Programs & Examples On #Facebook graph api

Facebook Graph API is a structured API for fetching objects and the connections between them from Facebook's social graph

Facebook Graph API, how to get users email?

The email in the profile can be obtained using extended permission but I Guess it's not possible to get the email used to login fb. In my app i wanted to display mulitple fb accounts of a user in a list, i wanted to show the login emails of fb accounts as a unique identifier of the respective accounts but i couldn't get it off from fb, all i got was the primary email in the user profile but in my case my login email and my primary email are different.

Facebook Graph API : get larger pictures in one request

I researched Graph API Explorer extensively and finally found full_picture

https://graph.facebook.com/v2.2/$id/posts?fields=picture,full_picture

P.S. I noticed that full_picture won't always provide full size image I want. 'attachments' does

https://graph.facebook.com/v2.2/$id/posts?fields=picture,full_picture,attachments

How to get share counts using graph API

You can use the https://graph.facebook.com/v3.0/{Place_your_Page_ID here}/feed?fields=id,shares,share_count&access_token={Place_your_access_token_here} to get the shares count.

How can I display the users profile pic using the facebook graph api?

  //create the url
  $profile_pic =  "http://graph.facebook.com/".$uid."/picture";

 //echo the image out
 echo "<img src=\"" . $profile_pic . "\" />"; 

Works fine for me

FB OpenGraph og:image not pulling images (possibly https?)

I ran into the same issue and then I noticed that I had a different domain for the og:url

Once I made sure that the domain was the same for og:url and og:image it worked.

Hope this helps.

Facebook Access Token for Pages

The documentation for this is good if not a little difficult to find.

Facebook Graph API - Page Tokens

After initializing node's fbgraph, you can run:

var facebookAccountID = yourAccountIdHere 

graph
.setOptions(options)
.get(facebookAccountId + "/accounts", function(err, res) {
  console.log(res); 
});

and receive a JSON response with the token you want to grab, located at:

res.data[0].access_token

List of IP Space used by Facebook

The list from 2020-05-23 is:

31.13.24.0/21
31.13.64.0/18
45.64.40.0/22
66.220.144.0/20
69.63.176.0/20
69.171.224.0/19
74.119.76.0/22
102.132.96.0/20
103.4.96.0/22
129.134.0.0/16
147.75.208.0/20
157.240.0.0/16
173.252.64.0/18
179.60.192.0/22
185.60.216.0/22
185.89.216.0/22
199.201.64.0/22
204.15.20.0/22

The method to fetch this list is already documented on Facebook's Developer site, you can make a whois call to see all IPs assigned to Facebook:

whois -h whois.radb.net -- '-i origin AS32934' | grep ^route

SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed

Adding gem 'certified', '~> 1.0' to my Gemfile and running bundle solved this issue for me.

"Uncaught (in promise) undefined" error when using with=location in Facebook Graph API query

The reject actually takes one parameter: that's the exception that occurred in your code that caused the promise to be rejected. So, when you call reject() the exception value is undefined, hence the "undefined" part in the error that you get.

You do not show the code that uses the promise, but I reckon it is something like this:

var promise = doSth();
promise.then(function() { doSthHere(); });

Try adding an empty failure call, like this:

promise.then(function() { doSthHere(); }, function() {});

This will prevent the error to appear.

However, I would consider calling reject only in case of an actual error, and also... having empty exception handlers isn't the best programming practice.

New og:image size for Facebook share?

Facebook.com og:image is 325x325 (1:1 aspect ratio, square)

https://www.facebook.com/images/fb_icon_325x325.png

Facebook login message: "URL Blocked: This redirect failed because the redirect URI is not whitelisted in the app’s Client OAuth Settings."

It might help somebody.

I had the similar error message, but only in dev and staging environments, not in production. The valid redirect URIs were correctly set, for the dev and staging subdomains as well as for production.

It turned out I forgot that for those environments we use the testing FB app, which is a separate one in the FB developer page. Had to select that and update its settings.

Facebook OAuth "The domain of this URL isn't included in the app's domain"

Can't Load URL: The domain of this URL isn't included in the app's domains. To be able to load this URL, add all domains and subdomains of your app to the App Domains field in your app settings.

I had this issue today, I find the Facebook documentation and SDK disrespectful and arogant towards other developers to say the least.

Besides having the "app domains" in two different locations without much information (3 if you add a "web" platform), you also need to go to app products / facebook login / settings and add your redirect URL under Valid OAuth Redirect URIs

The error says NOTHING about the oauth settings.

Getting full-size profile picture

For Angular:

getUserPicture(userId) {   
FB.api('/' + userId, {fields: 'picture.width(800).height(800)'}, function(response) {
  console.log('getUserPicture',response);
});
}

Redirecting to authentication dialog - "An error occurred. Please try again later"

I just encountered this problem myself. I'm developing an app internally, so my host is 'localhost'. It wasn't obvious how to set 'localhost' up in the app configuration. If you want to develop locally, set up your app by following these steps:

  1. Go to the place where you manage your Facebook app. Specifically, you want to be in "Basic" under the "Settings" menu.
  2. Add 'localhost' to "App Domain".
  3. Under "Select how your app integrates with Facebook", select "Website", and enter "http://localhost/".

Save and wait a couple of minutes for the information to propagate, although it worked right away for me.

Send private messages to friends

No, this isn't possible. In order for you to send messages of any kind to a Facebook user, you need that user's permission to do so.

If someone logs into your site with Facebook Connect, they are explicitly agreeing to share their Facebook data with your site, and you will then be able to send that person a message through the normal channels. You would also be able to fetch their friend list. However, you can not send messages to the friends.

When do I need a fb:app_id or fb:admins?

I think the documentation is reasonably helpful!

If you read it again, it says that adding open graph elements on your website will make your website act as a facebook page and you'll get the ability to publish updates to them etc.

So I think it's up to you - you can either just have a page with no OG elements, which is less work but also less 'rewarding' for you.

If you do use og, then set type to: blog

Finally: fb:admins or fb:app_id - A comma-separated list of either the Facebook IDs of page administrators or a Facebook Platform application ID. At a minimum, include only your own Facebook ID.

So just put your own fbid in there. As a tip, you can easily get this by looking at the url of your profile photo on facebook.

Facebook Graph API v2.0+ - /me/friends returns empty, or only friends who also use my application

In v2.0 of the Graph API, calling /me/friends returns the person's friends who also use the app.

In addition, in v2.0, you must request the user_friends permission from each user. user_friends is no longer included by default in every login. Each user must grant the user_friends permission in order to appear in the response to /me/friends. See the Facebook upgrade guide for more detailed information, or review the summary below.

If you want to access a list of non-app-using friends, there are two options:

  1. If you want to let your people tag their friends in stories that they publish to Facebook using your App, you can use the /me/taggable_friends API. Use of this endpoint requires review by Facebook and should only be used for the case where you're rendering a list of friends in order to let the user tag them in a post.

  2. If your App is a Game AND your Game supports Facebook Canvas, you can use the /me/invitable_friends endpoint in order to render a custom invite dialog, then pass the tokens returned by this API to the standard Requests Dialog.

In other cases, apps are no longer able to retrieve the full list of a user's friends (only those friends who have specifically authorized your app using the user_friends permission). This has been confirmed by Facebook as 'by design'.

For apps wanting allow people to invite friends to use an app, you can still use the Send Dialog on Web or the new Message Dialog on iOS and Android.

UPDATE: Facebook have published an FAQ on these changes here: https://developers.facebook.com/docs/apps/faq which explain all the options available to developers in order to invite friends etc.

facebook: permanent Page Access Token?

I found this answer which refers to this tool which really helped a lot.

I hope this answer is still valid when you read this.

How to get the Facebook user id using the access token

The easiest way is

https://graph.facebook.com/me?fields=id&access_token="xxxxx"

then you will get json response which contains only userid.

Facebook Graph API error code list

Facebook Developer Wiki (unofficial) contain not only list of FQL error codes but others too it's somehow updated but not contain full list of possible error codes.

There is no any official or updated (I mean really updated) list of error codes returned by Graph API. Every list that can be found online is outdated and not help that much...

There is official list describing some of API Errors and basic recovery tactics. Also there is couple of offcial lists for specific codes:

How to check if a user likes my Facebook Page or URL using Facebook's API

I tore my hair out over this one too. Your code only works if the user has granted an extended permission for that which is not ideal.

Here's another approach.

In a nutshell, if you turn on the OAuth 2.0 for Canvas advanced option, Facebook will send a $_REQUEST['signed_request'] along with every page requested within your tab app. If you parse that signed_request you can get some info about the user including if they've liked the page or not.

function parsePageSignedRequest() {
    if (isset($_REQUEST['signed_request'])) {
      $encoded_sig = null;
      $payload = null;
      list($encoded_sig, $payload) = explode('.', $_REQUEST['signed_request'], 2);
      $sig = base64_decode(strtr($encoded_sig, '-_', '+/'));
      $data = json_decode(base64_decode(strtr($payload, '-_', '+/'), true));
      return $data;
    }
    return false;
  }
  if($signed_request = parsePageSignedRequest()) {
    if($signed_request->page->liked) {
      echo "This content is for Fans only!";
    } else {
      echo "Please click on the Like button to view this tab!";
    }
  }

Creating a Facebook share button with customized url, title and image

This is the code as 2017:

<i class="fa fa-facebook-square"></i>
<a href="#" onclick="window.open('https://www.facebook.com/sharer/sharer.php?u='+encodeURIComponent(location.href),'facebook-share-dialog','width=626,height=436');return false;">Share on Facebook</a>

Facebook now takes all data from OG metatags.

NOTE: This code assumes you have OG metatags on in site's code.

Source

Facebook api: (#4) Application request limit reached

The Facebook "Graph API Rate Limiting" docs says that an error with code #4 is an app level rate limit, which is different than user level rate limits. Although it doesn't give any exact numbers, it describes their app level rate-limit as:

This rate limiting is applied globally at the app level. Ads api calls are excluded.

  • Rate limiting happens real time on sliding window for past one hour.
  • Stats is collected for number of calls and queries made, cpu time spent, memory used for each app.
  • There is a limit for each resource multiplied by monthly active users of a given app.
  • When the app uses more than its allowed resources the error is thrown.
  • Error, Code: 4, Message: Application request limit reached

The docs also give recommendations for avoiding the rate limits. For app level limits, they are:

Recommendations:

  • Verify the error code (4) to confirm the throttling type.
  • Do not make burst of calls, spread out the calls throughout the day.
  • Do smart fetching of data (important data, non duplicated data, etc).
    • Real-time insights, make sure API calls are structured in a way that you can read insights for as many as Page posts as possible, with minimum number of requests.
    • Don't fetch users feed twice (in the case that two App users have a specific friend in common)
    • Don't fetch all user's friends feed in a row if the number of friends is more than 250. Separate the fetches over different days. As an option, fetch first the app user's news feed (me/home) in order to detect which friends are more important to the App user. Then, fetch those friends feeds first.
  • Consider to limit/filter the requests by using the following parameters: "since", "until", "limit"
  • For page related calls use realtime updates to subscribe to changes in data.
  • Field expansion allows ton "join" multiple graph queries into a single call.
  • Etags to check if the data querying has changed since the last check.
  • For page management developers who does not have massive user base, have the admins of the page to accept the app to increase the number of users.

Finally, the docs give the following informational tips:

  • Batching calls will not reduce the number of api calls.
  • Making parallel calls will not reduce the number of api calls.

The developers of this app have not set up this app properly for Facebook Login?

This error also occurs when you try to log in in your test version of the Facebook app and you have not added the user you are trying to test the log in with in the Roles -> Testers section.

To fix it, just add the email address of the Facebook account you are trying to log in with in the section above.

Finally, make sure the user you added accepts the request sent before you try to test otherwise the log in process will fail in the second screen just after the user accept the conditions.

Facebook API "This app is in development mode"

I had also faced the same issue in which my FB app was automatically stopped and users were not able to login and were getting the message "app is in development mode.....".

Reason why FB automatically stopped my app was that I had not provided a valid PRIVACY policy & terms URL. So, make sure you enter these URLs on your app basic settings page and then make your app PUBLIC from app review page as described in above posts.

Facebook API: Get fans of / people who like a page

This page https://developers.facebook.com/docs/reference/fql/like/ wrote, you can't get fan list.

"The Post, Video, Note, Link, Photo and Album Graph API objects contain an equivalent connection called likes."

NOTE: fql like query is deprecated

Get user profile picture by Id

You can use AngularJs for this, Its two -way data binding feature will get solution with minimum effort and less code.

<div> <input type="text" name="" ng-model="fbid"><br/> <img src="https://graph.facebook.com/{{fbid}}/picture?type=normal"> </div>

I hope this answers your query.Note: You can use other library as well.

How to programmatically log out from Facebook SDK 3.0 without using Facebook login/logout button?

Since Facebook's Android SDK v4.0 (see changelog) you need to execute the following:

LoginManager.getInstance().logOut();

Getting the Facebook like/share count for a given URL

For graph API v2.1, you can get the like count using 1 call only and, therefore, no need to go through the paging.

For example, to get the number of likes of http://www.imdb.com

https://graph.facebook.com/414652589771/likes?summary=1

Graph API Explorer https://developers.facebook.com/tools/explorer/?method=GET&path=414652589771%2Flikes%3Fsummary%3D1&version=v2.1

It is somehow not documented (at least at the moment I submit this answer...). I found the answer in https://stackoverflow.com/a/18198957/1822624

nvarchar(max) vs NText

You should apparently use nvarchar(max):

MSDN

check if file exists in php

  1. The function expects a string.

  2. file_exists() does not work properly with HTTP URLs.

`IF` statement with 3 possible answers each based on 3 different ranges

=IF(X2>=85,0.559,IF(X2>=80,0.327,IF(X2>=75,0.255,-1)))

Explanation:

=IF(X2>=85,                  'If the value is in the highest bracket
      0.559,                 'Use the appropriate number
      IF(X2>=80,             'Otherwise, if the number is in the next highest bracket
           0.327,            'Use the appropriate number
           IF(X2>=75,        'Otherwise, if the number is in the next highest bracket
              0.255,         'Use the appropriate number
              -1             'Otherwise, we're not in any of the ranges (Error)
             )
        )
   )

android listview item height

You need to use padding on the list item layout so space is added on the edges of the item (just increasing the font size won't do that).

<?xml version="1.0" encoding="utf-8"?>
<TextView android:id="@+id/text1"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"
    android:padding="8dp" />

add image to uitableview cell

cell.imageView.image = [UIImage imageNamed:@"image.png"];

UPDATE: Like Steven Fisher said, this should only work for cells with style UITableViewCellStyleDefault which is the default style. For other styles, you'd need to add a UIImageView to the cell's contentView.

How to return the current timestamp with Moment.js?

Try this

console.log(moment().format("MM ddd, YYYY HH:mm:ss a"));

_x000D_
_x000D_
console.log(moment().format("MM ddd, YYYY hh:mm:ss a"));
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.1/moment.min.js"></script>
_x000D_
_x000D_
_x000D_

Casting to string in JavaScript

They behave the same but toString also provides a way to convert a number binary, octal, or hexadecimal strings:

Example:

var a = (50274).toString(16)  // "c462"
var b = (76).toString(8)      // "114"
var c = (7623).toString(36)   // "5vr"
var d = (100).toString(2)     // "1100100"

Checking for a null int value from a Java ResultSet

I think, it is redundant. rs.getObject("ID_PARENT") should return an Integer object or null, if the column value actually was NULL. So it should even be possible to do something like:

if (rs.next()) {
  Integer idParent = (Integer) rs.getObject("ID_PARENT");
  if (idParent != null) {
    iVal = idParent; // works for Java 1.5+
  } else {
    // handle this case
  }      
}

Cell Style Alignment on a range

  ExcelApp.Sheets[1].Range[ExcelApp.Sheets[1].Cells[1, 1], ExcelApp.Sheets[1].Cells[70, 15]].Cells.HorizontalAlignment =
                 Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignCenter;

This works fine for me.

Get value (String) of ArrayList<ArrayList<String>>(); in Java

Because the second element is null after you clear the list.

Use:

String s = myList.get(0);

And remember, index 0 is the first element.

What is middleware exactly?

Lets say your company makes 4 different products, your client has another 3 different products from another 3 different companies.

Someday the client thought, why don't we integrate all our systems into one huge system. Ten minutes later their IT department said that will take 2 years.

You (the wise developer) said, why don't we just integrate all the different systems and make them work together in a homogeneous environment? The client manager staring at you... You continued, we will use a Middleware, we will study the Inputs/Outputs of all different systems, the resources they use and then choose an appropriate Middleware framework.

Still explaining to the non tech manager
With Middleware framework in the middle, the first system will produce X stuff, the system Y and Z would consume those outputs and so on.

Accept function as parameter in PHP

PHP VERSION >= 5.3.0

Example 1: basic

function test($test_param, $my_function) {
    return $my_function($test_param);
}

test("param", function($param) {
    echo $param;
}); //will echo "param"

Example 2: std object

$obj = new stdClass();
$obj->test = function ($test_param, $my_function) {
    return $my_function($test_param);
};

$test = $obj->test;
$test("param", function($param) {
    echo $param;
});

Example 3: non static class call

class obj{
    public function test($test_param, $my_function) {
        return $my_function($test_param);
    }
}

$obj = new obj();
$obj->test("param", function($param) {
    echo $param;
});

Example 4: static class call

class obj {
    public static function test($test_param, $my_function) {
        return $my_function($test_param);
    }
}

obj::test("param", function($param) {
    echo $param;
});

Clone an image in cv2 python

My favorite method uses cv2.copyMakeBorder with no border, like so.

copy = cv2.copyMakeBorder(original,0,0,0,0,cv2.BORDER_REPLICATE)

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

First convert to p12:

openssl pkcs12 -export -in [filename-certificate] -inkey [filename-key] -name [host] -out [filename-new-PKCS-12.p12]

Create new JKS from p12:

keytool -importkeystore -deststorepass [password] -destkeystore [filename-new-keystore.jks] -srckeystore [filename-new-PKCS-12.p12] -srcstoretype PKCS12

Get PostGIS version

Other way to get the minor version is:

SELECT extversion
FROM pg_catalog.pg_extension
WHERE extname='postgis'

Changing capitalization of filenames in Git

You can open the ".git" directory and then edit the "config" file. Under "[core]" set, set "ignorecase = true" and you are done ;)

How do I install and use curl on Windows?

Assuming you got it from https://curl.haxx.se/download.html, just unzip it wherever you want. No need to install. If you are going to use SSL, you need to download the OpenSSL DLLs, available from curl's website.

Java - get index of key in HashMap?

I don't know is this what you're looking for

List keys = new ArrayList(map.keySet());
int index = keys.indexOf(element);

How to specify Memory & CPU limit in docker compose version 3

deploy:
  resources:
    limits:
      cpus: '0.001'
      memory: 50M
    reservations:
      cpus: '0.0001'
      memory: 20M

More: https://docs.docker.com/compose/compose-file/compose-file-v3/#resources

In you specific case:

version: "3"
services:
  node:
    image: USER/Your-Pre-Built-Image
    environment:
      - VIRTUAL_HOST=localhost
    volumes:
      - logs:/app/out/
    command: ["npm","start"]
    cap_drop:
      - NET_ADMIN
      - SYS_ADMIN
    deploy:
      resources:
        limits:
          cpus: '0.001'
          memory: 50M
        reservations:
          cpus: '0.0001'
          memory: 20M

volumes:
  - logs

networks:
  default:
    driver: overlay

Note:

  • Expose is not necessary, it will be exposed per default on your stack network.
  • Images have to be pre-built. Build within v3 is not possible
  • "Restart" is also deprecated. You can use restart under deploy with on-failure action
  • You can use a standalone one node "swarm", v3 most improvements (if not all) are for swarm

Also Note: Networks in Swarm mode do not bridge. If you would like to connect internally only, you have to attach to the network. You can 1) specify an external network within an other compose file, or have to create the network with --attachable parameter (docker network create -d overlay My-Network --attachable) Otherwise you have to publish the port like this:

ports:
  - 80:80

How to read html from a url in python 3

Reading an html page with urllib is fairly simple to do. Since you want to read it as a single string I will show you.

Import urllib.request:

#!/usr/bin/python3.5

import urllib.request

Prepare our request

request = urllib.request.Request('http://www.w3schools.com')

Always use a "try/except" when requesting a web page as things can easily go wrong. urlopen() requests the page.

try:
    response = urllib.request.urlopen(request)
except:
    print("something wrong")

Type is a great function that will tell us what 'type' a variable is. Here, response is a http.response object.

print(type(response))

The read function for our response object will store the html as bytes to our variable. Again type() will verify this.

htmlBytes = response.read()

print(type(htmlBytes))

Now we use the decode function for our bytes variable to get a single string.

htmlStr = htmlBytes.decode("utf8")

print(type(htmlStr))

If you do want to split up this string into separate lines, you can do so with the split() function. In this form we can easily iterate through to print out the entire page or do any other processing.

htmlSplit = htmlStr.split('\n')

print(type(htmlSplit))

for line in htmlSplit:
    print(line)

Hopefully this provides a little more detailed of an answer. Python documentation and tutorials are great, I would use that as a reference because it will answer most questions you might have.

How to list files inside a folder with SQL Server

Can be done using xp_DirTree, then looping through to generate a full file path if required.

Here is an extract of a script I use to restore databases to a test server automatically. It scans a folder and all subfolders for any backup files, then returns the full path.


  DECLARE @BackupDirectory SYSNAME = @BackupFolder

  IF OBJECT_ID('tempdb..#DirTree') IS NOT NULL
    DROP TABLE #DirTree

  CREATE TABLE #DirTree (
    Id int identity(1,1),
    SubDirectory nvarchar(255),
    Depth smallint,
    FileFlag bit,
    ParentDirectoryID int
   )

   INSERT INTO #DirTree (SubDirectory, Depth, FileFlag)
   EXEC master..xp_dirtree @BackupDirectory, 10, 1

   UPDATE #DirTree
   SET ParentDirectoryID = (
    SELECT MAX(Id) FROM #DirTree d2
    WHERE Depth = d.Depth - 1 AND d2.Id < d.Id
   )
   FROM #DirTree d

  DECLARE 
    @ID INT,
    @BackupFile VARCHAR(MAX),
    @Depth TINYINT,
    @FileFlag BIT,
    @ParentDirectoryID INT,
    @wkSubParentDirectoryID INT,
    @wkSubDirectory VARCHAR(MAX)

  DECLARE @BackupFiles TABLE
  (
    FileNamePath VARCHAR(MAX),
    TransLogFlag BIT,
    BackupFile VARCHAR(MAX),    
    DatabaseName VARCHAR(MAX)
  )

  DECLARE FileCursor CURSOR LOCAL FORWARD_ONLY FOR
  SELECT * FROM #DirTree WHERE FileFlag = 1

  OPEN FileCursor
  FETCH NEXT FROM FileCursor INTO 
    @ID,
    @BackupFile,
    @Depth,
    @FileFlag,
    @ParentDirectoryID  

  SET @wkSubParentDirectoryID = @ParentDirectoryID

  WHILE @@FETCH_STATUS = 0
  BEGIN
    --loop to generate path in reverse, starting with backup file then prefixing subfolders in a loop
    WHILE @wkSubParentDirectoryID IS NOT NULL
    BEGIN
      SELECT @wkSubDirectory = SubDirectory, @wkSubParentDirectoryID = ParentDirectoryID 
      FROM #DirTree 
      WHERE ID = @wkSubParentDirectoryID

      SELECT @BackupFile = @wkSubDirectory + '\' + @BackupFile
    END

    --no more subfolders in loop so now prefix the root backup folder
    SELECT @BackupFile = @BackupDirectory + @BackupFile

    --put backupfile into a table and then later work out which ones are log and full backups  
    INSERT INTO @BackupFiles (FileNamePath) VALUES(@BackupFile)

    FETCH NEXT FROM FileCursor INTO 
      @ID,
      @BackupFile,
      @Depth,
      @FileFlag,
      @ParentDirectoryID 

    SET @wkSubParentDirectoryID = @ParentDirectoryID      
  END

  CLOSE FileCursor
  DEALLOCATE FileCursor

When to use pthread_exit() and when to use pthread_join() in Linux?

pthread_exit terminates the calling thread while pthread_join suspends execution of calling thread until target threads completes execution.

They are pretty much well explained in detail in the open group documentation:

What is the difference between \r and \n?

In C and C++, \n is a concept, \r is a character, and \r\n is (almost always) a portability bug.

Think of an old teletype. The print head is positioned on some line and in some column. When you send a printable character to the teletype, it prints the character at the current position and moves the head to the next column. (This is conceptually the same as a typewriter, except that typewriters typically moved the paper with respect to the print head.)

When you wanted to finish the current line and start on the next line, you had to do two separate steps:

  1. move the print head back to the beginning of the line, then
  2. move it down to the next line.

ASCII encodes these actions as two distinct control characters:

  • \x0D (CR) moves the print head back to the beginning of the line. (Unicode encodes this as U+000D CARRIAGE RETURN.)
  • \x0A (LF) moves the print head down to the next line. (Unicode encodes this as U+000A LINE FEED.)

In the days of teletypes and early technology printers, people actually took advantage of the fact that these were two separate operations. By sending a CR without following it by a LF, you could print over the line you already printed. This allowed effects like accents, bold type, and underlining. Some systems overprinted several times to prevent passwords from being visible in hardcopy. On early serial CRT terminals, CR was one of the ways to control the cursor position in order to update text already on the screen.

But most of the time, you actually just wanted to go to the next line. Rather than requiring the pair of control characters, some systems allowed just one or the other. For example:

  • Unix variants (including modern versions of Mac) use just a LF character to indicate a newline.
  • Old (pre-OSX) Macintosh files used just a CR character to indicate a newline.
  • VMS, CP/M, DOS, Windows, and many network protocols still expect both: CR LF.
  • Old IBM systems that used EBCDIC standardized on NL--a character that doesn't even exist in the ASCII character set. In Unicode, NL is U+0085 NEXT LINE, but the actual EBCDIC value is 0x15.

Why did different systems choose different methods? Simply because there was no universal standard. Where your keyboard probably says "Enter", older keyboards used to say "Return", which was short for Carriage Return. In fact, on a serial terminal, pressing Return actually sends the CR character. If you were writing a text editor, it would be tempting to just use that character as it came in from the terminal. Perhaps that's why the older Macs used just CR.

Now that we have standards, there are more ways to represent line breaks. Although extremely rare in the wild, Unicode has new characters like:

  • U+2028 LINE SEPARATOR
  • U+2029 PARAGRAPH SEPARATOR

Even before Unicode came along, programmers wanted simple ways to represent some of the most useful control codes without worrying about the underlying character set. C has several escape sequences for representing control codes:

  • \a (for alert) which rings the teletype bell or makes the terminal beep
  • \f (for form feed) which moves to the beginning of the next page
  • \t (for tab) which moves the print head to the next horizontal tab position

(This list is intentionally incomplete.)

This mapping happens at compile-time--the compiler sees \a and puts whatever magic value is used to ring the bell.

Notice that most of these mnemonics have direct correlations to ASCII control codes. For example, \a would map to 0x07 BEL. A compiler could be written for a system that used something other than ASCII for the host character set (e.g., EBCDIC). Most of the control codes that had specific mnemonics could be mapped to control codes in other character sets.

Huzzah! Portability!

Well, almost. In C, I could write printf("\aHello, World!"); which rings the bell (or beeps) and outputs a message. But if I wanted to then print something on the next line, I'd still need to know what the host platform requires to move to the next line of output. CR LF? CR? LF? NL? Something else? So much for portability.

C has two modes for I/O: binary and text. In binary mode, whatever data is sent gets transmitted as-is. But in text mode, there's a run-time translation that converts a special character to whatever the host platform needs for a new line (and vice versa).

Great, so what's the special character?

Well, that's implementation dependent, too, but there's an implementation-independent way to specify it: \n. It's typically called the "newline character".

This is a subtle but important point: \n is mapped at compile time to an implementation-defined character value which (in text mode) is then mapped again at run time to the actual character (or sequence of characters) required by the underlying platform to move to the next line.

\n is different than all the other backslash literals because there are two mappings involved. This two-step mapping makes \n significantly different than even \r, which is simply a compile-time mapping to CR (or the most similar control code in whatever the underlying character set is).

This trips up many C and C++ programmers. If you were to poll 100 of them, at least 99 will tell you that \n means line feed. This is not entirely true. Most (perhaps all) C and C++ implementations use LF as the magic intermediate value for \n, but that's an implementation detail. It's feasible for a compiler to use a different value. In fact, if the host character set is not a superset of ASCII (e.g., if it's EBCDIC), then \n will almost certainly not be LF.

So, in C and C++:

  • \r is literally a carriage return.
  • \n is a magic value that gets translated (in text mode) at run-time to/from the host platform's newline semantics.
  • \r\n is almost always a portability bug. In text mode, this gets translated to CR followed by the platform's newline sequence--probably not what's intended. In binary mode, this gets translated to CR followed by some magic value that might not be LF--possibly not what's intended.
  • \x0A is the most portable way to indicate an ASCII LF, but you only want to do that in binary mode. Most text-mode implementations will treat that like \n.

What is the difference between vmalloc and kmalloc?

One of other differences is kmalloc will return logical address (else you specify GPF_HIGHMEM). Logical addresses are placed in "low memory" (in the first gigabyte of physical memory) and are mapped directly to physical addresses (use __pa macro to convert it). This property implies kmalloced memory is continuous memory.

In other hand, Vmalloc is able to return virtual addresses from "high memory". These addresses cannot be converted in physical addresses in a direct fashion (you have to use virt_to_page function).

How does GPS in a mobile phone work exactly?

There's 3 satellites at least that you must be able to receive from of the 24-32 out there, and they each broadcast a time from a synchronized atomic clock. The differences in those times that you receive at any one time tell you how long the broadcast took to reach you, and thus where you are in relation to the satellites. So, it sort of reads from something, but it doesn't connect to that thing. Note that this doesn't tell you your orientation, many GPSes fake that (and speed) by interpolating data points.

If you don't count the cost of the receiver, it's a free service. Apparently there's higher resolution services out there that are restricted to military use. Those are likely a fixed cost for a license to decrypt the signals along with a confidentiality agreement.

Now your device may support GPS tracking, in which case it might communicate, say via GPRS, to a database which will store the location the device has found itself to be at, so that multiple devices may be tracked. That would require some kind of connection.

Maps are either stored on the device or received over a connection. Navigation is computed based on those maps' databases. These likely are a licensed item with a cost associated, though if you use a service like Google Maps they have the license with NAVTEQ and others.

How to create JSON object using jQuery

Just put your data into an Object like this:

var myObject = new Object();
myObject.name = "John";
myObject.age = 12;
myObject.pets = ["cat", "dog"];

Afterwards stringify it via:

var myString = JSON.stringify(myObject);

You don't need jQuery for this. It's pure JS.

How to create a responsive image that also scales up in Bootstrap 3

If setting a fixed width on the image is not an option, here's an alternative solution.

Having a parent div with display: table & table-layout: fixed. Then setting the image to display: table-cell and max-width to 100%. That way the image will fit to the width of its parent.

Example:

<style>
    .wrapper { float: left; clear: left; display: table; table-layout: fixed; }
    img.img-responsive { display: table-cell; max-width: 100%; }
</style>
<div class="wrapper col-md-3">
    <img class="img-responsive" src="https://www.google.co.uk/images/srpr/logo11w.png"/>
</div>

Fiddle: http://jsfiddle.net/5y62c4af/

How to read/write arbitrary bits in C/C++

int x = 0xFF;   //your number - 11111111

How do I for example read a 3 bit integer value starting at the second bit

int y = x & ( 0x7 << 2 ) // 0x7 is 111
                         // and you shift it 2 to the left

Setting maxlength of textbox with JavaScript or jQuery

<head>
    <script type="text/javascript">
        function SetMaxLength () {
            var input = document.getElementById ("myInput");
            input.maxLength = 10;
        }
    </script>
</head>
<body>
    <input id="myInput" type="text" size="20" />
</body>

Failed Apache2 start, no error log

Thanks, Tim! Big stumper for me. A few other details others may find helpful:

(Apache2 on Ubuntu 12.04)

I have two sites running on the same server and had just updated the SSL cert for one of them. Upon restarting the server, I got that cryptic message and neither site worked (obviously). I too found the redirect for the log files in the config files. I tracked that down and found the issue (in the log file for the site I had just updated).

My config files are located in /etc/apache2/sites-available

vim or cat the file (cat {filename}) and look for the ErrorLog line. That tells you where to look on your server. cat that file and the error message I found was:

[error] Unable to configure RSA server private key
[error] SSL Library Error: 185073780 error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch
[warn] RSA server certificate CommonName (CN) `<snip>.com' does NOT match server name!?

I had copied one of my cert files to the wrong directory. I simply moved it to the correct directory and everything was fine on the next start. (tip: where those file should be is also in the config file ;)

How to increase the execution timeout in php?

if what you need to do is specific only for 1 or 2 pages i suggest to use set_time_limit so it did not affect the whole application.

set_time_limit(some_values);

but ofcourse these 2 values (post_max_size & upload_max_filesize) are subject to investigate.

you either can set it via ini_set function

ini_set('post_max_size','20M');
ini_set('upload_max_filesize','2M');

or directly in php.ini file like response above by Hannes, or even set it iin .htaccess like below

php_value upload_max_filesize 2M
php_value post_max_size 20M

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

Set decoding to true

Your decoding is not set to true. If you don't have access to set the source to true. The code below will fix it for you.

$WorkingArray = json_decode(json_encode($data),true);

Generate a sequence of numbers in Python

This works by exploiting the % properties of the list rather than the increments.

for num in range(1,100):
    if num % 4 == 1 or num % 4 ==2:
        n.append(num)
        continue
    pass

Command not found error in Bash variable assignment

You cannot have spaces around the = sign.

When you write:

STR = "foo"

bash tries to run a command named STR with 2 arguments (the strings = and foo)

When you write:

STR =foo

bash tries to run a command named STR with 1 argument (the string =foo)

When you write:

STR= foo

bash tries to run the command foo with STR set to the empty string in its environment.

I'm not sure if this helps to clarify or if it is mere obfuscation, but note that:

  1. the first command is exactly equivalent to: STR "=" "foo",
  2. the second is the same as STR "=foo",
  3. and the last is equivalent to STR="" foo.

The relevant section of the sh language spec, section 2.9.1 states:

A "simple command" is a sequence of optional variable assignments and redirections, in any sequence, optionally followed by words and redirections, terminated by a control operator.

In that context, a word is the command that bash is going to run. Any string containing = (in any position other than at the beginning of the string) which is not a redirection and in which the portion of the string before the = is a valid variable name is a variable assignment, while any string that is not a redirection or a variable assignment is a command. In STR = "foo", STR is not a variable assignment.

Clone() vs Copy constructor- which is recommended in java

clone() was designed with several mistakes (see this question), so it's best to avoid it.

From Effective Java 2nd Edition, Item 11: Override clone judiciously

Given all of the problems associated with Cloneable, it’s safe to say that other interfaces should not extend it, and that classes designed for inheritance (Item 17) should not implement it. Because of its many shortcomings, some expert programmers simply choose never to override the clone method and never to invoke it except, perhaps, to copy arrays. If you design a class for inheritance, be aware that if you choose not to provide a well-behaved protected clone method, it will be impossible for subclasses to implement Cloneable.

This book also describes the many advantages copy constructors have over Cloneable/clone.

  • They don't rely on a risk-prone extralinguistic object creation mechanism
  • They don't demand unenforceable adherence to thinly documented conventions
  • They don't conflict with the proper use of final fields
  • They don't throw unnecessary checked exceptions
  • They don't require casts.

All standard collections have copy constructors. Use them.

List<Double> original = // some list
List<Double> copy = new ArrayList<Double>(original);

JavaScript: Passing parameters to a callback function

Wrap the 'child' function(s) being passed as/with arguments within function wrappers to prevent them being evaluated when the 'parent' function is called.

function outcome(){
    return false;
}

function process(callbackSuccess, callbackFailure){
    if ( outcome() )
        callbackSuccess();
    else
        callbackFailure();
}

process(function(){alert("OKAY");},function(){alert("OOPS");})

Change application's starting activity

Just go to your AndroidManifest.xml file and add like below

<intent-filter>
    <action android:name="android.intent.action.MAIN" />
    <category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

then save and run your android project.

How to force a line break in a long word in a DIV?

Found that using the following worked across most major browsers (Chrome, IE, Safari iOS/OSX) except Firefox (v50.0.2) when using flexbox and relying on width: auto.

.your_element {
    word-wrap: break-word;   
    overflow-wrap: break-word;
    word-break: break-word;
}

Note: you may need to add browser vendor prefixes if you are not using an autoprefixer.

Another thing to watch out for is text using &nbsp; for spacing can cause line breaks mid-word.

node.js shell command execution

I used this more concisely :

var sys = require('sys')
var exec = require('child_process').exec;
function puts(error, stdout, stderr) { sys.puts(stdout) }
exec("ls -la", puts);

it works perfectly. :)

Re-order columns of table in Oracle

Since the release of Oracle 12c it is now easier to rearrange columns logically.

Oracle 12c added support for making columns invisible and that feature can be used to rearrange columns logically.

Quote from the documentation on invisible columns:

When you make an invisible column visible, the column is included in the table's column order as the last column.

Example

Create a table:

CREATE TABLE t (
    a INT,
    b INT,
    d INT,
    e INT
);

Add a column:

ALTER TABLE t ADD (c INT);

Move the column to the middle:

ALTER TABLE t MODIFY (d INVISIBLE, e INVISIBLE);
ALTER TABLE t MODIFY (d VISIBLE, e VISIBLE);

DESCRIBE t;

Name
----
A
B
C
D
E

Credits

I learned about this from an article by Tom Kyte on new features in Oracle 12c.

How to extract the hostname portion of a URL in JavaScript

Try

document.location.host

or

document.location.hostname

What's the safest way to iterate through the keys of a Perl hash?

The rule of thumb is to use the function most suited to your needs.

If you just want the keys and do not plan to ever read any of the values, use keys():

foreach my $key (keys %hash) { ... }

If you just want the values, use values():

foreach my $val (values %hash) { ... }

If you need the keys and the values, use each():

keys %hash; # reset the internal iterator so a prior each() doesn't affect the loop
while(my($k, $v) = each %hash) { ... }

If you plan to change the keys of the hash in any way except for deleting the current key during the iteration, then you must not use each(). For example, this code to create a new set of uppercase keys with doubled values works fine using keys():

%h = (a => 1, b => 2);

foreach my $k (keys %h)
{
  $h{uc $k} = $h{$k} * 2;
}

producing the expected resulting hash:

(a => 1, A => 2, b => 2, B => 4)

But using each() to do the same thing:

%h = (a => 1, b => 2);

keys %h;
while(my($k, $v) = each %h)
{
  $h{uc $k} = $h{$k} * 2; # BAD IDEA!
}

produces incorrect results in hard-to-predict ways. For example:

(a => 1, A => 2, b => 2, B => 8)

This, however, is safe:

keys %h;
while(my($k, $v) = each %h)
{
  if(...)
  {
    delete $h{$k}; # This is safe
  }
}

All of this is described in the perl documentation:

% perldoc -f keys
% perldoc -f each

Android: How to stretch an image to the screen width while maintaining aspect ratio?

Look there is a far easier solution to your problem:

ImageView imageView;

protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.your_layout);
    imageView =(ImageView)findViewById(R.id.your_imageView);
    Bitmap imageBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.your_image);
    Point screenSize = new Point();
    getWindowManager().getDefaultDisplay().getSize(screenSize);
    Bitmap temp = Bitmap.createBitmap(screenSize.x, screenSize.x, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(temp);
    canvas.drawBitmap(imageBitmap,null, new Rect(0,0,screenSize.x,screenSize.x), null);
    imageView.setImageBitmap(temp);
}

Default value to a parameter while passing by reference in C++

It's possible with const qualifier for State:

virtual const ULONG Write(const ULONG &State = 0, bool sequence = true);

How to refresh materialized view in oracle

If you're working with SQL Developer, you have to put the dbms_view in lowercase. The rest compiled fine for me although I haven't called the procedure from code yet.

CREATE OR REPLACE PROCEDURE "MAT_VIEW_FOO_TBL" AS 
BEGIN
  dbms_mview.refresh('v_materialized_foo_tbl');
END;

What to do with branch after merge

After the merge, it's safe to delete the branch:

git branch -d branch1

Additionally, git will warn you (and refuse to delete the branch) if it thinks you didn't fully merge it yet. If you forcefully delete a branch (with git branch -D) which is not completely merged yet, you have to do some tricks to get the unmerged commits back though (see below).

There are some reasons to keep a branch around though. For example, if it's a feature branch, you may want to be able to do bugfixes on that feature still inside that branch.

If you also want to delete the branch on a remote host, you can do:

git push origin :branch1

This will forcefully delete the branch on the remote (this will not affect already checked-out repositiories though and won't prevent anyone with push access to re-push/create it).


git reflog shows the recently checked out revisions. Any branch you've had checked out in the recent repository history will also show up there. Aside from that, git fsck will be the tool of choice at any case of commit-loss in git.

Setting property 'source' to 'org.eclipse.jst.jee.server:JSFTut' did not find a matching property

Update to the latest release

Since this commit, this is is fixed in the development version of Tomcat. And now in released versions 9.0.13, 8.5.35, and 7.0.92.

From the 9.0.13 changelog:

Ignore an attribute named source on Context elements provided by StandardContext. This is to suppress warnings generated by the Eclipse / Tomcat integration provided by Eclipse. Based on a patch by mdfst13. (markt)

There are similar entries in the 7.0.92 and 8.5.35 changelogs.

The effect of this change is to suppress a warning when a source attribute is declared on a Context element in either server.xml or a context.xml. Since those are the two places that Eclipse puts such an attribute, that fixes this particular issue.

TL;DR: update to the latest Tomcat version in its branch, e.g. 9.0.13 or newer.

How to make sure that string is valid JSON using JSON.NET

Use JContainer.Parse(str) method to check if the str is a valid Json. If this throws exception then it is not a valid Json.

JObject.Parse - Can be used to check if the string is a valid Json object
JArray.Parse - Can be used to check if the string is a valid Json Array
JContainer.Parse - Can be used to check for both Json object & Array

ASP.NET document.getElementById('<%=Control.ClientID%>'); returns null

Gotcha!

You have to use RegisterStartupScript instead of RegisterClientScriptBlock

Here My Example.

MasterPage:

<%@ Master Language="C#" AutoEventWireup="true" CodeBehind="MasterPage.master.cs"
    Inherits="prueba.MasterPage" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>

    <script type="text/javascript">

        function confirmCallBack() {
            var a = document.getElementById('<%= Page.Master.FindControl("ContentPlaceHolder1").FindControl("Button1").ClientID %>');

            alert(a.value);

        }

    </script>

    <asp:ContentPlaceHolder ID="head" runat="server">
    </asp:ContentPlaceHolder>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
        </asp:ContentPlaceHolder>
    </div>
    </form>
</body>
</html>

WebForm1.aspx

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.Master" AutoEventWireup="true"
    CodeBehind="WebForm1.aspx.cs" Inherits="prueba.WebForm1" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">

</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<asp:Button ID="Button1" runat="server" Text="Button" />
</asp:Content>

WebForm1.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace prueba
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            ClientScript.RegisterStartupScript(this.GetType(), "js", "confirmCallBack();", true);

        }
    }
}

How do I force git to checkout the master branch and remove carriage returns after I've normalized files using the "text" attribute?

As others have pointed out one could just delete all the files in the repo and then check them out. I prefer this method and it can be done with the code below

git ls-files -z | xargs -0 rm
git checkout -- .

or one line

git ls-files -z | xargs -0 rm ; git checkout -- .

I use it all the time and haven't found any down sides yet!

For some further explanation, the -z appends a null character onto the end of each entry output by ls-files, and the -0 tells xargs to delimit the output it was receiving by those null characters.

Finding the max/min value in an array of primitives using Java

I have a little helper class in all of my applications with methods like:

public static double arrayMax(double[] arr) {
    double max = Double.NEGATIVE_INFINITY;

    for(double cur: arr)
        max = Math.max(max, cur);

    return max;
}

Oracle "Partition By" Keyword

The concept is very well explained by the accepted answer, but I find that the more example one sees, the better it sinks in. Here's an incremental example:

1) Boss says "get me number of items we have in stock grouped by brand"

You say: "no problem"

SELECT 
      BRAND
      ,COUNT(ITEM_ID) 
FROM 
      ITEMS
GROUP BY 
      BRAND;

Result:

+--------------+---------------+
|  Brand       |   Count       | 
+--------------+---------------+
| H&M          |     50        |
+--------------+---------------+
| Hugo Boss    |     100       |
+--------------+---------------+
| No brand     |     22        |
+--------------+---------------+

2) The boss says "Now get me a list of all items, with their brand AND number of items that the respective brand has"

You may try:

 SELECT 
      ITEM_NR
      ,BRAND
      ,COUNT(ITEM_ID) 
 FROM 
      ITEMS
 GROUP BY 
      BRAND;

But you get:

ORA-00979: not a GROUP BY expression 

This is where the OVER (PARTITION BY BRAND) comes in:

 SELECT 
      ITEM_NR
      ,BRAND
      ,COUNT(ITEM_ID) OVER (PARTITION BY BRAND) 
 FROM 
      ITEMS;

Whic means:

  • COUNT(ITEM_ID) - get the number of items
  • OVER - Over the set of rows
  • (PARTITION BY BRAND) - that have the same brand

And the result is:

+--------------+---------------+----------+
|  Items       |  Brand        | Count()  |
+--------------+---------------+----------+
|  Item 1      |  Hugo Boss    |   100    | 
+--------------+---------------+----------+
|  Item 2      |  Hugo Boss    |   100    | 
+--------------+---------------+----------+
|  Item 3      |  No brand     |   22     | 
+--------------+---------------+----------+
|  Item 4      |  No brand     |   22     | 
+--------------+---------------+----------+
|  Item 5      |  H&M          |   50     | 
+--------------+---------------+----------+

etc...

iPad browser WIDTH & HEIGHT standard

The pixel width and height of your page will depend on orientation as well as the meta viewport tag, if specified. Here are the results of running jquery's $(window).width() and $(window).height() on iPad 1 browser.

When page has no meta viewport tag:

  • Portrait: 980x1208
  • Landscape: 980x661

When page has either of these two meta tags:

<meta name="viewport" content="initial-scale=1,user-scalable=no,maximum-scale=1,width=device-width">

<meta name="viewport" content="initial-scale=1,user-scalable=no,maximum-scale=1">

  • Portrait: 768x946
  • Landscape: 1024x690

With <meta name="viewport" content="width=device-width">:

  • Portrait: 768x946
  • Landscape: 768x518

With <meta name="viewport" content="height=device-height">:

  • Portrait: 980x1024
  • Landscape: 980x1024

With <meta name="viewport" content="height=device-height,width=device-width">:

  • Portrait: 768x1024
  • Landscape: 768x1024

With <meta name="viewport" content="initial-scale=1,user-scalable=no,maximum-scale=1,width=device-width,height=device-height">

  • Portrait: 768x1024
  • Landscape: 1024x1024

With <meta name="viewport" content="initial-scale=1,user-scalable=no,maximum-scale=1,height=device-height">

  • Portrait: 831x1024
  • Landscape: 1520x1024

Waiting for Target Device to Come Online

I've had the same problem (AVD not coming online) in a Linux system. In my case, I have solved it setting this environment variable:

$ export ANDROID_EMULATOR_USE_SYSTEM_LIBS = 1

This case is documented here: https://developer.android.com/studio/command-line/variables.html#studio_jdk

Reading an Excel file in PHP

Read XLSX (Excel 97-2003)
https://github.com/shuchkin/simplexls

if ( $xls = SimpleXLS::parse('book.xls') ) {
    print_r( $xls->rows() );
} else {
    echo SimpleXLS::parseError();
}

Read XLSX (Excel 2003+)
https://github.com/shuchkin/simplexlsx

if ( $xlsx = SimpleXLSX::parse('book.xlsx') ) {
    print_r( $xlsx->rows() );
} else {
    echo SimpleXLSX::parseError();
}

Output

Array (
    [0] => Array
        (
            [0] => ISBN
            [1] => title
            [2] => author
            [3] => publisher
            [4] => ctry
        )
    [1] => Array
        (
            [0] => 618260307
            [1] => The Hobbit
            [2] => J. R. R. Tolkien
            [3] => Houghton Mifflin
            [4] => USA
       )

)

CSV php reader
https://github.com/shuchkin/simplecsv

how to make log4j to write to the console as well

Your log4j File should look something like below read comments.

# Define the types of logger and level of logging    
log4j.rootLogger = DEBUG,console, FILE

# Define the File appender    
log4j.appender.FILE=org.apache.log4j.FileAppender    

# Define Console Appender    
log4j.appender.console=org.apache.log4j.ConsoleAppender    

# Define the layout for console appender. If you do not 
# define it, you will get an error    
log4j.appender.console.layout=org.apache.log4j.PatternLayout

# Set the name of the file    
log4j.appender.FILE.File=log.out

# Set the immediate flush to true (default)    
log4j.appender.FILE.ImmediateFlush=true

# Set the threshold to debug mode    
log4j.appender.FILE.Threshold=debug

# Set the append to false, overwrite    
log4j.appender.FILE.Append=false

# Define the layout for file appender    
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout    
log4j.appender.FILE.layout.conversionPattern=%m%n

Get folder name of the file in Python

this is pretty old, but if you are using Python 3.4 or above use PathLib.

# using OS
import os
path=os.path.dirname("C:/folder1/folder2/filename.xml")
print(path)
print(os.path.basename(path))

# using pathlib
import pathlib
path = pathlib.PurePath("C:/folder1/folder2/filename.xml")
print(path.parent)
print(path.parent.name)

Android 8.0: java.lang.IllegalStateException: Not allowed to start service Intent

it's actually happening because the phone is on offscreen, or you pressed the power button while starting the service. solution for this which worked for me is to start an activity and when it will go in onResume then start the service. in my case, it was booting up and starting a service.

Add Marker function with Google Maps API

You have added the add marker method call outside the function and that causes it to execute before the initialize method which will be called when google maps script loads and thus the marker is not added because map is not initialized Do as below.... Create separate method TestMarker and call it from initialize.

<script type="text/javascript">

    // Standard google maps function
    function initialize() {
        var myLatlng = new google.maps.LatLng(40.779502, -73.967857);
        var myOptions = {
            zoom: 12,
            center: myLatlng,
            mapTypeId: google.maps.MapTypeId.ROADMAP
        }
        map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);
        TestMarker();
    }

    // Function for adding a marker to the page.
    function addMarker(location) {
        marker = new google.maps.Marker({
            position: location,
            map: map
        });
    }

    // Testing the addMarker function
    function TestMarker() {
           CentralPark = new google.maps.LatLng(37.7699298, -122.4469157);
           addMarker(CentralPark);
    }
</script>

Serializing class instance to JSON

An approach which I have been using in my Flask app to serialize Class instance to JSON response.

Github project for reference

from json import JSONEncoder
import json
from typing import List

class ResponseEncoder(JSONEncoder):
    def default(self, o):
        return o.__dict__

class ListResponse:
    def __init__(self, data: List):
        self.data = data
        self.count = len(data)

class A:
    def __init__(self, message: str):
        self.message = message

class B:
    def __init__(self, record: A):
        self.record = record

class C:
    def __init__(self, data: B):
        self.data = data

Now create an instance of A, B, C then encode.

data_a = A('Test Data')
data_b = B(data_a)
data_c = C(data_b)

response = ResponseEncoder().encode(data_c)
json_response = json.loads(response)

Output

{
    "data": {
        "record": {
            "message": "Test Data"
        }
    }
}

For list type response

records = ['One', 'Two', 'Three']
list_response = ListResponse(records)
response = ResponseEncoder().encode(list_response)
json_response = json.loads(response)

Output

{
    "data": [
        "One",
        "Two",
        "Three"
    ],
    "count": 3
}

JavaScript TypeError: Cannot read property 'style' of null

For me my Script tag was outside the body element. Copied it just before closing the body tag. This worked

enter code here

<h1 id = 'title'>Black Jack</h1>
<h4> by Meg</h4>

<p id="text-area">Welcome to blackJack!</p>
<button id="new-button">New Game</button>
<button id="hitbtn">Hit!</button>
<button id="staybtn">Stay</button>

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

React fetch data in server before render

Responded to a similar question with a potentially simple solution to this if anyone is still after an answer, the catch is it involves the use of redux-sagas:

https://stackoverflow.com/a/38701184/978306

Or just skip straight to the article I wrote on the topic:

https://medium.com/@navgarcha7891/react-server-side-rendering-with-simple-redux-store-hydration-9f77ab66900a

Now() function with time trim

You could also use Format$(Now(), "Short Date") or whatever date format you want. Be aware, this function will return the Date as a string, so using Date() is a better approach.

What is a Subclass

It is a class that extends another class.

example taken from https://www.java-tips.org/java-se-tips-100019/24-java-lang/784-what-is-a-java-subclass.html, Cat is a sub class of Animal :-)

public class Animal {

    public static void hide() {
        System.out.println("The hide method in Animal.");
    }

    public void override() {
        System.out.println("The override method in Animal.");
    }
}

public class Cat extends Animal {

    public static void hide() {
        System.out.println("The hide method in Cat.");
    }

    public void override() {
        System.out.println("The override method in Cat.");
    }

    public static void main(String[] args) {
        Cat myCat = new Cat();
        Animal myAnimal = (Animal)myCat;
        myAnimal.hide();
        myAnimal.override();
    }
}

Pass a PHP string to a JavaScript variable (and escape newlines)

function escapeJavaScriptText($string)
{
    return str_replace("\n", '\n', str_replace('"', '\"', addcslashes(str_replace("\r", '', (string)$string), "\0..\37'\\")));
}

Why does this "Slow network detected..." log appear in Chrome?

This means the network is slow, and Chrome is replacing a web font (loaded with a @font-face rule) with a local fallback.

By default, the text rendered with a web font is invisible until the font is downloaded (“flash of invisible text”). With this change, the user on a slow network could start reading right when the content is loaded instead of looking into the empty page for several seconds.

IF EXISTS, THEN SELECT ELSE INSERT AND THEN SELECT

You just have to change the structure of the if...else..endif somewhat:

if exists(select * from Table where FieldValue='') then begin
  select TableID from Table where FieldValue=''
end else begin
  insert into Table (FieldValue) values ('')
  select TableID from Table where TableID = scope_identity()
end

You could also do:

if not exists(select * from Table where FieldValue='') then begin
  insert into Table (FieldValue) values ('')
end
select TableID from Table where FieldValue=''

Or:

if exists(select * from Table where FieldValue='') then begin
  select TableID from Table where FieldValue=''
end else begin
  insert into Table (FieldValue) values ('')
  select scope_identity() as TableID
end

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

This is one way to accomplish this using PowerShell:

<#
.SYNOPSIS
Restores (applies) a previously saved stash based on full or partial stash name.

.DESCRIPTION
Restores (applies) a previously saved stash based on full or partial stash name and then optionally drops the stash. Can be used regardless of whether "git stash save" was done or just "git stash". If no stash matches a message is given. If multiple stashes match a message is given along with matching stash info.

.PARAMETER message
A full or partial stash message name (see right side output of "git stash list"). Can also be "@stash{N}" where N is 0 based stash index.

.PARAMETER drop
If -drop is specified, the matching stash is dropped after being applied.

.EXAMPLE
Restore-Stash "Readme change"
Apply-Stash MyStashName
Apply-Stash MyStashName -drop
Apply-Stash "stash@{0}"
#>
function Restore-Stash  {
    [CmdletBinding()]
    [Alias("Apply-Stash")]
    PARAM (
        [Parameter(Mandatory=$true)] $message,         
        [switch]$drop
    )

    $stashId = $null

    if ($message -match "stash@{") {
        $stashId = $message
    }

    if (!$stashId) {
        $matches = git stash list | Where-Object { $_ -match $message }

        if (!$matches) {
            Write-Warning "No stashes found with message matching '$message' - check git stash list"
            return
        }

        if ($matches.Count -gt 1) {
            Write-Warning "Found $($matches.Count) matches for '$message'. Refine message or pass 'stash{@N}' to this function or git stash apply"
            return $matches
        }

        $parts = $matches -split ':'
        $stashId = $parts[0]
    }

    git stash apply ''$stashId''

    if ($drop) {
        git stash drop ''$stashId''
    }
}

More details here

What is the difference between the 'COPY' and 'ADD' commands in a Dockerfile?

From Docker docs:

ADD or COPY

Although ADD and COPY are functionally similar, generally speaking, COPY is preferred. That’s because it’s more transparent than ADD. COPY only supports the basic copying of local files into the container, while ADD has some features (like local-only tar extraction and remote URL support) that are not immediately obvious. Consequently, the best use for ADD is local tar file auto-extraction into the image, as in ADD rootfs.tar.xz /.

More: Best practices for writing Dockerfiles

Nginx: Permission denied for nginx on Ubuntu

I faced similar issue while restarting Nginx and found it to be a cause of SeLinux. Be sure to give a try after either disabling SeLinux or temporarily setting it to Permissive mode using below command:

setenforce 0

I hope it helps :)

How to exclude particular class name in CSS selector?

Method 1

The problem with your code is that you are selecting the .remode_hover that is a descendant of .remode_selected. So the first part of getting your code to work correctly is by removing that space

.reMode_selected.reMode_hover:hover

Then, in order to get the style to not work, you have to override the style set by the :hover. In other words, you need to counter the background-color property. So the final code will be

.reMode_selected.reMode_hover:hover {
  background-color:inherit;
}
.reMode_hover:hover {
  background-color: #f0ac00;
}

Fiddle

Method 2

An alternative method would be to use :not(), as stated by others. This will return any element that doesn't have the class or property stated inside the parenthesis. In this case, you would put .remode_selected in there. This will target all elements that don't have a class of .remode_selected

Fiddle

However, I would not recommend this method, because of the fact that it was introduced in CSS3, so browser support is not ideal.

Method 3

A third method would be to use jQuery. You can target the .not() selector, which would be similar to using :not() in CSS, but with much better browser support

Fiddle

How to shutdown my Jenkins safely?

The full list of commands is available at http://your-jenkins/cli

The command for a clean shutdown is http://your-jenkins/safe-shutdown

You may also want to use http://your-jenkins/safe-restart

How to print Unicode character in C++?

When compiling with -std=c++11, one can simply

  const char *s  = u8"\u0444";
  cout << s << endl;

Java - How do I make a String array with values?

Another way is with Arrays.setAll, or Arrays.fill:

String[] v = new String[1000];
Arrays.setAll(v, i -> Integer.toString(i * 30));
//v => ["0", "30", "60", "90"... ]

Arrays.fill(v, "initial value");
//v => ["initial value", "initial value"... ]

This is more usefull for initializing (possibly large) arrays where you can compute each element from its index.

Can .NET load and parse a properties file equivalent to Java Properties class?

No there is no built-in support for this.

You have to make your own "INIFileReader". Maybe something like this?

var data = new Dictionary<string, string>();
foreach (var row in File.ReadAllLines(PATH_TO_FILE))
  data.Add(row.Split('=')[0], string.Join("=",row.Split('=').Skip(1).ToArray()));

Console.WriteLine(data["ServerName"]);

Edit: Updated to reflect Paul's comment.

Implementing IDisposable correctly

IDisposable exists to provide a means for you to clean up unmanaged resources that won't be cleaned up automatically by the Garbage Collector.

All of the resources that you are "cleaning up" are managed resources, and as such your Dispose method is accomplishing nothing. Your class shouldn't implement IDisposable at all. The Garbage Collector will take care of all of those fields just fine on its own.

Android RatingBar change star colors

As the previous answer implies, it is not easy to change the color of the ratingbar. The stars are not programmatically drawn, they are images with fixed size and specific color gradients. To change the color you have to create your own star images with different colors then proceed to create your own drawable XML resource and pass it to the ratingsBar class using setProgressDrawable(Drawable d) or XML attribute android:progressDrawable.

How to remove a variable from a PHP session array

Currently you are clearing the name array, you need to call the array then the index you want to unset within the array:

$ar[0]==2
$ar[1]==7
$ar[2]==9

unset ($ar[2])

Two ways of unsetting values within an array:

<?php
# remove by key:
function array_remove_key ()
{
  $args  = func_get_args();
  return array_diff_key($args[0],array_flip(array_slice($args,1)));
}
# remove by value:
function array_remove_value ()
{
  $args = func_get_args();
  return array_diff($args[0],array_slice($args,1));
}

$fruit_inventory = array(
  'apples' => 52,
  'bananas' => 78,
  'peaches' => 'out of season',
  'pears' => 'out of season',
  'oranges' => 'no longer sold',
  'carrots' => 15,
  'beets' => 15,
);

echo "<pre>Original Array:\n",
     print_r($fruit_inventory,TRUE),
     '</pre>';

# For example, beets and carrots are not fruits...
$fruit_inventory = array_remove_key($fruit_inventory,
                                    "beets",
                                    "carrots");
echo "<pre>Array after key removal:\n",
     print_r($fruit_inventory,TRUE),
     '</pre>';

# Let's also remove 'out of season' and 'no longer sold' fruit...
$fruit_inventory = array_remove_value($fruit_inventory,
                                      "out of season",
                                      "no longer sold");
echo "<pre>Array after value removal:\n",
     print_r($fruit_inventory,TRUE),
     '</pre>';
?> 

So, unset has no effect to internal array counter!!!

http://us.php.net/unset

How to grant remote access to MySQL for a whole subnet?

It looks like you can also use a netmask, e.g.

GRANT ... TO 'user'@'192.168.0.0/255.255.255.0' IDENTIFIED BY ...

How to detect escape key press with pure JS or jQuery?

Best way is to make function for this

FUNCTION:

$.fn.escape = function (callback) {
    return this.each(function () {
        $(document).on("keydown", this, function (e) {
            var keycode = ((typeof e.keyCode !='undefined' && e.keyCode) ? e.keyCode : e.which);
            if (keycode === 27) {
                callback.call(this, e);
            };
        });
    });
};

EXAMPLE:

$("#my-div").escape(function () {
    alert('Escape!');
})

Capturing console output from a .NET application (C#)

I made a reactive version that accepts callbacks for stdOut and StdErr.
onStdOut and onStdErr are called asynchronously,
as soon as data arrives (before the process exits).

public static Int32 RunProcess(String path,
                               String args,
                       Action<String> onStdOut = null,
                       Action<String> onStdErr = null)
    {
        var readStdOut = onStdOut != null;
        var readStdErr = onStdErr != null;

        var process = new Process
        {
            StartInfo =
            {
                FileName = path,
                Arguments = args,
                CreateNoWindow = true,
                UseShellExecute = false,
                RedirectStandardOutput = readStdOut,
                RedirectStandardError = readStdErr,
            }
        };

        process.Start();

        if (readStdOut) Task.Run(() => ReadStream(process.StandardOutput, onStdOut));
        if (readStdErr) Task.Run(() => ReadStream(process.StandardError, onStdErr));

        process.WaitForExit();

        return process.ExitCode;
    }

    private static void ReadStream(TextReader textReader, Action<String> callback)
    {
        while (true)
        {
            var line = textReader.ReadLine();
            if (line == null)
                break;

            callback(line);
        }
    }


Example usage

The following will run executable with args and print

  • stdOut in white
  • stdErr in red

to the console.

RunProcess(
    executable,
    args,
    s => { Console.ForegroundColor = ConsoleColor.White; Console.WriteLine(s); },
    s => { Console.ForegroundColor = ConsoleColor.Red;   Console.WriteLine(s); } 
);

Why do we have to normalize the input for an artificial neural network?

In neural networks, it is good idea not just to normalize data but also to scale them. This is intended for faster approaching to global minima at error surface. See the following pictures: error surface before and after normalization

error surface before and after scaling

Pictures are taken from the coursera course about neural networks. Author of the course is Geoffrey Hinton.

Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1

in my case the problem was into outdated "../bootstrap/cache/packages.php and services.php"

I have had to. drop those files and rerun composer install...

  Erroneous data format for unserializing 'Symfony\Component\Routing\CompiledRoute'


Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1

How to query for today's date and 7 days before data?

Try this way:

select * from tab
where DateCol between DateAdd(DD,-7,GETDATE() ) and GETDATE() 

Preventing console window from closing on Visual Studio C/C++ Console application

Use Console.ReadLine() at the end of the program. This will keep the window open until you press the Enter key. See https://docs.microsoft.com/en-us/dotnet/api/system.console.readline for details.

How to set session attribute in java?

Try this.

<%@page language="java" session="true" %>

VB.NET Empty String Array

The array you created by Dim s(0) As String IS NOT EMPTY

In VB.Net, the subscript you use in the array is index of the last element. VB.Net by default starts indexing at 0, so you have an array that already has one element.

You should instead try using System.Collections.Specialized.StringCollection or (even better) System.Collections.Generic.List(Of String). They amount to pretty much the same thing as an array of string, except they're loads better for adding and removing items. And let's be honest: you'll rarely create an empty string array without wanting to add at least one element to it.

If you really want an empty string array, declare it like this:

Dim s As String()

or

Dim t() As String

How can I hide the Android keyboard using JavaScript?

There is no way you can hidde the keyboard properly with js because its a OS problem, so one thing you can easy do to "hidde" the keyboard, is instead of using an input Element you can make any "non-input html element" a key listener element just by adding the [tabindex] attribute, and then you can easily listen the keydown and keyup events and store the "$event.target.value" in a variable to get the input.

How to do perspective fixing?

The simple solution is to just remap coordinates from the original to the final image, copying pixels from one coordinate space to the other, rounding off as necessary -- which may result in some pixels being copied several times adjacent to each other, and other pixels being skipped, depending on whether you're stretching or shrinking (or both) in either dimension. Make sure your copying iterates through the destination space, so all pixels are covered there even if they're painted more than once, rather than thru the source which may skip pixels in the output.

The better solution involves calculating the corresponding source coordinate without rounding, and then using its fractional position between pixels to compute an appropriate average of the (typically) four pixels surrounding that location. This is essentially a filtering operation, so you lose some resolution -- but the result looks a LOT better to the human eye; it does a much better job of retaining small details and avoids creating straight-line artifacts which humans find objectionable.

Note that the same basic approach can be used to remap flat images onto any other shape, including 3D surface mapping.

MongoDB: Is it possible to make a case-insensitive query?

The aggregation framework was introduced in mongodb 2.2 . You can use the string operator "$strcasecmp" to make a case-insensitive comparison between strings. It's more recommended and easier than using regex.

Here's the official document on the aggregation command operator: https://docs.mongodb.com/manual/reference/operator/aggregation/strcasecmp/#exp._S_strcasecmp .

ORA-12505, TNS:listener does not currently know of SID given in connect descriptor

I was just creating the database link incorrectly.

Simple fix for me was to simply change 'SID' to SERVICE_NAME

CREATE DATABASE LINK my_db_link
CONNECT TO myUser IDENTIFIED BY myPassword
USING
'
(
    DESCRIPTION=
    (
        ADDRESS=
        (PROTOCOL=TCP)
        (HOST=host-name-heren)
        (PORT=1521)
    )
    (CONNECT_DATA=(SID=theNameOfTheDatabase))
)';

Changing

SID=theNameOfTheDatabase

to

SERVICE_NAME=theNameOfTheDatabase 

resolved my issue.

How to prevent buttons from submitting forms

You can simply get the reference of your buttons using jQuery, and prevent its propagation like below:

 $(document).ready(function () {
    $('#BUTTON_ID').click(function(e) {

            e.preventDefault();
            e.stopPropagation();
            e.stopImmediatePropagation();

            return false;
    });});

Adding two numbers concatenates them instead of calculating the sum

Try this:

<!DOCTYPE html>
<html>

    <body>
        <p>Add Section</p>

        <label>First Number:</label>
        <input id="txt1"  type="text"/><br />
        <label>Second Number:</label>
        <input id="txt2"  type="text"/><br />

        <input type="button" name="Add" value="Add" onclick="addTwoNumber()"/>
        <p id="demo"></p>

        <script>
            function myFunction() {
                document.getElementById("demo").innerHTML = Date();
            }

            function addTwoNumber(){
                var a = document.getElementById("txt1").value;
                var b = document.getElementById("txt2").value;

                var x = Number(a) + Number(b);
                document.getElementById("demo").innerHTML = "Add Value: " + x;
            }
        </script>
    </body>
</html>

How to convert const char* to char* in C?

To convert a const char* to char* you could create a function like this :

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

char* unconstchar(const char* s) {
    if(!s)
      return NULL;
    int i;
    char* res = NULL;
    res = (char*) malloc(strlen(s)+1);
    if(!res){
        fprintf(stderr, "Memory Allocation Failed! Exiting...\n");
        exit(EXIT_FAILURE);
    } else{
        for (i = 0; s[i] != '\0'; i++) {
            res[i] = s[i];
        }
        res[i] = '\0';
        return res;
    }
}

int main() {
    const char* s = "this is bikash";
    char* p = unconstchar(s);
    printf("%s",p);
    free(p);
}

Emulate/Simulate iOS in Linux

The only solution I can think of is to install VMWare or any other VT then install OSX on a VM.

It works pretty good for testing.

Import functions from another js file. Javascript

//In module.js add below code

export function multiply() {
    return 2 * 3;
}

// Consume the module in calc.js

import { multiply } from './modules.js';

const result = multiply();

console.log(`Result: ${result}`);

// Module.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Module</title>
</head>
<body>

  <script type="module" src="./calc.js"></script>
</body>
</html>

Its a design pattern same code can be found below, please use a live server to test it else you will get CORS error

https://github.com/rohan12patil/JSDesignPatterns/tree/master/Structural%20Patterns/module

How to use a class from one C# project with another C# project

All too often a new developer asks this simple question which is a common problem specifically with Visual Studio IDE's. Few people answer the specific question and often critique the question or give "guesses" for solutions which don't answer the common problems. The first common problem is the IDE leads you to create new projects rather than add new files (.java, .py, .cpp, .c) to the existing solution (by default it creates a new solution) unless you change the project name and add to the current solution. This problem occurs for Python, java, c#, C++ and C project folders.

The new developer selecting "new>project>project name and changing the solution directory to "use same solution" still creates a new "project" in the same solution space, but not in the same directory space as the current user interface file or command line file which still leads to problems with "package not found" errors when building and running the project or solution. This is why the above coding suggestions to importing packages, classes, methods and functions only work (and thus don't answer the question) when the "library" file or "separate behavior" file is not only in the same solution directory path, but also in the same "user interface" or "command shell" application directory space. This does does not happen when you add another project using the new>project>project type commands of the IDE. The problem here is the new project is stored in a different directory than the existing Client or User interface code files. To create a new "file" in the same project space rather than new project the beginner needs to do the following that Microsoft won't do for you and even misleads you away from the intuitively obvious by default.

  1. Select the "application" you want to import the new behavior into (from another file)
  2. Select project>add new item
  3. Select the "program file template type" such as filetype.py, filetype.java, filetype.c, filetype.cpp, filetype.C#, etc. or a library class file type (something other than startup file options you see when you create a new application project or create a new library project).
  4. A new file name with default name is created in your project.
  5. Change the default name of the file to something like library.py or façade.java, etc.

NOW the code recommendations to import libraries or using namespaces will work as described in the comments above and you don't have to change path statements or change solutions paths and solution names that Microsoft won't let you change easily (i.e. you can change the filenames or project names but the IDE won't automatically change the project path or the solution path names).

The following is a Python example but works similar for C#, java, or C/C++ using the includes, namespaces or using code commands appropriate to each language to find code in other classes/projects in the SAME DIRECTORY SPACE.

The application file "hello world" importing from other code files in the same directory.

Note the python white space delimiters are not going to space correctly in this stackoverflow comment editor:

print ("test")

from CIXMPythonFacade import ClassA

c1=ClassA
c1.methodA()

from CIXMPythonFacade import functionA 

functionA()


class ClassName(object): 
         def __init__(object, parameter):
         object.parameter = value

The library file or "façade" file containing classes, methods or functions you want to import.

class class1(object):
    """description of class"""

class ClassA(object):
    print ("test2")
    def methodA():
        print ("test3")

def functionA ():
    print ("test4")
    return (0)


pass

NOW how do you actually solve the mess that the IDE leads you into? To import code from another file in the same directory space you add a reference to it.

  1. Select the application file
  2. Select Project>add reference
  3. Choose the filename visible with the right directory path (check it)
  4. The reference is now available to the interpreter, the code checker and/or the compiler.

OK so now that you have this problem solved, how do you really link two separate projects together in the same solution space?

  1. You have to go to both the indexer or "intellisense" options and the compiler/interpreter and physically check or change/add the directory path statements if they are something other than what points to your "second" project or solution space. When you do the path changes or change the path variables to your workspace and to the specific locations of the projects which are different directory spaces the compiler and the code analyzer can then find these libraries, headers.h, namespaces, project or file locations.
  2. To remove old projects you created by mistake it is even worse. You have to exit the Visual Studio IDE, open windows explorer, go to the workspace directory ...documents\visualstudio xxx\solutionname\packagename select the file or folder, right click and "delete" file or folder.
  3. When you re-enter the IDE and select open solution or open package/solution, the old files and solution/package names are gone as are their misleading path statements which fools the compiler and code analyzer to look at the old directory even though you changed the filename and changed the project name, it does not change the directory path with it.

Microsoft really, really needs to fix these problem so you can intuitively create what most people want to create as new files in the same directories and remove solutions by selecting them and deleting them from the IDE. Beginners get so frustrated with directory path statements so flexible for seasoned developers, but so unfair to new developers in their defaults.

Hope this really helps you new guys and stops seasoned developers from giving you the wrong answers that don't work for you. They assume you already understand path statements and just want to type the right code...which is also why the tunnel in on trying to correct your code but does not help you fix the problem. This is probably the most common problem continually described on stackoverflow with wrong answers that don't work for new programmers.

align 3 images in same row with equal spaces?

HTML:

<div class="container">
    <span>
        <img ... >
    </span>
    <span>
        <img ... >
    </span>
    <span>
        <img ... >
    </span>
</div>

CSS:

.container{ width:50%; margin:0 auto; text-align:center}
.container span{ width:30%; margin:0 1%;  }

I haven't tested this, but hope this will work.

You can add 'display:inline-block' to .container span to make the span to have fixed 30% width

javascript regex for password containing at least 8 characters, 1 number, 1 upper and 1 lowercase

Using individual regular expressions to test the different parts would be considerably easier than trying to get one single regular expression to cover all of them. It also makes it easier to add or remove validation criteria.

Note, also, that your usage of .filter() was incorrect; it will always return a jQuery object (which is considered truthy in JavaScript). Personally, I'd use an .each() loop to iterate over all of the inputs, and report individual pass/fail statuses. Something like the below:

$(".buttonClick").click(function () {

    $("input[type=text]").each(function () {
        var validated =  true;
        if(this.value.length < 8)
            validated = false;
        if(!/\d/.test(this.value))
            validated = false;
        if(!/[a-z]/.test(this.value))
            validated = false;
        if(!/[A-Z]/.test(this.value))
            validated = false;
        if(/[^0-9a-zA-Z]/.test(this.value))
            validated = false;
        $('div').text(validated ? "pass" : "fail");
        // use DOM traversal to select the correct div for this input above
    });
});

Working demo

Javascript array sort and unique

The solution in a more elegant way.

_x000D_
_x000D_
var myData=['237','124','255','124','366','255'];

console.log(Array.from(new Set(myData)).sort());
_x000D_
_x000D_
_x000D_

I know the question is very old, but maybe someone will come in handy

What GRANT USAGE ON SCHEMA exactly do?

Well, this is my final solution for a simple db, for Linux:

# Read this before!
#
# * roles in postgres are users, and can be used also as group of users
# * $ROLE_LOCAL will be the user that access the db for maintenance and
#   administration. $ROLE_REMOTE will be the user that access the db from the webapp
# * you have to change '$ROLE_LOCAL', '$ROLE_REMOTE' and '$DB'
#   strings with your desired names
# * it's preferable that $ROLE_LOCAL == $DB

#-------------------------------------------------------------------------------

//----------- SKIP THIS PART UNTIL POSTGRES JDBC ADDS SCRAM - START ----------//

cd /etc/postgresql/$VERSION/main
sudo cp pg_hba.conf pg_hba.conf_bak
sudo -e pg_hba.conf

# change all `md5` with `scram-sha-256`
# save and exit

//------------ SKIP THIS PART UNTIL POSTGRES JDBC ADDS SCRAM - END -----------//

sudo -u postgres psql

# in psql:
create role $ROLE_LOCAL login createdb;
\password $ROLE_LOCAL
create role $ROLE_REMOTE login;
\password $ROLE_REMOTE

create database $DB owner $ROLE_LOCAL encoding "utf8";
\connect $DB $ROLE_LOCAL

# Create all tables and objects, and after that:

\connect $DB postgres

revoke connect on database $DB from public;
revoke all on schema public from public;
revoke all on all tables in schema public from public;

grant connect on database $DB to $ROLE_LOCAL;
grant all on schema public to $ROLE_LOCAL;
grant all on all tables in schema public to $ROLE_LOCAL;
grant all on all sequences in schema public to $ROLE_LOCAL;
grant all on all functions in schema public to $ROLE_LOCAL;

grant connect on database $DB to $ROLE_REMOTE;
grant usage on schema public to $ROLE_REMOTE;
grant select, insert, update, delete on all tables in schema public to $ROLE_REMOTE;
grant usage, select on all sequences in schema public to $ROLE_REMOTE;
grant execute on all functions in schema public to $ROLE_REMOTE;

alter default privileges for role $ROLE_LOCAL in schema public
    grant all on tables to $ROLE_LOCAL;

alter default privileges for role $ROLE_LOCAL in schema public
    grant all on sequences to $ROLE_LOCAL;

alter default privileges for role $ROLE_LOCAL in schema public
    grant all on functions to $ROLE_LOCAL;

alter default privileges for role $ROLE_REMOTE in schema public
    grant select, insert, update, delete on tables to $ROLE_REMOTE;

alter default privileges for role $ROLE_REMOTE in schema public
    grant usage, select on sequences to $ROLE_REMOTE;

alter default privileges for role $ROLE_REMOTE in schema public
    grant execute on functions to $ROLE_REMOTE;

# CTRL+D

In Postgresql, force unique on combination of two columns

If, like me, you landed here with:

  • a pre-existing table,
  • to which you need to add a new column, and
  • also need to add a new unique constraint on the new column as well as an old one, AND
  • be able to undo it all (i.e. write a down migration)

Here is what worked for me, utilizing one of the above answers and expanding it:

-- up

ALTER TABLE myoldtable ADD COLUMN newcolumn TEXT;
ALTER TABLE myoldtable ADD CONSTRAINT myoldtable_oldcolumn_newcolumn_key UNIQUE (oldcolumn, newcolumn);

---

ALTER TABLE myoldtable DROP CONSTRAINT myoldtable_oldcolumn_newcolumn_key;
ALTER TABLE myoldtable DROP COLUMN newcolumn;

-- down

How to run a script as root on Mac OS X?

sudo ./scriptname

sudo bash will basically switch you over to running a shell as root, although it's probably best to stay as su as little as possible.

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

To make use of regular expressions directly in Excel formulas the following UDF (user defined function) can be of help. It more or less directly exposes regular expression functionality as an excel function.

How it works

It takes 2-3 parameters.

  1. A text to use the regular expression on.
  2. A regular expression.
  3. A format string specifying how the result should look. It can contain $0, $1, $2, and so on. $0 is the entire match, $1 and up correspond to the respective match groups in the regular expression. Defaults to $0.

Some examples

Extracting an email address:

=regex("Peter Gordon: [email protected], 47", "\w+@\w+\.\w+")
=regex("Peter Gordon: [email protected], 47", "\w+@\w+\.\w+", "$0")

Results in: [email protected]

Extracting several substrings:

=regex("Peter Gordon: [email protected], 47", "^(.+): (.+), (\d+)$", "E-Mail: $2, Name: $1")

Results in: E-Mail: [email protected], Name: Peter Gordon

To take apart a combined string in a single cell into its components in multiple cells:

=regex("Peter Gordon: [email protected], 47", "^(.+): (.+), (\d+)$", "$" & 1)
=regex("Peter Gordon: [email protected], 47", "^(.+): (.+), (\d+)$", "$" & 2)

Results in: Peter Gordon [email protected] ...

How to use

To use this UDF do the following (roughly based on this Microsoft page. They have some good additional info there!):

  1. In Excel in a Macro enabled file ('.xlsm') push ALT+F11 to open the Microsoft Visual Basic for Applications Editor.
  2. Add VBA reference to the Regular Expressions library (shamelessly copied from Portland Runners++ answer):
    1. Click on Tools -> References (please excuse the german screenshot) Tools -> References
    2. Find Microsoft VBScript Regular Expressions 5.5 in the list and tick the checkbox next to it.
    3. Click OK.
  3. Click on Insert Module. If you give your module a different name make sure the Module does not have the same name as the UDF below (e.g. naming the Module Regex and the function regex causes #NAME! errors).

    Second icon in the icon row -> Module

  4. In the big text window in the middle insert the following:

    Function regex(strInput As String, matchPattern As String, Optional ByVal outputPattern As String = "$0") As Variant
        Dim inputRegexObj As New VBScript_RegExp_55.RegExp, outputRegexObj As New VBScript_RegExp_55.RegExp, outReplaceRegexObj As New VBScript_RegExp_55.RegExp
        Dim inputMatches As Object, replaceMatches As Object, replaceMatch As Object
        Dim replaceNumber As Integer
    
        With inputRegexObj
            .Global = True
            .MultiLine = True
            .IgnoreCase = False
            .Pattern = matchPattern
        End With
        With outputRegexObj
            .Global = True
            .MultiLine = True
            .IgnoreCase = False
            .Pattern = "\$(\d+)"
        End With
        With outReplaceRegexObj
            .Global = True
            .MultiLine = True
            .IgnoreCase = False
        End With
    
        Set inputMatches = inputRegexObj.Execute(strInput)
        If inputMatches.Count = 0 Then
            regex = False
        Else
            Set replaceMatches = outputRegexObj.Execute(outputPattern)
            For Each replaceMatch In replaceMatches
                replaceNumber = replaceMatch.SubMatches(0)
                outReplaceRegexObj.Pattern = "\$" & replaceNumber
    
                If replaceNumber = 0 Then
                    outputPattern = outReplaceRegexObj.Replace(outputPattern, inputMatches(0).Value)
                Else
                    If replaceNumber > inputMatches(0).SubMatches.Count Then
                        'regex = "A to high $ tag found. Largest allowed is $" & inputMatches(0).SubMatches.Count & "."
                        regex = CVErr(xlErrValue)
                        Exit Function
                    Else
                        outputPattern = outReplaceRegexObj.Replace(outputPattern, inputMatches(0).SubMatches(replaceNumber - 1))
                    End If
                End If
            Next
            regex = outputPattern
        End If
    End Function
    
  5. Save and close the Microsoft Visual Basic for Applications Editor window.

How can I join multiple SQL tables using the IDs?

SELECT 
    a.nameA, /* TableA.nameA */
    d.nameD /* TableD.nameD */
FROM TableA a 
    INNER JOIN TableB b on b.aID = a.aID 
    INNER JOIN TableC c on c.cID = b.cID 
    INNER JOIN TableD d on d.dID = a.dID 
WHERE DATE(c.`date`) = CURDATE()

Decimal number regular expression, where digit after decimal is optional

^[+-]?(([1-9][0-9]*)?[0-9](\.[0-9]*)?|\.[0-9]+)$

should reflect what people usually think of as a well formed decimal number.

The digits before the decimal point can be either a single digit, in which case it can be from 0 to 9, or more than one digits, in which case it cannot start with a 0.

If there are any digits present before the decimal sign, then the decimal and the digits following it are optional. Otherwise, a decimal has to be present followed by at least one digit. Note that multiple trailing 0's are allowed after the decimal point.

grep -E '^[+-]?(([1-9][0-9]*)?[0-9](\.[0-9]*)?|\.[0-9]+)$'

correctly matches the following:

9
0
10
10.
0.
0.0
0.100
0.10
0.01
10.0
10.10
.0
.1
.00
.100
.001

as well as their signed equivalents, whereas it rejects the following:

.
00
01
00.0
01.3

and their signed equivalents, as well as the empty string.

SOAP request to WebService with java

I have come across other similar question here. Both of above answers are perfect, but here trying to add additional information for someone looking for SOAP1.1, and not SOAP1.2.

Just change one line code provided by @acdcjunior, use SOAPMessageFactory1_1Impl implementation, it will change namespace to xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/", which is SOAP1.1 implementation.

Change callSoapWebService method first line to following.

SOAPMessage soapMessage = SOAPMessageFactory1_1Impl.newInstance().createMessage();

I hope it will be helpful to others.

What does LayoutInflater in Android do?

Inflater actually some sort of convert to data, views, instances, to visible UI representation.. ..thus it make use of data feed into from maybe adapters, etc. programmatically. then integrating it with an xml you defined, that tells it how the data should be represented in UI

Typescript empty object for a typed variable

user: USER

this.user = ({} as USER)

Magento How to debug blank white screen

As you said - there is one stand alone answer to this issue.

I had same issue after changing theme. Memory was set to 1024 before, so that's not the problem. Cache was cleared and there was nothing useful in error log.

In my case solution was different - old theme had custom homepage template... Switching it to standard one fixed it.

Create an Android GPS tracking application

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

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

Debugging the source code will surely help you.

linking problem: fatal error LNK1112: module machine type 'x64' conflicts with target machine type 'X86'

before going for the step "compile -DIPLIB=NONE filename.cxx" take the path of VIsual Studio installation upto the vcvarsall batch file and change the configuration as shown below.

*C:\apps\MVS9\VC\vcvarsall.bat x86_amd64*

now next step should be

compile -64bit -DIPLIB=none filename.cxx

this solved the problem for me

Match whitespace but not newlines

What you are looking for is the POSIX blank character class. In Perl it is referenced as:

[[:blank:]]

in Java (don't forget to enable UNICODE_CHARACTER_CLASS):

\p{Blank}

Compared to the similar \h, POSIX blank is supported by a few more regex engines (reference). A major benefit is that its definition is fixed in Annex C: Compatibility Properties of Unicode Regular Expressions and standard across all regex flavors that support Unicode. (In Perl, for example, \h chooses to additionally include the MONGOLIAN VOWEL SEPARATOR.) However, an argument in favor of \h is that it always detects Unicode characters (even if the engines don't agree on which), while POSIX character classes are often by default ASCII-only (as in Java).

But the problem is that even sticking to Unicode doesn't solve the issue 100%. Consider the following characters which are not considered whitespace in Unicode:

The aforementioned Mongolian vowel separator isn't included for what is probably a good reason. It, along with 200C and 200D, occur within words (AFAIK), and therefore breaks the cardinal rule that all other whitespace obeys: you can tokenize with it. They're more like modifiers. However, ZERO WIDTH SPACE, WORD JOINER, and ZERO WIDTH NON-BREAKING SPACE (if it used as other than a byte-order mark) fit the whitespace rule in my book. Therefore, I include them in my horizontal whitespace character class.

In Java:

static public final String HORIZONTAL_WHITESPACE = "[\\p{Blank}\\u200B\\u2060\\uFFEF]"

'foo' was not declared in this scope c++

In C++ you are supposed to declare functions before you can use them. In your code integrate is not declared before the point of the first call to integrate. The same applies to sum. Hence the error. Either reorder your definitions so that function definition precedes the first call to that function, or introduce a [forward] non-defining declaration for each function.

Additionally, defining external non-inline functions in header files in a no-no in C++. Your definitions of SkewNormalEvalutatable::SkewNormalEvalutatable, getSkewNormal, integrate etc. have no business being in header file.

Also SkewNormalEvalutatable e(); declaration in C++ declares a function e, not an object e as you seem to assume. The simple SkewNormalEvalutatable e; will declare an object initialized by default constructor.

Also, you receive the last parameter of integrate (and of sum) by value as an object of Evaluatable type. That means that attempting to pass SkewNormalEvalutatable as last argument of integrate will result in SkewNormalEvalutatable getting sliced to Evaluatable. Polymorphism won't work because of that. If you want polymorphic behavior, you have to receive this parameter by reference or by pointer, but not by value.

invalid conversion from 'const char*' to 'char*'

string::c.str() returns a string of type const char * as seen here

A quick fix: try casting printfunc(num,addr,(char *)data.str().c_str());

While the above may work, it is undefined behaviour, and unsafe.

Here's a nicer solution using templates:

char * my_argument = const_cast<char*> ( ...c_str() );

node.js + mysql connection pooling

I am using this base class connection with mysql:

"base.js"

var mysql   = require("mysql");

var pool = mysql.createPool({
    connectionLimit : 10,
    host: Config.appSettings().database.host,
    user: Config.appSettings().database.username,
    password: Config.appSettings().database.password,
    database: Config.appSettings().database.database
});


var DB = (function () {

    function _query(query, params, callback) {
        pool.getConnection(function (err, connection) {
            if (err) {
                connection.release();
                callback(null, err);
                throw err;
            }

            connection.query(query, params, function (err, rows) {
                connection.release();
                if (!err) {
                    callback(rows);
                }
                else {
                    callback(null, err);
                }

            });

            connection.on('error', function (err) {
                connection.release();
                callback(null, err);
                throw err;
            });
        });
    };

    return {
        query: _query
    };
})();

module.exports = DB;

Just use it like that:

var DB = require('../dal/base.js');

DB.query("select * from tasks", null, function (data, error) {
   callback(data, error);
});

Pandas df.to_csv("file.csv" encode="utf-8") still gives trash characters for minus sign

Your "bad" output is UTF-8 displayed as CP1252.

On Windows, many editors assume the default ANSI encoding (CP1252 on US Windows) instead of UTF-8 if there is no byte order mark (BOM) character at the start of the file. While a BOM is meaningless to the UTF-8 encoding, its UTF-8-encoded presence serves as a signature for some programs. For example, Microsoft Office's Excel requires it even on non-Windows OSes. Try:

df.to_csv('file.csv',encoding='utf-8-sig')

That encoder will add the BOM.

What is pipe() function in Angular

Two very different types of Pipes Angular - Pipes and RxJS - Pipes

Angular-Pipe

A pipe takes in data as input and transforms it to a desired output. In this page, you'll use pipes to transform a component's birthday property into a human-friendly date.

import { Component } from '@angular/core';

@Component({
  selector: 'app-hero-birthday',
  template: `<p>The hero's birthday is {{ birthday | date }}</p>`
})
export class HeroBirthdayComponent {
  birthday = new Date(1988, 3, 15); // April 15, 1988
}

RxJS - Pipe

Observable operators are composed using a pipe method known as Pipeable Operators. Here is an example.

import {Observable, range} from 'rxjs';
import {map, filter} from 'rxjs/operators';

const source$: Observable<number> = range(0, 10);

source$.pipe(
    map(x => x * 2),
    filter(x => x % 3 === 0)
).subscribe(x => console.log(x));

The output for this in the console would be the following:

0

6

12

18

For any variable holding an observable, we can use the .pipe() method to pass in one or multiple operator functions that can work on and transform each item in the observable collection.

So this example takes each number in the range of 0 to 10, and multiplies it by 2. Then, the filter function to filter the result down to only the odd numbers.

Is there a destructor for Java?

No Java doesn't have any destructors .The main reason behind it in Java is the Garbage Collectors that passively works in the background always and all the objects are made in the heap memory , that is the place where GC works .In c++ there we have to explicitly call the delete function since there is no Garbage collector like thing.

Reflection generic get field value

I use the reflections in the toString() implementation of my preference class to see the class members and values (simple and quick debugging).

The simplified code I'm using:

@Override
public String toString() {
    StringBuilder sb = new StringBuilder();

    Class<?> thisClass = null;
    try {
        thisClass = Class.forName(this.getClass().getName());

        Field[] aClassFields = thisClass.getDeclaredFields();
        sb.append(this.getClass().getSimpleName() + " [ ");
        for(Field f : aClassFields){
            String fName = f.getName();
            sb.append("(" + f.getType() + ") " + fName + " = " + f.get(this) + ", ");
        }
        sb.append("]");
    } catch (Exception e) {
        e.printStackTrace();
    }

    return sb.toString();
}

I hope that it will help someone, because I also have searched.

How to plot a 2D FFT in Matlab?

Assuming that I is your input image and F is its Fourier Transform (i.e. F = fft2(I))

You can use this code:

F = fftshift(F); % Center FFT

F = abs(F); % Get the magnitude
F = log(F+1); % Use log, for perceptual scaling, and +1 since log(0) is undefined
F = mat2gray(F); % Use mat2gray to scale the image between 0 and 1

imshow(F,[]); % Display the result

Can't access to HttpContext.Current

Adding a bit to mitigate the confusion here. Even though Darren Davies' (accepted) answer is more straight forward, I think Andrei's answer is a better approach for MVC applications.

The answer from Andrei means that you can use HttpContext just as you would use System.Web.HttpContext.Current. For example, if you want to do this:

System.Web.HttpContext.Current.User.Identity.Name

you should instead do this:

HttpContext.User.Identity.Name

Both achieve the same result, but (again) in terms of MVC, the latter is more recommended.

Another good and also straight forward information regarding this matter can be found here: Difference between HttpContext.Current and Controller.Context in MVC ASP.NET.

Django download a file

Reference:

In view.py Implement function like,

def download(request, id):
    obj = your_model_name.objects.get(id=id)
    filename = obj.model_attribute_name.path
    response = FileResponse(open(filename, 'rb'))
    return response

display: inline-block extra margin

A year later, stumbled across this question for a inline LI problem, but have found a great solution that may apply here.

http://robertnyman.com/2010/02/24/css-display-inline-block-why-it-rocks-and-why-it-sucks/

vertical-align:bottom on all my LI elements fixed my "extra margin" problem in all browsers.

How to put a UserControl into Visual Studio toolBox

Basic qustion if you are using generics in your base control. If yes:

lets say we have control:

public class MyComboDropDown : ComboDropDownComon<MyType>
{
    public MyComboDropDown() { }
}

MyComboDropDown will not allow to open designer on it and will be not shown in Toolbox. Why? Because base control is not already compiled - when MyComboDropDown is complied. You can modify to this:

public class MyComboDropDown : MyComboDropDownBase
{
    public MyComboDropDown() { }
}

public class MyComboDropDownBase : ComboDropDownComon<MyType>
{

}

Than after rebuild, and reset toolbox it should be able to see MyComboDropDown in designer and also in Toolbox

PHP calculate age

Looking over the provided solutions I'm always think about drawbacks of modern education in IT field. Most of the developers are forgetting that even modern CPU's suffer from executing conditional operators, while arithmetics operations, especially with powers of 2 are faster. So on the purpose I'm showing this solution in PHP thread without any optimizations:

  list($year,$month,$day) = explode("-",$birthday);
  $age=floor(((date("Y")-$year)*512+(date("m")-$month)*32+date("d")-$day)/512);

In other languages which have strict type definitions and capable replacing * and / by shifts, this formula will "fly". Also changing divisor you can calculate age in months, weeks &etc. Be carefull, the order of operands in differences is essential

How to change background color in android app

you can try with this way

android:background="@color/white"

What's the best way to store a group of constants that my program uses?

Yes, a static class for storing constants would be just fine, except for constants that are related to specific types.

New lines (\r\n) are not working in email body

Using <BR> is not allways enough. MS Outlook 2007 will ignore this if you dont tell outlook that it is a selfclosing html tag by using

 <BR />

How to Compare two strings using a if in a stored procedure in sql server 2008?

What you want is a SQL case statement. The form of these is either:

  select case [expression or column]
  when [value] then [result]
  when [value2] then [result2]
  else [value3] end

or:

  select case 
  when [expression or column] = [value] then [result]
  when [expression or column] = [value2] then [result2]
  else [value3] end

In your example you are after:

declare @temp as varchar(100)
set @temp='Measure'

select case @temp 
   when 'Measure' then Measure 
   else OtherMeasure end
from Measuretable

Split a vector into chunks

Try the ggplot2 function, cut_number:

library(ggplot2)
x <- 1:10
n <- 3
cut_number(x, n) # labels = FALSE if you just want an integer result
#>  [1] [1,4]  [1,4]  [1,4]  [1,4]  (4,7]  (4,7]  (4,7]  (7,10] (7,10] (7,10]
#> Levels: [1,4] (4,7] (7,10]

# if you want it split into a list:
split(x, cut_number(x, n))
#> $`[1,4]`
#> [1] 1 2 3 4
#> 
#> $`(4,7]`
#> [1] 5 6 7
#> 
#> $`(7,10]`
#> [1]  8  9 10

How to choose the id generation strategy when using JPA and Hibernate

I find this lecture very valuable https://vimeo.com/190275665, in point 3 it summarizes these generators and also gives some performance analysis and guideline one when you use each one.

Removing spaces from a variable input using PowerShell 4.0

The Replace operator means Replace something with something else; do not be confused with removal functionality.

Also you should send the result processed by the operator to a variable or to another operator. Neither .Replace(), nor -replace modifies the original variable.

To remove all spaces, use 'Replace any space symbol with empty string'

$string = $string -replace '\s',''

To remove all spaces at the beginning and end of the line, and replace all double-and-more-spaces or tab symbols to spacebar symbol, use

$string = $string -replace '(^\s+|\s+$)','' -replace '\s+',' '

or the more native System.String method

$string = $string.Trim()

Regexp is preferred, because ' ' means only 'spacebar' symbol, and '\s' means 'spacebar, tab and other space symbols'. Note that $string.Replace() does 'Normal' replace, and $string -replace does RegEx replace, which is more heavy but more functional.

Note that RegEx have some special symbols like dot (.), braces ([]()), slashes (\), hats (^), mathematical signs (+-) or dollar signs ($) that need do be escaped. ( 'my.space.com' -replace '\.','-' => 'my-space-com'. A dollar sign with a number (ex $1) must be used on a right part with care

'2033' -replace '(\d+)',$( 'Data: $1')
Data: 2033

UPDATE: You can also use $str = $str.Trim(), along with TrimEnd() and TrimStart(). Read more at System.String MSDN page.

Total number of items defined in an enum

I've run a benchmark today and came up with interesting result. Among these three:

var count1 = typeof(TestEnum).GetFields().Length;
var count2 = Enum.GetNames(typeof(TestEnum)).Length;
var count3 = Enum.GetValues(typeof(TestEnum)).Length;

GetNames(enum) is by far the fastest!

|         Method |      Mean |    Error |   StdDev |
|--------------- |---------- |--------- |--------- |
| DeclaredFields |  94.12 ns | 0.878 ns | 0.778 ns |
|       GetNames |  47.15 ns | 0.554 ns | 0.491 ns |
|      GetValues | 671.30 ns | 5.667 ns | 4.732 ns |

passing argument to DialogFragment

Using newInstance

public static MyDialogFragment newInstance(int num) {
    MyDialogFragment f = new MyDialogFragment();

    // Supply num input as an argument.
    Bundle args = new Bundle();
    args.putInt("num", num);
    f.setArguments(args);

    return f;
}

And get the Args like this

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mNum = getArguments().getInt("num");
    ...
}

See the full example here
http://developer.android.com/reference/android/app/DialogFragment.html

jQuery hide and show toggle div with plus and minus icon

Here is a quick edit of Enve's answer. I do like roXor's solution, but background images are not necessary. And everbody seems to forgot a preventDefault as well.

_x000D_
_x000D_
$(document).ready(function() {_x000D_
  $(".slidingDiv").hide();_x000D_
_x000D_
  $('.show_hide').click(function(e) {_x000D_
    $(".slidingDiv").slideToggle("fast");_x000D_
    var val = $(this).text() == "-" ? "+" : "-";_x000D_
    $(this).hide().text(val).fadeIn("fast");_x000D_
    e.preventDefault();_x000D_
  });_x000D_
});
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<a href="#" class="show_hide">+</a>_x000D_
_x000D_
<div class="slidingDiv">_x000D_
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer nec odio. Praesent libero. Sed cursus ante dapibus diam. Sed nisi. Nulla quis sem at nibh elementum imperdiet. Duis sagittis ipsum. Praesent mauris. Fusce nec tellus sed augue semper porta._x000D_
    Mauris massa. Vestibulum lacinia arcu eget nulla. </p>_x000D_
_x000D_
  <p>Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Curabitur sodales ligula in libero. Sed dignissim lacinia nunc. Curabitur tortor. Pellentesque nibh. Aenean quam. In scelerisque sem at dolor. Maecenas mattis._x000D_
    Sed convallis tristique sem. Proin ut ligula vel nunc egestas porttitor. Morbi lectus risus, iaculis vel, suscipit quis, luctus non, massa. Fusce ac turpis quis ligula lacinia aliquet. Mauris ipsum. </p>_x000D_
_x000D_
</div>
_x000D_
_x000D_
_x000D_

What is uintptr_t data type

uintptr_t is an unsigned integer type that is capable of storing a data pointer. Which typically means that it's the same size as a pointer.

It is optionally defined in C++11 and later standards.

A common reason to want an integer type that can hold an architecture's pointer type is to perform integer-specific operations on a pointer, or to obscure the type of a pointer by providing it as an integer "handle".

How do you create a Marker with a custom icon for google maps API v3?

Try

    var marker = new google.maps.Marker({
      position: map.getCenter(),
      icon: 'http://imageshack.us/a/img826/9489/x1my.png',
      map: map
    });

from here

https://developers.google.com/maps/documentation/javascript/examples/marker-symbol-custom

Login failed for user 'IIS APPPOOL\ASP.NET v4.0'

Don't use Integrated Security. Use User Id=yourUser; pwd=yourPwd;

This solves the problem.

Function inside a function.?

It is possible to define a function from inside another function. the inner function does not exist until the outer function gets executed.

echo function_exists("y") ? 'y is defined\n' : 'y is not defined \n';
$x=x(2);
echo function_exists("y") ? 'y is defined\n' : 'y is not defined \n';

Output

y is not defined

y is defined

Simple thing you can not call function y before executed x

Setting up SSL on a local xampp/apache server

You can enable SSL on XAMPP by creating self signed certificates and then installing those certificates. Type the below commands to generate and move the certificates to ssl folders.

openssl genrsa -des3 -out server.key 1024

openssl req -new -key server.key -out server.csr

cp server.key server.key.org

openssl rsa -in server.key.org -out server.key

openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt

cp server.crt /opt/lampp/etc/ssl.crt/domainname.crt

cp server.key /opt/lampp/etc/ssl.key/domainname.key

(Use sudo with each command if you are not the super user)

Now, Check that mod_ssl is enabled in [XAMPP_HOME]/etc/httpd.conf:

LoadModule ssl_module modules/mod_ssl.so

Add a virtual host, in this example "localhost.domainname.com" by editing [XAMPP_HOME]/etc/extra/httpd-ssl.conf as follows:

<virtualhost 127.0.1.4:443>
    ServerName localhost.domainname.com
    ServerAlias localhost.domainname.com *.localhost.domainname.com
    ServerAdmin admin@localhost

    DocumentRoot "/opt/lampp/htdocs/"

    DirectoryIndex index.php

    ErrorLog /opt/lampp/logs/domainname.local.error.log
    CustomLog /opt/lampp/logs/domainname.local.access.log combined

    SSLEngine on
    SSLCipherSuite ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP:+eNULL
    SSLCertificateFile /opt/lampp/etc/ssl.crt/domainname.crt
    SSLCertificateKeyFile /opt/lampp/etc/ssl.key/domainname.key

    <directory /opt/lampp/htdocs/>
            Options Indexes FollowSymLinks
            AllowOverride All
            Order allow,deny
            Allow from all
    </directory>
    BrowserMatch ".*MSIE.*" nokeepalive ssl-unclean-shutdown downgrade-1.0 force-response-1.0
</virtualhost>

Add the following entry to /etc/hosts:

127.0.1.4 localhost.domainname.com

Now, try installing the certificate/ try importing certificate to browser. I have checked this and this worked on Ubuntu.

Server Client send/receive simple text

    static void Main(string[] args)
    {
        //---listen at the specified IP and port no.---
        IPAddress localAdd = IPAddress.Parse(SERVER_IP);
        TcpListener listener = new TcpListener(localAdd, PORT_NO);
        Console.WriteLine("Listening...");
        listener.Start();
        while (true)
        {
            //---incoming client connected---
            TcpClient client = listener.AcceptTcpClient();

            //---get the incoming data through a network stream---
            NetworkStream nwStream = client.GetStream();
            byte[] buffer = new byte[client.ReceiveBufferSize];

            //---read incoming stream---
            int bytesRead = nwStream.Read(buffer, 0, client.ReceiveBufferSize);

            //---convert the data received into a string---
            string dataReceived = Encoding.ASCII.GetString(buffer, 0, bytesRead);
            Console.WriteLine("Received : " + dataReceived);

            //---write back the text to the client---
            Console.WriteLine("Sending back : " + dataReceived);
            nwStream.Write(buffer, 0, bytesRead);
            client.Close();
        }
        listener.Stop();
        Console.ReadLine();
    }

In addition to @Nudier Mena answer, keep a while loop to keep the server in listening mode. So that we can have multiple instance of client connected.

Error : Index was outside the bounds of the array.

You have declared an array that can store 8 elements not 9.

this.posStatus = new int[8]; 

It means postStatus will contain 8 elements from index 0 to 7.

Check if process returns 0 with batch file

To check whether a process/command returned 0 or not, use the operators && == 0 or not == 0 ||:

Just add operator to your script:

execute_command && (

       echo\Return 0, with no execution error
) || (
        echo\Return non 0, something went wrong
     )

command && echo\Return 0 || echo\Return non 0

How to put more than 1000 values into an Oracle IN clause

I am almost sure you can split values across multiple INs using OR:

select * from table1 where ID in (1,2,3,4,...,1000) or 
ID in (1001,1002,...,2000)

How to disable javax.swing.JButton in java?

This works.

public class TestButton {

public TestButton() {
    JFrame f = new JFrame();
    f.setSize(new Dimension(200,200));
    JPanel p = new JPanel();
    p.setLayout(new FlowLayout());

    final JButton stop = new JButton("Stop");
    final JButton start = new JButton("Start");
    p.add(start);
    p.add(stop);
    f.getContentPane().add(p);
    stop.setEnabled(false);
    stop.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            start.setEnabled(true);
            stop.setEnabled(false);

        }
    });

    start.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            start.setEnabled(false);
            stop.setEnabled(true);

        }
    });
    f.setVisible(true);
}

/**
 * @param args
 */
public static void main(String[] args) {
    new TestButton();

}

}

How to change MenuItem icon in ActionBar programmatically

Kotlin version:

toolbar.menu.findItem(R.id.notification).icon =
                    ContextCompat.getDrawable(requireContext(), R.drawable.ic_notification)

toolbar.menu.findItem(R.id.notification).isVisible = true

Print Pdf in C#

You can create the PDF document using PdfSharp. It is an open source .NET library.

When trying to print the document it get worse. I have looked allover for a open source way of doing it. There are some ways do do it using AcroRd32.exe but it all depends on the version, and it cannot be done without acrobat reader staying open.

I finally ended up using VintaSoftImaging.NET SDK. It costs some money but is much cheaper than the alternative and it solves the problem really easy.

var doc = new Vintasoft.Imaging.Print.ImagePrintDocument { DocumentName = @"C:\Test.pdf" };
doc.Print();

That just prints to the default printer without showing. There are several alternatives and options.

Split comma-separated values

A way to do this without Linq & Lambdas

string source = "a,b, b, c";
string[] items = source.Split(new char[] { ',', ' ' }, StringSplitOptions.RemoveEmptyEntries);

Why does ANT tell me that JAVA_HOME is wrong when it is not?

If need to run ant in eclipse with inbuilt eclipse jdk add the below line in build.xml

<property name="build.compiler" value="org.eclipse.jdt.core.JDTCompilerAdapter"/>

Python using enumerate inside list comprehension

Just to be really clear, this has nothing to do with enumerate and everything to do with list comprehension syntax.

This list comprehension returns a list of tuples:

[(i,j) for i in range(3) for j in 'abc']

this a list of dicts:

[{i:j} for i in range(3) for j in 'abc']

a list of lists:

[[i,j] for i in range(3) for j in 'abc']

a syntax error:

[i,j for i in range(3) for j in 'abc']

Which is inconsistent (IMHO) and confusing with dictionary comprehensions syntax:

>>> {i:j for i,j in enumerate('abcdef')}
{0: 'a', 1: 'b', 2: 'c', 3: 'd', 4: 'e', 5: 'f'}

And a set of tuples:

>>> {(i,j) for i,j in enumerate('abcdef')}
set([(0, 'a'), (4, 'e'), (1, 'b'), (2, 'c'), (5, 'f'), (3, 'd')])

As Óscar López stated, you can just pass the enumerate tuple directly:

>>> [t for t in enumerate('abcdef') ] 
[(0, 'a'), (1, 'b'), (2, 'c'), (3, 'd'), (4, 'e'), (5, 'f')]

How to break out of a loop in Bash?

while true ; do
    ...
    if [ something ]; then
        break
    fi
done

QuotaExceededError: Dom exception 22: An attempt was made to add something to storage that exceeded the quota

This can occur when Safari is in private mode browsing. While in private browsing, local storage is not available at all.

One solution is to warn the user that the app needs non-private mode to work.

UPDATE: This has been fixed in Safari 11, so the behaviour is now aligned with other browsers.

Assigning default values to shell variables with a single command in bash

Very close to what you posted, actually.

To get the assigned value, or default if it's missing:

FOO="${VARIABLE:-default}"  # If variable not set or null, use default.

Or to assign default to VARIABLE at the same time:

FOO="${VARIABLE:=default}"  # If variable not set or null, set it to default.

Structs in Javascript

I always use object literals

{id: 1, speaker:"john", country: "au"}

How to set a selected option of a dropdown list control using angular JS

i see here already wrote good answers, but sometime to write the same in other form can be helpful

<div ng-app ng-controller="MyCtrl">
  <select ng-model="referral.organization" ng-options="c for c in organizations"></select>
</div>

<script type='text/javascript'>
  function MyCtrl($scope) {
    $scope.organizations = ['a', 'b', 'c', 'd', 'e'];
    $scope.referral = {
      organization: $scope.organizations[2]
    };
  }
</script>

How do I get the value of text input field using JavaScript?

Just try this ..

_x000D_
_x000D_
function handleValueChange() {
    var y = document.getElementById('textbox_id').value;
    var x = document.getElementById('result');
    x.innerHTML = y;
}

function changeTextarea() {
  var a = document.getElementById('text-area').value;
  var b = document.getElementById('text-area-result');
  b.innerHTML = a;
}
_x000D_
input {
  padding: 5px;
}

p {
  white-space: pre;
}
_x000D_
<input type="text" id="textbox_id" placeholder="Enter string here..." oninput="handleValueChange()">
<p id="result"></p>

<textarea name="" id="text-area" cols="20" rows="5" oninput="changeTextarea()"></textarea>
<p id="text-area-result"></p>
_x000D_
_x000D_
_x000D_

Laravel Controller Subfolder routing

Add your controllers in your folders:

controllers\
---- folder1
---- folder2

Create your route not specifying the folder:

Route::get('/product/dashboard', 'MakeDashboardController@showDashboard');

Run

composer dump-autoload

And try again

Can't install any packages in Node.js using "npm install"

npm set registry http://85.10.209.91/

(this proxy fetches the original data from registry.npmjs.org and manipulates the tarball urls to fix the tarball file structure issue).

The other solutions seem to have outdated versions.

Bulk Insert into Oracle database: Which is better: FOR Cursor loop or a simple Select?

I think that in this question is missing one important information.

How many records will you insert?

  1. If from 1 to cca. 10.000 then you should use SQL statement (Like they said it is easy to understand and it is easy to write).
  2. If from cca. 10.000 to cca. 100.000 then you should use cursor, but you should add logic to commit on every 10.000 records.
  3. If from cca. 100.000 to millions then you should use bulk collect for better performance.

Width equal to content

Using display:inline-block; it will work only for a correct sentence with spaces like

_x000D_
_x000D_
#container {_x000D_
    width: 30%;_x000D_
    background-color: grey;_x000D_
    overflow:hidden;_x000D_
    margin:10px;_x000D_
}_x000D_
#container p{_x000D_
    display:inline-block;_x000D_
    background-color: green;_x000D_
}
_x000D_
<h5>Correct sentence with spaces </h5>_x000D_
<div id="container">_x000D_
    <p>Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1</p>_x000D_
</div>_x000D_
<h5>No specaes (not working )</h5>_x000D_
<div id="container">_x000D_
    <p>SampleSampleSampleSampleSampleSampleSampleSampleSampleSampleSamplesadasdsadasdasdsa</p>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Why not using word-wrap: break-word;? it's made to allow long words to be able to break and wrap onto the next line.

_x000D_
_x000D_
#container {_x000D_
    width: 30%;_x000D_
    background-color: grey;_x000D_
    overflow:hidden;_x000D_
    margin:10px;_x000D_
}_x000D_
#container p{_x000D_
   word-wrap: break-word;_x000D_
    background-color: green;_x000D_
}
_x000D_
<h5> Correct sentence with spaces </h5>_x000D_
<div id="container">_x000D_
    <p>Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1 Sample Text 1</p>_x000D_
</div>_x000D_
<h5>No specaes</h5>_x000D_
<div id="container">_x000D_
    <p>SampleSampleSampleSampleSampleSampleSampleSampleSampleSampleSamplesadasdsadasdasdsa</p>_x000D_
</div>
_x000D_
_x000D_
_x000D_

How to create Gmail filter searching for text only at start of subject line?

I was wondering how to do this myself; it seems Gmail has since silently implemented this feature. I created the following filter:

Matches: subject:([test])
Do this: Skip Inbox

And then I sent a message with the subject

[test] foo

And the message was archived! So it seems all that is necessary is to create a filter for the subject prefix you wish to handle.

How to determine the last Row used in VBA including blank spaces in between

You're really close. Try using a large row number with End(xlUp)

Function ultimaFilaBlanco(col As String) As Long

        Dim lastRow As Long
        With ActiveSheet
            lastRow = ActiveSheet.Cells(1048576, col).End(xlUp).row
        End With

        ultimaFilaBlanco = lastRow

End Function

Why do we assign a parent reference to the child object in Java?

You declare parent as Parent, so java will provide only methods and attributes of the Parent class.

Child child = new Child();

should work. Or

Parent child = new Child();
((Child)child).salary = 1;

CSS Font Border?

I once tried to do those round corners and drop shadows with css3. Later on, I found it is still poorly supported (Internet Explorer(s), of course!)

I ended up trying to do that in JS (HTML canvas with IE Canvas), but it impacts the performance a lot (even on my C2D machine). In short, if you really need the effect, consider JS libraries (most of them should be able to run on IE6) but don't over do it due to performance issues; if you still need an alternative... you could use SFiR, then PS it and SFiR it. CSS3 isn't ready today.

Responding with a JSON object in Node.js (converting object/array to JSON string)

Per JamieL's answer to another post:

Since Express.js 3x the response object has a json() method which sets all the headers correctly for you.

Example:

res.json({"foo": "bar"});

Unable to Connect to GitHub.com For Cloning

You can try to clone using the HTTPS protocol. Terminal command:

git clone https://github.com/RestKit/RestKit.git

What is unexpected T_VARIABLE in PHP?

There might be a semicolon or bracket missing a line before your pasted line.

It seems fine to me; every string is allowed as an array index.

WCF change endpoint address at runtime

app.config

<client>
    <endpoint address="" binding="basicHttpBinding" 
    bindingConfiguration="LisansSoap" 
    contract="Lisans.LisansSoap" 
    name="LisansSoap" />
</client>

program

 Lisans.LisansSoapClient test = new LisansSoapClient("LisansSoap",
                         "http://webservis.uzmanevi.com/Lisans/Lisans.asmx");

 MessageBox.Show(test.LisansKontrol("","",""));

How to remove numbers from a string?

This can be done without regex which is more efficient:

var questionText = "1 ding ?"
var index = 0;
var num = "";
do
{
    num += questionText[index];
} while (questionText[++index] >= "0" && questionText[index] <= "9");
questionText = questionText.substring(num.length);

And as a bonus, it also stores the number, which may be useful to some people.

"Initializing" variables in python?

There are several ways to assign the equal variables.

The easiest one:

grade_1 = grade_2 = grade_3 = average = 0.0

With unpacking:

grade_1, grade_2, grade_3, average = 0.0, 0.0, 0.0, 0.0

With list comprehension and unpacking:

>>> grade_1, grade_2, grade_3, average = [0.0 for _ in range(4)]
>>> print(grade_1, grade_2, grade_3, average)
0.0 0.0 0.0 0.0

Error launching Eclipse 4.4 "Version 1.6.0_65 of the JVM is not suitable for this product."

Please check if you got the x64 edition of eclipse. Someone answered this just a few hours ago.

Get first row of dataframe in Python Pandas based on criteria

This tutorial is a very good one for pandas slicing. Make sure you check it out. Onto some snippets... To slice a dataframe with a condition, you use this format:

>>> df[condition]

This will return a slice of your dataframe which you can index using iloc. Here are your examples:

  1. Get first row where A > 3 (returns row 2)

    >>> df[df.A > 3].iloc[0]
    A    4
    B    6
    C    3
    Name: 2, dtype: int64
    

If what you actually want is the row number, rather than using iloc, it would be df[df.A > 3].index[0].

  1. Get first row where A > 4 AND B > 3:

    >>> df[(df.A > 4) & (df.B > 3)].iloc[0]
    A    5
    B    4
    C    5
    Name: 4, dtype: int64
    
  2. Get first row where A > 3 AND (B > 3 OR C > 2) (returns row 2)

    >>> df[(df.A > 3) & ((df.B > 3) | (df.C > 2))].iloc[0]
    A    4
    B    6
    C    3
    Name: 2, dtype: int64
    

Now, with your last case we can write a function that handles the default case of returning the descending-sorted frame:

>>> def series_or_default(X, condition, default_col, ascending=False):
...     sliced = X[condition]
...     if sliced.shape[0] == 0:
...         return X.sort_values(default_col, ascending=ascending).iloc[0]
...     return sliced.iloc[0]
>>> 
>>> series_or_default(df, df.A > 6, 'A')
A    5
B    4
C    5
Name: 4, dtype: int64

As expected, it returns row 4.

Show space, tab, CRLF characters in editor of Visual Studio

Edit > Advanced > View White Space. The keyboard shortcut is CTRL+R, CTRL+W. The command is called Edit.ViewWhiteSpace.

It works in all Visual Studio versions at least since Visual Studio 2010, the current one being Visual Studio 2019 (at time of writing). In Visual Studio 2013, you can also use CTRL+E, S or CTRL+E, CTRL+S.

By default, end of line markers are not visualized. This functionality is provided by the End of the Line extension.

When to Redis? When to MongoDB?

And you should use neither if you have plenty of RAM. Redis and MongoDB come to the price of a general purpose tool. This introduce a lot of overhead.

There was the saying that Redis is 10 times faster than Mongo. That might not be that true anymore. MongoDB (if i remember correctly) claimed to beat memcache for storing and caching documents as long as the memory configurations are the same.

Anyhow. Redis good, MongoDB is good. If you care about substructures and need aggregation go for MongoDB. If storing keys and values is your main concern its all about Redis. (or any other key value store).

Remove a character at a certain position in a string - javascript

You can try it this way!!

var str ="Hello World";
var position = 6;//its 1 based
var newStr = str.substring(0,position - 1) + str.substring(postion, str.length);
alert(newStr);

Here is the live example: http://jsbin.com/ogagaq

Counting lines, words, and characters within a text file using Python

file__IO = input('\nEnter file name here to analize with path:: ')
with open(file__IO, 'r') as f:
    data = f.read()
    line = data.splitlines()
    words = data.split()
    spaces = data.split(" ")
    charc = (len(data) - len(spaces))

    print('\n Line number ::', len(line), '\n Words number ::', len(words), '\n Spaces ::', len(spaces), '\n Charecters ::', (len(data)-len(spaces)))

I tried this code & it works as expected.

html select scroll bar

One options will be to show the selected option above (or below) the select list like following:

HTML

<div id="selText"><span>&nbsp;</span></div><br/>
<select size="4" id="mySelect" style="width:65px;color:#f98ad3;">
    <option value="1" selected>option 1 The Long Option</option>
    <option value="2">option 2</option>
    <option value="3">option 3</option>
    <option value="4">option 4</option>
    <option value="5">option 5 Another Longer than the Long Option ;)</option>
    <option value="6">option 6</option>
</select>

JavaScript

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"   
  type="text/javascript"></script> 
<script type="text/javascript">
$(document).ready(function(){        
    $("select#mySelect").change(function(){
      //$("#selText").html($($(this).children("option:selected")[0]).text());
       var txt = $($(this).children("option:selected")[0]).text();
       $("<span>" + txt + "<br/></span>").appendTo($("#selText span:last"));
    });
});
</script>

PS:- Set height of div#selText otherwise it will keep shifting select list downward.

Can I get the name of the currently running function in JavaScript?

Since you have written a function named foo and you know it is in myfile.js why do you need to get this information dynamically?

That being said you can use arguments.callee.toString() inside the function (this is a string representation of the entire function) and regex out the value of the function name.

Here is a function that will spit out its own name:

function foo() {
    re = /^function\s+([^(]+)/
    alert(re.exec(arguments.callee.toString())[1]);             
}

Drop all duplicate rows across multiple columns in Python Pandas

Actually, drop rows 0 and 1 only requires (any observations containing matched A and C is kept.):

In [335]:

df['AC']=df.A+df.C
In [336]:

print df.drop_duplicates('C', take_last=True) #this dataset is a special case, in general, one may need to first drop_duplicates by 'c' and then by 'a'.
     A  B  C    AC
2  foo  1  B  fooB
3  bar  1  A  barA

[2 rows x 4 columns]

But I suspect what you really want is this (one observation containing matched A and C is kept.):

In [337]:

print df.drop_duplicates('AC')
     A  B  C    AC
0  foo  0  A  fooA
2  foo  1  B  fooB
3  bar  1  A  barA

[3 rows x 4 columns]

Edit:

Now it is much clearer, therefore:

In [352]:
DG=df.groupby(['A', 'C'])   
print pd.concat([DG.get_group(item) for item, value in DG.groups.items() if len(value)==1])
     A  B  C
2  foo  1  B
3  bar  1  A

[2 rows x 3 columns]

Using an authorization header with Fetch in React Native

Example fetch with authorization header:

fetch('URL_GOES_HERE', { 
   method: 'post', 
   headers: new Headers({
     'Authorization': 'Basic '+btoa('username:password'), 
     'Content-Type': 'application/x-www-form-urlencoded'
   }), 
   body: 'A=1&B=2'
 });

SQL Server Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >=

Even after 9 years of the original post, this helped me.

If you are receiving these types of errors without any clue, there should be a trigger, function related to the table, and obviously it should end up with an SP, or function with selecting/filtering data NOT USING Primary Unique column. If you are searching/filtering using the Primary Unique column there won't be any multiple results. Especially when you are assigning value for a declared variable. The SP never gives you en error but only an runtime error.

 "System.Data.SqlClient.SqlException (0x80131904): Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.
    The statement has been terminated."

In my case obviously there was no clue, but only this error message. There was a trigger connected to the table and the table updating by the trigger also had another trigger likewise it ended up with two triggers and in the end with an SP. The SP was having a select clause which was resulting in multiple rows.

SET @Variable1 =(
        SELECT column_gonna_asign
        FROM dbo.your_db
        WHERE Non_primary_non_unique_key= @Variable2

If this returns multiple rows, you are in trouble.

What is time(NULL) in C?

The time function returns the current time (as a time_t value) in seconds since some point (on Unix systems, since midnight UTC January 1, 1970), and it takes one argument, a time_t pointer in which the time is stored. Passing NULL as the argument causes time to return the time as a normal return value but not store it anywhere else.

How to create a cron job using Bash automatically without the interactive editor?

Here is a bash function for adding a command to crontab without duplication

function addtocrontab () {
  local frequency=$1
  local command=$2
  local job="$frequency $command"
  cat <(fgrep -i -v "$command" <(crontab -l)) <(echo "$job") | crontab -
}
addtocrontab "0 0 1 * *" "echo hello"

How to do a less than or equal to filter in Django queryset?

Less than or equal:

User.objects.filter(userprofile__level__lte=0)

Greater than or equal:

User.objects.filter(userprofile__level__gte=0)

Likewise, lt for less than and gt for greater than. You can find them all in the documentation.

Hadoop/Hive : Loading data from .csv on a local machine

For csv file formate data will be in below format

"column1", "column2","column3","column4"

And if we will use field terminated by ',' then each column will get values like below.

"column1"    "column2"     "column3"     "column4"

also if any of the column value has comma as value then it will not work at all .

So the correct way to create a table would be by using OpenCSVSerde

create table tableName (column1 datatype, column2 datatype , column3 datatype , column4 datatype)
ROW FORMAT SERDE 
'org.apache.hadoop.hive.serde2.OpenCSVSerde' 
STORED AS TEXTFILE ;

Using Node.JS, how do I read a JSON file into (server) memory?

So many answers, and no one ever made a benchmark to compare sync vs async vs require. I described the difference in use cases of reading json in memory via require, readFileSync and readFile here.

How to find the 'sizeof' (a pointer pointing to an array)?

For dynamic arrays (malloc or C++ new) you need to store the size of the array as mentioned by others or perhaps build an array manager structure which handles add, remove, count, etc. Unfortunately C doesn't do this nearly as well as C++ since you basically have to build it for each different array type you are storing which is cumbersome if you have multiple types of arrays that you need to manage.

For static arrays, such as the one in your example, there is a common macro used to get the size, but it is not recommended as it does not check if the parameter is really a static array. The macro is used in real code though, e.g. in the Linux kernel headers although it may be slightly different than the one below:

#if !defined(ARRAY_SIZE)
    #define ARRAY_SIZE(x) (sizeof((x)) / sizeof((x)[0]))
#endif

int main()
{
    int days[] = {1,2,3,4,5};
    int *ptr = days;
    printf("%u\n", ARRAY_SIZE(days));
    printf("%u\n", sizeof(ptr));
    return 0;
}

You can google for reasons to be wary of macros like this. Be careful.

If possible, the C++ stdlib such as vector which is much safer and easier to use.

Change header text of columns in a GridView

You can do it with gridview's datarow bound event. try the following sample of code:

protected void grv_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.Header)
{
e.Row.Cells[0].Text = "TiTle";
}
}

For more details about the row databound event study Thsi....

Removing address bar from browser (to view on Android)

If you've loaded jQuery, you can see if the height of the content is greater than the viewport height. If not, then you can make it that height (or a little less). I ran the following code in WVGA800 mode in the Android emulator, and then ran it on my Samsung Galaxy Tab, and in both cases it hid the addressbar.

$(document).ready(function() {

  if (navigator.userAgent.match(/Android/i)) {
    window.scrollTo(0,0); // reset in case prev not scrolled  
    var nPageH = $(document).height();
    var nViewH = window.outerHeight;
    if (nViewH > nPageH) {
      nViewH -= 250;
      $('BODY').css('height',nViewH + 'px');
    }
    window.scrollTo(0,1);
  }

});

Merge some list items in a Python List

That example is pretty vague, but maybe something like this?

items = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
items[3:6] = [''.join(items[3:6])]

It basically does a splice (or assignment to a slice) operation. It removes items 3 to 6 and inserts a new list in their place (in this case a list with one item, which is the concatenation of the three items that were removed.)

For any type of list, you could do this (using the + operator on all items no matter what their type is):

items = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
items[3:6] = [reduce(lambda x, y: x + y, items[3:6])]

This makes use of the reduce function with a lambda function that basically adds the items together using the + operator.

Get Date Object In UTC format in Java

final Date currentTime = new Date();
final SimpleDateFormat sdf = new SimpleDateFormat("EEE, MMM d, yyyy hh:mm:ss a z");
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println("UTC time: " + sdf.format(currentTime));

Add to python path mac os x

Mathew's answer works for the terminal python shell, but it didn't work for IDLE shell in my case because many versions of python existed before I replaced them all with Python2.7.7. How I solved the problem with IDLE.

  1. In terminal, cd /Applications/Python\ 2.7/IDLE.app/Contents/Resources/
  2. then sudo nano idlemain.py, enter password if required.
  3. after os.chdir(os.path.expanduser('~/Documents')) this line, I added sys.path.append("/Users/admin/Downloads....") NOTE: replace contents of the quotes with the directory where python module to be added
  4. to save the change, ctrl+x and enter Now open idle and try to import the python module, no error for me!!!

Plotting a list of (x, y) coordinates in python matplotlib

If you want to plot a single line connecting all the points in the list

plt.plot(li[:])

plt.show()

This will plot a line connecting all the pairs in the list as points on a Cartesian plane from the starting of the list to the end. I hope that this is what you wanted.