Programs & Examples On #Sigpipe

SIGPIPE is the signal sent to a process when it attempts to write to a pipe without a process connected to the other end.

How to prevent SIGPIPEs (or handle them properly)

I'm super late to the party, but SO_NOSIGPIPE isn't portable, and might not work on your system (it seems to be a BSD thing).

A nice alternative if you're on, say, a Linux system without SO_NOSIGPIPE would be to set the MSG_NOSIGNAL flag on your send(2) call.

Example replacing write(...) by send(...,MSG_NOSIGNAL) (see nobar's comment)

char buf[888];
//write( sockfd, buf, sizeof(buf) );
send(    sockfd, buf, sizeof(buf), MSG_NOSIGNAL );

IOError: [Errno 32] Broken pipe: Python

I feel obliged to point out that the method using

signal(SIGPIPE, SIG_DFL) 

is indeed dangerous (as already suggested by David Bennet in the comments) and in my case led to platform-dependent funny business when combined with multiprocessing.Manager (because the standard library relies on BrokenPipeError being raised in several places). To make a long and painful story short, this is how I fixed it:

First, you need to catch the IOError (Python 2) or BrokenPipeError (Python 3). Depending on your program you can try to exit early at that point or just ignore the exception:

from errno import EPIPE

try:
    broken_pipe_exception = BrokenPipeError
except NameError:  # Python 2
    broken_pipe_exception = IOError

try:
    YOUR CODE GOES HERE
except broken_pipe_exception as exc:
    if broken_pipe_exception == IOError:
        if exc.errno != EPIPE:
            raise

However, this isn't enough. Python 3 may still print a message like this:

Exception ignored in: <_io.TextIOWrapper name='<stdout>' mode='w' encoding='UTF-8'>
BrokenPipeError: [Errno 32] Broken pipe

Unfortunately getting rid of that message is not straightforward, but I finally found http://bugs.python.org/issue11380 where Robert Collins suggests this workaround that I turned into a decorator you can wrap your main function with (yes, that's some crazy indentation):

from functools import wraps
from sys import exit, stderr, stdout
from traceback import print_exc


def suppress_broken_pipe_msg(f):
    @wraps(f)
    def wrapper(*args, **kwargs):
        try:
            return f(*args, **kwargs)
        except SystemExit:
            raise
        except:
            print_exc()
            exit(1)
        finally:
            try:
                stdout.flush()
            finally:
                try:
                    stdout.close()
                finally:
                    try:
                        stderr.flush()
                    finally:
                        stderr.close()
    return wrapper


@suppress_broken_pipe_msg
def main():
    YOUR CODE GOES HERE

Disable scrolling in an iPhone web application?

The page has to be launched from the Home screen for the meta tag to work.

What is the difference between Digest and Basic Authentication?

Let us see the difference between the two HTTP authentication using Wireshark (Tool to analyse packets sent or received) .

1. Http Basic Authentication

Basic

As soon as the client types in the correct username:password,as requested by the Web-server, the Web-Server checks in the Database if the credentials are correct and gives the access to the resource .

Here is how the packets are sent and received :

enter image description here In the first packet the Client fill the credentials using the POST method at the resource - lab/webapp/basicauth .In return the server replies back with http response code 200 ok ,i.e, the username:password were correct .

Detail of HTTP packet

Now , In the Authorization header it shows that it is Basic Authorization followed by some random string .This String is the encoded (Base64) version of the credentials admin:aadd (including colon ) .

2 . Http Digest Authentication(rfc 2069)

So far we have seen that the Basic Authentication sends username:password in plaintext over the network .But the Digest Auth sends a HASH of the Password using Hash algorithm.

Here are packets showing the requests made by the client and response from the server .

Digest

As soon as the client types the credentials requested by the server , the Password is converted to a response using an algorithm and then is sent to the server , If the server Database has same response as given by the client the server gives the access to the resource , otherwise a 401 error .

Detailed digest auth packet In the above Authorization , the response string is calculated using the values of Username,Realm,Password,http-method,URI and Nonce as shown in the image :

Response algorithm (colons are included)

Hence , we can see that the Digest Authentication is more Secure as it involve Hashing (MD5 encryption) , So the packet sniffer tools cannot sniff the Password although in Basic Auth the exact Password was shown on Wireshark.

How do I analyze a program's core dump file with GDB when it has command-line parameters?

A slightly different approach will allow you to skip GDB entirely. If all you want is a backtrace, the Linux-specific utility 'catchsegv' will catch SIGSEGV and display a backtrace.

How to interactively (visually) resolve conflicts in SourceTree / git

When the Resolve Conflicts->Content Menu are disabled, one may be on the Pending files list. We need to select the Conflicted files option from the drop down (top)

hope it helps

How do you declare string constants in C?

There's one more (at least) road to Rome:

static const char HELLO3[] = "Howdy";

(static — optional — is to prevent it from conflicting with other files). I'd prefer this one over const char*, because then you'll be able to use sizeof(HELLO3) and therefore you don't have to postpone till runtime what you can do at compile time.

The define has an advantage of compile-time concatenation, though (think HELLO ", World!") and you can sizeof(HELLO) as well.

But then you can also prefer const char* and use it across multiple files, which would save you a morsel of memory.

In short — it depends.

how do I loop through a line from a csv file in powershell

$header3 = @("Field_1","Field_2","Field_3","Field_4","Field_5")     

Import-Csv $fileName -Header $header3 -Delimiter "`t" | select -skip 3 | Foreach-Object {

    $record = $indexName 
    foreach ($property in $_.PSObject.Properties){

        #doSomething $property.Name, $property.Value

            if($property.Name -like '*TextWrittenAsNumber*'){

                $record = $record + "," + '"' + $property.Value + '"' 
            }
            else{
                $record = $record + "," + $property.Value 
            }                           
    }               

        $array.add($record) | out-null  
        #write-host $record                         
}

Mouseover or hover vue.js

With mouseover and mouseleave events you can define a toggle function that implements this logic and react on the value in the rendering.

Check this example:

_x000D_
_x000D_
var vm = new Vue({_x000D_
 el: '#app',_x000D_
 data: {btn: 'primary'}_x000D_
});
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.min.js"></script>_x000D_
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css">_x000D_
_x000D_
_x000D_
<div id='app'>_x000D_
    <button_x000D_
        @mouseover="btn='warning'"_x000D_
        @mouseleave="btn='primary'"_x000D_
        :class='"btn btn-block btn-"+btn'>_x000D_
        {{ btn }}_x000D_
    </button>_x000D_
</div>
_x000D_
_x000D_
_x000D_

jquery: how to get the value of id attribute?

$('.select_continent').click(function () {
    alert($(this).attr('value'));
});

What is use of c_str function In c++

It's used to make std::string interoperable with C code that requires a null terminated char*.

Android map v2 zoom to show all the markers

Google Map V2

The following solution works for Android Marshmallow 6 (API 23, API 24, API 25, API 26, API 27, API 28). It also works in Xamarin.

LatLngBounds.Builder builder = new LatLngBounds.Builder();

//the include method will calculate the min and max bound.
builder.include(marker1.getPosition());
builder.include(marker2.getPosition());
builder.include(marker3.getPosition());
builder.include(marker4.getPosition());

LatLngBounds bounds = builder.build();

int width = getResources().getDisplayMetrics().widthPixels;
int height = getResources().getDisplayMetrics().heightPixels;
int padding = (int) (width * 0.10); // offset from edges of the map 10% of screen

CameraUpdate cu = CameraUpdateFactory.newLatLngBounds(bounds, width, height, padding);

mMap.animateCamera(cu);

How do I run Java .class files?

To run Java class file from the command line, the syntax is:

java -classpath /path/to/jars <packageName>.<MainClassName>

where packageName (usually starts with either com or org) is the folder name where your class file is present.

For example if your main class name is App and Java package name of your app is com.foo.app, then your class file needs to be in com/foo/app folder (separate folder for each dot), so you run your app as:

$ java com.foo.app.App

Note: $ is indicating shell prompt, ignore it when typing

If your class doesn't have any package name defined, simply run as: java App.

If you've any other jar dependencies, make sure you specified your classpath parameter either with -cp/-classpath or using CLASSPATH variable which points to the folder with your jar/war/ear/zip/class files. So on Linux you can prefix the command with: CLASSPATH=/path/to/jars, on Windows you need to add the folder into system variable. If not set, the user class path consists of the current directory (.).


Practical example

Given we've created sample project using Maven as:

$ mvn archetype:generate -DgroupId=com.foo.app -DartifactId=my-app -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false 

and we've compiled our project by mvn compile in our my-app/ dir, it'll generate our class file is in target/classes/com/foo/app/App.class.

To run it, we can either specify class path via -cp or going to it directly, check examples below:

$ find . -name "*.class"
./target/classes/com/foo/app/App.class
$ CLASSPATH=target/classes/ java com.foo.app.App
Hello World!
$ java -cp target/classes com.foo.app.App
Hello World!
$ java -classpath .:/path/to/other-jars:target/classes com.foo.app.App
Hello World!
$ cd target/classes && java com.foo.app.App
Hello World!

To double check your class and package name, you can use Java class file disassembler tool, e.g.:

$ javap target/classes/com/foo/app/App.class
Compiled from "App.java"
public class com.foo.app.App {
  public com.foo.app.App();
  public static void main(java.lang.String[]);
}

Note: javap won't work if the compiled file has been obfuscated.

Android, ListView IllegalStateException: "The content of the adapter has changed but ListView did not receive a notification"

i had the same problem. finally i got the solution

before updating listview, if the soft keypad is present close it first. after that set data source and call notifydatasetchanged().

while closing keypad internally listview will update its ui. it keep calling till closing keypad. that time if data source change it willl throw this exception. if data is updating in onActivityResult, there is a chance for same error.

 InputMethodManager imm = (InputMethodManager) activity.getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(v.getWindowToken(), 0);

        view.postDelayed(new Runnable() {
            @Override
            public void run() {
                refreshList();
            }
        },100L);

How do I escape ampersands in XML so they are rendered as entities in HTML?

<xsl:text disable-output-escaping="yes">&amp;&nbsp;</xsl:text> will do the trick.

What is uintptr_t data type

It's an unsigned integer type exactly the size of a pointer. Whenever you need to do something unusual with a pointer - like for example invert all bits (don't ask why) you cast it to uintptr_t and manipulate it as a usual integer number, then cast back.

GCC -fPIC option

Code that is built into shared libraries should normally be position-independent code, so that the shared library can readily be loaded at (more or less) any address in memory. The -fPIC option ensures that GCC produces such code.

How to split a string between letters and digits (or between digits and letters)?

Didn't use Java for ages, so just some pseudo code, that should help get you started (faster for me than looking up everything :) ).

 string a = "123abc345def";
 string[] result;
 while(a.Length > 0)
 {
      string part;
      if((part = a.Match(/\d+/)).Length) // match digits
           ;
      else if((part = a.Match(/\a+/)).Length) // match letters
           ;
      else
           break; // something invalid - neither digit nor letter
      result.append(part);
      a = a.SubStr(part.Length - 1); // remove the part we've found
 }

Split string on the first white space occurrence

In ES6 you can also

let [first, ...second] = str.split(" ")
second = second.join(" ")

Making Enter key on an HTML form submit instead of activating button

Given there is only one (or with this solution potentially not even one) submit button, here is jQuery based solution that will work for multiple forms on the same page...

<script type="text/javascript">
    $(document).ready(function () {

        var makeAllFormSubmitOnEnter = function () {
            $('form input, form select').live('keypress', function (e) {
                if (e.which && e.which == 13) {
                    $(this).parents('form').submit();
                    return false;
                } else {
                    return true;
                }
            });
        };

        makeAllFormSubmitOnEnter();
    });
</script>

AngularJS ng-if with multiple conditions

HTML code

<div ng-app>
<div ng-controller='ctrl'>
    <div ng-class='whatClassIsIt(call.state[0])'>{{call.state[0]}}</div>
    <div ng-class='whatClassIsIt(call.state[1])'>{{call.state[1]}}</div>
    <div ng-class='whatClassIsIt(call.state[2])'>{{call.state[2]}}</div>
    <div ng-class='whatClassIsIt(call.state[3])'>{{call.state[3]}}</div>
    <div ng-class='whatClassIsIt(call.state[4])'>{{call.state[4]}}</div>
    <div ng-class='whatClassIsIt(call.state[5])'>{{call.state[5]}}</div>
    <div ng-class='whatClassIsIt(call.state[6])'>{{call.state[6]}}</div>
    <div ng-class='whatClassIsIt(call.state[7])'>{{call.state[7]}}</div>
</div>

JavaScript Code

function ctrl($scope){
$scope.call={state:['second','first','nothing','Never', 'Gonna', 'Give', 'You', 'Up']}


$scope.whatClassIsIt= function(someValue){
     if(someValue=="first")
            return "ClassA"
     else if(someValue=="second")
         return "ClassB";
    else
         return "ClassC";
}
}

What happens when a duplicate key is put into a HashMap?

It replaces the existing value in the map for the respective key. And if no key exists with the same name then it creates a key with the value provided. eg:

Map mymap = new HashMap();
mymap.put("1","one");
mymap.put("1","two");

OUTPUT key = "1", value = "two"

So, the previous value gets overwritten.

Storing Objects in HTML5 localStorage

Recommend using an abstraction library for many of the features discussed here as well as better compatibility. Lots of options:

How to check if there exists a process with a given pid in Python?

I'd say use the PID for whatever purpose you're obtaining it and handle the errors gracefully. Otherwise, it's a classic race (the PID may be valid when you check it's valid, but go away an instant later)

Rethrowing exceptions in Java without losing the stack trace

something like this

try 
{
  ...
}
catch (FooException e) 
{
  throw e;
}
catch (Exception e)
{
  ...
}

Splitting a list into N parts of approximately equal length

Another attempt at simple readable chunker that works.

def chunk(iterable, count): # returns a *generator* that divides `iterable` into `count` of contiguous chunks of similar size
    assert count >= 1
    return (iterable[int(_*len(iterable)/count+0.5):int((_+1)*len(iterable)/count+0.5)] for _ in range(count))

print("Chunk count:  ", len(list(         chunk(range(105),10))))
print("Chunks:       ",     list(         chunk(range(105),10)))
print("Chunks:       ",     list(map(list,chunk(range(105),10))))
print("Chunk lengths:",     list(map(len, chunk(range(105),10))))

print("Testing...")
for iterable_length in range(100):
    for chunk_count in range(1,100):
        chunks = list(chunk(range(iterable_length),chunk_count))
        assert chunk_count == len(chunks)
        assert iterable_length == sum(map(len,chunks))
        assert all(map(lambda _:abs(len(_)-iterable_length/chunk_count)<=1,chunks))
print("Okay")

Outputs:

Chunk count:   10
Chunks:        [range(0, 11), range(11, 21), range(21, 32), range(32, 42), range(42, 53), range(53, 63), range(63, 74), range(74, 84), range(84, 95), range(95, 105)]
Chunks:        [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10], [11, 12, 13, 14, 15, 16, 17, 18, 19, 20], [21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31], [32, 33, 34, 35, 36, 37, 38, 39, 40, 41], [42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52], [53, 54, 55, 56, 57, 58, 59, 60, 61, 62], [63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73], [74, 75, 76, 77, 78, 79, 80, 81, 82, 83], [84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94], [95, 96, 97, 98, 99, 100, 101, 102, 103, 104]]
Chunk lengths: [11, 10, 11, 10, 11, 10, 11, 10, 11, 10]
Testing...
Okay

How to convert md5 string to normal text?

Md5 is a hashing algorithm. There is no way to retrieve the original input from the hashed result.

If you want to add a "forgotten password?" feature, you could send your user an email with a temporary link to create a new password.

Note: Sending passwords in plain text is a BAD idea :)

When to use AtomicReference in Java?

When do we use AtomicReference?

AtomicReference is flexible way to update the variable value atomically without use of synchronization.

AtomicReference support lock-free thread-safe programming on single variables.

There are multiple ways of achieving Thread safety with high level concurrent API. Atomic variables is one of the multiple options.

Lock objects support locking idioms that simplify many concurrent applications.

Executors define a high-level API for launching and managing threads. Executor implementations provided by java.util.concurrent provide thread pool management suitable for large-scale applications.

Concurrent collections make it easier to manage large collections of data, and can greatly reduce the need for synchronization.

Atomic variables have features that minimize synchronization and help avoid memory consistency errors.

Provide a simple example where AtomicReference should be used.

Sample code with AtomicReference:

String initialReference = "value 1";

AtomicReference<String> someRef =
    new AtomicReference<String>(initialReference);

String newReference = "value 2";
boolean exchanged = someRef.compareAndSet(initialReference, newReference);
System.out.println("exchanged: " + exchanged);

Is it needed to create objects in all multithreaded programs?

You don't have to use AtomicReference in all multi threaded programs.

If you want to guard a single variable, use AtomicReference. If you want to guard a code block, use other constructs like Lock /synchronized etc.

How to query GROUP BY Month in a Year

You can use:

    select FK_Items,Sum(PoiQuantity) Quantity  from PurchaseOrderItems POI
    left join PurchaseOrder PO ON po.ID_PurchaseOrder=poi.FK_PurchaseOrder
    group by FK_Items,DATEPART(MONTH, TransDate)

Java Date vs Calendar

A little bit late at party, but Java has a new Date Time API in JDK 8. You may want to upgrade your JDK version and embrace the standard. No more messy date/calendar, no more 3rd party jars.

Git: How to check if a local repo is up to date?

Another alternative is to view the status of the remote branch using git show-branch remote/branch to use it as a comparison you could see git show-branch *branch to see the branch in all remotes as well as your repository! check out this answer for more https://stackoverflow.com/a/3278427/2711378

Abstract methods in Java

Abstract methods means there is no default implementation for it and an implementing class will provide the details.

Essentially, you would have

abstract class AbstractObject {
   public abstract void method();
}

class ImplementingObject extends AbstractObject {
  public void method() {
    doSomething();
  }
}

So, it's exactly as the error states: your abstract method can not have a body.

There's a full tutorial on Oracle's site at: http://download.oracle.com/javase/tutorial/java/IandI/abstract.html

The reason you would do something like this is if multiple objects can share some behavior, but not all behavior.

A very simple example would be shapes:

You can have a generic graphic object, which knows how to reposition itself, but the implementing classes will actually draw themselves.

(This is taken from the site I linked above)

abstract class GraphicObject {
    int x, y;
    ...
    void moveTo(int newX, int newY) {
        ...
    }
    abstract void draw();
    abstract void resize();
}

class Circle extends GraphicObject {
    void draw() {
        ...
    }
    void resize() {
        ...
    }
}
class Rectangle extends GraphicObject {
    void draw() {
        ...
    }
    void resize() {
        ...
    }
}

How do I trigger a macro to run after a new mail is received in Outlook?

This code will add an event listener to the default local Inbox, then take some action on incoming emails. You need to add that action in the code below.

Private WithEvents Items As Outlook.Items 
Private Sub Application_Startup() 
  Dim olApp As Outlook.Application 
  Dim objNS As Outlook.NameSpace 
  Set olApp = Outlook.Application 
  Set objNS = olApp.GetNamespace("MAPI") 
  ' default local Inbox
  Set Items = objNS.GetDefaultFolder(olFolderInbox).Items 
End Sub
Private Sub Items_ItemAdd(ByVal item As Object) 

  On Error Goto ErrorHandler 
  Dim Msg As Outlook.MailItem 
  If TypeName(item) = "MailItem" Then
    Set Msg = item 
    ' ******************
    ' do something here
    ' ******************
  End If
ProgramExit: 
  Exit Sub
ErrorHandler: 
  MsgBox Err.Number & " - " & Err.Description 
  Resume ProgramExit 
End Sub

After pasting the code in ThisOutlookSession module, you must restart Outlook.

Getting "file not found" in Bridging Header when importing Objective-C frameworks into Swift project

I had an issue and fixed it after spending 2 hours to find. My environment as below:

cocoapod 0.39.0

swift 2.x

XCode 7.3.1

Steps:

  1. project path: project_name/project_name/your_bridging_header.h
  2. In Swift section at Build Setting, Objective-C Bridging Header should be: project_name/your_bridging_header.h
  3. In your_bridging_header.h, change all declarations from .h to #import
  4. In class which is being used your_3rd_party. Declare import your_3rd_party

Add space between HTML elements only using CSS

add these rules to the parent container:

display: grid
grid-auto-flow: column
grid-column-gap: 10px

Good reference: https://cssreference.io/

Browser compatibility: https://gridbyexample.com/browsers/

Create an empty list in python with certain size

Make it more reusable as a function.

def createEmptyList(length,fill=None):
    '''
    return a (empty) list of a given length
    Example:
        print createEmptyList(3,-1)
        >> [-1, -1, -1]
        print createEmptyList(4)
        >> [None, None, None, None]
    '''
    return [fill] * length

How to make Java 6, which fails SSL connection with "SSL peer shut down incorrectly", succeed like Java 7?

It seems that in the debug log for Java 6 the request is send in SSLv2 format.

main, WRITE: SSLv2 client hello message, length = 110

This is not mentioned as enabled by default in Java 7.
Change the client to use SSLv3 and above to avoid such interoperability issues.

Look for differences in JSSE providers in Java 7 and Java 6

How do I get an empty array of any size in python?

You can use numpy:

import numpy as np

Example from Empty Array:

np.empty([2, 2])
array([[ -9.74499359e+001,   6.69583040e-309],
       [  2.13182611e-314,   3.06959433e-309]])  

Why does DEBUG=False setting make my django Static Files Access fail?

In urls.py I added this line:

from django.views.static import serve 

add those two urls in urlpatterns:

url(r'^media/(?P<path>.*)$', serve,{'document_root': settings.MEDIA_ROOT}), 
url(r'^static/(?P<path>.*)$', serve,{'document_root': settings.STATIC_ROOT}), 

and both static and media files were accesible when DEBUG=FALSE.
Hope it helps :)

How to remove specific substrings from a set of strings in Python?

if you delete something from list , u can use this way : (method sub is case sensitive)

new_list = []
old_list= ["ABCDEFG","HKLMNOP","QRSTUV"]

for data in old_list:
     new_list.append(re.sub("AB|M|TV", " ", data))

print(new_list) // output : [' CDEFG', 'HKL NOP', 'QRSTUV']

MySQL - Using COUNT(*) in the WHERE clause

i think you can not add count() with where. now see why ....

where is not same as having , having means you are working or dealing with group and same work of count , it is also dealing with the whole group ,

now how count it is working as whole group

create a table and enter some id's and then use:

select count(*) from table_name

you will find the total values means it is indicating some group ! so where does added with count() ;

Connect to SQL Server 2012 Database with C# (Visual Studio 2012)

Try:

SqlConnection myConnection = new SqlConnection("Database=testDB;Server=Paul-PC\\SQLEXPRESS;Integrated Security=True;connect timeout = 30");

"The page has expired due to inactivity" - Laravel 5.5

This caused because of Illuminate\Session\TokenMismatchException look at this code sample how to handle it properly:

https://gist.github.com/jrmadsen67/bd0f9ad0ef1ed6bb594e

How to embed a YouTube channel into a webpage

YouTube supports a fairly easy to use iframe and url interface to embed videos, playlists and all user uploads to your channel: https://developers.google.com/youtube/player_parameters

For example this HTML will embed a player loaded with a playlist of all the videos uploaded to your channel. Replace YOURCHANNELNAME with the actual name of your channel:

<iframe src="http://www.youtube.com/embed/?listType=user_uploads&list=YOURCHANNELNAME" width="480" height="400"></iframe>

Could not install packages due to an EnvironmentError: [Errno 13]

I had the same problem while installing numpy with pip install numpy.

Then I tried

sudo -H pip3 install --upgrade pip

sudo -H pip3 install numpy

It worked well for me.

Explanation : The -H (HOME) option with sudo sets the HOME environment variable to the home directory of the target user (root by default). By default, sudo does not modify HOME.

How to locate the Path of the current project directory in Java (IDE)?

I've just used this :

System.out.println(System.getenv().get("PWD"));

Using OpenJDK 11

How do I select child elements of any depth using XPath?

You're almost there. Simply use:

//form[@id='myform']//input[@type='submit']

The // shortcut can also be used inside an expression.

How to include a font .ttf using CSS?

Did you try format?

@font-face {
  font-family: 'The name of the Font Family Here';
  src: URL('font.ttf') format('truetype');
}

Read this article: http://css-tricks.com/snippets/css/using-font-face/

Also, might depend on browser as well.

The order of keys in dictionaries

You could use OrderedDict (requires Python 2.7) or higher.

Also, note that OrderedDict({'a': 1, 'b':2, 'c':3}) won't work since the dict you create with {...} has already forgotten the order of the elements. Instead, you want to use OrderedDict([('a', 1), ('b', 2), ('c', 3)]).

As mentioned in the documentation, for versions lower than Python 2.7, you can use this recipe.

How to set the "Content-Type ... charset" in the request header using a HTML link

This is not possible from HTML on. The closest what you can get is the accept-charset attribute of the <form>. Only MSIE browser adheres that, but even then it is doing it wrong (e.g. CP1252 is actually been used when it says that it has sent ISO-8859-1). Other browsers are fully ignoring it and they are using the charset as specified in the Content-Type header of the response. Setting the character encoding right is basically fully the responsiblity of the server side. The client side should just send it back in the same charset as the server has sent the response in.

To the point, you should really configure the character encoding stuff entirely from the server side on. To overcome the inability to edit URIEncoding attribute, someone here on SO wrote a (complex) filter: Detect the URI encoding automatically in Tomcat. You may find it useful as well (note: I haven't tested it).


Update: Noted should be that the meta tag as given in your question is ignored when the content is been transferred over HTTP. Instead, the HTTP response Content-Type header will be used to determine the content type and character encoding. You can determine the HTTP header with for example Firebug, in the Net panel.

alt text

Date / Timestamp to record when a record was added to the table?

You can use a datetime field and set it's default value to GetDate().

CREATE TABLE [dbo].[Test](
    [TimeStamp] [datetime] NOT NULL CONSTRAINT [DF_Test_TimeStamp] DEFAULT (GetDate()),
    [Foo] [varchar](50) NOT NULL
) ON [PRIMARY]

Why is my toFixed() function not working?

You're not assigning the parsed float back to your value var:

value = parseFloat(value).toFixed(2);

should fix things up.

SQL - Rounding off to 2 decimal places

Following query is useful and simple-

declare @floatExchRate float;
set @floatExchRate=(select convert(decimal(10, 2), 0.2548712))
select  @floatExchRate

Gives output as 0.25.

How can I get column names from a table in Oracle?

describe YOUR_TABLE;

In your case :

describe EVENT_LOG;

Truncating a table in a stored procedure

All DDL statements in Oracle PL/SQL should use Execute Immediate before the statement. Hence you should use:

execute immediate 'truncate table schema.tablename';

How to use sed/grep to extract text between two words?

GNU grep can also support positive & negative look-ahead & look-back: For your case, the command would be:

echo "Here is a string" | grep -o -P '(?<=Here).*(?=string)'

If there are multiple occurrences of Here and string, you can choose whether you want to match from the first Here and last string or match them individually. In terms of regex, it is called as greedy match (first case) or non-greedy match (second case)

$ echo 'Here is a string, and Here is another string.' | grep -oP '(?<=Here).*(?=string)' # Greedy match
 is a string, and Here is another 
$ echo 'Here is a string, and Here is another string.' | grep -oP '(?<=Here).*?(?=string)' # Non-greedy match (Notice the '?' after '*' in .*)
 is a 
 is another 

Batch files - number of command line arguments

A robust solution is to delegate counting to a subroutine invoked with call; the subroutine uses goto statements to emulate a loop in which shift is used to consume the (subroutine-only) arguments iteratively:

@echo off
setlocal

:: Call the argument-counting subroutine with all arguments received,
:: without interfering with the ability to reference the arguments
:: with %1, ... later.
call :count_args %*

:: Print the result.
echo %ReturnValue% argument(s) received.

:: Exit the batch file.
exit /b

:: Subroutine that counts the arguments given.
:: Returns the count in %ReturnValue%
:count_args
  set /a ReturnValue = 0
  :count_args_for

    if %1.==. goto :eof

    set /a ReturnValue += 1

    shift
  goto count_args_for

How to run a task when variable is undefined in ansible?

Strictly stated you must check all of the following: defined, not empty AND not None.

For "normal" variables it makes a difference if defined and set or not set. See foo and bar in the example below. Both are defined but only foo is set.

On the other side registered variables are set to the result of the running command and vary from module to module. They are mostly json structures. You probably must check the subelement you're interested in. See xyz and xyz.msg in the example below:

cat > test.yml <<EOF
- hosts: 127.0.0.1

  vars:
    foo: ""          # foo is defined and foo == '' and foo != None
    bar:             # bar is defined and bar != '' and bar == None

  tasks:

  - debug:
      msg : ""
    register: xyz    # xyz is defined and xyz != '' and xyz != None
                     # xyz.msg is defined and xyz.msg == '' and xyz.msg != None

  - debug:
      msg: "foo is defined and foo == '' and foo != None"
    when: foo is defined and foo == '' and foo != None

  - debug:
      msg: "bar is defined and bar != '' and bar == None"
    when: bar is defined and bar != '' and bar == None

  - debug:
      msg: "xyz is defined and xyz != '' and xyz != None"
    when: xyz is defined and xyz != '' and xyz != None
  - debug:
      msg: "{{ xyz }}"

  - debug:
      msg: "xyz.msg is defined and xyz.msg == '' and xyz.msg != None"
    when: xyz.msg is defined and xyz.msg == '' and xyz.msg != None
  - debug:
      msg: "{{ xyz.msg }}"
EOF
ansible-playbook -v test.yml

Not unique table/alias

Your query contains columns which could be present with the same name in more than one table you are referencing, hence the not unique error. It's best if you make the references explicit and/or use table aliases when joining.

Try

    SELECT pa.ProjectID, p.Project_Title, a.Account_ID, a.Username, a.Access_Type, c.First_Name, c.Last_Name
      FROM Project_Assigned pa
INNER JOIN Account a
        ON pa.AccountID = a.Account_ID
INNER JOIN Project p
        ON pa.ProjectID = p.Project_ID
INNER JOIN Clients c
        ON a.Account_ID = c.Account_ID
     WHERE a.Access_Type = 'Client';

"unrecognized import path" with go get

I installed Go with brew on OSX 10.11, and found I had to set GOROOT to:

/usr/local/Cellar/go/1.5.1/libexec

(Of course replace the version in this path with go version you have)

Brew uses symlinks, which were fooling the gotool. So follow the links home.

Gradle proxy configuration

Try the following:

gradle -Dhttp.proxyHost=yourProxy -Dhttp.proxyPort=yourPort -Dhttp.proxyUser=usernameProxy -Dhttp.proxyPassword=yourPassoword

Android emulator not able to access the internet

macOS: long Story short.. make sure your DNS settings 8.8.8.8 is the first in line, wipe your data and do a cold boot.

enter image description here

How to convert a string to lower case in Bash?

Using GNU sed:

sed 's/.*/\L&/'

Example:

$ foo="Some STRIng";
$ foo=$(echo "$foo" | sed 's/.*/\L&/')
$ echo "$foo"
some string

php codeigniter count rows

Try This :) I created my on model of count all results

in library_model

function count_all_results($column_name = array(),$where=array(), $table_name = array())
{
        $this->db->select($column_name);
        // If Where is not NULL
        if(!empty($where) && count($where) > 0 )
        {
            $this->db->where($where);
        }
        // Return Count Column
        return $this->db->count_all_results($table_name[0]);//table_name array sub 0
}

Your Controller will look like this

public function my_method()
{
  $data = array(
     $countall = $this->model->your_method_model()
  );
   $this->load->view('page',$data);
}

Then Simple Call The Library Model In Your Model

function your_method_model()
{
        return $this->library_model->count_all_results(
               ['id'],
               ['where],
               ['table name']
           );
}

form_for but to post to a different action

I have done it like that

<%= form_for :user, url: {action: "update", params: {id: @user.id}} do |f| %>

Note the optional parameter id set to user instance id attribute.

Is there a way to make Firefox ignore invalid ssl-certificates?

I ran into this issue when trying to get to one of my companies intranet sites. Here is the solution I used:

  1. enter about:config into the firefox address bar and agree to continue.
  2. search for the preference named security.ssl.enable_ocsp_stapling.
  3. double-click this item to change its value to false.

This will lower your security as you will be able to view sites with invalid certs. Firefox will still prompt you that the cert is invalid and you have the choice to proceed forward, so it was worth the risk for me.

iOS Simulator to test website on Mac

You can use the iOS simulator to do this. You need to enable "Developer Mode" on Safari (Preferences -> Advanced).

Then open the website you want to debug in the iOS simulator. Go back to safari and under Develop you will see the simulator and the tabs open on safari.

If you want to test an actual device, then just plug it into your computer and it should show there too.

That's how I do it.

Replace contents of factor column in R dataframe

A more general solution that works with all the data frame at once and where you don't have to add new factors levels is:

data.mtx <- as.matrix(data.df)
data.mtx[which(data.mtx == "old.value.to.replace")] <- "new.value"
data.df <- as.data.frame(data.mtx)

A nice feature of this code is that you can assign as many values as you have in your original data frame at once, not only one "new.value", and the new values can be random values. Thus you can create a complete new random data frame with the same size as the original.

Get bytes from std::string in C++

std::string::data would seem to be sufficient and most efficient. If you want to have non-const memory to manipulate (strange for encryption) you can copy the data to a buffer using memcpy:

unsigned char buffer[mystring.length()];
memcpy(buffer, mystring.data(), mystring.length());

STL fanboys would encourage you to use std::copy instead:

std::copy(mystring.begin(), mystring.end(), buffer);

but there really isn't much of an upside to this. If you need null termination use std::string::c_str() and the various string duplication techniques others have provided, but I'd generally avoid that and just query for the length. Particularly with cryptography you just know somebody is going to try to break it by shoving nulls in to it, and using std::string::data() discourages you from lazily making assumptions about the underlying bits in the string.

How to store a large (10 digits) integer?

You can store this in a long. A long can store a value from -9223372036854775808 to 9223372036854775807.

Split string with string as delimiter

I recently discovered an interesting trick that allows to "Split String With String As Delimiter", so I couldn't resist the temptation to post it here as a new answer. Note that "obviously the question wasn't accurate. Firstly, both string1 and string2 can contain spaces. Secondly, both string1 and string2 can contain ampersands ('&')". This method correctly works with the new specifications (posted as a comment below Stephan's answer).

@echo off
setlocal

set "str=string1&with spaces by string2&with spaces.txt"

set "string1=%str: by =" & set "string2=%"
set "string2=%string2:.txt=%"

echo "%string1%"
echo "%string2%"

For further details on the split method, see this post.

This Row already belongs to another table error when trying to add rows?

you can give some id to the columns and name it uniquely.

IE and Edge fix for object-fit: cover;

I achieved satisfying results with:

min-height: 100%;
min-width: 100%;

this way you always maintain the aspect ratio.

The complete css for an image that will replace "object-fit: cover;":

width: auto;
height: auto;
min-width: 100%;
min-height: 100%;
position: absolute;
right: 50%;
transform: translate(50%, 0);

Python List & for-each access (Find/Replace in built-in list)

You could replace something in there by getting the index along with the item.

>>> foo = ['a', 'b', 'c', 'A', 'B', 'C']
>>> for index, item in enumerate(foo):
...     print(index, item)
...
(0, 'a')
(1, 'b')
(2, 'c')
(3, 'A')
(4, 'B')
(5, 'C')
>>> for index, item in enumerate(foo):
...     if item in ('a', 'A'):
...         foo[index] = 'replaced!'
...
>>> foo
['replaced!', 'b', 'c', 'replaced!', 'B', 'C']

Note that if you want to remove something from the list you have to iterate over a copy of the list, else you will get errors since you're trying to change the size of something you are iterating over. This can be done quite easily with slices.

Wrong:

>>> foo = ['a', 'b', 'c', 1, 2, 3]
>>> for item in foo:
...     if isinstance(item, int):
...         foo.remove(item)
...
>>> foo 
['a', 'b', 'c', 2]

The 2 is still in there because we modified the size of the list as we iterated over it. The correct way would be:

>>> foo = ['a', 'b', 'c', 1, 2, 3]
>>> for item in foo[:]:
...     if isinstance(item, int):
...         foo.remove(item)
...
>>> foo 
['a', 'b', 'c']

Servlet Mapping using web.xml

It allows servlets to have multiple servlet mappings:

<servlet>
    <servlet-name>Servlet1</servlet-name>
    <servlet-path>foo.Servlet</servlet-path>
</servlet>
<servlet-mapping>
    <servlet-name>Servlet1</servlet-name>
    <url-pattern>/enroll</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>Servlet1</servlet-name>
    <url-pattern>/pay</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>Servlet1</servlet-name>
    <url-pattern>/bill</url-pattern>
</servlet-mapping>

It allows filters to be mapped on the particular servlet:

<filter-mapping>
    <filter-name>Filter1</filter-name>
    <servlet-name>Servlet1</servlet-name>
</filter-mapping>

Your proposal would support neither of them. Note that the web.xml is read and parsed only once during application's startup, not on every HTTP request as you seem to think.

Since Servlet 3.0, there's the @WebServlet annotation which minimizes this boilerplate:

@WebServlet("/enroll")
public class Servlet1 extends HttpServlet {

See also:

How to delete and recreate from scratch an existing EF Code First database

If you created your database following this tutorial: https://msdn.microsoft.com/en-au/data/jj193542.aspx

... then this might work:

  1. Delete all .mdf and .ldf files in your project directory
  2. Go to View / SQL Server Object Explorer and delete the database from the (localdb)\v11.0 subnode. See also https://stackoverflow.com/a/15832184/2279059

Cannot find module cv2 when using OpenCV

I solve this by run code pip install opencv_contrib_python

Specify an SSH key for git push for a given domain

From git 2.10 upwards it is also possible to use the gitconfig sshCommand setting. Docs state :

If this variable is set, git fetch and git push will use the specified command instead of ssh when they need to connect to a remote system. The command is in the same form as the GIT_SSH_COMMAND environment variable and is overridden when the environment variable is set.

An usage example would be: git config core.sshCommand "ssh -i ~/.ssh/[insert_your_keyname]

In some cases this doesn't work because ssh_config overriding the command, in this case try ssh -i ~/.ssh/[insert_your_keyname] -F /dev/null to not use the ssh_config.

Catching FULL exception message

I keep coming back to these questions trying to figure out where exactly the data I'm interested in is buried in what is truly a monolithic ErrorRecord structure. Almost all answers give piecemeal instructions on how to pull certain bits of data.

But I've found it immensely helpful to dump the entire object with ConvertTo-Json so that I can visually see LITERALLY EVERYTHING in a comprehensible layout.

    try {
        Invoke-WebRequest...
    }
    catch {
        Write-Host ($_ | ConvertTo-Json)
    }

Use ConvertTo-Json's -Depth parameter to expand deeper values, but use extreme caution going past the default depth of 2 :P

https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.utility/convertto-json

"date(): It is not safe to rely on the system's timezone settings..."

This answer above from CtrlX is the correct answer, but it may not work completely. I added this line to my php.ini file:

date.timezone = "America/Los_Angeles"

but it did not remove the PHP error for all my files because some of my PHP scripts are in subfolders. So I had to edit .htaccess file to setup php.ini to be used recursively (in subfolders):

suphp_configpath /home/account_name/public_html

where account_name is your cpanel account name and public_html is the folder your php.ini file is in.

What's the difference between "git reset" and "git checkout"?

In their simplest form, reset resets the index without touching the working tree, while checkout changes the working tree without touching the index.

Resets the index to match HEAD, working tree left alone:

git reset

Conceptually, this checks out the index into the working tree. To get it to actually do anything you would have to use -f to force it to overwrite any local changes. This is a safety feature to make sure that the "no argument" form isn't destructive:

git checkout

Once you start adding parameters it is true that there is some overlap.

checkout is usually used with a branch, tag or commit. In this case it will reset HEAD and the index to the given commit as well as performing the checkout of the index into the working tree.

Also, if you supply --hard to reset you can ask reset to overwrite the working tree as well as resetting the index.

If you current have a branch checked out out there is a crucial different between reset and checkout when you supply an alternative branch or commit. reset will change the current branch to point at the selected commit whereas checkout will leave the current branch alone but will checkout the supplied branch or commit instead.

Other forms of reset and commit involve supplying paths.

If you supply paths to reset you cannot supply --hard and reset will only change the index version of the supplied paths to the version in the supplied commit (or HEAD if you don't specify a commit).

If you supply paths to checkout, like reset it will update the index version of the supplied paths to match the supplied commit (or HEAD) but it will always checkout the index version of the supplied paths into the working tree.

Cannot obtain value of local or argument as it is not available at this instruction pointer, possibly because it has been optimized away

I have faced the same issue and the solution for me is change Solution Configuration from Release to Debug. Hope it helps

Room persistance library. Delete all

As of Room 1.1.0 you can use clearAllTables() which:

Deletes all rows from all the tables that are registered to this database as entities().

MySQL Query GROUP BY day / month / year

If you want to group by date in MySQL then use the code below:

 SELECT COUNT(id)
 FROM stats
 GROUP BY DAYOFMONTH(record_date)

Hope this saves some time for the ones who are going to find this thread.

How to create composite primary key in SQL Server 2008

To create a composite unique key on table

ALTER TABLE [TableName] ADD UNIQUE ([Column1], [Column2], [column3]);

How to query nested objects?

The two query mechanism work in different ways, as suggested in the docs at the section Subdocuments:

When the field holds an embedded document (i.e, subdocument), you can either specify the entire subdocument as the value of a field, or “reach into” the subdocument using dot notation, to specify values for individual fields in the subdocument:

Equality matches within subdocuments select documents if the subdocument matches exactly the specified subdocument, including the field order.


In the following example, the query matches all documents where the value of the field producer is a subdocument that contains only the field company with the value 'ABC123' and the field address with the value '123 Street', in the exact order:

db.inventory.find( {
    producer: {
        company: 'ABC123',
        address: '123 Street'
    }
});

MySQL - Make an existing Field Unique

ALTER IGNORE TABLE mytbl ADD UNIQUE (columnName);

is the right answer

the insert part

INSERT IGNORE INTO mytable ....

How to use conditional statement within child attribute of a Flutter Widget (Center Widget)

****You can also use conditions by using this method** **

 int _moneyCounter = 0;
  void _rainMoney(){
    setState(() {
      _moneyCounter +=  100;
    });
  }

new Expanded(
          child: new Center(
            child: new Text('\$$_moneyCounter', 

            style:new TextStyle(
              color: _moneyCounter > 1000 ? Colors.blue : Colors.amberAccent,
              fontSize: 47,
              fontWeight: FontWeight.w800
            )

            ),
          ) 
        ),

html table cell width for different rows

with 5 columns and colspan, this is possible (click here) (but doesn't make much sense to me):

<table width="100%" border="1" bgcolor="#ffffff">
    <colgroup>
        <col width="25%">
        <col width="25%">
        <col width="25%">
        <col width="5%">
        <col width="20%">
    </colgroup>
    <tr>
        <td>25</td>
        <td colspan="2">50</td>
        <td colspan="2">25</td>     
    </tr>
    <tr>
        <td colspan="2">50</td>
        <td colspan="2">30</td>
        <td>20</td>
    </tr>
</table>

How to set the range of y-axis for a seaborn boxplot?

It is standard matplotlib.pyplot:

...
import matplotlib.pyplot as plt
plt.ylim(10, 40)

Or simpler, as mwaskom comments below:

ax.set(ylim=(10, 40))

enter image description here

How to always show the vertical scrollbar in a browser?

try calling a function on the onload method of your body tag and in that function change the style of body like this document.body.style.overflow = 'scroll'; also you might need to set the width of your html as this will show horizontal scroll bars as well

your html file will look something like this

<script language="javascript">
    function showscroll() {
        document.body.style.overflow = 'scroll';
    }
</script>
</head>
<body onload="showscroll()">

ASP.NET Identity - HttpContext has no extension method for GetOwinContext

To get UserManager in API

return HttpContext.Current.GetOwinContext().GetUserManager<AppUserManager>();

where AppUserManager is the class that inherits from UserManager.

How can you run a command in bash over and over until success?

until passwd
do
  echo "Try again"
done

or

while ! passwd
do
  echo "Try again"
done

RequestDispatcher.forward() vs HttpServletResponse.sendRedirect()

The RequestDispatcher interface allows you to do a server side forward/include whereas sendRedirect() does a client side redirect. In a client side redirect, the server will send back an HTTP status code of 302 (temporary redirect) which causes the web browser to issue a brand new HTTP GET request for the content at the redirected location. In contrast, when using the RequestDispatcher interface, the include/forward to the new resource is handled entirely on the server side.

Appending a list to a list of lists in R

Just a note on Brian's answer below, the first assignment to outlist can also be an append statement so you could also do something like this:

resultsa <- list(1,2,3,4,5)
resultsb <- list(6,7,8,9,10)
resultsc <- list(11,12,13,14,15)

outlist <- list()
outlist <- append(outlist,list(resultsa))
outlist <- append(outlist, list(resultsb))
outlist <- append(outlist, list(resultsc))

This is sometimes helpful if you want to build a list from scratch in a loop.

Changing button color programmatically

Here is an example using HTML:

<input type="button" value="click me" onclick="this.style.color='#000000';
this.style.backgroundColor = '#ffffff'" />

And here is an example using JavaScript:

document.getElementById("button").bgcolor="#Insert Color Here";

How do I convert a number to a numeric, comma-separated formatted string?

For SQL Server 2012, or later, an easier solution is to use FORMAT ()Documentation.
EG:

SELECT Format(1234567.8, '##,##0') 

Results in: 1,234,568

How can I determine if a variable is 'undefined' or 'null'?

Best way:

if(typeof variable==='undefined' || variable===null) {

/* do your stuff */
}

Column standard deviation R

The general idea is to sweep the function across. You have many options, one is apply():

R> set.seed(42)
R> M <- matrix(rnorm(40),ncol=4)
R> apply(M, 2, sd)
[1] 0.835449 1.630584 1.156058 1.115269
R> 

Setting std=c99 flag in GCC

How about alias gcc99= gcc -std=c99?

Setting java locale settings

One way to control the locale settings is to set the java system properties user.language and user.region.

Credit card expiration dates - Inclusive or exclusive?

How do time zones factor in this analysis. Does a card expire in New York before California? Does it depend on the billing or shipping addresses?

Commit history on remote repository

Here's a bash function that makes it easy to view the logs on a remote. It takes two optional arguments. The first one is the branch, it defaults to master. The second one is the remote, it defaults to staging.

git_log_remote() {
  branch=${1:-master}
  remote=${2:-staging}
  
  git fetch $remote
  git checkout $remote/$branch
  git log
  git checkout -
}

examples:

 $ git_log_remote
 $ git_log_remote development origin

Loading state button in Bootstrap 3

You need to detect the click from js side, your HTML remaining same. Note: this method is deprecated since v3.5.5 and removed in v4.

$("button").click(function() {
    var $btn = $(this);
    $btn.button('loading');
    // simulating a timeout
    setTimeout(function () {
        $btn.button('reset');
    }, 1000);
});

Also, don't forget to load jQuery and Bootstrap js (based on jQuery) file in your page.

JSFIDDLE

Official Documentation

Count Vowels in String Python

What you want can be done quite simply like so:

>>> mystr = input("Please type a sentence: ")
Please type a sentence: abcdE
>>> print(*map(mystr.lower().count, "aeiou"))
1 1 0 0 0
>>>

In case you don't know them, here is a reference on map and one on the *.

How do I record audio on iPhone with AVAudioRecorder?

Its really helpful. The only problem i had was the size of sound file created after recording. I needed to reduce the file size so i did some changes in settings.

NSMutableDictionary *recordSetting = [[NSMutableDictionary alloc] init];
[recordSetting setValue :[NSNumber numberWithInt:kAudioFormatAppleIMA4] forKey:AVFormatIDKey];
[recordSetting setValue:[NSNumber numberWithFloat:16000.0] forKey:AVSampleRateKey];
[recordSetting setValue:[NSNumber numberWithInt: 1] forKey:AVNumberOfChannelsKey];

File size reduced from 360kb to just 25kb (2 seconds recording).

How can I detect whether an iframe is loaded?

You may try this (using jQuery)

_x000D_
_x000D_
$(function(){_x000D_
    $('#MainPopupIframe').load(function(){_x000D_
        $(this).show();_x000D_
        console.log('iframe loaded successfully')_x000D_
    });_x000D_
        _x000D_
    $('#click').on('click', function(){_x000D_
        $('#MainPopupIframe').attr('src', 'https://heera.it');    _x000D_
    });_x000D_
});
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<button id='click'>click me</button>_x000D_
_x000D_
<iframe style="display:none" id='MainPopupIframe' src='' /></iframe>
_x000D_
_x000D_
_x000D_

jsfiddle DEMO.

Update: Using plain javascript

_x000D_
_x000D_
window.onload=function(){_x000D_
    var ifr=document.getElementById('MainPopupIframe');_x000D_
    ifr.onload=function(){_x000D_
        this.style.display='block';_x000D_
        console.log('laod the iframe')_x000D_
    };_x000D_
    var btn=document.getElementById('click');    _x000D_
    btn.onclick=function(){_x000D_
        ifr.src='https://heera.it';    _x000D_
    };_x000D_
};
_x000D_
<button id='click'>click me</button>_x000D_
_x000D_
<iframe style="display:none" id='MainPopupIframe' src='' /></iframe>
_x000D_
_x000D_
_x000D_

jsfiddle DEMO.

Update: Also you can try this (dynamic iframe)

_x000D_
_x000D_
$(function(){_x000D_
    $('#click').on('click', function(){_x000D_
        var ifr=$('<iframe/>', {_x000D_
            id:'MainPopupIframe',_x000D_
            src:'https://heera.it',_x000D_
            style:'display:none;width:320px;height:400px',_x000D_
            load:function(){_x000D_
                $(this).show();_x000D_
                alert('iframe loaded !');_x000D_
            }_x000D_
        });_x000D_
        $('body').append(ifr);    _x000D_
    });_x000D_
});
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<button id='click'>click me</button><br />
_x000D_
_x000D_
_x000D_

jsfiddle DEMO.

Calculate the center point of multiple latitude/longitude coordinate pairs

Very useful post! I've implemented this in JavaScript, hereby my code. I've used this successfully.

function rad2degr(rad) { return rad * 180 / Math.PI; }
function degr2rad(degr) { return degr * Math.PI / 180; }

/**
 * @param latLngInDeg array of arrays with latitude and longtitude
 *   pairs in degrees. e.g. [[latitude1, longtitude1], [latitude2
 *   [longtitude2] ...]
 *
 * @return array with the center latitude longtitude pairs in 
 *   degrees.
 */
function getLatLngCenter(latLngInDegr) {
    var LATIDX = 0;
    var LNGIDX = 1;
    var sumX = 0;
    var sumY = 0;
    var sumZ = 0;

    for (var i=0; i<latLngInDegr.length; i++) {
        var lat = degr2rad(latLngInDegr[i][LATIDX]);
        var lng = degr2rad(latLngInDegr[i][LNGIDX]);
        // sum of cartesian coordinates
        sumX += Math.cos(lat) * Math.cos(lng);
        sumY += Math.cos(lat) * Math.sin(lng);
        sumZ += Math.sin(lat);
    }

    var avgX = sumX / latLngInDegr.length;
    var avgY = sumY / latLngInDegr.length;
    var avgZ = sumZ / latLngInDegr.length;

    // convert average x, y, z coordinate to latitude and longtitude
    var lng = Math.atan2(avgY, avgX);
    var hyp = Math.sqrt(avgX * avgX + avgY * avgY);
    var lat = Math.atan2(avgZ, hyp);

    return ([rad2degr(lat), rad2degr(lng)]);
}

Any way to return PHP `json_encode` with encode UTF-8 and not Unicode?

I resolved my problem doing this:

  • The .php file is encoded to ANSI. In this file is the function to create the .json file.
  • I use json_encode($array, JSON_UNESCAPED_UNICODE) to encode the data;

The result is a .json file encoded to ANSI as UTF-8.

What is the proper declaration of main in C++?

The main function must be declared as a non-member function in the global namespace. This means that it cannot be a static or non-static member function of a class, nor can it be placed in a namespace (even the unnamed namespace).

The name main is not reserved in C++ except as a function in the global namespace. You are free to declare other entities named main, including among other things, classes, variables, enumerations, member functions, and non-member functions not in the global namespace.

You can declare a function named main as a member function or in a namespace, but such a function would not be the main function that designates where the program starts.

The main function cannot be declared as static or inline. It also cannot be overloaded; there can be only one function named main in the global namespace.

The main function cannot be used in your program: you are not allowed to call the main function from anywhere in your code, nor are you allowed to take its address.

The return type of main must be int. No other return type is allowed (this rule is in bold because it is very common to see incorrect programs that declare main with a return type of void; this is probably the most frequently violated rule concerning the main function).

There are two declarations of main that must be allowed:

int main()               // (1)
int main(int, char*[])   // (2)

In (1), there are no parameters.

In (2), there are two parameters and they are conventionally named argc and argv, respectively. argv is a pointer to an array of C strings representing the arguments to the program. argc is the number of arguments in the argv array.

Usually, argv[0] contains the name of the program, but this is not always the case. argv[argc] is guaranteed to be a null pointer.

Note that since an array type argument (like char*[]) is really just a pointer type argument in disguise, the following two are both valid ways to write (2) and they both mean exactly the same thing:

int main(int argc, char* argv[])
int main(int argc, char** argv)

Some implementations may allow other types and numbers of parameters; you'd have to check the documentation of your implementation to see what it supports.

main() is expected to return zero to indicate success and non-zero to indicate failure. You are not required to explicitly write a return statement in main(): if you let main() return without an explicit return statement, it's the same as if you had written return 0;. The following two main() functions have the same behavior:

int main() { }
int main() { return 0; }

There are two macros, EXIT_SUCCESS and EXIT_FAILURE, defined in <cstdlib> that can also be returned from main() to indicate success and failure, respectively.

The value returned by main() is passed to the exit() function, which terminates the program.

Note that all of this applies only when compiling for a hosted environment (informally, an environment where you have a full standard library and there's an OS running your program). It is also possible to compile a C++ program for a freestanding environment (for example, some types of embedded systems), in which case startup and termination are wholly implementation-defined and a main() function may not even be required. If you're writing C++ for a modern desktop OS, though, you're compiling for a hosted environment.

What are the differences between char literals '\n' and '\r' in Java?

The difference is not Java-specific, but platform specific. Historically UNIX-like OSes have used \n as newline character, some other deprecated OSes have used \r and Windows OSes have employed \r\n.

How to trigger the window resize event in JavaScript?

Combining pomber's and avetisk's answers to cover all browsers and not causing warnings:

if (typeof(Event) === 'function') {
  // modern browsers
  window.dispatchEvent(new Event('resize'));
} else {
  // for IE and other old browsers
  // causes deprecation warning on modern browsers
  var evt = window.document.createEvent('UIEvents'); 
  evt.initUIEvent('resize', true, false, window, 0); 
  window.dispatchEvent(evt);
}

Dynamically create checkbox with JQuery from text input

<div id="cblist">
    <input type="checkbox" value="first checkbox" id="cb1" /> <label for="cb1">first checkbox</label>
</div>

<input type="text" id="txtName" />
<input type="button" value="ok" id="btnSave" />

<script type="text/javascript">
$(document).ready(function() {
    $('#btnSave').click(function() {
        addCheckbox($('#txtName').val());
    });
});

function addCheckbox(name) {
   var container = $('#cblist');
   var inputs = container.find('input');
   var id = inputs.length+1;

   $('<input />', { type: 'checkbox', id: 'cb'+id, value: name }).appendTo(container);
   $('<label />', { 'for': 'cb'+id, text: name }).appendTo(container);
}
</script>

Convert an ArrayList to an object array

You can use this code

ArrayList<TypeA> a = new ArrayList<TypeA>();
Object[] o = a.toArray();

Then if you want that to get that object back into TypeA just check it with instanceOf method.

IsNullOrEmpty with Object

IsNullOrEmpty is essentially shorthand for the following:

return str == null || str == String.Empty;

So, no there is no function that just checks for nulls because it would be too simple. obj != null is the correct way. But you can create such a (superfluous) function yourself using the following extension:

public bool IsNull(this object obj)
{
    return obj == null;
}

Then you are able to run anyObject.IsNull().

send mail to multiple receiver with HTML mailto

"There are no safe means of assigning multiple recipients to a single mailto: link via HTML. There are safe, non-HTML, ways of assigning multiple recipients from a mailto: link."

http://www.sightspecific.com/~mosh/www_faq/multrec.html

For a quick fix to your problem, change your ; to a comma , and eliminate the spaces between email addresses

<a href='mailto:[email protected],[email protected]'>Email Us</a>

How to get the current URL within a Django template?

In django template
Simply get current url from {{request.path}}
For getting full url with parameters {{request.get_full_path}}

Note: You must add request in django TEMPLATE_CONTEXT_PROCESSORS

How to communicate between Docker containers via "hostname"

That should be what --link is for, at least for the hostname part.
With docker 1.10, and PR 19242, that would be:

docker network create --net-alias=[]: Add network-scoped alias for the container

(see last section below)

That is what Updating the /etc/hosts file details

In addition to the environment variables, Docker adds a host entry for the source container to the /etc/hosts file.

For instance, launch an LDAP server:

docker run -t  --name openldap -d -p 389:389 larrycai/openldap

And define an image to test that LDAP server:

FROM ubuntu
RUN apt-get -y install ldap-utils
RUN touch /root/.bash_aliases
RUN echo "alias lds='ldapsearch -H ldap://internalopenldap -LL -b
ou=Users,dc=openstack,dc=org -D cn=admin,dc=openstack,dc=org -w
password'" > /root/.bash_aliases
ENTRYPOINT bash

You can expose the 'openldap' container as 'internalopenldap' within the test image with --link:

 docker run -it --rm --name ldp --link openldap:internalopenldap ldaptest

Then, if you type 'lds', that alias will work:

ldapsearch -H ldap://internalopenldap ...

That would return people. Meaning internalopenldap is correctly reached from the ldaptest image.


Of course, docker 1.7 will add libnetwork, which provides a native Go implementation for connecting containers. See the blog post.
It introduced a more complete architecture, with the Container Network Model (CNM)

https://blog.docker.com/media/2015/04/cnm-model.jpg

That will Update the Docker CLI with new “network” commands, and document how the “-net” flag is used to assign containers to networks.


docker 1.10 has a new section Network-scoped alias, now officially documented in network connect:

While links provide private name resolution that is localized within a container, the network-scoped alias provides a way for a container to be discovered by an alternate name by any other container within the scope of a particular network.
Unlike the link alias, which is defined by the consumer of a service, the network-scoped alias is defined by the container that is offering the service to the network.

Continuing with the above example, create another container in isolated_nw with a network alias.

$ docker run --net=isolated_nw -itd --name=container6 -alias app busybox
8ebe6767c1e0361f27433090060b33200aac054a68476c3be87ef4005eb1df17

--alias=[]         

Add network-scoped alias for the container

You can use --link option to link another container with a preferred alias

You can pause, restart, and stop containers that are connected to a network. Paused containers remain connected and can be revealed by a network inspect. When the container is stopped, it does not appear on the network until you restart it.

If specified, the container's IP address(es) is reapplied when a stopped container is restarted. If the IP address is no longer available, the container fails to start.

One way to guarantee that the IP address is available is to specify an --ip-range when creating the network, and choose the static IP address(es) from outside that range. This ensures that the IP address is not given to another container while this container is not on the network.

$ docker network create --subnet 172.20.0.0/16 --ip-range 172.20.240.0/20 multi-host-network

$ docker network connect --ip 172.20.128.2 multi-host-network container2
$ docker network connect --link container1:c1 multi-host-network container2

How to throw RuntimeException ("cannot find symbol")

Just for others: be sure it is new RuntimeException, not new RuntimeErrorException which needs error as an argument.

How to count total lines changed by a specific author in a Git repository?

The output of the following command should be reasonably easy to send to script to add up the totals:

git log --author="<authorname>" --oneline --shortstat

This gives stats for all commits on the current HEAD. If you want to add up stats in other branches you will have to supply them as arguments to git log.

For passing to a script, removing even the "oneline" format can be done with an empty log format, and as commented by Jakub Narebski, --numstat is another alternative. It generates per-file rather than per-line statistics but is even easier to parse.

git log --author="<authorname>" --pretty=tformat: --numstat

How do I remove my IntelliJ license in 2019.3?

For Windows : Using batch program.

Write this code in a text file and save it.

REM Delete eval folder with licence key and options.xml which contains a reference  to it
for %%I in ("WebStorm", "IntelliJ", "CLion", "Rider", "GoLand", "PhpStorm") do (
  for /d %%a in ("%USERPROFILE%\.%%I*") do (
    rd /s /q "%%a/config/eval"
    del /q "%%a\config\options\other.xml"
  )
)

REM Delete registry key and jetbrains folder (not sure if needet but however)
rmdir /s /q "%APPDATA%\JetBrains"
reg delete "HKEY_CURRENT_USER\Software\JavaSoft" /f

Now rename the file fileName.txt to fileName.bat

Close phpstorm if running. Disconnect internet. Then run the file. Open phpstorm again. If nothing goes wrong you will see the magic.

worst case : If phpstorm still shows "License Expired", at first uninstall and then apply the above technique.

What is memoization and how can I use it in Python?

Memoization is keeping the results of expensive calculations and returning the cached result rather than continuously recalculating it.

Here's an example:

def doSomeExpensiveCalculation(self, input):
    if input not in self.cache:
        <do expensive calculation>
        self.cache[input] = result
    return self.cache[input]

A more complete description can be found in the wikipedia entry on memoization.

TypeError: coercing to Unicode: need string or buffer

You're trying to open each file twice! First you do:

infile=open('110331_HS1A_1_rtTA.result','r')

and then you pass infile (which is a file object) to the open function again:

with open (infile, mode='r', buffering=-1)

open is of course expecting its first argument to be a file name, not an opened file!

Open the file once only and you should be fine.

Is it possible to use vh minus pixels in a CSS calc()?

It does work indeed. Issue was with my less compiler. It was compiled in to:

.container {
  min-height: calc(-51vh);
}

Fixed with the following code in less file:

.container {
  min-height: calc(~"100vh - 150px");
}

Thanks to this link: Less Aggressive Compilation with CSS3 calc

How to deal with "java.lang.OutOfMemoryError: Java heap space" error?

You could specify per project how much heap space your project wants

Following is for Eclipse Helios/Juno/Kepler:

Right mouse click on

 Run As - Run Configuration - Arguments - Vm Arguments, 

then add this

-Xmx2048m

python dict to numpy structured array

Similarly to the approved answer. If you want to create an array from dictionary keys:

np.array( tuple(dict.keys()) )

If you want to create an array from dictionary values:

np.array( tuple(dict.values()) )

Angular2: child component access parent class variable/function

The main article in the Angular2 documentation on this subject is :

https://angular.io/docs/ts/latest/cookbook/component-communication.html#!#parent-to-child

It covers the following:

  • Pass data from parent to child with input binding

  • Intercept input property changes with a setter

  • Intercept input property changes with ngOnChanges

  • Parent listens for child event

  • Parent interacts with child via a local variable

  • Parent calls a ViewChild

  • Parent and children communicate via a service

How to make php display \t \n as tab and new line instead of characters

"\t" not '\t', php doesnt escape in single quotes

Font-awesome, input type 'submit'

You can use font awesome utf cheatsheet

<input type="submit" class="btn btn-success" value="&#xf011; Login"/>

here is the link for the cheatsheet http://fortawesome.github.io/Font-Awesome/cheatsheet/

Binding IIS Express to an IP Address

Below are the complete changes I needed to make to run my x64 bit IIS application using IIS Express, so that it was accessible to a remote host:

iisexpress /config:"C:\Users\test-user\Documents\IISExpress\config\applicationhost.config" /site:MyWebSite
Starting IIS Express ...
Successfully registered URL "http://192.168.2.133:8080/" for site "MyWebSite" application "/"
Registration completed for site "MyWebSite"
IIS Express is running.
Enter 'Q' to stop IIS Express

The configuration file (applicationhost.config) had a section added as follows:

<sites>
  <site name="MyWebsite" id="2">
    <application path="/" applicationPool="Clr4IntegratedAppPool">
      <virtualDirectory path="/" physicalPath="C:\build\trunk\MyWebsite" />
    </application>
    <bindings>
      <binding protocol="http" bindingInformation=":8080:192.168.2.133" />
    </bindings>
  </site>

The 64 bit version of the .NET framework can be enabled as follows:

<globalModules>
    <!--
        <add name="ManagedEngine" image="%windir%\Microsoft.NET\Framework\v2.0.50727\webengine.dll" preCondition="integratedMode,runtimeVersionv2.0,bitness32" />
        <add name="ManagedEngineV4.0_32bit" image="%windir%\Microsoft.NET\Framework\v4.0.30319\webengine4.dll" preCondition="integratedMode,runtimeVersionv4.0,bitness32" />
    -->             
    <add name="ManagedEngine64" image="%windir%\Microsoft.NET\Framework64\v4.0.30319\webengine4.dll" preCondition="integratedMode,runtimeVersionv4.0,bitness64" />

Log4Net configuring log level

Within the definition of the appender, I believe you can do something like this:

<appender name="AdoNetAppender" type="log4net.Appender.AdoNetAppender">
    <filter type="log4net.Filter.LevelRangeFilter">
        <param name="LevelMin" value="INFO"/>
        <param name="LevelMax" value="INFO"/>
    </filter>
    ...
</appender>

Task vs Thread differences

Thread is a lower-level concept: if you're directly starting a thread, you know it will be a separate thread, rather than executing on the thread pool etc.

Task is more than just an abstraction of "where to run some code" though - it's really just "the promise of a result in the future". So as some different examples:

  • Task.Delay doesn't need any actual CPU time; it's just like setting a timer to go off in the future
  • A task returned by WebClient.DownloadStringTaskAsync won't take much CPU time locally; it's representing a result which is likely to spend most of its time in network latency or remote work (at the web server)
  • A task returned by Task.Run() really is saying "I want you to execute this code separately"; the exact thread on which that code executes depends on a number of factors.

Note that the Task<T> abstraction is pivotal to the async support in C# 5.

In general, I'd recommend that you use the higher level abstraction wherever you can: in modern C# code you should rarely need to explicitly start your own thread.

How to remove gem from Ruby on Rails application?

How about something like:

gem dependency devise --pipe | cut -d \  -f 1 | xargs gem uninstall -a

(this assumes that you're not using bundler - but I guess you're not since removing from your bundle gemspec would solve the problem)

Html.HiddenFor value property not getting set

Simple way

@{
   Model.CRN = ViewBag.CRN;
}

@Html.HiddenFor(x => x.CRN)

Android Studio: Drawable Folder: How to put Images for Multiple dpi?

The easiest way I have found to have the proper "directory" structure appear under the drawable folder for my icons is this:

  1. Right click "Drawable"
  2. Click on "New", then "Image Asset"
  3. Change "Asset Type" to "Action Bar and Tab Icons"
  4. For "Foreground" choose "ClipArt"
  5. For "Clipart" click and "Choose" button and pick any icon
  6. For "Resource Name" type in you icon file name

Now the pseudo-directories have been created for you under the Drawable folder in the Android view. Open up the true directories on your file system "main/res/drawable-xxhdpi", "main/res/drawable-xhdpi" and replace the icons in each folder with your own of the proper density.

Can I run HTML files directly from GitHub, instead of just viewing their source?

This solution only for chrome browser. I am not sure about other browser.

  1. Add "Modify Content-Type Options" extension in chrome browser.
  2. Open "chrome-extension://jnfofbopfpaoeojgieggflbpcblhfhka/options.html" url in browser.
  3. Add the rule for raw file url. For example:
    • URL Filter: https:///raw/master//fileName.html
    • Original Type: text/plain
    • Replacement Type: text/html
  4. Open the file browser which you added url in rule (in step 3).

JavaScript + Unicode regexes

Having also not found a good solution, I wrote a small script a long time ago, by downloading data from the unicode specification (v.5.0.0) and generating intervals for each unicode category and subcategory in the BMP (lately replaced by a small Java program that uses its own native Unicode support).

Basically it converts \p{...} to a range of values, much like the output of the tool mentioned by Tomalak, but the intervals can end up quite large (since it's not dealing with blocks, but with characters scattered through many different places).

For instance, a Regex written like this:

var regex = unicode_hack(/\p{L}(\p{L}|\p{Nd})*/g);

Will be converted to something like this:

/[\u0041-\u005a\u0061-\u007a...]([...]|[\u0030-\u0039\u0660-\u0669...])*/g

Haven't used it a lot in practice, but it seems to work fine from my tests, so I'm posting here in case someone find it useful. Despite the length of the resulting regexes (the example above has 3591 characters when expanded), the performance seems to be acceptable (see the tests at jsFiddle; thanks to @modiX and @Lwangaman for the improvements).

Here's the source (raw, 27.5KB; minified, 24.9KB, not much better...). It might be made smaller by unescaping the unicode characters, but OTOH will run the risk of encoding issues, so I'm leaving as it is. Hopefully with ES6 this kind of thing won't be necessary anymore.

Update: this looks like the same strategy adopted in the XRegExp Unicode plug-in mentioned by Tim Down, except that in this case regular JavaScript regexes are being used.

php: how to get associative array key from numeric index?

$array = array( 'one' =>'value', 'two' => 'value2' );

$allKeys = array_keys($array);
echo $allKeys[0];

Which will output:

one

Most efficient way to convert an HTMLCollection to an Array

var arr = Array.prototype.slice.call( htmlCollection )

will have the same effect using "native" code.

Edit

Since this gets a lot of views, note (per @oriol's comment) that the following more concise expression is effectively equivalent:

var arr = [].slice.call(htmlCollection);

But note per @JussiR's comment, that unlike the "verbose" form, it does create an empty, unused, and indeed unusable array instance in the process. What compilers do about this is outside the programmer's ken.

Edit

Since ECMAScript 2015 (ES 6) there is also Array.from:

var arr = Array.from(htmlCollection);

Edit

ECMAScript 2015 also provides the spread operator, which is functionally equivalent to Array.from (although note that Array.from supports a mapping function as the second argument).

var arr = [...htmlCollection];

I've confirmed that both of the above work on NodeList.

A performance comparison for the mentioned methods: http://jsben.ch/h2IFA

VBA procedure to import csv file into access

Your file seems quite small (297 lines) so you can read and write them quite quickly. You refer to Excel CSV, which does not exists, and you show space delimited data in your example. Furthermore, Access is limited to 255 columns, and a CSV is not, so there is no guarantee this will work

Sub StripHeaderAndFooter()
Dim fs As Object ''FileSystemObject
Dim tsIn As Object, tsOut As Object ''TextStream
Dim sFileIn As String, sFileOut As String
Dim aryFile As Variant

    sFileIn = "z:\docs\FileName.csv"
    sFileOut = "z:\docs\FileOut.csv"

    Set fs = CreateObject("Scripting.FileSystemObject")
    Set tsIn = fs.OpenTextFile(sFileIn, 1) ''ForReading

    sTmp = tsIn.ReadAll

    Set tsOut = fs.CreateTextFile(sFileOut, True) ''Overwrite
    aryFile = Split(sTmp, vbCrLf)

    ''Start at line 3 and end at last line -1
    For i = 3 To UBound(aryFile) - 1
        tsOut.WriteLine aryFile(i)
    Next

    tsOut.Close

    DoCmd.TransferText acImportDelim, , "NewCSV", sFileOut, False
End Sub

Edit re various comments

It is possible to import a text file manually into MS Access and this will allow you to choose you own cell delimiters and text delimiters. You need to choose External data from the menu, select your file and step through the wizard.

About importing and linking data and database objects -- Applies to: Microsoft Office Access 2003

Introduction to importing and exporting data -- Applies to: Microsoft Access 2010

Once you get the import working using the wizards, you can save an import specification and use it for you next DoCmd.TransferText as outlined by @Olivier Jacot-Descombes. This will allow you to have non-standard delimiters such as semi colon and single-quoted text.

Calculate mean across dimension in a 2D array

Here is a non-numpy solution:

>>> a = [[40, 10], [50, 11]]
>>> [float(sum(l))/len(l) for l in zip(*a)]
[45.0, 10.5]

#if DEBUG vs. Conditional("DEBUG")

I'm sure plenty will disagree with me, but having spent time as a build guy constantly hearing "But it works on my machine!", I take the standpoint that you should pretty much never use either. If you really need something for testing and debugging, figure out a way to make that testability seperate from the actual production code.

Abstract the scenarios with mocking in unit tests, make one off versions of things for one off scenarios you want to test, but don't put tests for debug into the code for binaries which you test and write for production release. These debug tests just hide possible bugs from devs so they aren't found until later in the process.

How to get duplicate items from a list using LINQ?

I wrote this extension method based off @Lee's response to the OP. Note, a default parameter was used (requiring C# 4.0). However, an overloaded method call in C# 3.0 would suffice.

/// <summary>
/// Method that returns all the duplicates (distinct) in the collection.
/// </summary>
/// <typeparam name="T">The type of the collection.</typeparam>
/// <param name="source">The source collection to detect for duplicates</param>
/// <param name="distinct">Specify <b>true</b> to only return distinct elements.</param>
/// <returns>A distinct list of duplicates found in the source collection.</returns>
/// <remarks>This is an extension method to IEnumerable&lt;T&gt;</remarks>
public static IEnumerable<T> Duplicates<T>
         (this IEnumerable<T> source, bool distinct = true)
{
     if (source == null)
     {
        throw new ArgumentNullException("source");
     }

     // select the elements that are repeated
     IEnumerable<T> result = source.GroupBy(a => a).SelectMany(a => a.Skip(1));

     // distinct?
     if (distinct == true)
     {
        // deferred execution helps us here
        result = result.Distinct();
     }

     return result;
}

How to save a spark DataFrame as csv on disk?

I had similar issue where i had to save the contents of the dataframe to a csv file of name which i defined. df.write("csv").save("<my-path>") was creating directory than file. So have to come up with the following solutions. Most of the code is taken from the following dataframe-to-csv with little modifications to the logic.

def saveDfToCsv(df: DataFrame, tsvOutput: String, sep: String = ",", header: Boolean = false): Unit = {
    val tmpParquetDir = "Posts.tmp.parquet"

    df.repartition(1).write.
        format("com.databricks.spark.csv").
        option("header", header.toString).
        option("delimiter", sep).
        save(tmpParquetDir)

    val dir = new File(tmpParquetDir)
    val newFileRgex = tmpParquetDir + File.separatorChar + ".part-00000.*.csv"
    val tmpTsfFile = dir.listFiles.filter(_.toPath.toString.matches(newFileRgex))(0).toString
    (new File(tmpTsvFile)).renameTo(new File(tsvOutput))

    dir.listFiles.foreach( f => f.delete )
    dir.delete
    }

force Maven to copy dependencies into target/lib

It's a heavy solution for embedding heavy dependencies, but Maven's Assembly Plugin does the trick for me.

@Rich Seller's answer should work, although for simpler cases you should only need this excerpt from the usage guide:

<project>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <version>2.2.2</version>
                <configuration>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

Binding a list in @RequestParam

Arrays in @RequestParam are used for binding several parameters of the same name:

myparam=myValue1&myparam=myValue2&myparam=myValue3

If you need to bind @ModelAttribute-style indexed parameters, I guess you need @ModelAttribute anyway.

How to lose margin/padding in UITextView?

Here's an easy little extension that will remove Apple's default margin from every text view in your app.

Note: Interface Builder will still show the old margin, but your app will work as expected.

extension UITextView {

   open override func awakeFromNib() {
      super.awakeFromNib();
      removeMargins();
   }

   /** Removes the Apple textview margins. */
   public func removeMargins() {
      self.contentInset = UIEdgeInsetsMake(
         0, -textContainer.lineFragmentPadding,
         0, -textContainer.lineFragmentPadding);
   }
}

How to open my files in data_folder with pandas using relative path?

I was also looking for the relative path version, this works OK. Note when run (Spyder 3.6) you will see (unicode error) 'unicodeescape' codec can't decode bytes at the closing triple quote. Remove the offending comment lines 14 and 15 and adjust the file names and location for your environment and check for indentation.

-- coding: utf-8 --

""" Created on Fri Jan 24 12:12:40 2020

Source: Read a .csv into pandas from F: drive on Windows 7

Demonstrates: Load a csv not in the CWD by specifying relative path - windows version

@author: Doug

From CWD C:\Users\Doug\.spyder-py3\Data Camp\pandas we will load file

C:/Users/Doug/.spyder-py3/Data Camp/Cleaning/g1803.csv

"""

import csv

trainData2 = []

with open(r'../Cleaning/g1803.csv', 'r') as train2Csv:

  trainReader2 = csv.reader(train2Csv, delimiter=',', quotechar='"')

  for row in trainReader2:

      trainData2.append(row)

print(trainData2)

How to have Android Service communicate with Activity

Besides LocalBroadcastManager , Event Bus and Messenger already answered in this question,we can use Pending Intent to communicate from service.

As mentioned here in my blog post

Communication between service and Activity can be done using PendingIntent.For that we can use createPendingResult().createPendingResult() creates a new PendingIntent object which you can hand to service to use and to send result data back to your activity inside onActivityResult(int, int, Intent) callback.Since a PendingIntent is Parcelable , and can therefore be put into an Intent extra,your activity can pass this PendingIntent to the service.The service, in turn, can call send() method on the PendingIntent to notify the activity via onActivityResult of an event.

Activity

public class PendingIntentActivity extends AppCompatActivity
{
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

PendingIntent pendingResult = createPendingResult(
100, new Intent(), 0);
Intent intent = new Intent(getApplicationContext(), PendingIntentService.class);
intent.putExtra("pendingIntent", pendingResult);
startService(intent);

}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == 100 && resultCode==200) {
Toast.makeText(this,data.getStringExtra("name"),Toast.LENGTH_LONG).show();
}
super.onActivityResult(requestCode, resultCode, data);
}
}

Service

public class PendingIntentService extends Service {

    private static final String[] items= { "lorem", "ipsum", "dolor",
            "sit", "amet", "consectetuer", "adipiscing", "elit", "morbi",
            "vel", "ligula", "vitae", "arcu", "aliquet", "mollis", "etiam",
            "vel", "erat", "placerat", "ante", "porttitor", "sodales",
            "pellentesque", "augue", "purus" };
    private PendingIntent data;

    @Override
    public void onCreate() {
        super.onCreate();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        data = intent.getParcelableExtra("pendingIntent");

        new LoadWordsThread().start();
        return START_NOT_STICKY;
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
    }

    class LoadWordsThread extends Thread {
        @Override
        public void run() {
            for (String item : items) {
                if (!isInterrupted()) {

                    Intent result = new Intent();
                    result.putExtra("name", item);
                    try {
                        data.send(PendingIntentService.this,200,result);
                    } catch (PendingIntent.CanceledException e) {

                        e.printStackTrace();
                    }
                    SystemClock.sleep(400);

                }
            }
        }
    }
}

How do I get started with Node.js

First, learn the core concepts of Node.js:

Then, you're going to want to see what the community has to offer:

The gold standard for Node.js package management is NPM.

Finally, you're going to want to know what some of the more popular packages are for various tasks:

Useful Tools for Every Project:

  • Underscore contains just about every core utility method you want.
  • Lo-Dash is a clone of Underscore that aims to be faster, more customizable, and has quite a few functions that underscore doesn't have. Certain versions of it can be used as drop-in replacements of underscore.
  • TypeScript makes JavaScript considerably more bearable, while also keeping you out of trouble!
  • JSHint is a code-checking tool that'll save you loads of time finding stupid errors. Find a plugin for your text editor that will automatically run it on your code.

Unit Testing:

  • Mocha is a popular test framework.
  • Vows is a fantastic take on asynchronous testing, albeit somewhat stale.
  • Expresso is a more traditional unit testing framework.
  • node-unit is another relatively traditional unit testing framework.
  • AVA is a new test runner with Babel built-in and runs tests concurrently.

Web Frameworks:

  • Express.js is by far the most popular framework.
  • Koa is a new web framework designed by the team behind Express.js, which aims to be a smaller, more expressive, and more robust foundation for web applications and APIs.
  • sails.js the most popular MVC framework for Node.js, and is based on express. It is designed to emulate the familiar MVC pattern of frameworks like Ruby on Rails, but with support for the requirements of modern apps: data-driven APIs with a scalable, service-oriented architecture.
  • Meteor bundles together jQuery, Handlebars, Node.js, WebSocket, MongoDB, and DDP and promotes convention over configuration without being a Ruby on Rails clone.
  • Tower (deprecated) is an abstraction of a top of Express.js that aims to be a Ruby on Rails clone.
  • Geddy is another take on web frameworks.
  • RailwayJS is a Ruby on Rails inspired MVC web framework.
  • Sleek.js is a simple web framework, built upon Express.js.
  • Hapi is a configuration-centric framework with built-in support for input validation, caching, authentication, etc.
  • Trails is a modern web application framework. It builds on the pedigree of Rails and Grails to accelerate development by adhering to a straightforward, convention-based, API-driven design philosophy.

  • Danf is a full-stack OOP framework providing many features in order to produce a scalable, maintainable, testable and performant applications and allowing to code the same way on both the server (Node.js) and client (browser) sides.

  • Derbyjs is a reactive full-stack JavaScript framework. They are using patterns like reactive programming and isomorphic JavaScript for a long time.

  • Loopback.io is a powerful Node.js framework for creating APIs and easily connecting to backend data sources. It has an Angular.js SDK and provides SDKs for iOS and Android.

Web Framework Tools:

Networking:

  • Connect is the Rack or WSGI of the Node.js world.
  • Request is a very popular HTTP request library.
  • socket.io is handy for building WebSocket servers.

Command Line Interaction:

  • minimist just command line argument parsing.
  • Yargs is a powerful library for parsing command-line arguments.
  • Commander.js is a complete solution for building single-use command-line applications.
  • Vorpal.js is a framework for building mature, immersive command-line applications.
  • Chalk makes your CLI output pretty.

Code Generators:

  • Yeoman Scaffolding tool from the command-line.
  • Skaffolder Code generator with visual and command-line interface. It generates a customizable CRUD application starting from the database schema or an OpenAPI 3.0 YAML file.

Work with streams:

Why am I getting error for apple-touch-icon-precomposed.png

I guess apple devices make those requests if the device owner adds the site to it. This is the equivalent of the favicon. To resolve, add 2 100×100 png files, save it as apple-touch-icon-precomposed.png and apple-touch-icon.png and upload it to the root directory of the server. After that, the error should be gone.

I noticed lots of requests for apple-touch-icon-precomposed.png and apple-touch-icon.png in the logs that tried to load the images from the root directory of the site. I first thought it was a misconfiguration of the mobile theme and plugin, but found out later that Apple devices make those requests if the device owner adds the site to it.

Source: Why Webmasters Should Analyze Their 404 Error Log (Mar 2012; by Martin Brinkmann)

Html table with button on each row

Put a single listener on the table. When it gets a click from an input with a button that has a name of "edit" and value "edit", change its value to "modify". Get rid of the input's id (they aren't used for anything here), or make them all unique.

<script type="text/javascript">

function handleClick(evt) {
  var node = evt.target || evt.srcElement;
  if (node.name == 'edit') {
    node.value = "Modify";
  }
}

</script>

<table id="table1" border="1" onclick="handleClick(event);">
    <thead>
      <tr>
          <th>Select
    </thead>
    <tbody>
       <tr> 
           <td>
               <form name="f1" action="#" >
                <input id="edit1" type="submit" name="edit" value="Edit">
               </form>
       <tr> 
           <td>
               <form name="f2" action="#" >
                <input id="edit2" type="submit" name="edit" value="Edit">
               </form>
       <tr> 
           <td>
               <form name="f3" action="#" >
                <input id="edit3" type="submit" name="edit" value="Edit">
               </form>

   </tbody>
</table>

Why specify @charset "UTF-8"; in your CSS file?

This is useful in contexts where the encoding is not told per HTTP header or other meta data, e.g. the local file system.

Imagine the following stylesheet:

[rel="external"]::after
{
    content: ' ?';
}

If a reader saves the file to a hard drive and you omit the @charset rule, most browsers will read it in the OS’ locale encoding, e.g. Windows-1252, and insert ↗ instead of an arrow.

Unfortunately, you cannot rely on this mechanism as the support is rather … rare. And remember that on the net an HTTP header will always override the @charset rule.

The correct rules to determine the character set of a stylesheet are in order of priority:

  1. HTTP Charset header.
  2. Byte Order Mark.
  3. The first @charset rule.
  4. UTF-8.

The last rule is the weakest, it will fail in some browsers.
The charset attribute in <link rel='stylesheet' charset='utf-8'> is obsolete in HTML 5.
Watch out for conflict between the different declarations. They are not easy to debug.

Recommended reading

#include errors detected in vscode

I ended up here after struggling for a while, but actually what I was missing was just:

If a #include file or one of its dependencies cannot be found, you can also click on the red squiggles under the include statements to view suggestions for how to update your configuration.

enter image description here

source: https://code.visualstudio.com/docs/languages/cpp#_intellisense

How to upload a file from Windows machine to Linux machine using command lines via PuTTy?

Use putty. Put install directory path in environment values (PATH), and restart your PC if required.

Open cmd (command prompt) and type

C:/> pscp "C:\Users/gsjha/Desktop/example.txt" user@host:/home/

It'll be copied to the system.

Script not served by static file handler on IIS7.5

In addition to above, if you need WCF support, you might need to run this:

c:\Windows\Microsoft.NET\Framework\v3.0\Windows Communication Foundation\ServiceModelReg.exe -i

Replace v3.0 to whatever your current framework version is.

Capture the screen shot using .NET

It's certainly possible to grab a screenshot using the .NET Framework. The simplest way is to create a new Bitmap object and draw into that using the Graphics.CopyFromScreen method.

Sample code:

using (Bitmap bmpScreenCapture = new Bitmap(Screen.PrimaryScreen.Bounds.Width, 
                                            Screen.PrimaryScreen.Bounds.Height))
using (Graphics g = Graphics.FromImage(bmpScreenCapture))
{
    g.CopyFromScreen(Screen.PrimaryScreen.Bounds.X,
                     Screen.PrimaryScreen.Bounds.Y,
                     0, 0,
                     bmpScreenCapture.Size,
                     CopyPixelOperation.SourceCopy);
}

Caveat: This method doesn't work properly for layered windows. Hans Passant's answer here explains the more complicated method required to get those in your screen shots.

What is the MySQL VARCHAR max size?

Keep in mind that MySQL has a maximum row size limit

The internal representation of a MySQL table has a maximum row size limit of 65,535 bytes, not counting BLOB and TEXT types. BLOB and TEXT columns only contribute 9 to 12 bytes toward the row size limit because their contents are stored separately from the rest of the row. Read more about Limits on Table Column Count and Row Size.

Maximum size a single column can occupy, is different before and after MySQL 5.0.3

Values in VARCHAR columns are variable-length strings. The length can be specified as a value from 0 to 255 before MySQL 5.0.3, and 0 to 65,535 in 5.0.3 and later versions. The effective maximum length of a VARCHAR in MySQL 5.0.3 and later is subject to the maximum row size (65,535 bytes, which is shared among all columns) and the character set used.

However, note that the limit is lower if you use a multi-byte character set like utf8 or utf8mb4.

Use TEXT types inorder to overcome row size limit.

The four TEXT types are TINYTEXT, TEXT, MEDIUMTEXT, and LONGTEXT. These correspond to the four BLOB types and have the same maximum lengths and storage requirements.

More details on BLOB and TEXT Types

Even more

Checkout more details on Data Type Storage Requirements which deals with storage requirements for all data types.

How to include NA in ifelse?

It sounds like you want the ifelse statement to interpret NA values as FALSE instead of NA in the comparison. I use the following functions to handle this situation so I don't have to continuously handle the NA situation:

falseifNA <- function(x){
  ifelse(is.na(x), FALSE, x)
}

ifelse2 <- function(x, a, b){
  ifelse(falseifNA(x), a, b)
}

You could also combine these functions into one to be more efficient. So to return the result you want, you could use:

test$ID <- ifelse2(is.na(test$time) | test$type == "A", NA, "1")

What exactly is node.js used for?

Node.js is a runtime that compiles and executes javaScript. It can be used to develop application that runs end-to-end in JavaScript i..e both client side and server side uses javascript code unlike most of todays' application with rich client framework (angularJs, extJs) and RESTful server side APIs

How to add a new line in textarea element?

Try this one:

_x000D_
_x000D_
    <textarea cols='60' rows='8'>This is my statement one.&#13;&#10;This is my statement2</textarea>
_x000D_
_x000D_
_x000D_

&#10; Line Feed and &#13; Carriage Return are HTML entitieswikipedia. This way you are actually parsing the new line ("\n") rather than displaying it as text.

chart.js load totally new data

I had loads of trouble with this too. I have data and labels in separate arrays then I reinitialise the chart data. I added the line.destroy(); as suggested above which has done the trick

_x000D_
_x000D_
var ctx = document.getElementById("canvas").getContext("2d");_x000D_
if(window.myLine){_x000D_
 window.myLine.destroy();_x000D_
}_x000D_
window.myLine = new Chart(ctx).Line(lineChartData, {_x000D_
  etc_x000D_
  etc
_x000D_
_x000D_
_x000D_

Applying Comic Sans Ms font style

The font may exist with different names, and not at all on some systems, so you need to use different variations and fallback to get the closest possible look on all systems:

font-family: "Comic Sans MS", "Comic Sans", cursive;

Be careful what you use this font for, though. Many consider it as ugly and overused, so it should not be use for something that should look professional.

Ignore case in Python strings

This is how you'd do it with re:

import re
p = re.compile('^hello$', re.I)
p.match('Hello')
p.match('hello')
p.match('HELLO')

How to write lists inside a markdown table?

If you use the html approach:

don't add blank lines

Like this:

<table>
    <tbody>

        <tr>
            <td>1</td>
            <td>2</td>
        </tr>

        <tr>
            <td>1</td>
            <td>2</td>
        </tr>

    </tbody>
</table>

the markup will break.

Remove blank lines:

<table>
    <tbody>
        <tr>
            <td>1</td>
            <td>2</td>
        </tr>
        <tr>
            <td>1</td>
            <td>2</td>
        </tr>
    </tbody>
</table>

Using a SELECT statement within a WHERE clause

It's not bad practice at all. They are usually referred as SUBQUERY, SUBSELECT or NESTED QUERY.

It's a relatively expensive operation, but it's quite common to encounter a lot of subqueries when dealing with databases since it's the only way to perform certain kind of operations on data.

svn: E155004: ..(path of resource).. is already locked

Just cleanup. Happened in JetBrains PhpStorm

disable a hyperlink using jQuery

You can bind a click handler that returns false:

$('.my-link').click(function () {return false;});

To re-enable it again, unbind the handler:

$('.my-link').unbind('click');

Note that disabled doesn't work because it is designed for form inputs only.


jQuery has anticipated this already, providing a shortcut as of jQuery 1.4.3:

$('.my-link').bind('click', false);

And to unbind / re-enable:

$('.my-link').unbind('click', false);

How to I say Is Not Null in VBA

you can do like follows. Remember, IsNull is a function which returns TRUE if the parameter passed to it is null, and false otherwise.

Not IsNull(Fields!W_O_Count.Value)

adding comment in .properties files

Writing the properties file with multiple comments is not supported. Why ?

PropertyFile.java

public class PropertyFile extends Task {

    /* ========================================================================
     *
     * Instance variables.
     */

    // Use this to prepend a message to the properties file
    private String              comment;

    private Properties          properties;

The ant property file task is backed by a java.util.Properties class which stores comments using the store() method. Only one comment is taken from the task and that is passed on to the Properties class to save into the file.

The way to get around this is to write your own task that is backed by commons properties instead of java.util.Properties. The commons properties file is backed by a property layout which allows settings comments for individual keys in the properties file. Save the properties file with the save() method and modify the new task to accept multiple comments through <comment> elements.

Checkbox Check Event Listener

Short answer: Use the change event. Here's a couple of practical examples. Since I misread the question, I'll include jQuery examples along with plain JavaScript. You're not gaining much, if anything, by using jQuery though.

Single checkbox

Using querySelector.

_x000D_
_x000D_
var checkbox = document.querySelector("input[name=checkbox]");

checkbox.addEventListener('change', function() {
  if (this.checked) {
    console.log("Checkbox is checked..");
  } else {
    console.log("Checkbox is not checked..");
  }
});
_x000D_
<input type="checkbox" name="checkbox" />
_x000D_
_x000D_
_x000D_

Single checkbox with jQuery

_x000D_
_x000D_
$('input[name=checkbox]').change(function() {
  if ($(this).is(':checked')) {
    console.log("Checkbox is checked..")
  } else {
    console.log("Checkbox is not checked..")
  }
});
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<input type="checkbox" name="checkbox" />
_x000D_
_x000D_
_x000D_

Multiple checkboxes

Here's an example of a list of checkboxes. To select multiple elements we use querySelectorAll instead of querySelector. Then use Array.filter and Array.map to extract checked values.

_x000D_
_x000D_
// Select all checkboxes with the name 'settings' using querySelectorAll.
var checkboxes = document.querySelectorAll("input[type=checkbox][name=settings]");
let enabledSettings = []

/*
For IE11 support, replace arrow functions with normal functions and
use a polyfill for Array.forEach:
https://vanillajstoolkit.com/polyfills/arrayforeach/
*/

// Use Array.forEach to add an event listener to each checkbox.
checkboxes.forEach(function(checkbox) {
  checkbox.addEventListener('change', function() {
    enabledSettings = 
      Array.from(checkboxes) // Convert checkboxes to an array to use filter and map.
      .filter(i => i.checked) // Use Array.filter to remove unchecked checkboxes.
      .map(i => i.value) // Use Array.map to extract only the checkbox values from the array of objects.
      
    console.log(enabledSettings)
  })
});
_x000D_
<label>
   <input type="checkbox" name="settings" value="forcefield">
   Enable forcefield
</label>
<label>
  <input type="checkbox" name="settings" value="invisibilitycloak">
  Enable invisibility cloak
</label>
<label>
  <input type="checkbox" name="settings" value="warpspeed">
  Enable warp speed
</label>
_x000D_
_x000D_
_x000D_

Multiple checkboxes with jQuery

_x000D_
_x000D_
let checkboxes = $("input[type=checkbox][name=settings]")
let enabledSettings = [];

// Attach a change event handler to the checkboxes.
checkboxes.change(function() {
  enabledSettings = checkboxes
    .filter(":checked") // Filter out unchecked boxes.
    .map(function() { // Extract values using jQuery map.
      return this.value;
    }) 
    .get() // Get array.
    
  console.log(enabledSettings);
});
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<label>
   <input type="checkbox" name="settings" value="forcefield">
   Enable forcefield
</label>
<label>
  <input type="checkbox" name="settings" value="invisibilitycloak">
  Enable invisibility cloak
</label>
<label>
  <input type="checkbox" name="settings" value="warpspeed">
  Enable warp speed
</label>
_x000D_
_x000D_
_x000D_

How do I show running processes in Oracle DB?

I suspect you would just want to grab a few columns from V$SESSION and the SQL statement from V$SQL. Assuming you want to exclude the background processes that Oracle itself is running

SELECT sess.process, sess.status, sess.username, sess.schemaname, sql.sql_text
  FROM v$session sess,
       v$sql     sql
 WHERE sql.sql_id(+) = sess.sql_id
   AND sess.type     = 'USER'

The outer join is to handle those sessions that aren't currently active, assuming you want those. You could also get the sql_fulltext column from V$SQL which will have the full SQL statement rather than the first 1000 characters, but that is a CLOB and so likely a bit more complicated to deal with.

Realistically, you probably want to look at everything that is available in V$SESSION because it's likely that you can get a lot more information than SP_WHO provides.

Pandas Merging 101

This post will go through the following topics:

  • how to correctly generalize to multiple DataFrames (and why merge has shortcomings here)
  • merging on unique keys
  • merging on non-unqiue keys

BACK TO TOP



Generalizing to multiple DataFrames

Oftentimes, the situation arises when multiple DataFrames are to be merged together. Naively, this can be done by chaining merge calls:

df1.merge(df2, ...).merge(df3, ...)

However, this quickly gets out of hand for many DataFrames. Furthermore, it may be necessary to generalise for an unknown number of DataFrames.

Here I introduce pd.concat for multi-way joins on unique keys, and DataFrame.join for multi-way joins on non-unique keys. First, the setup.

# Setup.
np.random.seed(0)
A = pd.DataFrame({'key': ['A', 'B', 'C', 'D'], 'valueA': np.random.randn(4)})    
B = pd.DataFrame({'key': ['B', 'D', 'E', 'F'], 'valueB': np.random.randn(4)})
C = pd.DataFrame({'key': ['D', 'E', 'J', 'C'], 'valueC': np.ones(4)})
dfs = [A, B, C] 

# Note, the "key" column values are unique, so the index is unique.
A2 = A.set_index('key')
B2 = B.set_index('key')
C2 = C.set_index('key')

dfs2 = [A2, B2, C2]

Multiway merge on unique keys

If your keys (here, the key could either be a column or an index) are unique, then you can use pd.concat. Note that pd.concat joins DataFrames on the index.

# merge on `key` column, you'll need to set the index before concatenating
pd.concat([
    df.set_index('key') for df in dfs], axis=1, join='inner'
).reset_index()

  key    valueA    valueB  valueC
0   D  2.240893 -0.977278     1.0

# merge on `key` index
pd.concat(dfs2, axis=1, sort=False, join='inner')

       valueA    valueB  valueC
key                            
D    2.240893 -0.977278     1.0

Omit join='inner' for a FULL OUTER JOIN. Note that you cannot specify LEFT or RIGHT OUTER joins (if you need these, use join, described below).


Multiway merge on keys with duplicates

concat is fast, but has its shortcomings. It cannot handle duplicates.

A3 = pd.DataFrame({'key': ['A', 'B', 'C', 'D', 'D'], 'valueA': np.random.randn(5)})
pd.concat([df.set_index('key') for df in [A3, B, C]], axis=1, join='inner')
ValueError: Shape of passed values is (3, 4), indices imply (3, 2)

In this situation, we can use join since it can handle non-unique keys (note that join joins DataFrames on their index; it calls merge under the hood and does a LEFT OUTER JOIN unless otherwise specified).

# join on `key` column, set as the index first
# For inner join. For left join, omit the "how" argument.
A.set_index('key').join(
    [df.set_index('key') for df in (B, C)], how='inner').reset_index()

  key    valueA    valueB  valueC
0   D  2.240893 -0.977278     1.0

# join on `key` index
A3.set_index('key').join([B2, C2], how='inner')

       valueA    valueB  valueC
key                            
D    1.454274 -0.977278     1.0
D    0.761038 -0.977278     1.0


Continue Reading

Jump to other topics in Pandas Merging 101 to continue learning:

* you are here

How to stop/terminate a python script from running?

You can also do it if you use the exit() function in your code. More ideally, you can do sys.exit(). sys.exit() which might terminate Python even if you are running things in parallel through the multiprocessing package.

Note: In order to use the sys.exit(), you must import it: import sys

Get first element of Series without knowing the index

Use iloc to access by position (rather than label):

In [11]: df = pd.DataFrame([[1, 2], [3, 4]], ['a', 'b'], ['A', 'B'])

In [12]: df
Out[12]: 
   A  B
a  1  2
b  3  4

In [13]: df.iloc[0]  # first row in a DataFrame
Out[13]: 
A    1
B    2
Name: a, dtype: int64

In [14]: df['A'].iloc[0]  # first item in a Series (Column)
Out[14]: 1

how to query for a list<String> in jdbctemplate

You can't use placeholders for column names, table names, data type names, or basically anything that isn't data.

What's the purpose of SQL keyword "AS"?

Everyone who answered before me is correct. You use it kind of as an alias shortcut name for a table when you have long queries or queries that have joins. Here's a couple examples.

Example 1

SELECT P.ProductName,
       P.ProductGroup,
       P.ProductRetailPrice
FROM   Products AS P

Example 2

SELECT P.ProductName,
       P.ProductRetailPrice,
       O.Quantity
FROM   Products AS P
LEFT OUTER JOIN Orders AS O ON O.ProductID = P.ProductID
WHERE  O.OrderID = 123456

Example 3 It's a good practice to use the AS keyword, and very recommended, but it is possible to perform the same query without one (and I do often).

SELECT P.ProductName,
       P.ProductRetailPrice,
       O.Quantity
FROM   Products P
LEFT OUTER JOIN Orders O ON O.ProductID = P.ProductID
WHERE  O.OrderID = 123456

As you can tell, I left out the AS keyword in the last example. And it can be used as an alias.

Example 4

SELECT P.ProductName AS "Product",
       P.ProductRetailPrice AS "Retail Price",
       O.Quantity AS "Quantity Ordered"
FROM   Products P
LEFT OUTER JOIN Orders O ON O.ProductID = P.ProductID
WHERE  O.OrderID = 123456

Output of Example 4

Product             Retail Price     Quantity Ordered
Blue Raspberry Gum  $10 pk/$50 Case  2 Cases
Twizzler            $5 pk/$25 Case   10 Cases

How do I subtract minutes from a date in javascript?

This is what I found:

//First, start with a particular time
var date = new Date();

//Add two hours
var dd = date.setHours(date.getHours() + 2);

//Go back 3 days
var dd = date.setDate(date.getDate() - 3);

//One minute ago...
var dd = date.setMinutes(date.getMinutes() - 1);

//Display the date:
var monthNames = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
var date = new Date(dd);
var day = date.getDate();
var monthIndex = date.getMonth();
var year = date.getFullYear();
var displayDate = monthNames[monthIndex] + ' ' + day + ', ' + year;
alert('Date is now: ' + displayDate);

Sources:

http://www.javascriptcookbook.com/article/Perform-date-manipulations-based-on-adding-or-subtracting-time/

https://stackoverflow.com/a/12798270/1873386

How to use img src in vue.js?

Try this:

<img v-bind:src="'/media/avatars/' + joke.avatar" /> 

Don't forget single quote around your path string. also in your data check you have correctly defined image variable.

joke: {
  avatar: 'image.jpg'
}

A working demo here: http://jsbin.com/pivecunode/1/edit?html,js,output

Making heatmap from pandas DataFrame

If you don't need a plot per say, and you're simply interested in adding color to represent the values in a table format, you can use the style.background_gradient() method of the pandas data frame. This method colorizes the HTML table that is displayed when viewing pandas data frames in e.g. the JupyterLab Notebook and the result is similar to using "conditional formatting" in spreadsheet software:

import numpy as np 
import pandas as pd


index= ['aaa', 'bbb', 'ccc', 'ddd', 'eee']
cols = ['A', 'B', 'C', 'D']
df = pd.DataFrame(abs(np.random.randn(5, 4)), index=index, columns=cols)
df.style.background_gradient(cmap='Blues')

enter image description here

For detailed usage, please see the more elaborate answer I provided on the same topic previously and the styling section of the pandas documentation.

How do you beta test an iphone app?

Diawi Alternatives

Since diawi.com have added some limitations for free accounds.

Next best available and easy to use alternative is

Microsoft

https://appcenter.ms

Google

https://firebase.google.com/docs/app-distribution/ios/distribute-console

Others

https://hockeyapp.net/

http://buildtry.com

Happy build sharing!

SyntaxError: "can't assign to function call"

You have done it backwards, it should be:

amount = invest(amount,top_company(5,year,year+1),year)

Remove a character at a certain position in a string - javascript

If you omit the particular index character then use this method

function removeByIndex(str,index) {
      return str.slice(0,index) + str.slice(index+1);
}
    
var str = "Hello world", index=3;
console.log(removeByIndex(str,index));

// Output: "Helo world"

What is a stack pointer used for in microprocessors?

The stack pointer stores the address of the most recent entry that was pushed onto the stack.

To push a value onto the stack, the stack pointer is incremented to point to the next physical memory address, and the new value is copied to that address in memory.

To pop a value from the stack, the value is copied from the address of the stack pointer, and the stack pointer is decremented, pointing it to the next available item in the stack.

The most typical use of a hardware stack is to store the return address of a subroutine call. When the subroutine is finished executing, the return address is popped off the top of the stack and placed in the Program Counter register, causing the processor to resume execution at the next instruction following the call to the subroutine.

http://en.wikipedia.org/wiki/Stack_%28data_structure%29#Hardware_stacks

CakePHP find method with JOIN

        $services = $this->Service->find('all', array(
            'limit' =>4,
            'fields' => array('Service.*','ServiceImage.*'),
            'joins' => array(
                array(
                        'table' => 'services_images',
                        'alias' => 'ServiceImage',
                        'type' => 'INNER',
                        'conditions' => array(
                        'ServiceImage.service_id' =>'Service.id'
                        )
                    ),
                ),
            )
        );

It goges to array is null.

MySQL: Invalid use of group function

First, the error you're getting is due to where you're using the COUNT function -- you can't use an aggregate (or group) function in the WHERE clause.

Second, instead of using a subquery, simply join the table to itself:

SELECT a.pid 
FROM Catalog as a LEFT JOIN Catalog as b USING( pid )
WHERE a.sid != b.sid
GROUP BY a.pid

Which I believe should return only rows where at least two rows exist with the same pid but there is are at least 2 sids. To make sure you get back only one row per pid I've applied a grouping clause.

How do I get the current date in JavaScript?

This is good to get formatted date

_x000D_
_x000D_
let date = new Date().toLocaleDateString("en", {year:"numeric", day:"2-digit", month:"2-digit"});_x000D_
console.log(date);
_x000D_
_x000D_
_x000D_

Bootstrap css hides portion of container below navbar navbar-fixed-top

I too have had this problem but solved it without script and only using CSS. I start by following the recommended padding-top for a fixed menu by setting of 60px described on the Bootstrap website. Then I added three media tags that resize the padding at the cutoff points where my menu also resizes.

<style>      
    body{
        padding-top:60px;
    }
    /* fix padding under menu after resize */
    @media screen and (max-width: 767px) {
        body { padding-top: 60px; }
    }
    @media screen and (min-width:768px) and (max-width: 991px) {
        body { padding-top: 110px; }
    }
    @media screen and (min-width: 992px) {
        body { padding-top: 60px; }
    }
</style>

One note, when my menu width is between 768 and 991, the menu logo in my layout plus the <li> options cause the menu to wrap to two lines. Therefore, I had to adjust the padding-top to prevent the menu from covering the content, hence 110px.

Hope this helps...

What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?

You can use Optional in functional style to avoid NullPointerException and ArrayIndexOutOfBoundsException :

String[] array = new String[]{"aaa", null, "ccc"};
for (int i = 0; i < 4; i++) {
    String result = Optional.ofNullable(array.length > i ? array[i] : null)
            .map(x -> x.toUpperCase()) //some operation here
            .orElse("NO_DATA");
    System.out.println(result);
}

Output:

AAA
NO_DATA
CCC
NO_DATA

duplicate 'row.names' are not allowed error

Then tell read.table not to use row.names:

systems <- read.table("http://getfile.pl?test.csv", 
                      header=TRUE, sep=",", row.names=NULL)

and now your rows will simply be numbered.

Also look at read.csv which is a wrapper for read.table which already sets the sep=',' and header=TRUE arguments so that your call simplifies to

systems <- read.csv("http://getfile.pl?test.csv", row.names=NULL)

How can I create a copy of an object in Python?

How can I create a copy of an object in Python?

So, if I change values of the fields of the new object, the old object should not be affected by that.

You mean a mutable object then.

In Python 3, lists get a copy method (in 2, you'd use a slice to make a copy):

>>> a_list = list('abc')
>>> a_copy_of_a_list = a_list.copy()
>>> a_copy_of_a_list is a_list
False
>>> a_copy_of_a_list == a_list
True

Shallow Copies

Shallow copies are just copies of the outermost container.

list.copy is a shallow copy:

>>> list_of_dict_of_set = [{'foo': set('abc')}]
>>> lodos_copy = list_of_dict_of_set.copy()
>>> lodos_copy[0]['foo'].pop()
'c'
>>> lodos_copy
[{'foo': {'b', 'a'}}]
>>> list_of_dict_of_set
[{'foo': {'b', 'a'}}]

You don't get a copy of the interior objects. They're the same object - so when they're mutated, the change shows up in both containers.

Deep copies

Deep copies are recursive copies of each interior object.

>>> lodos_deep_copy = copy.deepcopy(list_of_dict_of_set)
>>> lodos_deep_copy[0]['foo'].add('c')
>>> lodos_deep_copy
[{'foo': {'c', 'b', 'a'}}]
>>> list_of_dict_of_set
[{'foo': {'b', 'a'}}]

Changes are not reflected in the original, only in the copy.

Immutable objects

Immutable objects do not usually need to be copied. In fact, if you try to, Python will just give you the original object:

>>> a_tuple = tuple('abc')
>>> tuple_copy_attempt = a_tuple.copy()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'copy'

Tuples don't even have a copy method, so let's try it with a slice:

>>> tuple_copy_attempt = a_tuple[:]

But we see it's the same object:

>>> tuple_copy_attempt is a_tuple
True

Similarly for strings:

>>> s = 'abc'
>>> s0 = s[:]
>>> s == s0
True
>>> s is s0
True

and for frozensets, even though they have a copy method:

>>> a_frozenset = frozenset('abc')
>>> frozenset_copy_attempt = a_frozenset.copy()
>>> frozenset_copy_attempt is a_frozenset
True

When to copy immutable objects

Immutable objects should be copied if you need a mutable interior object copied.

>>> tuple_of_list = [],
>>> copy_of_tuple_of_list = tuple_of_list[:]
>>> copy_of_tuple_of_list[0].append('a')
>>> copy_of_tuple_of_list
(['a'],)
>>> tuple_of_list
(['a'],)
>>> deepcopy_of_tuple_of_list = copy.deepcopy(tuple_of_list)
>>> deepcopy_of_tuple_of_list[0].append('b')
>>> deepcopy_of_tuple_of_list
(['a', 'b'],)
>>> tuple_of_list
(['a'],)

As we can see, when the interior object of the copy is mutated, the original does not change.

Custom Objects

Custom objects usually store data in a __dict__ attribute or in __slots__ (a tuple-like memory structure.)

To make a copyable object, define __copy__ (for shallow copies) and/or __deepcopy__ (for deep copies).

from copy import copy, deepcopy

class Copyable:
    __slots__ = 'a', '__dict__'
    def __init__(self, a, b):
        self.a, self.b = a, b
    def __copy__(self):
        return type(self)(self.a, self.b)
    def __deepcopy__(self, memo): # memo is a dict of id's to copies
        id_self = id(self)        # memoization avoids unnecesary recursion
        _copy = memo.get(id_self)
        if _copy is None:
            _copy = type(self)(
                deepcopy(self.a, memo), 
                deepcopy(self.b, memo))
            memo[id_self] = _copy 
        return _copy

Note that deepcopy keeps a memoization dictionary of id(original) (or identity numbers) to copies. To enjoy good behavior with recursive data structures, make sure you haven't already made a copy, and if you have, return that.

So let's make an object:

>>> c1 = Copyable(1, [2])

And copy makes a shallow copy:

>>> c2 = copy(c1)
>>> c1 is c2
False
>>> c2.b.append(3)
>>> c1.b
[2, 3]

And deepcopy now makes a deep copy:

>>> c3 = deepcopy(c1)
>>> c3.b.append(4)
>>> c1.b
[2, 3]

Why does the 'int' object is not callable error occur when using the sum() function?

This means that somewhere else in your code, you have something like:

sum = 0

Which shadows the builtin sum (which is callable) with an int (which isn't).

Unable to find velocity template resources

I faced a similar issue. I was copying the velocity engine mail templates in wrong folder. Since JavaMailSender and VelocityEngine are declared as resources under MailService, its required to add the templates under resource folder declared for the project.

I made the changes and it worked. Put the templates as

src/main/resources/templates/<package>/sampleMail.vm

Bind event to right mouse click

I found this answer here and I'm using it like this.

Code from my Library:

$.fn.customContextMenu = function(callBack){
    $(this).each(function(){
        $(this).bind("contextmenu",function(e){
             e.preventDefault();
             callBack();
        });
    }); 
}

Code from my page's script:

$("#newmagazine").customContextMenu(function(){
    alert("some code");
});

Joining three tables using MySQL

Simply use:

select s.name "Student", c.name "Course"
from student s, bridge b, course c
where b.sid = s.sid and b.cid = c.cid 

How to make a new line or tab in <string> XML (eclipse/android)?

\n didn't work for me. So I used <br></br> HTML tag

    <string name="message_register_success">
Sign up is complete. <br></br>
 Enjoy a new shopping life at MageMobile!!
</string>

How to render pdfs using C#

There are a few other choices in case the Adobe ActiveX isn't what you're looking for (since Acrobat must be present on the user machine and you can't ship it yourself).

For creating the PDF preview, first have a look at some other discussions on the subject on StackOverflow:

In the last two I talk about a few things you can try:

  • You can get a commercial renderer (PDFViewForNet, PDFRasterizer.NET, ABCPDF, ActivePDF, XpdfRasterizer and others in the other answers...).
    Most are fairly expensive though, especially if all you care about is making a simple preview/thumbnails.

  • In addition to Omar Shahine's code snippet, there is a CodeProject article that shows how to use the Adobe ActiveX, but it may be out of date, easily broken by new releases and its legality is murky (basically it's ok for internal use but you can't ship it and you can't use it on a server to produce images of PDF).

  • You could have a look at the source code for SumatraPDF, an OpenSource PDF viewer for windows.

  • There is also Poppler, a rendering engine that uses Xpdf as a rendering engine. All of these are great but they will require a fair amount of commitment to make make them work and interface with .Net and they tend to be be distributed under the GPL.

  • You may want to consider using GhostScript as an interpreter because rendering pages is a fairly simple process.
    The drawback is that you will need to either re-package it to install it with your app, or make it a pre-requisite (or at least a part of your install process).
    It's not a big challenge, and it's certainly easier than having to massage the other rendering engines into cooperating with .Net.
    I did a small project that you will find on the Developer Express forums as an attachment.
    Be careful of the license requirements for GhostScript through.
    If you can't leave with that then commercial software is probably your only choice.

How to override equals method in Java

@Override
public boolean equals(Object that){
  if(this == that) return true;//if both of them points the same address in memory

  if(!(that instanceof People)) return false; // if "that" is not a People or a childclass

  People thatPeople = (People)that; // than we can cast it to People safely

  return this.name.equals(thatPeople.name) && this.age == thatPeople.age;// if they have the same name and same age, then the 2 objects are equal unless they're pointing to different memory adresses
}

Updating a JSON object using Javascript

For example I am using this technique in Basket functionality.

Let us add new Item to Basket.

var productArray=[];


$(document).on('click','[cartBtn]',function(e){
  e.preventDefault();
  $(this).html('<i class="fa fa-check"></i>Added to cart');
  console.log('Item added ');
  var productJSON={"id":$(this).attr('pr_id'), "nameEn":$(this).attr('pr_name_en'), "price":$(this).attr('pr_price'), "image":$(this).attr('pr_image'), "quantity":1, "discount":0, "total":$(this).attr('pr_price')};


  if(localStorage.getObj('product')!==null){
    productArray=localStorage.getObj('product');
    productArray.push(productJSON);  
    localStorage.setObj('product', productArray);  
  }
  else{
    productArray.push(productJSON);  
    localStorage.setObj('product', productArray);  
  }


  itemCountInCart(productArray.length);

});

After adding some item to basket - generates json array like this

[
    {
        "id": "95",
        "nameEn": "New Braslet",
        "price": "8776",
        "image": "1462012394815.jpeg",
        "quantity": 1,
        "discount": 0,
        "total": "8776"
    },
    {
        "id": "96",
        "nameEn": "new braslet",
        "price": "76",
        "image": "1462012431497.jpeg",
        "quantity": 1,
        "discount": 0,
        "total": "76"
    },
    {
        "id": "97",
        "nameEn": "khjk",
        "price": "87",
        "image": "1462012483421.jpeg",
        "quantity": 1,
        "discount": 0,
        "total": "87"
    }
]

For Removing some item from Basket.

$(document).on('click','[itemRemoveBtn]',function(){

var arrayFromLocal=localStorage.getObj('product');
findAndRemove(arrayFromLocal,"id",$(this).attr('basketproductid'));
localStorage.setObj('product', arrayFromLocal);
loadBasketFromLocalStorageAndRender();
});

//This function will remove element by specified property. In my case this is ID.
function findAndRemove(array, property, value) {
  array.forEach(function(result, index) {
    if(result[property] === value) {
      //Remove from array
      console.log('Removed from index is '+index+' result is '+JSON.stringify(result));
      array.splice(index, 1);

    }    
  });
}

And Finally the real answer of the question "Updating a JSON object using JS". In my example updating product quantity and total price on changing the "number" element value.

$(document).on('keyup mouseup','input[type=number]',function(){

  var arrayFromLocal=localStorage.getObj('product');
  setQuantityAndTotalPrice(arrayFromLocal,$(this).attr('updateItemid'),$(this).val());
  localStorage.setObj('product', arrayFromLocal);
  loadBasketFromLocalStorageAndRender();
});

function setQuantityAndTotalPrice(array,id,quantity) {

  array.forEach(function(result, index) {
    if(result.id === id) {
      result.quantity=quantity;
      result.total=(quantity*result.price);
    }    
  });

}

Is it possible to assign numeric value to an enum in Java?

Yes, and then some, example from documentation:

public enum Planet {
    MERCURY (3.303e+23, 2.4397e6),
    VENUS   (4.869e+24, 6.0518e6),
    EARTH   (5.976e+24, 6.37814e6),
    MARS    (6.421e+23, 3.3972e6),
    JUPITER (1.9e+27,   7.1492e7),
    SATURN  (5.688e+26, 6.0268e7),
    URANUS  (8.686e+25, 2.5559e7),
    NEPTUNE (1.024e+26, 2.4746e7);

    // in kilograms
    private final double mass;
    // in meters
    private final double radius;
    Planet(double mass, double radius) {
        this.mass = mass;
        this.radius = radius;
    }
    private double mass() { return mass; }
    private double radius() { return radius; }

    // universal gravitational 
    // constant  (m3 kg-1 s-2)
    public static final double G = 6.67300E-11;

    double surfaceGravity() {
        return G * mass / (radius * radius);
    }
    double surfaceWeight(double otherMass) {
        return otherMass * surfaceGravity();
    }
    public static void main(String[] args) {
        if (args.length != 1) {
            System.err.println("Usage: java Planet <earth_weight>");
            System.exit(-1);
        }
        double earthWeight = Double.parseDouble(args[0]);
        double mass = earthWeight/EARTH.surfaceGravity();
        for (Planet p : Planet.values())
           System.out.printf("Your weight on %s is %f%n",
                             p, p.surfaceWeight(mass));
    }
}