }
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
_x000D_
<div class="box">Hi</div>_x000D_
<button class="clickme">Click me</button>
_x000D_
_x000D_
_x000D_

More info on jQuery Triggers

What is the difference between connection and read timeout for sockets?

These are timeout values enforced by JVM for TCP connection establishment and waiting on reading data from socket.

If the value is set to infinity, you will not wait forever. It simply means JVM doesn't have timeout and OS will be responsible for all the timeouts. However, the timeouts on OS may be really long. On some slow network, I've seen timeouts as long as 6 minutes.

Even if you set the timeout value for socket, it may not work if the timeout happens in the native code. We can reproduce the problem on Linux by connecting to a host blocked by firewall or unplugging the cable on switch.

The only safe approach to handle TCP timeout is to run the connection code in a different thread and interrupt the thread when it takes too long.

Environment Variable with Maven

There is a maven plugin called properties-maven-plugin this one provides a goal set-system-properties to set system variables. This is especially useful if you have a file containing all these properties. So you're able to read a property file and set them as system variable.

How to put php inside JavaScript?

Try this:

<?php $htmlString= 'testing'; ?>
<html>
  <body>
    <script type="text/javascript">  
      // notice the quotes around the ?php tag         
      var htmlString="<?php echo $htmlString; ?>";
      alert(htmlString);
    </script>
  </body>
</html>

When you run into problems like this one, a good idea is to check your browser for JavaScript errors. Different browsers have different ways of showing this, but look for a javascript console or something like that. Also, check the source of your page as viewed by the browser.

Sometimes beginners are confused about the quotes in the string: In the PHP part, you assigned 'testing' to $htmlString. This puts a string value inside that variable, but the value does not have the quotes in it: They are just for the interpreter, so he knows: oh, now comes a string literal.

Calling Javascript from a html form

Everything seems to be perfect in your code except the fact that handleClick() isn't working because this function lacks a parameter in its function call invocation(but the function definition within has an argument which makes a function mismatch to occur).

The following is a sample working code for calculating all semester's total marks and corresponding grade. It demonstrates the use of a JavaScript function(call) within a html file and also solves the problem you are facing.

<!DOCTYPE html>
<html>
<head>
    <title> Semester Results </title>
</head>
<body>
    <h1> Semester Marks </h1> <br> 
    <script type = "text/javascript">
        function checkMarks(total)
        {
            document.write("<h1> Final Result !!! </h1><br>");
            document.write("Total Marks = " + total + "<br><br>");
            var avg = total / 6.0;
            document.write("CGPA = " + (avg / 10.0).toFixed(2) + "<br><br>");
            if(avg >= 90)
                document.write("Grade = A");
            else if(avg >= 80)
                document.write("Grade = B");
            else if(avg >= 70)
                document.write("Grade = C");
            else if(avg >= 60)
                document.write("Grade = D");
            else if(avg >= 50)
                document.write("Grade = Pass");
            else
                document.write("Grade = Fail");
       }
    </script>
    <form name = "myform" action = "javascript:checkMarks(Number(s1.value) + Number(s2.value) + Number(s3.value) + Number(s4.value) + Number(s5.value) + Number(s6.value))"/>
        Semester 1:  <input type = "text" id = "s1"/> <br><br>
        Semester 2:  <input type = "text" id = "s2"/> <br><br>
        Semester 3:  <input type = "text" id = "s3"/> <br><br>
        Semester 4:  <input type = "text" id = "s4"/> <br><br>
        Semester 5:  <input type = "text" id = "s5"/> <br><br>
        Semester 6:  <input type = "text" id = "s6"/> <br><br><br>
        <input type = "submit" value = "Submit"/>
    </form>
</body>
</html>

Set a Fixed div to 100% width of the parent container

You can use margin for .wrap container instead of padding for .wrapper:

body{ height:20000px }
#wrapper { padding: 0%; }
#wrap{ 
    float: left;
    position: relative;
    margin: 10%;
    width: 40%; 
    background:#ccc; 
}
#fixed{ 
    position:fixed;
    width:inherit;
    padding:0px; 
    height:10px;
    background-color:#333;    
}

jsfiddle

What is Parse/parsing?

From dictionary.reference.com:

Computers. to analyze (a string of characters) in order to associate groups of characters with the syntactic units of the underlying grammar.

The context of the definition is the translation of program text or a language in the general sense into its component parts with respect to a defined grammar -- turning program text into code. In the context of a particular language keyword, though, it generally means to convert the string value of a fundamental data type into an internal representation of that data type. For example, the string "10" becomes the number (integer) 10.

Different ways of adding to Dictionary

To answer the question first we need to take a look at the purpose of a dictionary and underlying technology.

Dictionary is the list of KeyValuePair<Tkey, Tvalue> where each value is represented by its unique key. Let's say we have a list of your favorite foods. Each value (food name) is represented by its unique key (a position = how much you like this food).

Example code:

Dictionary<int, string> myDietFavorites = new Dictionary<int, string>()
{
    { 1, "Burger"},
    { 2, "Fries"},
    { 3, "Donuts"}
};

Let's say you want to stay healthy, you've changed your mind and you want to replace your favorite "Burger" with salad. Your list is still a list of your favorites, you won't change the nature of the list. Your favorite will remain number one on the list, only it's value will change. This is when you call this:

/*your key stays 1, you only replace the value assigned to this key
  you alter existing record in your dictionary*/
myDietFavorites[1] = "Salad";

But don't forget you're the programmer, and from now on you finishes your sentences with ; you refuse to use emojis because they would throw compilation error and all list of favorites is 0 index based.

Your diet changed too! So you alter your list again:

/*you don't want to replace Salad, you want to add this new fancy 0
  position to your list. It wasn't there before so you can either define it*/
myDietFavorites[0] = "Pizza";

/*or Add it*/
myDietFavorites.Add(0, "Pizza");

There are two possibilities with defining, you either want to give a new definition for something not existent before or you want to change definition which already exists.

Add method allows you to add a record but only under one condition: key for this definition may not exist in your dictionary.

Now we are going to look under the hood. When you are making a dictionary your compiler make a reservation for the bucket (spaces in memory to store your records). Bucket don't store keys in the way you define them. Each key is hashed before going to the bucket (defined by Microsoft), worth mention that value part stays unchanged.

I'll use the CRC32 hashing algorithm to simplify my example. When you defining:

myDietFavorites[0] = "Pizza";

What is going to the bucket is db2dc565 "Pizza" (simplified).

When you alter the value in with:

myDietFavorites[0] = "Spaghetti";

You hash your 0 which is again db2dc565 then you look up this value in your bucket to find if it's there. If it's there you simply rewrite the value assigned to the key. If it's not there you'll place your value in the bucket.

When you calling Add function on your dictionary like:

myDietFavorite.Add(0, "Chocolate");

You hash your 0 to compare it's value to ones in the bucket. You may place it in the bucket only if it's not there.

It's crucial to know how it works especially if you work with dictionaries of string or char type of key. It's case sensitive because of undergoing hashing. So for example "name" != "Name". Let's use our CRC32 to depict this.

Value for "name" is: e04112b1 Value for "Name" is: 1107fb5b

What process is listening on a certain port on Solaris?

From Solaris 11.2 onwards you can indeed do this with the netstat command. Have a look here. The -u switch is what you are looking for.

If you are on a lower version of Solaris then - as others have pointed out - the Solaris way of doing this is some kind of script wrapper around pfiles command. Beware though that pfiles command halts the process for a split second in order to inspect it. For 99.9% of processes this is unimportant. Unfortunately we have a process that will give a core dump if it is hit with a pfiles command so we are a bit cautious about using the command. Your situation may be totally different if you are in the 99.9%, meaning you can safely use the pfiles command.

How to see log files in MySQL?

From the MySQL reference manual:

By default, all log files are created in the data directory.

Check /var/lib/mysql folder.

In jQuery, how do I get the value of a radio button when they all have the same name?

in your selector, you should also specify that you want the checked radiobutton:

$(function(){
    $("#submit").click(function(){      
        alert($('input[name=q12_3]:checked').val());
    });
 });

What to gitignore from the .idea folder?

Github uses the following .gitignore for their programs

https://github.com/github/gitignore/blob/master/Global/JetBrains.gitignore

# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio and WebStorm
# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839

# User-specific stuff
.idea/**/workspace.xml
.idea/**/tasks.xml
.idea/**/usage.statistics.xml
.idea/**/dictionaries
.idea/**/shelf

# Generated files
.idea/**/contentModel.xml

# Sensitive or high-churn files
.idea/**/dataSources/
.idea/**/dataSources.ids
.idea/**/dataSources.local.xml
.idea/**/sqlDataSources.xml
.idea/**/dynamic.xml
.idea/**/uiDesigner.xml
.idea/**/dbnavigator.xml

# Gradle
.idea/**/gradle.xml
.idea/**/libraries

# Gradle and Maven with auto-import
# When using Gradle or Maven with auto-import, you should exclude module files,
# since they will be recreated, and may cause churn.  Uncomment if using
# auto-import.
# .idea/modules.xml
# .idea/*.iml
# .idea/modules

# CMake
cmake-build-*/

# Mongo Explorer plugin
.idea/**/mongoSettings.xml

# File-based project format
*.iws

# IntelliJ
out/

# mpeltonen/sbt-idea plugin
.idea_modules/

# JIRA plugin
atlassian-ide-plugin.xml

# Cursive Clojure plugin
.idea/replstate.xml

# Crashlytics plugin (for Android Studio and IntelliJ)
com_crashlytics_export_strings.xml
crashlytics.properties
crashlytics-build.properties
fabric.properties

# Editor-based Rest Client
.idea/httpRequests

# Android studio 3.1+ serialized cache file
.idea/caches/build_file_checksums.ser

Casting objects in Java

The example you are referring to is called Upcasting in java.

It creates a subclass object with a super class variable pointing to it.

The variable does not change, it is still the variable of the super class but it is pointing to the object of subclass.

For example lets say you have two classes Machine and Camera ; Camera is a subclass of Machine

class Machine{

    public void start(){

        System.out.println("Machine Started");
    }
}

class Camera extends Machine{
     public void start(){

            System.out.println("Camera Started");
        }
     public void snap(){
         System.out.println("Photo taken");
     }
 }
Machine machine1 = new Camera();
machine1.start();

If you execute the above statements it will create an instance of Camera class with a reference of Machine class pointing to it.So, now the output will be "Camera Started" The variable is still a reference of Machine class. If you attempt machine1.snap(); the code will not compile

The takeaway here is all Cameras are Machines since Camera is a subclass of Machine but all Machines are not Cameras. So you can create an object of subclass and point it to a super class refrence but you cannot ask the super class reference to do all the functions of a subclass object( In our example machine1.snap() wont compile). The superclass reference has access to only the functions known to the superclass (In our example machine1.start()). You can not ask a machine reference to take a snap. :)

How to parse a string to an int in C++?

This is a safer C way than atoi()

const char* str = "123";
int i;

if(sscanf(str, "%d", &i)  == EOF )
{
   /* error */
}

C++ with standard library stringstream: (thanks CMS )

int str2int (const string &str) {
  stringstream ss(str);
  int num;
  if((ss >> num).fail())
  { 
      //ERROR 
  }
  return num;
}

With boost library: (thanks jk)

#include <boost/lexical_cast.hpp>
#include <string>

try
{
    std::string str = "123";
    int number = boost::lexical_cast< int >( str );
}
catch( const boost::bad_lexical_cast & )
{
    // Error
}

Edit: Fixed the stringstream version so that it handles errors. (thanks to CMS's and jk's comment on original post)

Read Content from Files which are inside Zip file

As of Java 7, the NIO Api provides a better and more generic way of accessing the contents of Zip or Jar files. Actually, it is now a unified API which allows you to treat Zip files exactly like normal files.

In order to extract all of the files contained inside of a zip file in this API, you'd do this:

In Java 8:

private void extractAll(URI fromZip, Path toDirectory) throws IOException{
    FileSystems.newFileSystem(fromZip, Collections.emptyMap())
            .getRootDirectories()
            .forEach(root -> {
                // in a full implementation, you'd have to
                // handle directories 
                Files.walk(root).forEach(path -> Files.copy(path, toDirectory));
            });
}

In java 7:

private void extractAll(URI fromZip, Path toDirectory) throws IOException{
    FileSystem zipFs = FileSystems.newFileSystem(fromZip, Collections.emptyMap());

    for(Path root : zipFs.getRootDirectories()) {
        Files.walkFileTree(root, new SimpleFileVisitor<Path>() {
            @Override
            public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) 
                    throws IOException {
                // You can do anything you want with the path here
                Files.copy(file, toDirectory);
                return FileVisitResult.CONTINUE;
            }

            @Override
            public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) 
                    throws IOException {
                // In a full implementation, you'd need to create each 
                // sub-directory of the destination directory before 
                // copying files into it
                return super.preVisitDirectory(dir, attrs);
            }
        });
    }
}

Connection string using Windows Authentication

For connecting to a sql server database via Windows authentication basically needs which server you want to connect , what is your database name , Integrated Security info and provider name.

Basically this works:

<connectionStrings>      
<add name="MyConnectionString"
         connectionString="data source=ServerName;
   Initial Catalog=DatabaseName;Integrated Security=True;"
         providerName="System.Data.SqlClient" />
</connectionStrings> 

Setting Integrated Security field true means basically you want to reach database via Windows authentication, if you set this field false Windows authentication will not work.

It is also working different according which provider you are using.

  • SqlClient both Integrated Security=true; or IntegratedSecurity=SSPI; is working.

  • OleDb it is Integrated Security=SSPI;

  • Odbc it is Trusted_Connection=yes;
  • OracleClient it is Integrated Security=yes;

Integrated Security=true throws an exception when used with the OleDb provider.

Using :before and :after CSS selector to insert Html

content doesn't support HTML, only text. You should probably use javascript, jQuery or something like that.

Another problem with your code is " inside a " block. You should mix ' and " (class='headingDetail').

If content did support HTML you could end up in an infinite loop where content is added inside content.

data.table vs dplyr: can one do something well the other can't or does poorly?

We need to cover at least these aspects to provide a comprehensive answer/comparison (in no particular order of importance): Speed, Memory usage, Syntax and Features.

My intent is to cover each one of these as clearly as possible from data.table perspective.

Note: unless explicitly mentioned otherwise, by referring to dplyr, we refer to dplyr's data.frame interface whose internals are in C++ using Rcpp.


The data.table syntax is consistent in its form - DT[i, j, by]. To keep i, j and by together is by design. By keeping related operations together, it allows to easily optimise operations for speed and more importantly memory usage, and also provide some powerful features, all while maintaining the consistency in syntax.

1. Speed

Quite a few benchmarks (though mostly on grouping operations) have been added to the question already showing data.table gets faster than dplyr as the number of groups and/or rows to group by increase, including benchmarks by Matt on grouping from 10 million to 2 billion rows (100GB in RAM) on 100 - 10 million groups and varying grouping columns, which also compares pandas. See also updated benchmarks, which include Spark and pydatatable as well.

On benchmarks, it would be great to cover these remaining aspects as well:

  • Grouping operations involving a subset of rows - i.e., DT[x > val, sum(y), by = z] type operations.

  • Benchmark other operations such as update and joins.

  • Also benchmark memory footprint for each operation in addition to runtime.

2. Memory usage

  1. Operations involving filter() or slice() in dplyr can be memory inefficient (on both data.frames and data.tables). See this post.

    Note that Hadley's comment talks about speed (that dplyr is plentiful fast for him), whereas the major concern here is memory.

  2. data.table interface at the moment allows one to modify/update columns by reference (note that we don't need to re-assign the result back to a variable).

    # sub-assign by reference, updates 'y' in-place
    DT[x >= 1L, y := NA]
    

    But dplyr will never update by reference. The dplyr equivalent would be (note that the result needs to be re-assigned):

    # copies the entire 'y' column
    ans <- DF %>% mutate(y = replace(y, which(x >= 1L), NA))
    

    A concern for this is referential transparency. Updating a data.table object by reference, especially within a function may not be always desirable. But this is an incredibly useful feature: see this and this posts for interesting cases. And we want to keep it.

    Therefore we are working towards exporting shallow() function in data.table that will provide the user with both possibilities. For example, if it is desirable to not modify the input data.table within a function, one can then do:

    foo <- function(DT) {
        DT = shallow(DT)          ## shallow copy DT
        DT[, newcol := 1L]        ## does not affect the original DT 
        DT[x > 2L, newcol := 2L]  ## no need to copy (internally), as this column exists only in shallow copied DT
        DT[x > 2L, x := 3L]       ## have to copy (like base R / dplyr does always); otherwise original DT will 
                                  ## also get modified.
    }
    

    By not using shallow(), the old functionality is retained:

    bar <- function(DT) {
        DT[, newcol := 1L]        ## old behaviour, original DT gets updated by reference
        DT[x > 2L, x := 3L]       ## old behaviour, update column x in original DT.
    }
    

    By creating a shallow copy using shallow(), we understand that you don't want to modify the original object. We take care of everything internally to ensure that while also ensuring to copy columns you modify only when it is absolutely necessary. When implemented, this should settle the referential transparency issue altogether while providing the user with both possibilties.

    Also, once shallow() is exported dplyr's data.table interface should avoid almost all copies. So those who prefer dplyr's syntax can use it with data.tables.

    But it will still lack many features that data.table provides, including (sub)-assignment by reference.

  3. Aggregate while joining:

    Suppose you have two data.tables as follows:

    DT1 = data.table(x=c(1,1,1,1,2,2,2,2), y=c("a", "a", "b", "b"), z=1:8, key=c("x", "y"))
    #    x y z
    # 1: 1 a 1
    # 2: 1 a 2
    # 3: 1 b 3
    # 4: 1 b 4
    # 5: 2 a 5
    # 6: 2 a 6
    # 7: 2 b 7
    # 8: 2 b 8
    DT2 = data.table(x=1:2, y=c("a", "b"), mul=4:3, key=c("x", "y"))
    #    x y mul
    # 1: 1 a   4
    # 2: 2 b   3
    

    And you would like to get sum(z) * mul for each row in DT2 while joining by columns x,y. We can either:

    • 1) aggregate DT1 to get sum(z), 2) perform a join and 3) multiply (or)

      # data.table way
      DT1[, .(z = sum(z)), keyby = .(x,y)][DT2][, z := z*mul][]
      
      # dplyr equivalent
      DF1 %>% group_by(x, y) %>% summarise(z = sum(z)) %>% 
          right_join(DF2) %>% mutate(z = z * mul)
      
    • 2) do it all in one go (using by = .EACHI feature):

      DT1[DT2, list(z=sum(z) * mul), by = .EACHI]
      

    What is the advantage?

    • We don't have to allocate memory for the intermediate result.

    • We don't have to group/hash twice (one for aggregation and other for joining).

    • And more importantly, the operation what we wanted to perform is clear by looking at j in (2).

    Check this post for a detailed explanation of by = .EACHI. No intermediate results are materialised, and the join+aggregate is performed all in one go.

    Have a look at this, this and this posts for real usage scenarios.

    In dplyr you would have to join and aggregate or aggregate first and then join, neither of which are as efficient, in terms of memory (which in turn translates to speed).

  4. Update and joins:

    Consider the data.table code shown below:

    DT1[DT2, col := i.mul]
    

    adds/updates DT1's column col with mul from DT2 on those rows where DT2's key column matches DT1. I don't think there is an exact equivalent of this operation in dplyr, i.e., without avoiding a *_join operation, which would have to copy the entire DT1 just to add a new column to it, which is unnecessary.

    Check this post for a real usage scenario.

To summarise, it is important to realise that every bit of optimisation matters. As Grace Hopper would say, Mind your nanoseconds!

3. Syntax

Let's now look at syntax. Hadley commented here:

Data tables are extremely fast but I think their concision makes it harder to learn and code that uses it is harder to read after you have written it ...

I find this remark pointless because it is very subjective. What we can perhaps try is to contrast consistency in syntax. We will compare data.table and dplyr syntax side-by-side.

We will work with the dummy data shown below:

DT = data.table(x=1:10, y=11:20, z=rep(1:2, each=5))
DF = as.data.frame(DT)
  1. Basic aggregation/update operations.

    # case (a)
    DT[, sum(y), by = z]                       ## data.table syntax
    DF %>% group_by(z) %>% summarise(sum(y)) ## dplyr syntax
    DT[, y := cumsum(y), by = z]
    ans <- DF %>% group_by(z) %>% mutate(y = cumsum(y))
    
    # case (b)
    DT[x > 2, sum(y), by = z]
    DF %>% filter(x>2) %>% group_by(z) %>% summarise(sum(y))
    DT[x > 2, y := cumsum(y), by = z]
    ans <- DF %>% group_by(z) %>% mutate(y = replace(y, which(x > 2), cumsum(y)))
    
    # case (c)
    DT[, if(any(x > 5L)) y[1L]-y[2L] else y[2L], by = z]
    DF %>% group_by(z) %>% summarise(if (any(x > 5L)) y[1L] - y[2L] else y[2L])
    DT[, if(any(x > 5L)) y[1L] - y[2L], by = z]
    DF %>% group_by(z) %>% filter(any(x > 5L)) %>% summarise(y[1L] - y[2L])
    
    • data.table syntax is compact and dplyr's quite verbose. Things are more or less equivalent in case (a).

    • In case (b), we had to use filter() in dplyr while summarising. But while updating, we had to move the logic inside mutate(). In data.table however, we express both operations with the same logic - operate on rows where x > 2, but in first case, get sum(y), whereas in the second case update those rows for y with its cumulative sum.

      This is what we mean when we say the DT[i, j, by] form is consistent.

    • Similarly in case (c), when we have if-else condition, we are able to express the logic "as-is" in both data.table and dplyr. However, if we would like to return just those rows where the if condition satisfies and skip otherwise, we cannot use summarise() directly (AFAICT). We have to filter() first and then summarise because summarise() always expects a single value.

      While it returns the same result, using filter() here makes the actual operation less obvious.

      It might very well be possible to use filter() in the first case as well (does not seem obvious to me), but my point is that we should not have to.

  2. Aggregation / update on multiple columns

    # case (a)
    DT[, lapply(.SD, sum), by = z]                     ## data.table syntax
    DF %>% group_by(z) %>% summarise_each(funs(sum)) ## dplyr syntax
    DT[, (cols) := lapply(.SD, sum), by = z]
    ans <- DF %>% group_by(z) %>% mutate_each(funs(sum))
    
    # case (b)
    DT[, c(lapply(.SD, sum), lapply(.SD, mean)), by = z]
    DF %>% group_by(z) %>% summarise_each(funs(sum, mean))
    
    # case (c)
    DT[, c(.N, lapply(.SD, sum)), by = z]     
    DF %>% group_by(z) %>% summarise_each(funs(n(), mean))
    
    • In case (a), the codes are more or less equivalent. data.table uses familiar base function lapply(), whereas dplyr introduces *_each() along with a bunch of functions to funs().

    • data.table's := requires column names to be provided, whereas dplyr generates it automatically.

    • In case (b), dplyr's syntax is relatively straightforward. Improving aggregations/updates on multiple functions is on data.table's list.

    • In case (c) though, dplyr would return n() as many times as many columns, instead of just once. In data.table, all we need to do is to return a list in j. Each element of the list will become a column in the result. So, we can use, once again, the familiar base function c() to concatenate .N to a list which returns a list.

    Note: Once again, in data.table, all we need to do is return a list in j. Each element of the list will become a column in result. You can use c(), as.list(), lapply(), list() etc... base functions to accomplish this, without having to learn any new functions.

    You will need to learn just the special variables - .N and .SD at least. The equivalent in dplyr are n() and .

  3. Joins

    dplyr provides separate functions for each type of join where as data.table allows joins using the same syntax DT[i, j, by] (and with reason). It also provides an equivalent merge.data.table() function as an alternative.

    setkey(DT1, x, y)
    
    # 1. normal join
    DT1[DT2]            ## data.table syntax
    left_join(DT2, DT1) ## dplyr syntax
    
    # 2. select columns while join    
    DT1[DT2, .(z, i.mul)]
    left_join(select(DT2, x, y, mul), select(DT1, x, y, z))
    
    # 3. aggregate while join
    DT1[DT2, .(sum(z) * i.mul), by = .EACHI]
    DF1 %>% group_by(x, y) %>% summarise(z = sum(z)) %>% 
        inner_join(DF2) %>% mutate(z = z*mul) %>% select(-mul)
    
    # 4. update while join
    DT1[DT2, z := cumsum(z) * i.mul, by = .EACHI]
    ??
    
    # 5. rolling join
    DT1[DT2, roll = -Inf]
    ??
    
    # 6. other arguments to control output
    DT1[DT2, mult = "first"]
    ??
    
    • Some might find a separate function for each joins much nicer (left, right, inner, anti, semi etc), whereas as others might like data.table's DT[i, j, by], or merge() which is similar to base R.

    • However dplyr joins do just that. Nothing more. Nothing less.

    • data.tables can select columns while joining (2), and in dplyr you will need to select() first on both data.frames before to join as shown above. Otherwise you would materialiase the join with unnecessary columns only to remove them later and that is inefficient.

    • data.tables can aggregate while joining (3) and also update while joining (4), using by = .EACHI feature. Why materialse the entire join result to add/update just a few columns?

    • data.table is capable of rolling joins (5) - roll forward, LOCF, roll backward, NOCB, nearest.

    • data.table also has mult = argument which selects first, last or all matches (6).

    • data.table has allow.cartesian = TRUE argument to protect from accidental invalid joins.

Once again, the syntax is consistent with DT[i, j, by] with additional arguments allowing for controlling the output further.

  1. do()...

    dplyr's summarise is specially designed for functions that return a single value. If your function returns multiple/unequal values, you will have to resort to do(). You have to know beforehand about all your functions return value.

    DT[, list(x[1], y[1]), by = z]                 ## data.table syntax
    DF %>% group_by(z) %>% summarise(x[1], y[1]) ## dplyr syntax
    DT[, list(x[1:2], y[1]), by = z]
    DF %>% group_by(z) %>% do(data.frame(.$x[1:2], .$y[1]))
    
    DT[, quantile(x, 0.25), by = z]
    DF %>% group_by(z) %>% summarise(quantile(x, 0.25))
    DT[, quantile(x, c(0.25, 0.75)), by = z]
    DF %>% group_by(z) %>% do(data.frame(quantile(.$x, c(0.25, 0.75))))
    
    DT[, as.list(summary(x)), by = z]
    DF %>% group_by(z) %>% do(data.frame(as.list(summary(.$x))))
    
    • .SD's equivalent is .

    • In data.table, you can throw pretty much anything in j - the only thing to remember is for it to return a list so that each element of the list gets converted to a column.

    • In dplyr, cannot do that. Have to resort to do() depending on how sure you are as to whether your function would always return a single value. And it is quite slow.

Once again, data.table's syntax is consistent with DT[i, j, by]. We can just keep throwing expressions in j without having to worry about these things.

Have a look at this SO question and this one. I wonder if it would be possible to express the answer as straightforward using dplyr's syntax...

To summarise, I have particularly highlighted several instances where dplyr's syntax is either inefficient, limited or fails to make operations straightforward. This is particularly because data.table gets quite a bit of backlash about "harder to read/learn" syntax (like the one pasted/linked above). Most posts that cover dplyr talk about most straightforward operations. And that is great. But it is important to realise its syntax and feature limitations as well, and I am yet to see a post on it.

data.table has its quirks as well (some of which I have pointed out that we are attempting to fix). We are also attempting to improve data.table's joins as I have highlighted here.

But one should also consider the number of features that dplyr lacks in comparison to data.table.

4. Features

I have pointed out most of the features here and also in this post. In addition:

  • fread - fast file reader has been available for a long time now.

  • fwrite - a parallelised fast file writer is now available. See this post for a detailed explanation on the implementation and #1664 for keeping track of further developments.

  • Automatic indexing - another handy feature to optimise base R syntax as is, internally.

  • Ad-hoc grouping: dplyr automatically sorts the results by grouping variables during summarise(), which may not be always desirable.

  • Numerous advantages in data.table joins (for speed / memory efficiency and syntax) mentioned above.

  • Non-equi joins: Allows joins using other operators <=, <, >, >= along with all other advantages of data.table joins.

  • Overlapping range joins was implemented in data.table recently. Check this post for an overview with benchmarks.

  • setorder() function in data.table that allows really fast reordering of data.tables by reference.

  • dplyr provides interface to databases using the same syntax, which data.table does not at the moment.

  • data.table provides faster equivalents of set operations (written by Jan Gorecki) - fsetdiff, fintersect, funion and fsetequal with additional all argument (as in SQL).

  • data.table loads cleanly with no masking warnings and has a mechanism described here for [.data.frame compatibility when passed to any R package. dplyr changes base functions filter, lag and [ which can cause problems; e.g. here and here.


Finally:

  • On databases - there is no reason why data.table cannot provide similar interface, but this is not a priority now. It might get bumped up if users would very much like that feature.. not sure.

  • On parallelism - Everything is difficult, until someone goes ahead and does it. Of course it will take effort (being thread safe).

    • Progress is being made currently (in v1.9.7 devel) towards parallelising known time consuming parts for incremental performance gains using OpenMP.

how to fetch array keys with jQuery?

Use an object (key/value pairs, the nearest JavaScript has to an associative array) for this and not the array object. Other than that, I believe that is the most elegant way

var foo = {};
foo['alfa'] = "first item";
foo['beta'] = "second item";

for (var key in foo) {
        console.log(key);
}

Note: JavaScript doesn't guarantee any particular order for the properties. So you cannot expect the property that was defined first to appear first, it might come last.

EDIT:

In response to your comment, I believe that this article best sums up the cases for why arrays in JavaScript should not be used in this fashion -

Retrieving the text of the selected <option> in <select> element

Similar to @artur just without jQuery, with plain javascript:

// Using @Sean-bright's "elt" variable

var selection=elt.options[elt.selectedIndex].innerHTML;

JUnit tests pass in Eclipse but fail in Maven Surefire

It is most likely that your configuration files are in src/main/resources, while they must be under src/test/resources to work properly under maven.

https://cwiki.apache.org/UIMA/differences-between-running-unit-tests-in-eclipse-and-in-maven.html

I'm replying this after two years 'cause I couldn't find this answer here and I think it is the right one.

Struct like objects in Java

There is nothing wrong with that type of code, provided that the author knows they are structs (or data shuttles) instead of objects. Lots of Java developers can't tell the difference between a well-formed object (not just a subclass of java.lang.Object, but a true object in a specific domain) and a pineapple. Ergo,they end up writing structs when they need objects and viceversa.

How do I multiply each element in a list by a number?

Multiplying each element in my_list by k:

k = 5
my_list = [1,2,3,4]
result = list(map(lambda x: x * k, my_list))

resulting in: [5, 10, 15, 20]

Finding the length of a Character Array in C

There is also a compact form for that, if you do not want to rely on strlen. Assuming that the character array you are considering is "msg":

  unsigned int len=0;
  while(*(msg+len) ) len++;

How to merge two files line by line in Bash

You can use paste:

paste file1.txt file2.txt > fileresults.txt

Adding/removing items from a JavaScript object with jQuery

Keep things simple :)

var my_form_obj = {};
my_form_obj.name = "Captain America";
my_form_obj.weapon = "Shield";

Hope this helps!

Using the && operator in an if statement

So to make your expression work, changing && for -a will do the trick.

It is correct like this:

 if [ -f $VAR1 ] && [ -f $VAR2 ] && [ -f $VAR3 ]
 then  ....

or like

 if [[ -f $VAR1 && -f $VAR2 && -f $VAR3 ]]
 then  ....

or even

 if [ -f $VAR1 -a -f $VAR2 -a -f $VAR3 ]
 then  ....

You can find further details in this question bash : Multiple Unary operators in if statement and some references given there like What is the difference between test, [ and [[ ?.

Press Keyboard keys using a batch file

Wow! Mean this that you must learn a different programming language just to send two keys to the keyboard? There are simpler ways for you to achieve the same thing. :-)

The Batch file below is an example that start another program (cmd.exe in this case), send a command to it and then send an Up Arrow key, that cause to recover the last executed command. The Batch file is simple enough to be understand with no problems, so you may modify it to fit your needs.

@if (@CodeSection == @Batch) @then


@echo off

rem Use %SendKeys% to send keys to the keyboard buffer
set SendKeys=CScript //nologo //E:JScript "%~F0"

rem Start the other program in the same Window
start "" /B cmd

%SendKeys% "echo off{ENTER}"

set /P "=Wait and send a command: " < NUL
ping -n 5 -w 1 127.0.0.1 > NUL
%SendKeys% "echo Hello, world!{ENTER}"

set /P "=Wait and send an Up Arrow key: [" < NUL
ping -n 5 -w 1 127.0.0.1 > NUL
%SendKeys% "{UP}"

set /P "=] Wait and send an Enter key:" < NUL
ping -n 5 -w 1 127.0.0.1 > NUL
%SendKeys% "{ENTER}"

%SendKeys% "exit{ENTER}"

goto :EOF


@end


// JScript section

var WshShell = WScript.CreateObject("WScript.Shell");
WshShell.SendKeys(WScript.Arguments(0));

For a list of key names for SendKeys, see: http://msdn.microsoft.com/en-us/library/8c6yea83(v=vs.84).aspx

For example:

LEFT ARROW    {LEFT}
RIGHT ARROW   {RIGHT}

For a further explanation of this solution, see: GnuWin32 openssl s_client conn to WebSphere MQ server not closing at EOF, hangs

Using multiple property files (via PropertyPlaceholderConfigurer) in multiple projects/modules

If you ensure that every place holder, in each of the contexts involved, is ignoring unresolvable keys then both of these approaches work. For example:

<context:property-placeholder
location="classpath:dao.properties,
          classpath:services.properties,
          classpath:user.properties"
ignore-unresolvable="true"/>

or

    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:dao.properties</value>
                <value>classpath:services.properties</value>
                <value>classpath:user.properties</value>
            </list>
        </property> 
        <property name="ignoreUnresolvablePlaceholders" value="true"/>
    </bean>

OAuth 2.0 Authorization Header

You can still use the Authorization header with OAuth 2.0. There is a Bearer type specified in the Authorization header for use with OAuth bearer tokens (meaning the client app simply has to present ("bear") the token). The value of the header is the access token the client received from the Authorization Server.

It's documented in this spec: https://tools.ietf.org/html/rfc6750#section-2.1

E.g.:

   GET /resource HTTP/1.1
   Host: server.example.com
   Authorization: Bearer mF_9.B5f-4.1JqM

Where mF_9.B5f-4.1JqM is your OAuth access token.

Check if an image is loaded (no errors) with jQuery

This is how I got it to work cross browser using a combination of the methods above (I also needed to insert images dynamically into the dom):

$('#domTarget').html('<img src="" />');

var url = '/some/image/path.png';

$('#domTarget img').load(function(){}).attr('src', url).error(function() {
    if ( isIE ) {
       var thisImg = this;
       setTimeout(function() {
          if ( ! thisImg.complete ) {
             $(thisImg).attr('src', '/web/css/img/picture-broken-url.png');
          }
       },250);
    } else {
       $(this).attr('src', '/web/css/img/picture-broken-url.png');
    }
});

Note: You will need to supply a valid boolean state for the isIE variable.

Getting value of select (dropdown) before change

I go for Avi Pinto's solution which uses jquery.data()

Using focus isn't a valid solution. It works at first time you change the options, but if you stay on that select element, and press key "up" or "down". It won't go through the focus event again.

So the solution should be more looks like the following,

//set the pre data, usually needed after you initialize the select element
$('mySelect').data('pre', $(this).val());

$('mySelect').change(function(e){
    var before_change = $(this).data('pre');//get the pre data
    //Do your work here
    $(this).data('pre', $(this).val());//update the pre data
})

PowerShell Connect to FTP server and get files

Here is the full working code to download all files (with wildcard or file extension) from the FTP site to local directory. Set the variable values.

    #FTP Server Information - SET VARIABLES
    $ftp = "ftp://XXX.com/" 
    $user = 'UserName' 
    $pass = 'Password'
    $folder = 'FTP_Folder'
    $target = "C:\Folder\Folder1\"

    #SET CREDENTIALS
    $credentials = new-object System.Net.NetworkCredential($user, $pass)

    function Get-FtpDir ($url,$credentials) {
        $request = [Net.WebRequest]::Create($url)
        $request.Method = [System.Net.WebRequestMethods+FTP]::ListDirectory
        if ($credentials) { $request.Credentials = $credentials }
        $response = $request.GetResponse()
        $reader = New-Object IO.StreamReader $response.GetResponseStream() 
        while(-not $reader.EndOfStream) {
            $reader.ReadLine()
        }
        #$reader.ReadToEnd()
        $reader.Close()
        $response.Close()
    }

    #SET FOLDER PATH
    $folderPath= $ftp + "/" + $folder + "/"

    $files = Get-FTPDir -url $folderPath -credentials $credentials

    $files 

    $webclient = New-Object System.Net.WebClient 
    $webclient.Credentials = New-Object System.Net.NetworkCredential($user,$pass) 
    $counter = 0
    foreach ($file in ($files | where {$_ -like "*.txt"})){
        $source=$folderPath + $file  
        $destination = $target + $file 
        $webclient.DownloadFile($source, $target+$file)

        #PRINT FILE NAME AND COUNTER
        $counter++
        $counter
        $source
    }

Plotting a 3d cube, a sphere and a vector in Matplotlib

My answer is an amalgamation of the above two with extension to drawing sphere of user-defined opacity and some annotation. It finds application in b-vector visualization on a sphere for magnetic resonance image (MRI). Hope you find it useful:

from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure()
ax = fig.gca(projection='3d')

# draw sphere
u, v = np.mgrid[0:2*np.pi:50j, 0:np.pi:50j]
x = np.cos(u)*np.sin(v)
y = np.sin(u)*np.sin(v)
z = np.cos(v)
# alpha controls opacity
ax.plot_surface(x, y, z, color="g", alpha=0.3)


# a random array of 3D coordinates in [-1,1]
bvecs= np.random.randn(20,3)

# tails of the arrows
tails= np.zeros(len(bvecs))

# heads of the arrows with adjusted arrow head length
ax.quiver(tails,tails,tails,bvecs[:,0], bvecs[:,1], bvecs[:,2],
          length=1.0, normalize=True, color='r', arrow_length_ratio=0.15)

ax.set_xlabel('X-axis')
ax.set_ylabel('Y-axis')
ax.set_zlabel('Z-axis')

ax.set_title('b-vectors on unit sphere')

plt.show()

ReportViewer Client Print Control "Unable to load client print control"?

Found a Fix:

  1. First ensure that printing is working from Report Manager (open a report in Report Manager and print from there).

  2. If it works go to Step 3, if you received the same error you need to install the following patches on the Report Server.

  3. Download and install the following update:

Convert DateTime to a specified Format

Easy peasy:

var date = DateTime.Parse("14/11/2011"); // may need some Culture help here
Console.Write(date.ToString("yyyy-MM-dd"));

Take a look at DateTime.ToString() method, Custom Date and Time Format Strings and Standard Date and Time Format Strings

string customFormattedDateTimeString = DateTime.Now.ToString("yyyy-MM-dd");

Using Axios GET with Authorization Header in React-Native App

Could not get this to work until I put Authorization in single quotes:

axios.get(URL, { headers: { 'Authorization': AuthStr } })

Apache POI Excel - how to configure columns to be expanded?

After you have added all your data to the sheet, you can call autoSizeColumn(int column) on your sheet to autofit the columns to the proper size

Here is a link to the API.

See this post for more reference Problem in fitting the excel cell size to the size of the content when using apache poi

No visible cause for "Unexpected token ILLEGAL"

When running OS X, the filesystem creates hidden forks of basically all your files, if they are on a hard drive that doesn't support HFS+. This can sometimes (happened to me just now) lead to your JavaScript engine tries to run the data-fork instead of the code you intend it to run. When this happens, you will also receive

SyntaxError: Unexpected token ILLEGAL

because the data fork of your file will contain the Unicode U+200B character. Removing the data fork file will make your script run your actual, intended code, instead of a binary data fork of your code.

.whatever : These files are created on volumes that don't natively support full HFS file characteristics (e.g. ufs volumes, Windows fileshares, etc). When a Mac file is copied to such a volume, its data fork is stored under the file's regular name, and the additional HFS information (resource fork, type & creator codes, etc) is stored in a second file (in AppleDouble format), with a name that starts with ".". (These files are, of course, invisible as far as OS-X is concerned, but not to other OS's; this can sometimes be annoying...)

How do you install Google frameworks (Play, Accounts, etc.) on a Genymotion virtual device?

Alright, this is probably the easiest way to do it:

  1. First of all, you will have to install GAPPS.
  2. Next, open the virtual box and wait for the home screen to show up on Genymotion.
  3. Drag and drop the GAPPS folder that you had downloaded earlier on into Genymotion.
  4. You would get a prompt. Click OK. You would see a lot of errors, but just ignore them and wait for the successful prompt to come up. Click OK again and restart the virtual device.
  5. A Google account screen should show up. Open up the playstore app if it doesn't show up. Sign into your account. Again ignore the errors.
  6. The playstore should open now and should be fully functional.

MySql export schema without data

To get an individual table's creation script:
- select all the table (with shift key)
- just right click on the table name and click Copy to Clipboard > Create Statement.

Select statement to find duplicates on certain fields

CREATE TABLE #tmp
(
    sizeId Varchar(MAX)
)

INSERT  #tmp 
    VALUES ('44'),
        ('44,45,46'),
        ('44,45,46'),
        ('44,45,46'),
        ('44,45,46'),
        ('44,45,46'),
        ('44,45,46')


SELECT * FROM #tmp
DECLARE @SqlStr VARCHAR(MAX)

SELECT @SqlStr = STUFF((SELECT ',' + sizeId
              FROM #tmp
              ORDER BY sizeId
              FOR XML PATH('')), 1, 1, '') 


SELECT TOP 1 * FROM (
select items, count(*)AS Occurrence
  FROM dbo.Split(@SqlStr,',')
  group by items
  having count(*) > 1
  )K
  ORDER BY K.Occurrence DESC    

Combine Regexp?

Combining the regex for the fourth option with any of the others doesn't work within one regex. 4 + 1 would mean either the string starts with @ or doesn't contain @ at all. You're going to need two separate comparisons to do that.

How to find the process id of a running Java process on Windows? And how to kill the process alone?

You can also find the PID of a java program with the task manager. You enable the PID and Command Line columns View -> Select Columns and are then able to find the right process.

Your result will be something like this : enter image description here

Java Compare Two Lists

EDIT

Here are two versions. One using ArrayList and other using HashSet

Compare them and create your own version from this, until you get what you need.

This should be enough to cover the:

P.S: It is not a school assignment :) So if you just guide me it will be enough

part of your question.

continuing with the original answer:

You may use a java.util.Collection and/or java.util.ArrayList for that.

The retainAll method does the following:

Retains only the elements in this collection that are contained in the specified collection

see this sample:

import java.util.Collection;
import java.util.ArrayList;
import java.util.Arrays;

public class Repeated {
    public static void main( String  [] args ) {
        Collection listOne = new ArrayList(Arrays.asList("milan","dingo", "elpha", "hafil", "meat", "iga", "neeta.peeta"));
        Collection listTwo = new ArrayList(Arrays.asList("hafil", "iga", "binga", "mike", "dingo"));

        listOne.retainAll( listTwo );
        System.out.println( listOne );
    }
}

EDIT

For the second part ( similar values ) you may use the removeAll method:

Removes all of this collection's elements that are also contained in the specified collection.

This second version gives you also the similar values and handles repeated ( by discarding them).

This time the Collection could be a Set instead of a List ( the difference is, the Set doesn't allow repeated values )

import java.util.Collection;
import java.util.HashSet;
import java.util.Arrays;

class Repeated {
      public static void main( String  [] args ) {

          Collection<String> listOne = Arrays.asList("milan","iga",
                                                    "dingo","iga",
                                                    "elpha","iga",
                                                    "hafil","iga",
                                                    "meat","iga", 
                                                    "neeta.peeta","iga");

          Collection<String> listTwo = Arrays.asList("hafil",
                                                     "iga",
                                                     "binga", 
                                                     "mike", 
                                                     "dingo","dingo","dingo");

          Collection<String> similar = new HashSet<String>( listOne );
          Collection<String> different = new HashSet<String>();
          different.addAll( listOne );
          different.addAll( listTwo );

          similar.retainAll( listTwo );
          different.removeAll( similar );

          System.out.printf("One:%s%nTwo:%s%nSimilar:%s%nDifferent:%s%n", listOne, listTwo, similar, different);
      }
}

Output:

$ java Repeated
One:[milan, iga, dingo, iga, elpha, iga, hafil, iga, meat, iga, neeta.peeta, iga]

Two:[hafil, iga, binga, mike, dingo, dingo, dingo]

Similar:[dingo, iga, hafil]

Different:[mike, binga, milan, meat, elpha, neeta.peeta]

If it doesn't do exactly what you need, it gives you a good start so you can handle from here.

Question for the reader: How would you include all the repeated values?

Confusing error in R: Error in scan(file, what, nmax, sep, dec, quote, skip, nlines, na.strings, : line 1 did not have 42 elements)

To read characters try

scan("/PathTo/file.csv", "")

If you're reading numeric values, then just use

scan("/PathTo/file.csv")

scan by default will use white space as separator. The type of the second arg defines 'what' to read (defaults to double()).

Passing an Array as Arguments, not an Array, in PHP

Also note that if you want to apply an instance method to an array, you need to pass the function as:

call_user_func_array(array($instance, "MethodName"), $myArgs);

Play multiple CSS animations at the same time

You can indeed run multiple animations simultaneously, but your example has two problems. First, the syntax you use only specifies one animation. The second style rule hides the first. You can specify two animations using syntax like this:

-webkit-animation-name: spin, scale
-webkit-animation-duration: 2s, 4s

as in this fiddle (where I replaced "scale" with "fade" due to the other problem explained below... Bear with me.): http://jsfiddle.net/rwaldin/fwk5bqt6/

Second, both of your animations alter the same CSS property (transform) of the same DOM element. I don't believe you can do that. You can specify two animations on different elements, the image and a container element perhaps. Just apply one of the animations to the container, as in this fiddle: http://jsfiddle.net/rwaldin/fwk5bqt6/2/

T-test in Pandas

EDIT: I had not realized this was about the data format. You could use

import pandas as pd
import scipy
two_data = pd.DataFrame(data, index=data['Category'])

Then accessing the categories is as simple as

scipy.stats.ttest_ind(two_data.loc['cat'], two_data.loc['cat2'], equal_var=False)

The loc operator accesses rows by label.


As @G Garcia said

one sided or two sided dependent or independent

If you have two independent samples but you do not know that they have equal variance, you can use Welch's t-test. It is as simple as

scipy.stats.ttest_ind(cat1['values'], cat2['values'], equal_var=False)

For reasons to prefer Welch's test, see https://stats.stackexchange.com/questions/305/when-conducting-a-t-test-why-would-one-prefer-to-assume-or-test-for-equal-vari.

For two dependent samples, you can use

scipy.stats.ttest_rel(cat1['values'], cat2['values'])

Regular Expression for alphanumeric and underscores

Um...question: Does it need to have at least one character or no? Can it be an empty string?

^[A-Za-z0-9_]+$

Will do at least one upper or lower case alphanumeric or underscore. If it can be zero length, then just substitute the + for *

^[A-Za-z0-9_]*$

Edit:

If diacritics need to be included (such as cedilla - ç) then you would need to use the word character which does the same as the above, but includes the diacritic characters:

^\w+$

Or

^\w*$

MVC4 StyleBundle not resolving images

Just remember to fix multiple CSS inclusions in a bundle such as:

bundles.Add(new StyleBundle("~/Content/styles/jquery-ui")
    .Include("~/Content/css/path1/somestyle1.css", "~/Content/css/path2/somestyle2.css"));

You cannot just add new CssRewriteUrlTransform() to the end as you can with one CSS file as the method does not support it, so you have to use Include multiple times:

bundles.Add(new StyleBundle("~/Content/styles/jquery-ui")
    .Include("~/Content/css/path1/somestyle1.css", new CssRewriteUrlTransform())
    .Include("~/Content/css/path2/somestyle2.css", new CssRewriteUrlTransform()));

Render partial from different folder (not shared)

The VirtualPathProviderViewEngine, on which the WebFormsViewEngine is based, is supposed to support the "~" and "/" characters at the front of the path so your examples above should work.

I noticed your examples use the path "~/Account/myPartial.ascx", but you mentioned that your user control is in the Views/Account folder. Have you tried

<%Html.RenderPartial("~/Views/Account/myPartial.ascx");%>

or is that just a typo in your question?

What are the undocumented features and limitations of the Windows FINDSTR command?

/D tip for multiple directories: put your directory list before the search string. These all work:

findstr /D:dir1;dir2 "searchString" *.*
findstr /D:"dir1;dir2" "searchString" *.*
findstr /D:"\path\dir1\;\path\dir2\" "searchString" *.*

As expected, the path is relative to location if you don't start the directories with \. Surrounding the path with " is optional if there are no spaces in the directory names. The ending \ is optional. The output of location will include whatever path you give it. It will work with or without surrounding the directory list with ".

Local and global temporary tables in SQL Server

I didn't see any answers that show users where we can find a Global Temp table. You can view Local and Global temp tables in the same location when navigating within SSMS. Screenshot below taken from this link.

Databases --> System Databases --> tempdb --> Temporary Tables

enter image description here

Cannot create Maven Project in eclipse

In my case following solution worked.

  1. Delete RELEASE directory & resolver-status.properties file in your local Maven repository under directory .m2/../maven-archetype-quickstart.
  2. Create Maven project in Eclipse or STS (Spring Tool Suite). It will automatically download quickstart archetype & work as expected.

I hope this may help someone.

preg_match(); - Unknown modifier '+'

This happened to me because I put a variable in the regex and sometimes its string value included a slash. Solution: preg_quote.

matplotlib set yaxis label size

If you are using the 'pylab' for interactive plotting you can set the labelsize at creation time with pylab.ylabel('Example', fontsize=40).

If you use pyplot programmatically you can either set the fontsize on creation with ax.set_ylabel('Example', fontsize=40) or afterwards with ax.yaxis.label.set_size(40).

Change Name of Import in Java, or import two classes with the same name

Actually it is possible to create a shortcut so you can use shorter names in your code by doing something like this:

package com.mycompany.installer;
public abstract class ConfigurationReader {
    private static class Implementation extends com.mycompany.installer.implementation.ConfigurationReader {}
    public abstract String getLoaderVirtualClassPath();
    public static QueryServiceConfigurationReader getInstance() {
        return new Implementation();
    }
}

In that way you only need to specify the long name once, and you can have as many specially named classes you want.

Another thing I like about this pattern is that you can name the implementing class the same as the abstract base class, and just place it in a different namespace. That is unrelated to the import/renaming pattern though.

Shell Script: How to write a string to file and to stdout on console?

Use the tee command:

echo "hello" | tee logfile.txt

How to call a JavaScript function from PHP?

Thats not possible. PHP is a Server side language and JavaScript client side and they don't really know a lot about each other. You would need a Server sided JavaScript Interpreter (like Aptanas Jaxer). Maybe what you actually want to do is to use an Ajax like Architecture (JavaScript function calls PHP script asynchronously and does something with the result).

<td onClick= loadxml()><i>Click for Details</i></td>

function loadxml()
{
    result = loadScriptWithAjax("/script.php?event=button_clicked");
    alert(result);
}

// script.php
<?php
    if($_GET['event'] == 'button_clicked')
        echo "\"You clicked a button\"";
?>

How can I remove non-ASCII characters but leave periods and spaces using Python?

Working my way through Fluent Python (Ramalho) - highly recommended. List comprehension one-ish-liners inspired by Chapter 2:

onlyascii = ''.join([s for s in data if ord(s) < 127])
onlymatch = ''.join([s for s in data if s in
              'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'])

Is it possible to center text in select box?

Not quite Centering but using example above you can make a left margin in select box.

<style>.UName { text-indent: 5px; }</style><br>

<select  name="UserName" id="UserName" size="1">
    <option class="UName" selected value="select">Select User</option>
    <option class="UName" value="User1">User 1 Name</option>
    <option class="UName" value="User2">User 2 Name </option>
    <option class="UName" value="User3">User 3 Name</option>
</select>

In C#, what is the difference between public, private, protected, and having no access modifier?

C# has, in total, 6 access modifiers:

private: The member declared with this accessibility can be visible within the containing type, it is not visible to any derived types, other types in the same assembly or types outside of the containing assembly. i.e., access is limited to the containing type only.

protected: The member declared with this accessibility can be visible within the types derived from the containing type within the containing assembly, and the types derived from the containing type outside of the containing assembly. i.e., access is limited to derived types of the containing type.

internal: The member declared with this accessibility can be visible within the assembly containing this member, it is not visible to any assembly outside of the containing assembly. i.e., access is limited to containing assembly only.

internal protected: The member declared with this accessibility can be visible within the types derived from the containing type within or outside of the containing assembly, it is also visible to any types within the containing assembly. i.e., access is limited to containing assembly or derived types.

public: The member declared with this accessibility can be visible within the assembly containing this member, or any other assembly that references the containing assembly. i.e., access is not limited.

In C# 7.2, a new level of accessibility was added:

private protected: The member declared with this accessibility can be visible within the types derived from this containing type within the containing assembly. It is not visible to any types not derived from the containing type, or outside of the containing assembly. i.e., the access is limited to derived types within the containing assembly.

Source including a sample code of the new private protected access modifier

How to find out what group a given user has?

This one shows the user's uid as well as all the groups (with their gids) they belong to

id userid

How do I remove the first characters of a specific column in a table?

The Complete thing

DECLARE @v varchar(10)

SET @v='#temp'

select STUFF(@v, 1, 1, '')
WHERE LEFT(@v,1)='#'

Laravel Unknown Column 'updated_at'

For those who are using laravel 5 or above must use public modifier other wise it will throw an exception

Access level to App\yourModelName::$timestamps must be
public (as in class Illuminate\Database\Eloquent\Model)

public $timestamps = false;

New to unit testing, how to write great tests?

For unit testing, I found both Test Driven (tests first, code second) and code first, test second to be extremely useful.

Instead of writing code, then writing test. Write code then look at what you THINK the code should be doing. Think about all the intended uses of it and then write a test for each. I find writing tests to be faster but more involved than the coding itself. The tests should test the intention. Also thinking about the intentions you wind up finding corner cases in the test writing phase. And of course while writing tests you might find one of the few uses causes a bug (something I often find, and I am very glad this bug did not corrupt data and go unchecked).

Yet testing is almost like coding twice. In fact I had applications where there was more test code (quantity) than application code. One example was a very complex state machine. I had to make sure that after adding more logic to it, the entire thing always worked on all previous use cases. And since those cases were quite hard to follow by looking at the code, I wound up having such a good test suite for this machine that I was confident that it would not break even after making changes, and the tests saved my ass a few times. And as users or testers were finding bugs with the flow or corner cases unaccounted for, guess what, added to tests and never happened again. This really gave users confidence in my work in addition to making the whole thing super stable. And when it had to be re-written for performance reasons, guess what, it worked as expected on all inputs thanks to the tests.

All the simple examples like function square(number) is great and all, and are probably bad candidates to spend lots of time testing. The ones that do important business logic, thats where the testing is important. Test the requirements. Don't just test the plumbing. If the requirements change then guess what, the tests must too.

Testing should not be literally testing that function foo invoked function bar 3 times. That is wrong. Check if the result and side-effects are correct, not the inner mechanics.

I keep getting this error for my simple python program: "TypeError: 'float' object cannot be interpreted as an integer"

range() can only work with integers, but dividing with the / operator always results in a float value:

>>> 450 / 10
45.0
>>> range(450 / 10)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'float' object cannot be interpreted as an integer

Make the value an integer again:

for i in range(int(c / 10)):

or use the // floor division operator:

for i in range(c // 10):

How is attr_accessible used in Rails 4?

We can use

params.require(:person).permit(:name, :age)

where person is Model, you can pass this code on a method person_params & use in place of params[:person] in create method or else method

Recursively look for files with a specific extension

find {directory} -type f -name '*.extension'

Example: To find all csv files in the current directory and its sub-directories, use:

find . -type f -name '*.csv'

How can I find where Python is installed on Windows?

If anyone needs to do this in C# I'm using the following code:

static string GetPythonExecutablePath(int major = 3)
{
    var software = "SOFTWARE";
    var key = Registry.CurrentUser.OpenSubKey(software);
    if (key == null)
        key = Registry.LocalMachine.OpenSubKey(software);
    if (key == null)
        return null;

    var pythonCoreKey = key.OpenSubKey(@"Python\PythonCore");
    if (pythonCoreKey == null)
        pythonCoreKey = key.OpenSubKey(@"Wow6432Node\Python\PythonCore");
    if (pythonCoreKey == null)
        return null;

    var pythonVersionRegex = new Regex("^" + major + @"\.(\d+)-(\d+)$");
    var targetVersion = pythonCoreKey.GetSubKeyNames().
                                        Select(n => pythonVersionRegex.Match(n)).
                                        Where(m => m.Success).
                                        OrderByDescending(m => int.Parse(m.Groups[1].Value)).
                                        ThenByDescending(m => int.Parse(m.Groups[2].Value)).
                                        Select(m => m.Groups[0].Value).First();

    var installPathKey = pythonCoreKey.OpenSubKey(targetVersion + @"\InstallPath");
    if (installPathKey == null)
        return null;

    return (string)installPathKey.GetValue("ExecutablePath");
}

Binding value to input in Angular JS

If you don't wan't to use ng-model there is ng-value you can try.

Here's the fiddle for this: http://jsfiddle.net/Rg9sG/1/

VBA code to show Message Box popup if the formula in the target cell exceeds a certain value

You could add the following VBA code to your sheet:

Private Sub Worksheet_Change(ByVal Target As Range)
    If Range("A1") > 0.5 Then
        MsgBox "Discount too high"
    End If
End Sub

Every time a cell is changed on the sheet, it will check the value of cell A1.

Notes:

  • if A1 also depends on data located in other spreadsheets, the macro will not be called if you change that data.
  • the macro will be called will be called every time something changes on your sheet. If it has lots of formula (as in 1000s) it could be slow.

Widor uses a different approach (Worksheet_Calculate instead of Worksheet_Change):

  • Pros: his method will work if A1's value is linked to cells located in other sheets.
  • Cons: if you have many links on your sheet that reference other sheets, his method will run a bit slower.

Conclusion: use Worksheet_Change if A1 only depends on data located on the same sheet, use Worksheet_Calculate if not.

How can I count all the lines of code in a directory recursively?

You didn't specify how many files are there or what is the desired output.

This may be what you are looking for:

find . -name '*.php' | xargs wc -l

Unresponsive KeyListener for JFrame

I got the same problem until i read that the real problem is about FOCUS the your JFrame has already added Listeners but tour frame is never on Focus because you got a lot of components inside your JFrame that also are focusable so try:

JFrame.setFocusable(true);

Good Luck

Find package name for Android apps to use Intent to launch Market app from web

If you want this information in your phone, then best is to use an app like 'APKit' that shows the full package name of each app in you phone. This information can then be used in your phone.

How to parse a string in JavaScript?

Use the Javascript string split() function.

var coolVar = '123-abc-itchy-knee';
var partsArray = coolVar.split('-');

// Will result in partsArray[0] == '123', partsArray[1] == 'abc', etc

Difference between multitasking, multithreading and multiprocessing?

A multiprogramming is the process when a computer system is performing different tasks all at once in a single computer system.

Check, using jQuery, if an element is 'display:none' or block on click

another shortcut i personally prefer more than .is() or .length:

if($('.myclass:visible')[0]){
   // is visible
}else {
   // is hidden
}

Text border using css (border around text)

Use multiple text shadows:

text-shadow: 2px 0 0 #fff, -2px 0 0 #fff, 0 2px 0 #fff, 0 -2px 0 #fff, 1px 1px #fff, -1px -1px 0 #fff, 1px -1px 0 #fff, -1px 1px 0 #fff;

enter image description here

_x000D_
_x000D_
body {_x000D_
  font-family: sans-serif;_x000D_
  background: #222;_x000D_
  color: darkred;_x000D_
  }_x000D_
h1 {_x000D_
  text-shadow: 2px 0 0 #fff, -2px 0 0 #fff, 0 2px 0 #fff, 0 -2px 0 #fff, 1px 1px #fff, -1px -1px 0 #fff, 1px -1px 0 #fff, -1px 1px 0 #fff;_x000D_
}
_x000D_
<h1>test</h1>
_x000D_
_x000D_
_x000D_

Alternatively, you could use text stroke, which only works in webkit:

-webkit-text-stroke-width: 2px;
-webkit-text-stroke-color: #fff;

enter image description here

_x000D_
_x000D_
body {_x000D_
  font-family: sans-serif;_x000D_
  background: #222;_x000D_
  color: darkred;_x000D_
  }_x000D_
h1 {_x000D_
  -webkit-text-stroke-width: 2px;_x000D_
-webkit-text-stroke-color: #fff;_x000D_
}
_x000D_
<h1>test</h1>
_x000D_
_x000D_
_x000D_

Also read more as CSS-Tricks.

How to solve the memory error in Python

Assuming your example text is representative of all the text, one line would consume about 75 bytes on my machine:

In [3]: sys.getsizeof('usedfor zipper fasten_coat')
Out[3]: 75

Doing some rough math:

75 bytes * 8,000,000 lines / 1024 / 1024 = ~572 MB

So roughly 572 meg to store the strings alone for one of these files. Once you start adding in additional, similarly structured and sized files, you'll quickly approach your virtual address space limits, as mentioned in @ShadowRanger's answer.

If upgrading your python isn't feasible for you, or if it only kicks the can down the road (you have finite physical memory after all), you really have two options: write your results to temporary files in-between loading in and reading the input files, or write your results to a database. Since you need to further post-process the strings after aggregating them, writing to a database would be the superior approach.

How to export dataGridView data Instantly to Excel on button click?

I solved this by simple copy and paste method. I don't know it is the best way to do this but,for me it works good and almost instantaneously. Here is my code.

    private void copyAlltoClipboard()
    {
        dataGridView1.SelectAll();
        DataObject dataObj = dataGridView1.GetClipboardContent();
        if (dataObj != null)
            Clipboard.SetDataObject(dataObj);
    }
    private void button3_Click_1(object sender, EventArgs e)
    {
        copyAlltoClipboard();
        Microsoft.Office.Interop.Excel.Application xlexcel;
        Microsoft.Office.Interop.Excel.Workbook xlWorkBook;
        Microsoft.Office.Interop.Excel.Worksheet xlWorkSheet;
        object misValue = System.Reflection.Missing.Value;
        xlexcel = new Excel.Application();
        xlexcel.Visible = true;
        xlWorkBook = xlexcel.Workbooks.Add(misValue);
        xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
        Excel.Range CR = (Excel.Range)xlWorkSheet.Cells[1, 1];
        CR.Select();
        xlWorkSheet.PasteSpecial(CR, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, true);          
    }

Thanks.

Add items to comboBox in WPF

Use this

string[] str = new string[] {"Foo", "Bar"};

myComboBox.ItemsSource = str;
myComboBox.SelectedIndex = 0;

OR

foreach (string s in str)
    myComboBox.Items.Add(s);

myComboBox.SelectedIndex = 0;      

How can I keep Bootstrap popovers alive while being hovered?

I used the trigger set to hover and gave the container set to the #element and finally adding a placement of the box to right.

This should be your setup:

$('#example').popover({
    html: true,
    trigger: 'hover',
    container: '#example',
    placement: 'right',
    content: function () {
        return '<div class="box"></div>';
    }
});

and #example css needs position:relative; check the jsfiddle below:

https://jsfiddle.net/9qn6pw4p/1/

Edited

This fiddle has both links that work with no problems http://jsfiddle.net/davidchase03/FQE57/4/

Better naming in Tuple classes than "Item1", "Item2"

This is very annoying and I expect future versions of C# will address this need. I find the easiest work around to be either use a different data structure type or rename the "items" for your sanity and for the sanity of others reading your code.

Tuple<ApiResource, JSendResponseStatus> result = await SendApiRequest();
ApiResource apiResource = result.Item1;
JSendResponseStatus jSendStatus = result.Item2;

Inserting Image Into BLOB Oracle 10g

You cannot access a local directory from pl/sql. If you use bfile, you will setup a directory (create directory) on the server where Oracle is running where you will need to put your images.

If you want to insert a handful of images from your local machine, you'll need a client side app to do this. You can write your own, but I typically use Toad for this. In schema browser, click onto the table. Click the data tab, and hit + sign to add a row. Double click the BLOB column, and a wizard opens. The far left icon will load an image into the blob:

enter image description here

SQL Developer has a similar feature. See the "Load" link below:

enter image description here

If you need to pull images over the wire, you can do it using pl/sql, but its not straight forward. First, you'll need to setup ACL list access (for security reasons) to allow a user to pull over the wire. See this article for more on ACL setup.

Assuming ACL is complete, you'd pull the image like this:

declare
    l_url varchar2(4000) := 'http://www.oracleimg.com/us/assets/12_c_navbnr.jpg';
    l_http_request   UTL_HTTP.req;
    l_http_response  UTL_HTTP.resp;
    l_raw RAW(2000);
    l_blob BLOB;
begin
   -- Important: setup ACL access list first!

    DBMS_LOB.createtemporary(l_blob, FALSE);

    l_http_request  := UTL_HTTP.begin_request(l_url);
    l_http_response := UTL_HTTP.get_response(l_http_request);

  -- Copy the response into the BLOB.
  BEGIN
    LOOP
      UTL_HTTP.read_raw(l_http_response, l_raw, 2000);
      DBMS_LOB.writeappend (l_blob, UTL_RAW.length(l_raw), l_raw);
    END LOOP;
  EXCEPTION
    WHEN UTL_HTTP.end_of_body THEN
      UTL_HTTP.end_response(l_http_response);
  END;

  insert into my_pics (pic_id, pic) values (102, l_blob);
  commit;

  DBMS_LOB.freetemporary(l_blob); 
end;

Hope that helps.

How do I remove  from the beginning of a file?

Three words for you:

Byte Order Mark (BOM)

That's the representation for the UTF-8 BOM in ISO-8859-1. You have to tell your editor to not use BOMs or use a different editor to strip them out.

To automatize the BOM's removal you can use awk as shown in this question.

As another answer says, the best would be for PHP to actually interpret the BOM correctly, for that you can use mb_internal_encoding(), like this:

 <?php
   //Storing the previous encoding in case you have some other piece 
   //of code sensitive to encoding and counting on the default value.      
   $previous_encoding = mb_internal_encoding();

   //Set the encoding to UTF-8, so when reading files it ignores the BOM       
   mb_internal_encoding('UTF-8');

   //Process the CSS files...

   //Finally, return to the previous encoding
   mb_internal_encoding($previous_encoding);

   //Rest of the code...
  ?>

How to set proxy for wget?

Type in command line :

$ export http_proxy=http://proxy_host:proxy_port

for authenticated proxy,

$ export http_proxy=http://username:password@proxy_host:proxy_port

and then run

$ wget fileurl

for https, just use https_proxy instead of http_proxy. You could also put these lines in your ~/.bashrc file so that you don't need to execute this everytime.

Add support library to Android Studio project

You can simply download the library which you want to include and copy it to libs folder of your project. Then select that file (in my case it was android-support-v4 library) right click on it and select "Add as Library"

Remove all special characters from a string

Update

The solution below has a "SEO friendlier" version:

function hyphenize($string) {
    $dict = array(
        "I'm"      => "I am",
        "thier"    => "their",
        // Add your own replacements here
    );
    return strtolower(
        preg_replace(
          array( '#[\\s-]+#', '#[^A-Za-z0-9. -]+#' ),
          array( '-', '' ),
          // the full cleanString() can be downloaded from http://www.unexpectedit.com/php/php-clean-string-of-utf8-chars-convert-to-similar-ascii-char
          cleanString(
              str_replace( // preg_replace can be used to support more complicated replacements
                  array_keys($dict),
                  array_values($dict),
                  urldecode($string)
              )
          )
        )
    );
}

function cleanString($text) {
    $utf8 = array(
        '/[áàâãªä]/u'   =>   'a',
        '/[ÁÀÂÃÄ]/u'    =>   'A',
        '/[ÍÌÎÏ]/u'     =>   'I',
        '/[íìîï]/u'     =>   'i',
        '/[éèêë]/u'     =>   'e',
        '/[ÉÈÊË]/u'     =>   'E',
        '/[óòôõºö]/u'   =>   'o',
        '/[ÓÒÔÕÖ]/u'    =>   'O',
        '/[úùûü]/u'     =>   'u',
        '/[ÚÙÛÜ]/u'     =>   'U',
        '/ç/'           =>   'c',
        '/Ç/'           =>   'C',
        '/ñ/'           =>   'n',
        '/Ñ/'           =>   'N',
        '/–/'           =>   '-', // UTF-8 hyphen to "normal" hyphen
        '/[’‘‹›‚]/u'    =>   ' ', // Literally a single quote
        '/[“”«»„]/u'    =>   ' ', // Double quote
        '/ /'           =>   ' ', // nonbreaking space (equiv. to 0x160)
    );
    return preg_replace(array_keys($utf8), array_values($utf8), $text);
}

The rationale for the above functions (which I find way inefficient - the one below is better) is that a service that shall not be named apparently ran spelling checks and keyword recognition on the URLs.

After losing a long time on a customer's paranoias, I found out they were not imagining things after all -- their SEO experts [I am definitely not one] reported that, say, converting "Viaggi Economy Perù" to viaggi-economy-peru "behaved better" than viaggi-economy-per (the previous "cleaning" removed UTF8 characters; Bogotà became bogot, Medellìn became medelln and so on).

There were also some common misspellings that seemed to influence the results, and the only explanation that made sense to me is that our URL were being unpacked, the words singled out, and used to drive God knows what ranking algorithms. And those algorithms apparently had been fed with UTF8-cleaned strings, so that "Perù" became "Peru" instead of "Per". "Per" did not match and sort of took it in the neck.

In order to both keep UTF8 characters and replace some misspellings, the faster function below became the more accurate (?) function above. $dict needs to be hand tailored, of course.

Previous answer

A simple approach:

// Remove all characters except A-Z, a-z, 0-9, dots, hyphens and spaces
// Note that the hyphen must go last not to be confused with a range (A-Z)
// and the dot, NOT being special (I know. My life was a lie), is NOT escaped

$str = preg_replace('/[^A-Za-z0-9. -]/', '', $str);

// Replace sequences of spaces with hyphen
$str = preg_replace('/  */', '-', $str);

// The above means "a space, followed by a space repeated zero or more times"
// (should be equivalent to / +/)

// You may also want to try this alternative:
$str = preg_replace('/\\s+/', '-', $str);

// where \s+ means "zero or more whitespaces" (a space is not necessarily the
// same as a whitespace) just to be sure and include everything

Note that you might have to first urldecode() the URL, since %20 and + both are actually spaces - I mean, if you have "Never%20gonna%20give%20you%20up" you want it to become Never-gonna-give-you-up, not Never20gonna20give20you20up . You might not need it, but I thought I'd mention the possibility.

So the finished function along with test cases:

function hyphenize($string) {
    return 
    ## strtolower(
          preg_replace(
            array('#[\\s-]+#', '#[^A-Za-z0-9. -]+#'),
            array('-', ''),
        ##     cleanString(
              urldecode($string)
        ##     )
        )
    ## )
    ;
}

print implode("\n", array_map(
    function($s) {
            return $s . ' becomes ' . hyphenize($s);
    },
    array(
    'Never%20gonna%20give%20you%20up',
    "I'm not the man I was",
    "'Légeresse', dit sa majesté",
    )));


Never%20gonna%20give%20you%20up    becomes  never-gonna-give-you-up
I'm not the man I was              becomes  im-not-the-man-I-was
'Légeresse', dit sa majesté        becomes  legeresse-dit-sa-majeste

To handle UTF-8 I used a cleanString implementation found online (link broken since, but a stripped down copy with all the not-too-esoteric UTF8 characters is at the beginning of the answer; it's also easy to add more characters to it if you need) that converts UTF8 characters to normal characters, thus preserving the word "look" as much as possible. It could be simplified and wrapped inside the function here for performance.

The function above also implements converting to lowercase - but that's a taste. The code to do so has been commented out.

Importing class from another file

Your problem is basically that you never specified the right path to the file.

Try instead, from your main script:

from folder.file import Klasa

Or, with from folder import file:

from folder import file
k = file.Klasa()

Or again:

import folder.file as myModule
k = myModule.Klasa()

how to use "AND", "OR" for RewriteCond on Apache?

After many struggles and to achive a general, flexible and more readable solution, in my case I ended up saving the ORs results into ENV variables and doing the ANDs of those variables.

# RESULT_ONE = A OR B
RewriteRule ^ - [E=RESULT_ONE:False]
RewriteCond ...A... [OR]
RewriteCond ...B...
RewriteRule ^ - [E=RESULT_ONE:True]

# RESULT_TWO = C OR D
RewriteRule ^ - [E=RESULT_TWO:False]
RewriteCond ...C... [OR]
RewriteCond ...D...
RewriteRule ^ - [E=RESULT_TWO:True]

# if ( RESULT_ONE AND RESULT_TWO ) then ( RewriteRule ...something... )
RewriteCond %{ENV:RESULT_ONE} =True
RewriteCond %{ENV:RESULT_TWO} =True
RewriteRule ...something...

Requirements:

How to change a field name in JSON using Jackson

Be aware that there is org.codehaus.jackson.annotate.JsonProperty in Jackson 1.x and com.fasterxml.jackson.annotation.JsonProperty in Jackson 2.x. Check which ObjectMapper you are using (from which version), and make sure you use the proper annotation.

Non-conformable arrays error in code

The problem is that omega in your case is matrix of dimensions 1 * 1. You should convert it to a vector if you wish to multiply t(X) %*% X by a scalar (that is omega)

In particular, you'll have to replace this line:

omega   = rgamma(1,a0,1) / L0

with:

omega   = as.vector(rgamma(1,a0,1) / L0)

everywhere in your code. It happens in two places (once inside the loop and once outside). You can substitute as.vector(.) or c(t(.)). Both are equivalent.

Here's the modified code that should work:

gibbs = function(data, m01 = 0, m02 = 0, k01 = 0.1, k02 = 0.1, 
                     a0 = 0.1, L0 = 0.1, nburn = 0, ndraw = 5000) {
    m0      = c(m01, m02) 
    C0      = matrix(nrow = 2, ncol = 2) 
    C0[1,1] = 1 / k01 
    C0[1,2] = 0 
    C0[2,1] = 0 
    C0[2,2] = 1 / k02 
    beta    = mvrnorm(1,m0,C0) 
    omega   = as.vector(rgamma(1,a0,1) / L0)
    draws   = matrix(ncol = 3,nrow = ndraw) 
    it      = -nburn 

    while (it < ndraw) {
        it    = it + 1 
        C1    = solve(solve(C0) + omega * t(X) %*% X) 
        m1    = C1 %*% (solve(C0) %*% m0 + omega * t(X) %*% y)
        beta  = mvrnorm(1, m1, C1) 
        a1    = a0 + n / 2 
        L1    = L0 + t(y - X %*% beta) %*% (y - X %*% beta) / 2 
        omega = as.vector(rgamma(1, a1, 1) / L1)
        if (it > 0) { 
            draws[it,1] = beta[1]
            draws[it,2] = beta[2]
            draws[it,3] = omega
        }
    }
    return(draws)
}

What is the purpose of flush() in Java streams?

From the docs of the flush method:

Flushes the output stream and forces any buffered output bytes to be written out. The general contract of flush is that calling it is an indication that, if any bytes previously written have been buffered by the implementation of the output stream, such bytes should immediately be written to their intended destination.

The buffering is mainly done to improve the I/O performance. More on this can be read from this article: Tuning Java I/O Performance.

Extracting text OpenCV

@dhanushka's approach showed the most promise but I wanted to play around in Python so went ahead and translated it for fun:

import cv2
import numpy as np
from cv2 import boundingRect, countNonZero, cvtColor, drawContours, findContours, getStructuringElement, imread, morphologyEx, pyrDown, rectangle, threshold

large = imread(image_path)
# downsample and use it for processing
rgb = pyrDown(large)
# apply grayscale
small = cvtColor(rgb, cv2.COLOR_BGR2GRAY)
# morphological gradient
morph_kernel = getStructuringElement(cv2.MORPH_ELLIPSE, (3, 3))
grad = morphologyEx(small, cv2.MORPH_GRADIENT, morph_kernel)
# binarize
_, bw = threshold(src=grad, thresh=0, maxval=255, type=cv2.THRESH_BINARY+cv2.THRESH_OTSU)
morph_kernel = getStructuringElement(cv2.MORPH_RECT, (9, 1))
# connect horizontally oriented regions
connected = morphologyEx(bw, cv2.MORPH_CLOSE, morph_kernel)
mask = np.zeros(bw.shape, np.uint8)
# find contours
im2, contours, hierarchy = findContours(connected, cv2.RETR_CCOMP, cv2.CHAIN_APPROX_SIMPLE)
# filter contours
for idx in range(0, len(hierarchy[0])):
    rect = x, y, rect_width, rect_height = boundingRect(contours[idx])
    # fill the contour
    mask = drawContours(mask, contours, idx, (255, 255, 2555), cv2.FILLED)
    # ratio of non-zero pixels in the filled region
    r = float(countNonZero(mask)) / (rect_width * rect_height)
    if r > 0.45 and rect_height > 8 and rect_width > 8:
        rgb = rectangle(rgb, (x, y+rect_height), (x+rect_width, y), (0,255,0),3)

Now to display the image:

from PIL import Image
Image.fromarray(rgb).show()

Not the most Pythonic of scripts but I tried to resemble the original C++ code as closely as possible for readers to follow.

It works almost as well as the original. I'll be happy to read suggestions how it could be improved/fixed to resemble the original results fully.

enter image description here

enter image description here

enter image description here

How to split a string by spaces in a Windows batch file?

Here is a solution based on a "function" which processes each character until it finds the delimiter character.

It is relatively slow, but it is at least not a brain teaser (except for the function part).

:: Example #1:
set data=aa bb cc
echo Splitting off from "%data%":
call :split_once "%data%" " " "left" "right"
echo Split off: %left%
echo Remaining: %right%
echo.

:: Example #2:
echo List of paths in PATH env var:
set paths=%PATH%
:loop
    call :split_once "%paths%" ";" "left" "paths"
    if "%left%" equ "" goto loop_end
    echo %left%
goto loop
:loop_end



:: HERE BE FUNCTIONS
goto :eof

:: USAGE:
::   call :split_once "string to split once" "delimiter_char" "left_var" "right_var"
:split_once
    setlocal
    set right=%~1
    set delimiter_char=%~2
    set left=

    if "%right%" equ "" goto split_once_done

    :split_once_loop
        if "%right:~0,1%" equ "%delimiter_char%" set right=%right:~1%&& goto split_once_done
        if "%right:~0,1%" neq "%delimiter_char%" set left=%left%%right:~0,1%
        if "%right:~0,1%" neq "%delimiter_char%" set right=%right:~1%
        if "%right%" equ "" goto split_once_done
    goto split_once_loop

    :split_once_done
    endlocal & set %~3=%left%& set %~4=%right%
goto:eof

How do I mock an autowired @Value field in Spring with Mockito?

Whenever possible, I set the field visibility as package-protected so it can be accessed from the test class. I document that using Guava's @VisibleForTesting annotation (in case the next guy wonders why it's not private). This way I don't have to rely on the string name of the field and everything stays type-safe.

I know it goes against standard encapsulation practices we were taught in school. But as soon as there is some agreement in the team to go this way, I found it the most pragmatic solution.

WCF Error - Could not find default endpoint element that references contract 'UserService.UserService'

Had to add the service in the calling App.config file to have it work. Make sure that you but it after all . This seemed to work for me.

how to get the last part of a string before a certain character?

You are looking for str.rsplit(), with a limit:

print x.rsplit('-', 1)[0]

.rsplit() searches for the splitting string from the end of input string, and the second argument limits how many times it'll split to just once.

Another option is to use str.rpartition(), which will only ever split just once:

print x.rpartition('-')[0]

For splitting just once, str.rpartition() is the faster method as well; if you need to split more than once you can only use str.rsplit().

Demo:

>>> x = 'http://test.com/lalala-134'
>>> print x.rsplit('-', 1)[0]
http://test.com/lalala
>>> 'something-with-a-lot-of-dashes'.rsplit('-', 1)[0]
'something-with-a-lot-of'

and the same with str.rpartition()

>>> print x.rpartition('-')[0]
http://test.com/lalala
>>> 'something-with-a-lot-of-dashes'.rpartition('-')[0]
'something-with-a-lot-of'

CakePHP select default value in SELECT input

cakephp version >= 3.6

echo $this->Form->control('field_name', ['type' => 'select', 'options' => $departments, 'default' => 'your value']);

Convert integer to binary in C#

Your example has an integer expressed as a string. Let's say your integer was actually an integer, and you want to take the integer and convert it to a binary string.

int value = 8;
string binary = Convert.ToString(value, 2);

Which returns 1000.

SQLAlchemy: print the actual query

So building on @zzzeek's comments on @bukzor's code I came up with this to easily get a "pretty-printable" query:

def prettyprintable(statement, dialect=None, reindent=True):
    """Generate an SQL expression string with bound parameters rendered inline
    for the given SQLAlchemy statement. The function can also receive a
    `sqlalchemy.orm.Query` object instead of statement.
    can 

    WARNING: Should only be used for debugging. Inlining parameters is not
             safe when handling user created data.
    """
    import sqlparse
    import sqlalchemy.orm
    if isinstance(statement, sqlalchemy.orm.Query):
        if dialect is None:
            dialect = statement.session.get_bind().dialect
        statement = statement.statement
    compiled = statement.compile(dialect=dialect,
                                 compile_kwargs={'literal_binds': True})
    return sqlparse.format(str(compiled), reindent=reindent)

I personally have a hard time reading code which is not indented so I've used sqlparse to reindent the SQL. It can be installed with pip install sqlparse.

How do I add a resources folder to my Java project in Eclipse

If aim is to create a resources folder parallel to src/main/java, then do the following:

Right Click on your project > New > Source Folder
Provide Folder Name as src/main/resources
Finish

Get the second largest number in a list in linear time

If you do not mind using numpy (import numpy as np):

np.partition(numbers, -2)[-2]

gives you the 2nd largest element of the list with a guaranteed worst-case O(n) running time.

The partition(a, kth) methods returns an array where the kth element is the same it would be in a sorted array, all elements before are smaller, and all behind are larger.

java: run a function after a specific number of seconds

public static Timer t;

public synchronized void startPollingTimer() {
        if (t == null) {
            TimerTask task = new TimerTask() {
                @Override
                public void run() {
                   //Do your work
                }
            };

            t = new Timer();
            t.scheduleAtFixedRate(task, 0, 1000);
        }
    }

python: unhashable type error

  File "C:\pythonwork\readthefile080410.py", line 120, in medications_minimum3
    counter[row[11]]+=1
TypeError: unhashable type: 'list'

row[11] is unhashable. It's a list. That is precisely (and only) what the error message means. You might not like it, but that is the error message.

Do this

counter[tuple(row[11])]+=1

Also, simplify.

d= [ row for row in c if counter[tuple(row[11])]>=sample_cutoff ]

How do I remove lines between ListViews on Android?

If this android:divider="@null" doesn't work, maybe changing your ListViews for Recycler Views? 

Why should I use the keyword "final" on a method parameter in Java?

I use final all the time on parameters.

Does it add that much? Not really.

Would I turn it off? No.

The reason: I found 3 bugs where people had written sloppy code and failed to set a member variable in accessors. All bugs proved difficult to find.

I'd like to see this made the default in a future version of Java. The pass by value/reference thing trips up an awful lot of junior programmers.

One more thing.. my methods tend to have a low number of parameters so the extra text on a method declaration isn't an issue.

jQuery & CSS - Remove/Add display:none

The only way to remove an inline "display:none" via jQuery's css-api is by resetting it with the empty string (null does NOT work btw!!).

According to the jQuery docu this is the general way to "remove" a once set inline style property.

$("#mydiv").css("display","");

or

$("#mydiv").css({display:""});

should do the trick properly.

IMHO there is a method missing in jQuery that could be called "unhide" or "reveal" which instead of just setting another inline style property unsets the display value properly as described above. Or maybe hide() should store the initial inline value and show() should restore that...

Batch file: Find if substring is in string (not in a file)

If you are detecting for presence, here's the easiest solution:

SET STRING=F00BAH
SET SUBSTRING=F00
ECHO %STRING% | FINDSTR /C:"%SUBSTRING%" >nul & IF ERRORLEVEL 1 (ECHO CASE TRUE) else (ECHO CASE FALSE)

This works great for dropping the output of windows commands into a boolean variable. Just replace the echo with the command you want to run. You can also string Findstr's together to further qualify a statement using pipes. E.G. for Service Control (SC.exe)

SC QUERY WUAUSERV | findstr /C:"STATE" | FINDSTR /C:"RUNNING" & IF ERRORLEVEL 1 (ECHO case True) else (ECHO CASE FALSE)

That one evaluates the output of SC Query for windows update services which comes out as a multiline text, finds the line containing "state" then finds if the word "running" occurs on that line, and sets the errorlevel accordingly.

How to convert list of key-value tuples into dictionary?

l=[['A', 1], ['B', 2], ['C', 3]]
d={}
for i,j in l:
d.setdefault(i,j)
print(d)

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

This is how I would start to solve this:

  1. Create a video writer:

    import cv2.cv as cv
    videowriter = cv.CreateVideoWriter( filename, fourcc, fps, frameSize)
    

    Check here for valid parameters

  2. Loop to retrieve[1] and write the frames:

    cv.WriteFrame( videowriter, frame )
    

    WriteFrame doc

[1] zenpoy already pointed in the correct direction. You just need to know that you can retrieve images from a webcam or a file :-)

Hopefully I understood the requirements correct.

Sort an Array by keys based on another Array?

I used the Darkwaltz4's solution but used array_fill_keys instead of array_flip, to fill with NULL if a key is not set in $array.

$properOrderedArray = array_replace(array_fill_keys($keys, null), $array);

GIT_DISCOVERY_ACROSS_FILESYSTEM not set

For android source code with repo, I beleive you should use REPO. if you really want to use git, you should know if the project has .git directory with ls -a. Or you have to enter the sub project directory which should include the .git.

How to list physical disks?

I just ran across this in my RSS Reader today. I've got a cleaner solution for you. This example is in Delphi, but can very easily be converted to C/C++ (It's all Win32).

Query all value names from the following registry location: HKLM\SYSTEM\MountedDevices

One by one, pass them into the following function and you will be returned the device name. Pretty clean and simple! I found this code on a blog here.

function VolumeNameToDeviceName(const VolName: String): String;
var
  s: String;
  TargetPath: Array[0..MAX_PATH] of WideChar;
  bSucceeded: Boolean;
begin
  Result := ”;
  // VolumeName has a format like this: \\?\Volume{c4ee0265-bada-11dd-9cd5-806e6f6e6963}\
  // We need to strip this to Volume{c4ee0265-bada-11dd-9cd5-806e6f6e6963}
  s :=  Copy(VolName, 5, Length(VolName) - 5);

  bSucceeded := QueryDosDeviceW(PWideChar(WideString(s)), TargetPath, MAX_PATH) <> 0;
  if bSucceeded then
  begin
    Result := TargetPath;
  end
  else begin
    // raise exception
  end;

end;

Padding or margin value in pixels as integer using jQuery

You could also extend the jquery framework yourself with something like:

jQuery.fn.margin = function() {
var marginTop = this.outerHeight(true) - this.outerHeight();
var marginLeft = this.outerWidth(true) - this.outerWidth();

return {
    top: marginTop,
    left: marginLeft
}};

Thereby adding a function on your jquery objects called margin(), which returns a collection like the offset function.

fx.

$("#myObject").margin().top

How to check if an element does NOT have a specific class?

I don't know why, but the accepted answer didn't work for me. Instead this worked:

if ($(this).hasClass("test") !== false) {}

Child inside parent with min-height: 100% not inheriting height

For googlers:

This jquery-workaround makes #containment get a height automatically (by, height: auto), then gets the actual height assigned as a pixel value.

<script type="text/javascript">
<!--
    $(function () {

        // workaround for webkit-bug http://stackoverflow.com/a/8468131/348841

        var rz = function () {
            $('#containment')
            .css('height', 'auto')
            .css('height', $('#containment').height() + 'px');
        };

        $(window).resize(function () {
            rz();
        });

        rz();

    })
-->
</script>

Which is preferred: Nullable<T>.HasValue or Nullable<T> != null?

I did some research on this by using different methods to assign values to a nullable int. Here is what happened when I did various things. Should clarify what's going on. Keep in mind: Nullable<something> or the shorthand something? is a struct for which the compiler seems to be doing a lot of work to let us use with null as if it were a class.
As you'll see below, SomeNullable == null and SomeNullable.HasValue will always return an expected true or false. Although not demonstrated below, SomeNullable == 3 is valid too (assuming SomeNullable is an int?).
While SomeNullable.Value gets us a runtime error if we assigned null to SomeNullable. This is in fact the only case where nullables could cause us a problem, thanks to a combination of overloaded operators, overloaded object.Equals(obj) method, and compiler optimization and monkey business.

Here is a description of some code I ran, and what output it produced in labels:

int? val = null;
lbl_Val.Text = val.ToString(); //Produced an empty string.
lbl_ValVal.Text = val.Value.ToString(); //Produced a runtime error. ("Nullable object must have a value.")
lbl_ValEqNull.Text = (val == null).ToString(); //Produced "True" (without the quotes)
lbl_ValNEqNull.Text = (val != null).ToString(); //Produced "False"
lbl_ValHasVal.Text = val.HasValue.ToString(); //Produced "False"
lbl_NValHasVal.Text = (!(val.HasValue)).ToString(); //Produced "True"
lbl_ValValEqNull.Text = (val.Value == null).ToString(); //Produced a runtime error. ("Nullable object must have a value.")
lbl_ValValNEqNull.Text = (val.Value != null).ToString(); //Produced a runtime error. ("Nullable object must have a value.")

Ok, lets try the next initialization method:

int? val = new int?();
lbl_Val.Text = val.ToString(); //Produced an empty string.
lbl_ValVal.Text = val.Value.ToString(); //Produced a runtime error. ("Nullable object must have a value.")
lbl_ValEqNull.Text = (val == null).ToString(); //Produced "True" (without the quotes)
lbl_ValNEqNull.Text = (val != null).ToString(); //Produced "False"
lbl_ValHasVal.Text = val.HasValue.ToString(); //Produced "False"
lbl_NValHasVal.Text = (!(val.HasValue)).ToString(); //Produced "True"
lbl_ValValEqNull.Text = (val.Value == null).ToString(); //Produced a runtime error. ("Nullable object must have a value.")
lbl_ValValNEqNull.Text = (val.Value != null).ToString(); //Produced a runtime error. ("Nullable object must have a value.")

All the same as before. Keep in mind that initializing with int? val = new int?(null);, with null passed to the constructor, would have produced a COMPILE time error, since the nullable object's VALUE is NOT nullable. It is only the wrapper object itself that can equal null.

Likewise, we would get a compile time error from:

int? val = new int?();
val.Value = null;

not to mention that val.Value is a read-only property anyway, meaning we can't even use something like:

val.Value = 3;

but again, polymorphous overloaded implicit conversion operators let us do:

val = 3;

No need to worry about polysomthing whatchamacallits though, so long as it works right? :)

Converting JSONarray to ArrayList

public static List<JSONObject> getJSONObjectListFromJSONArray(JSONArray array) 
        throws JSONException {
  ArrayList<JSONObject> jsonObjects = new ArrayList<>();
  for (int i = 0; 
           i < (array != null ? array.length() : 0);           
           jsonObjects.add(array.getJSONObject(i++))
       );
  return jsonObjects;
}

What are alternatives to document.write?

Try to use getElementById() or getElementsByName() to access a specific element and then to use innerHTML property:

<html>
    <body>
        <div id="myDiv1"></div>
        <div id="myDiv2"></div>
    </body>

    <script type="text/javascript">
        var myDiv1 = document.getElementById("myDiv1");
        var myDiv2 = document.getElementById("myDiv2");

        myDiv1.innerHTML = "<b>Content of 1st DIV</b>";
        myDiv2.innerHTML = "<i>Content of second DIV element</i>";
    </script>
</html>

How to get root directory in yii2

Open file D:\wamp\www\yiistore2\common\config\params-local.php

Paste below code before return

Yii::setAlias('@anyname', realpath(dirname(__FILE__).'/../../'));

After inserting above code in params-local.php file your file should look like this.

Yii::setAlias('@anyname', realpath(dirname(__FILE__).'/../../'));

return [
];

Now to get path of your root (in my case its D:\wamp\www\yiistore2) directory you can use below code in any php file.

echo Yii::getAlias('@anyname');

Grant execute permission for a user on all stored procedures in database?

use below code , change proper database name and user name and then take that output and execute in SSMS. FOR SQL 2005 ABOVE

USE <database_name> 
select 'GRANT EXECUTE ON ['+name+'] TO [userName]  '  
from sys.objects  
where type ='P' 
and is_ms_shipped = 0  

Delete directory with files in it?

For windows:

system("rmdir ".escapeshellarg($path) . " /s /q");

Passing null arguments to C# methods

You can use 2 ways: int? or Nullable, both have the same behavior. You could to make a mix without problems but is better choice one to make code cleanest.

Option 1 (With ?):

private void Example(int? arg1, int? arg2)
    {
        if (arg1.HasValue)
        {
            //do something
        }
        if (arg1.HasValue)
        {
            //do something else
        }
    }

Option 2 (With Nullable):

private void Example(Nullable<int> arg1, Nullable<int> arg2)
    {
        if (arg1.HasValue)
        {
            //do something
        }
        if (arg1.HasValue)
        {
            //do something else
        }
    }

From C#4.0 comes a new way to do the same with more flexibility, in this case the framework offers optional parameters with default values, of this way you can set a default value if the method is called without all parameters.

Option 3 (With default values)

private void Example(int arg1 = 0, int arg2 = 1)
    {
        //do something else
    }

Oracle query execution time

I'd recommend looking at consistent gets/logical reads as a better proxy for 'work' than run time. The run time can be skewed by what else is happening on the database server, how much stuff is in the cache etc.

But if you REALLY want SQL executing time, the V$SQL view has both CPU_TIME and ELAPSED_TIME.

Is it possible to append to innerHTML without destroying descendants' event listeners?

Yes it is possible if you bind events using tag attribute onclick="sayHi()" directly in template similar like your <body onload="start()"> - this approach similar to frameworks angular/vue/react/etc. You can also use <template> to operate on 'dynamic' html like here. It is not strict unobtrusive js however it is acceptable for small projects

_x000D_
_x000D_
function start() {_x000D_
  mydiv.innerHTML += "bar";_x000D_
}_x000D_
_x000D_
function sayHi() {_x000D_
  alert("hi");_x000D_
}
_x000D_
<body onload="start()">_x000D_
  <div id="mydiv" style="border: solid red 2px">_x000D_
    <span id="myspan" onclick="sayHi()">foo</span>_x000D_
  </div>_x000D_
</body>
_x000D_
_x000D_
_x000D_

How to redirect to another page using PHP

header won't work for all

Use below simple code

<?php
        echo "<script> location.href='new_url'; </script>";
        exit;
?>

MongoDB query with an 'or' condition

MongoDB query with an 'or' condition

db.getCollection('movie').find({$or:[{"type":"smartreply"},{"category":"small_talk"}]})

MongoDB query with an 'or', 'and', condition combined.

db.getCollection('movie').find({"applicationId":"2b5958d9629026491c30b42f2d5256fa8",$or:[{"type":"smartreply"},{"category":"small_talk"}]})

SQL Server: Maximum character length of object names

Yes, it is 128, except for temp tables, whose names can only be up to 116 character long. It is perfectly explained here.

And the verification can be easily made with the following script contained in the blog post before:

DECLARE @i NVARCHAR(800)
SELECT @i = REPLICATE('A', 116)
SELECT @i = 'CREATE TABLE #'+@i+'(i int)'
PRINT @i
EXEC(@i)

Response.Redirect to new window

I used Hyperlink instead of LinkButton and it worked just fine, it has the Target property so it solved my problem. There was the solution with Response.Write but that was messing up my layout, and the one with ScriptManager, at every refresh or back was reopening the window. So this is how I solved it:

<asp:HyperLink CssClass="hlk11" ID="hlkLink" runat="server" Text='<%# Eval("LinkText") %>' Visible='<%# !(bool)Eval("IsDocument") %>' Target="_blank" NavigateUrl='<%# Eval("WebAddress") %>'></asp:HyperLink>

How to get the root dir of the Symfony2 application?

You can also use regular expression in addition to this:

    $directoryPath = $this->container->getParameter('kernel.root_dir') . '/../web/bundles/yourbundle/';
    $directoryPath = preg_replace("/app..../i", "", $directoryPath);
    echo $directoryPath;

What is the correct way to free memory in C#

As Brian points out the GC can collect anything that is unreachable including objects that are still in scope and even while instance methods of those objects are still executing. consider the following code:

class foo
{
    static int liveFooInstances;

    public foo()
    {
        Interlocked.Increment(ref foo.liveFooInstances);
    }

    public void TestMethod()
    {
        Console.WriteLine("entering method");
        while (Interlocked.CompareExchange(ref foo.liveFooInstances, 1, 1) == 1)
        {
            Console.WriteLine("running GC.Collect");
            GC.Collect();
            GC.WaitForPendingFinalizers();
        }
        Console.WriteLine("exiting method");
    }

    ~foo()
    {
        Console.WriteLine("in ~foo");
        Interlocked.Decrement(ref foo.liveFooInstances);
    }

}

class Program
{

    static void Main(string[] args)
    {
        foo aFoo = new foo();
        aFoo.TestMethod();
        //Console.WriteLine(aFoo.ToString()); // if this line is uncommented TestMethod will never return
    }
}

if run with a debug build, with the debugger attached, or with the specified line uncommented TestMethod will never return. But running without a debugger attached TestMethod will return.

Remove all items from RecyclerView

Avoid deleting your items in a for loop and calling notifyDataSetChanged in every iteration. Instead just call the clear method in your list myList.clear(); and then notify your adapter

public void clearData() {
    myList.clear(); // clear list
    mAdapter.notifyDataSetChanged(); // let your adapter know about the changes and reload view.
}

SSIS Excel Connection Manager failed to Connect to the Source

I found that my excel file that was created in Excel 365 was incompatible with any of the versions available. I re-saved the excel file in 97-2003 version and of course chose that version in the dropdown list and it read the file OK.

How to get the number of days of difference between two dates on mysql?

Note if you want to count FULL 24h days between 2 dates, datediff can return wrong values for you.

As documentation states:

Only the date parts of the values are used in the calculation.

which results in

select datediff('2016-04-14 11:59:00', '2016-04-13 12:00:00')

returns 1 instead of expected 0.

Solution is using select timestampdiff(DAY, '2016-04-13 11:00:01', '2016-04-14 11:00:00'); (note the opposite order of arguments compared to datediff).

Some examples:

  • select timestampdiff(DAY, '2016-04-13 11:00:01', '2016-04-14 11:00:00'); returns 0
  • select timestampdiff(DAY, '2016-04-13 11:00:00', '2016-04-14 11:00:00'); returns 1
  • select timestampdiff(DAY, '2016-04-13 11:00:00', now()); returns how many full 24h days has passed since 2016-04-13 11:00:00 until now.

Hope it will help someone, because at first it isn't much obvious why datediff returns values which seems to be unexpected or wrong.

How to copy directory recursively in python and overwrite all?

In Python 3.8 the dirs_exist_ok keyword argument was added to shutil.copytree():

dirs_exist_ok dictates whether to raise an exception in case dst or any missing parent directory already exists.

So, the following will work in recent versions of Python, even if the destination directory already exists:

shutil.copytree(src, dest, dirs_exist_ok=True)  # 3.8+ only!

One major benefit is that it's more flexible than distutils.dir_util.copy_tree() as it takes additional arguments on files to ignore, etc. There is also a draft PEP (PEP 632, associated discussion), which suggests that distutils may be deprecated and then removed in future versions of Python 3.

Call japplet from jframe

First of all, Applets are designed to be run from within the context of a browser (or applet viewer), they're not really designed to be added into other containers.

Technically, you can add a applet to a frame like any other component, but personally, I wouldn't. The applet is expecting a lot more information to be available to it in order to allow it to work fully.

Instead, I would move all of the "application" content to a separate component, like a JPanel for example and simply move this between the applet or frame as required...

ps- You can use f.setLocationRelativeTo(null) to center the window on the screen ;)

Updated

You need to go back to basics. Unless you absolutely must have one, avoid applets until you understand the basics of Swing, case in point...

Within the constructor of GalzyTable2 you are doing...

JApplet app = new JApplet(); add(app); app.init(); app.start(); 

...Why are you adding another applet to an applet??

Case in point...

Within the main method, you are trying to add the instance of JFrame to itself...

f.getContentPane().add(f, button2); 

Instead, create yourself a class that extends from something like JPanel, add your UI logical to this, using compound components if required.

Then, add this panel to whatever top level container you need.

Take the time to read through Creating a GUI with Swing

Updated with example

import java.awt.BorderLayout; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.event.ActionEvent; import javax.swing.ImageIcon; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException;  public class GalaxyTable2 extends JPanel {      private static final int PREF_W = 700;     private static final int PREF_H = 600;      String[] columnNames                     = {"Phone Name", "Brief Description", "Picture", "price",                         "Buy"};  // Create image icons     ImageIcon Image1 = new ImageIcon(                     getClass().getResource("s1.png"));     ImageIcon Image2 = new ImageIcon(                     getClass().getResource("s2.png"));     ImageIcon Image3 = new ImageIcon(                     getClass().getResource("s3.png"));     ImageIcon Image4 = new ImageIcon(                     getClass().getResource("s4.png"));     ImageIcon Image5 = new ImageIcon(                     getClass().getResource("note.png"));     ImageIcon Image6 = new ImageIcon(                     getClass().getResource("note2.png"));     ImageIcon Image7 = new ImageIcon(                     getClass().getResource("note3.png"));      Object[][] rowData = {         {"Galaxy S", "3G Support,CPU 1GHz",             Image1, 120, false},         {"Galaxy S II", "3G Support,CPU 1.2GHz",             Image2, 170, false},         {"Galaxy S III", "3G Support,CPU 1.4GHz",             Image3, 205, false},         {"Galaxy S4", "4G Support,CPU 1.6GHz",             Image4, 230, false},         {"Galaxy Note", "4G Support,CPU 1.4GHz",             Image5, 190, false},         {"Galaxy Note2 II", "4G Support,CPU 1.6GHz",             Image6, 190, false},         {"Galaxy Note 3", "4G Support,CPU 2.3GHz",             Image7, 260, false},};      MyTable ss = new MyTable(                     rowData, columnNames);      // Create a table     JTable jTable1 = new JTable(ss);      public GalaxyTable2() {         jTable1.setRowHeight(70);          add(new JScrollPane(jTable1),                         BorderLayout.CENTER);          JPanel buttons = new JPanel();          JButton button = new JButton("Home");         buttons.add(button);         JButton button2 = new JButton("Confirm");         buttons.add(button2);          add(buttons, BorderLayout.SOUTH);     }      @Override      public Dimension getPreferredSize() {         return new Dimension(PREF_W, PREF_H);     }      public void actionPerformed(ActionEvent e) {         new AMainFrame7().setVisible(true);     }      public static void main(String[] args) {          EventQueue.invokeLater(new Runnable() {             @Override             public void run() {                 try {                     UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());                 } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {                     ex.printStackTrace();                 }                  JFrame frame = new JFrame("Testing");                 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);                 frame.add(new GalaxyTable2());                 frame.pack();                 frame.setLocationRelativeTo(null);                 frame.setVisible(true);             }         });     } } 

You also seem to have a lack of understanding about how to use layout managers.

Take the time to read through Creating a GUI with Swing and Laying components out in a container

How To Set Text In An EditText

If you check the docs for EditText, you'll find a setText() method. It takes in a String and a TextView.BufferType. For example:

EditText editText = (EditText)findViewById(R.id.edit_text);
editText.setText("This sets the text.", TextView.BufferType.EDITABLE);

It also inherits TextView's setText(CharSequence) and setText(int) methods, so you can set it just like a regular TextView:

editText.setText("Hello world!");
editText.setText(R.string.hello_world);

Links not going back a directory?

To go up a directory in a link, use ... This means "go up one directory", so your link will look something like this:

<a href="../index.html">Home</a>

Unix ls command: show full path when using options

Try this, works for me: ls -d /a/b/c/*

cURL POST command line on WINDOWS RESTful service

  1. Try to use double quotes (") instead of single ones (').
  2. To preserve JSON format quotes, try doubling them ("").
  3. To preserve quotes inside data, try to double-escape them like this (\\"").

    curl ... -d "{""data1"": ""data1 goes here"", ""data2"": ""data2 goes here""}"
    curl ... -d "{""data"": ""data \\""abc\\"" goes here""}"
    

How to make a countdown timer in Android?

Just Call below function by passing seconds and textview object

public void reverseTimer(int Seconds,final TextView tv){

    new CountDownTimer(Seconds* 1000+1000, 1000) {

        public void onTick(long millisUntilFinished) {
            int seconds = (int) (millisUntilFinished / 1000);
            int minutes = seconds / 60;
            seconds = seconds % 60;
            tv.setText("TIME : " + String.format("%02d", minutes)
                    + ":" + String.format("%02d", seconds));
        }

        public void onFinish() {
            tv.setText("Completed");
        }
    }.start();
}

How to convert a Scikit-learn dataset to a Pandas dataset?

from sklearn.datasets import load_iris
import pandas as pd

data = load_iris()
df = pd.DataFrame(data.data, columns=data.feature_names)
df.head()

This tutorial maybe of interest: http://www.neural.cz/dataset-exploration-boston-house-pricing.html

Debugging WebSocket in Google Chrome

They seem to continuously change stuff in Chrome, but here's what works right now :-)

  • First you must click on the red record button or you'll get nothing.

  • I never noticed the WS before but it filters out the web socket connections.

  • Select it and then you can see the Frames (now called Messages) which will show you error messages etc.

enter image description here

How do I remove all null and empty string values from an object?

According to Alexis King answer, here is a plain JavaScript version.

_x000D_
_x000D_
function cleanUp(obj) {_x000D_
    for (var attrKey in obj) {_x000D_
        var attrValue = obj[attrKey];_x000D_
        if (attrValue === null || attrValue === "") {_x000D_
            delete obj[attrKey];_x000D_
        } else if (Object.prototype.toString.call(attrValue) === "[object Object]") {_x000D_
            cleanUp(attrValue);_x000D_
        } else if (Array.isArray(attrValue)) {_x000D_
            attrValue.forEach(function (arrayValue) {_x000D_
                cleanUp(arrayValue);_x000D_
            });_x000D_
        }_x000D_
    }_x000D_
}
_x000D_
_x000D_
_x000D_

Convert array of indices to 1-hot encoded numpy array

You can use sklearn.preprocessing.LabelBinarizer:

Example:

import sklearn.preprocessing
a = [1,0,3]
label_binarizer = sklearn.preprocessing.LabelBinarizer()
label_binarizer.fit(range(max(a)+1))
b = label_binarizer.transform(a)
print('{0}'.format(b))

output:

[[0 1 0 0]
 [1 0 0 0]
 [0 0 0 1]]

Amongst other things, you may initialize sklearn.preprocessing.LabelBinarizer() so that the output of transform is sparse.

Have Excel formulas that return 0, make the result blank

Just append an empty string to the end. It forces Excel to see it for what it is.

For example:

=IFERROR(1/1/INDEX(A,B,C) & "","")

How to replace all occurrences of a character in string?

If you're willing to use std::strings, you can use this sample-app's strsub function as-is, or update it if you want it to take a different type or set of parameters to achieve roughly the same goal. Basically, it uses the properties and functionalities of std::string to quickly erase the matching set of characters, and insert the desired characters directly within the std::string. Every time it does this replacement operation, the offset updates if it can still find matching chars to replace, and if it can't due to nothing more to replace, it returns the string in its state from the last update.

#include <iostream>
#include <string>

std::string strsub(std::string stringToModify,
                   std::string charsToReplace,
                   std::string replacementChars);

int main()
{
    std::string silly_typos = "annoiiyyyng syyyllii tiipos.";

    std::cout << "Look at these " << silly_typos << std::endl;
    silly_typos = strsub(silly_typos, "yyy", "i");
    std::cout << "After a little elbow-grease, a few less " << silly_typos << std::endl;
    silly_typos = strsub(silly_typos, "ii", "y");

    std::cout << "There, no more " << silly_typos << std::endl;
    return 0;
}

std::string strsub(std::string stringToModify,
                   std::string charsToReplace,
                   std::string replacementChars)
{
    std::string this_string = stringToModify;

    std::size_t this_occurrence = this_string.find(charsToReplace);
    while (this_occurrence != std::string::npos)
    {
        this_string.erase(this_occurrence, charsToReplace.size());
        this_string.insert(this_occurrence, replacementChars);
        this_occurrence = this_string.find(charsToReplace,
                                           this_occurrence + replacementChars.size());
    }

    return this_string;
}

If you don't want to rely on using std::strings as your parameters so you can pass in C-style strings instead, you can see the updated sample below:

#include <iostream>
#include <string>

std::string strsub(const char * stringToModify,
                   const char * charsToReplace,
                   const char * replacementChars,
                   uint64_t sizeOfCharsToReplace,
                   uint64_t sizeOfReplacementChars);

int main()
{
    std::string silly_typos = "annoiiyyyng syyyllii tiipos.";

    std::cout << "Look at these " << silly_typos << std::endl;
    silly_typos = strsub(silly_typos.c_str(), "yyy", "i", 3, 1);
    std::cout << "After a little elbow-grease, a few less " << silly_typos << std::endl;
    silly_typos = strsub(silly_typos.c_str(), "ii", "y", 2, 1);

    std::cout << "There, no more " << silly_typos << std::endl;
    return 0;
}

std::string strsub(const char * stringToModify,
                   const char * charsToReplace,
                   const char * replacementChars,
                   uint64_t sizeOfCharsToReplace,
                   uint64_t sizeOfReplacementChars)
{
    std::string this_string = stringToModify;

    std::size_t this_occurrence = this_string.find(charsToReplace);
    while (this_occurrence != std::string::npos)
    {
        this_string.erase(this_occurrence, sizeOfCharsToReplace);
        this_string.insert(this_occurrence, replacementChars);
        this_occurrence = this_string.find(charsToReplace,
            this_occurrence + sizeOfReplacementChars);
    }

    return this_string;
}

How to combine two byte arrays

String temp = passwordSalt;
byte[] byteSalt = temp.getBytes();
int start = 32;
for (int i = 0; i < byteData.length; i ++)
{
    byteData[start + i] = byteSalt[i];
}

The problem with your code here is that the variable i that is being used to index the arrays is going past both the byteSalt array and the byteData array. So, Make sure that byteData is dimensioned to be at least the maximum length of the passwordSalt string plus 32. What will correct it is replacing the following line:

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

with:

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

How to cast ArrayList<> from List<>

When you do the second one, you're making a new arraylist, you're not trying to pretend the other list is an arraylist.

I mean, what if the original list is implemented as a linkedlist, or some custom list? You won't know. The second approach is preferred if you really need to make an arraylist from the result. But you can just leave it as a list, that's one of the best advantages of using Interfaces!

Creating a simple XML file using python

For the simplest choice, I'd go with minidom: http://docs.python.org/library/xml.dom.minidom.html . It is built in to the python standard library and is straightforward to use in simple cases.

Here's a pretty easy to follow tutorial: http://www.boddie.org.uk/python/XML_intro.html

What does 'wb' mean in this code, using Python?

File mode, write and binary. Since you are writing a .jpg file, it looks fine.

But if you supposed to read that jpg file you need to use 'rb'

More info

On Windows, 'b' appended to the mode opens the file in binary mode, so there are also modes like 'rb', 'wb', and 'r+b'. Python on Windows makes a distinction between text and binary files; the end-of-line characters in text files are automatically altered slightly when data is read or written. This behind-the-scenes modification to file data is fine for ASCII text files, but it’ll corrupt binary data like that in JPEG or EXE files.

Try-catch-finally-return clarification

If the return in the try block is reached, it transfers control to the finally block, and the function eventually returns normally (not a throw).

If an exception occurs, but then the code reaches a return from the catch block, control is transferred to the finally block and the function eventually returns normally (not a throw).

In your example, you have a return in the finally, and so regardless of what happens, the function will return 34, because finally has the final (if you will) word.

Although not covered in your example, this would be true even if you didn't have the catch and if an exception were thrown in the try block and not caught. By doing a return from the finally block, you suppress the exception entirely. Consider:

public class FinallyReturn {
  public static final void main(String[] args) {
    System.out.println(foo(args));
  }

  private static int foo(String[] args) {
    try {
      int n = Integer.parseInt(args[0]);
      return n;
    }
    finally {
      return 42;
    }
  }
}

If you run that without supplying any arguments:

$ java FinallyReturn

...the code in foo throws an ArrayIndexOutOfBoundsException. But because the finally block does a return, that exception gets suppressed.

This is one reason why it's best to avoid using return in finally.

Compute mean and standard deviation by group for multiple variables in a data.frame

Here's another take on the data.table answers, using @Carson's data, that's a bit more readable (and also a little faster, because of using lapply instead of sapply):

library(data.table)
set.seed(1)
dt = data.table(ID=c(1:3), Obs_1=rnorm(9), Obs_2=rnorm(9), Obs_3=rnorm(9))

dt[, c(mean = lapply(.SD, mean), sd = lapply(.SD, sd)), by = ID]
#   ID mean.Obs_1 mean.Obs_2 mean.Obs_3  sd.Obs_1  sd.Obs_2  sd.Obs_3
#1:  1  0.4854187 -0.3238542  0.7410611 1.1108687 0.2885969 0.1067961
#2:  2  0.4171586 -0.2397030  0.2041125 0.2875411 1.8732682 0.3438338
#3:  3 -0.3601052  0.8195368 -0.4087233 0.8105370 0.3829833 1.4705692

Unknown version of Tomcat was specified in Eclipse

it throws the same error for me too that brought me here.

However, I just waited for some time and it got installed without doing anything.

hope this helps

How can I pass a Bitmap object from one activity to another

All of the above solutions doesn't work for me, Sending bitmap as parceableByteArray also generates error android.os.TransactionTooLargeException: data parcel size.

Solution

  1. Saved the bitmap in internal storage as:
public String saveBitmap(Bitmap bitmap) {
        String fileName = "ImageName";//no .png or .jpg needed
        try {
            ByteArrayOutputStream bytes = new ByteArrayOutputStream();
            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, bytes);
            FileOutputStream fo = openFileOutput(fileName, Context.MODE_PRIVATE);
            fo.write(bytes.toByteArray());
            // remember close file output
            fo.close();
        } catch (Exception e) {
            e.printStackTrace();
            fileName = null;
        }
        return fileName;
    }
  1. and send in putExtra(String) as
Intent intent = new Intent(ActivitySketcher.this,ActivityEditor.class);
intent.putExtra("KEY", saveBitmap(bmp));
startActivity(intent);
  1. and Receive it in other activity as:
if(getIntent() != null){
  try {
           src = BitmapFactory.decodeStream(openFileInput("myImage"));
       } catch (FileNotFoundException e) {
            e.printStackTrace();
      }

 }


Jenkins pipeline if else not working

        if ( params.build_deploy == '1' ) {
            println "build_deploy ? ${params.build_deploy}"
              jobB = build job: 'k8s-core-user_deploy', propagate: false, wait: true, parameters: [
                         string(name:'environment', value: "${params.environment}"),
                         string(name:'branch_name', value: "${params.branch_name}"),
                         string(name:'service_name', value: "${params.service_name}"),                      
                     ]
            println jobB.getResult()
        }

How do I escape a string inside JavaScript code inside an onClick handler?

I faced the same problem, and I solved it in a tricky way. First make global variables, v1, v2, and v3. And in the onclick, send an indicator, 1, 2, or 3 and in the function check for 1, 2, 3 to put the v1, v2, and v3 like:

onclick="myfun(1)"
onclick="myfun(2)"
onclick="myfun(3)"

function myfun(var)
{
    if (var ==1)
        alert(v1);

    if (var ==2)
        alert(v2);

    if (var ==3)
        alert(v3);
}

Dynamic SQL - EXEC(@SQL) versus EXEC SP_EXECUTESQL(@SQL)

  1. Declare the variable
  2. Set it by your command and add dynamic parts like use parameter values of sp(here @IsMonday and @IsTuesday are sp params)
  3. execute the command

    declare  @sql varchar (100)
    set @sql ='select * from #td1'
    
    if (@IsMonday+@IsTuesday !='')
    begin
    set @sql= @sql+' where PickupDay in ('''+@IsMonday+''','''+@IsTuesday+''' )'
    end
    exec( @sql)
    

How to increment a variable on a for loop in jinja template?

if anyone want to add a value inside loop then you can use this its working 100%

{% set ftotal= {'total': 0} %} 
{%- for pe in payment_entry -%}
    {% if ftotal.update({'total': ftotal.total + 5}) %}{% endif %} 
{%- endfor -%}

{{ftotal.total}}

output = 5