Programs & Examples On #Red gate ants

W3WP.EXE using 100% CPU - where to start?

It's not much of an answer, but you might need to go old school and capture an image snapshot of the IIS process and debug it. You might also want to check out Tess Ferrandez's blog - she is a kick a** microsoft escalation engineer and her blog focuses on debugging windows ASP.NET, but the blog is relevant to windows debugging in general. If you select the ASP.NET tag (which is what I've linked to) then you'll see several items that are similar.

Execute ssh with password authentication via windows command prompt

PuTTY's plink has a command-line argument for a password. Some other suggestions have been made in the answers to this question: using Expect (which is available for Windows), or writing a launcher in Python with Paramiko.

CSS pseudo elements in React

Depending if you only need a couple attributes to be styled inline you can do something like this solution (and saves you from having to install a special package or create an extra element):

<span class="something" datacustomattribute="">
.something::before {
  content: attr(datascustomattribute);
  position: absolute;

Note that the datacustomattribute must start with data and be all lowercase to satisfy React.

Gradle - Could not find or load main class

If you're using Spring Boot, this might be the issue:

Basically, the output directories changed in Gradle 4.0, so if you have them hardcoded the execution will fail.

The solution is to replace:

bootRun {
   dependsOn pathingJar
   doFirst {
      classpath = files("$buildDir/classes/main", "$buildDir/resources/main", pathingJar.archivePath)


bootRun {
   dependsOn pathingJar
   doFirst {
      classpath = files(sourceSets.main.output.files, pathingJar.archivePath)

How to check if a Unix .tar.gz file is a valid file without uncompressing?

These are all very sub-optimal solutions. From the GZIP spec

ID2 (IDentification 2)
These have the fixed values ID1 = 31 (0x1f, \037), ID2 = 139 (0x8b, \213), to identify the file as being in gzip format.

Has to be coded into whatever language you're using.

Enum "Inheritance"

Ignoring the fact that base is a reserved word you cannot do inheritance of enum.

The best thing you could do is something like that:

public enum Baseenum
   x, y, z

public enum Consume
   x = Baseenum.x,
   y = Baseenum.y,
   z = Baseenum.z

public void Test()
   Baseenum a = Baseenum.x;
   Consume newA = (Consume) a;

   if ((Int32) a == (Int32) newA)

Since they're all the same base type (ie: int) you could assign the value from an instance of one type to the other which a cast. Not ideal but it work.

How to create a popup window (PopupWindow) in Android

This an example from my code how to address a widget(button) in popupwindow

View v=LayoutInflater.from(getContext()).inflate(R.layout.popupwindow, null, false);
    final PopupWindow pw = new PopupWindow(v,500,500, true);
    final Button button = rootView.findViewById(;
    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            pw.showAtLocation(rootView.findViewById(, Gravity.CENTER, 0, 0);

    final Button popup_btn=v.findViewById(;

    popup_btn.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {

Hope this help you

How to print table using Javascript?

You can also use a jQuery plugin to do that

jQuery PrintPage plugin


Correct way to pause a Python program

I think I like this solution:

import getpass
getpass.getpass("Press Enter to Continue")

It hides whatever the user types in, which helps clarify that input is not used here.

But be mindful on the OS X platform. It displays a key which may be confusing.

It shows a key, like I said

Probably the best solution would be to do something similar to the getpass module yourself, without making a read -s call. Maybe making the foreground color match the background?

How to show PIL images on the screen?

If you find that PIL has problems on some platforms, using a native image viewer may help."tmp.png") #Save the image to a PNG file called tmp.png.

For MacOS:

import os
os.system("open tmp.png") #Will open in Preview.

For most GNU/Linux systems with X.Org and a desktop environment:

import os
os.system("xdg-open tmp.png")

For Windows:

import os
os.system("powershell -c tmp.png")

Android Webview - Webpage should fit the device screen

I had video in html string, and width of web view was larger that screen width and this is working for me.

Add these lines to HTML string.

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

Result after adding above code to HTML string:

<!DOCTYPE html>

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


Dynamically select data frame columns using $ and a character value

if you want to select column with specific name then just do

#and then

you can run it in loop as well reverse way to add dynamic name eg if A is data frame and xyz is column to be named as x then I do like this


again this can also be added in loop

Better way to revert to a previous SVN revision of a file?

What you're looking for is called a "reverse merge". You should consult the docs regarding the merge function in the SVN book (as luapyad, or more precisely the first commenter on that post, points out). If you're using Tortoise, you can also just go into the log view and right-click and choose "revert changes from this revision" on the one where you made the mistake.

How to find all occurrences of a substring?

>>> help(str.find)
Help on method_descriptor:

    S.find(sub [,start [,end]]) -> int

Thus, we can build it ourselves:

def find_all(a_str, sub):
    start = 0
    while True:
        start = a_str.find(sub, start)
        if start == -1: return
        yield start
        start += len(sub) # use start += 1 to find overlapping matches

list(find_all('spam spam spam spam', 'spam')) # [0, 5, 10, 15]

No temporary strings or regexes required.

Array vs. Object efficiency in JavaScript

It depends on usage. If the case is lookup objects is very faster.

Here is a Plunker example to test performance of array and object lookups.

You will see that; Looking up for 5.000 items in 5.000 length array collection, take over 3000 milisecons

However Looking up for 5.000 items in object has 5.000 properties, take only 2 or 3 milisecons

Also making object tree don't make huge difference

getting the reason why websockets closed with close code 1006

I've got the error while using Chrome as client and golang gorilla websocket as server under nginx proxy

And sending just some "ping" message from server to client every x second resolved problem

SQL multiple columns in IN clause

You could do like this:

SELECT city FROM user WHERE (firstName, lastName) IN (('a', 'b'), ('c', 'd'));

The sqlfiddle.

How to search images from private 1.0 registry in docker?

Modifying the answer from @mre to get the list just from one command (valid at least for Docker Registry v2).

docker exec -it <your_registry_container_id> ls -a /var/lib/registry/docker/registry/v2/repositories/

How to set ANDROID_HOME path in ubuntu?

first open the .bashrc file by gedit ~/.bashrc

# Added ANDROID_HOME variable. export ANDROID_HOME=$HOME/Android/Sdk export PATH=$PATH:$ANDROID_HOME/tools export PATH=$PATH:$ANDROID_HOME/platform-tools

save the file and reopen the terminal


it will show the path like /home/pathTo/Android/Sdk

How to open a different activity on recyclerView item onclick

public class AdapterClass extends RecyclerView.Adapter<AdapterClass.MyViewHolder> {_x000D_
    private LayoutInflater inflater;_x000D_
    private Context context;_x000D_
List<Information>data= Collections.emptyList();_x000D_
    public AdapterClass(Context context,List<Information>data){_x000D_
        inflater= LayoutInflater.from(context);_x000D_;_x000D_
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {_x000D_
       View view= inflater.inflate(R.layout.custom_row,parent,false);_x000D_
        MyViewHolder holder=new MyViewHolder(view);_x000D_
        return holder;_x000D_
    public void onBindViewHolder(MyViewHolder holder, int position) {_x000D_
        Information current=data.get(position);_x000D_
    public int getItemCount() {_x000D_
        return data.size();_x000D_
    class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{_x000D_
        TextView title;_x000D_
        ImageView icon;_x000D_
        public MyViewHolder(View itemView) {_x000D_
        public void onClick(View v) {_x000D_
            Toast.makeText(context,"The Item Clicked is: "+getPosition(),Toast.LENGTH_SHORT).show();_x000D_

public class AdapterClass extends RecyclerView.Adapter<AdapterClass.MyViewHolder> {_x000D_
    private LayoutInflater inflater;_x000D_
    private Context context;_x000D_
List<Information>data= Collections.emptyList();_x000D_
    public AdapterClass(Context context,List<Information>data){_x000D_
        inflater= LayoutInflater.from(context);_x000D_;_x000D_
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {_x000D_
       View view= inflater.inflate(R.layout.custom_row,parent,false);_x000D_
        MyViewHolder holder=new MyViewHolder(view);_x000D_
        return holder;_x000D_
    public void onBindViewHolder(MyViewHolder holder, int position) {_x000D_
        Information current=data.get(position);_x000D_
    public int getItemCount() {_x000D_
        return data.size();_x000D_
    class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{_x000D_
        TextView title;_x000D_
        ImageView icon;_x000D_
        public MyViewHolder(View itemView) {_x000D_
        public void onClick(View v) {_x000D_
            Toast.makeText(context,"The Item Clicked is: "+getPosition(),Toast.LENGTH_SHORT).show();_x000D_

VMware Workstation and Device/Credential Guard are not compatible

I'm still not convinced that Hyper-V is The Thing for me, even with last year's Docker trials and tribulations and I guess you won't want to switch very frequently, so rather than creating a new boot and confirming the boot default or waiting out the timeout with every boot I switch on demand in the console in admin mode by

bcdedit /set hypervisorlaunchtype off

Another reason for this post -- to save you some headache: You thought you switch Hyper-V on with the "on" argument again? Nope. Too simple for MiRKoS..t. It's auto!

Have fun!

how to change attribute "hidden" in jquery

Use prop() for updating the hidden property, and change() for handling the change event.

$('#check').change(function() {_x000D_
  $("#delete").prop("hidden", !this.checked);_x000D_
<script src=""></script>_x000D_
      <input id="check" type="checkbox" name="del_attachment_id[]" value="<?php echo $attachment['link'];?>">_x000D_
    <td id="delete" hidden="true">_x000D_
      the file will be deleted from the newsletter_x000D_

Moment JS start and end of given month

That's because endOf mutates the original value.

Relevant quote:

Mutates the original moment by setting it to the end of a unit of time.

Here's an example function that gives you the output you want:

function getMonthDateRange(year, month) {
    var moment = require('moment');

    // month in moment is 0 based, so 9 is actually october, subtract 1 to compensate
    // array is 'year', 'month', 'day', etc
    var startDate = moment([year, month - 1]);

    // Clone the value before .endOf()
    var endDate = moment(startDate).endOf('month');

    // just for demonstration:

    // make sure to call toDate() for plain JavaScript date type
    return { start: startDate, end: endDate };


HTML Input - already filled in text

<input type="text" value="Your value">

Use the value attribute for the pre filled in values.

keycode and charcode

Handling key events consistently is not at all easy.

Firstly, there are two different types of codes: keyboard codes (a number representing the key on the keyboard the user pressed) and character codes (a number representing a Unicode character). You can only reliably get character codes in the keypress event. Do not try to get character codes for keyup and keydown events.

Secondly, you get different sets of values in a keypress event to what you get in a keyup or keydown event.

I recommend this page as a useful resource. As a summary:

If you're interested in detecting a user typing a character, use the keypress event. IE bizarrely only stores the character code in keyCode while all other browsers store it in which. Some (but not all) browsers also store it in charCode and/or keyCode. An example keypress handler:

function(evt) {
  evt = evt || window.event;
  var charCode = evt.which || evt.keyCode;
  var charStr = String.fromCharCode(charCode);

If you're interested in detecting a non-printable key (such as a cursor key), use the keydown event. Here keyCode is always the property to use. Note that keyup events have the same properties.

function(evt) {
  evt = evt || window.event;
  var keyCode = evt.keyCode;

  // Check for left arrow key
  if (keyCode == 37) {
    alert("Left arrow");

I get conflicting provisioning settings error when I try to archive to submit an iOS app

If you are from Ionic world. You might get a "conflict code signing" error when you in the "archive" stage, as below:

... is automatically signed for development, but a conflicting code signing identity iPhone Distribution has been manually specified. Set the code signing identity value to "iPhone Developer" in the build settings editor, or switch to manual signing in the project editor. Code signing is required for product type 'Application' in SDK 'iOS 10.x'

In this case, please go to Build Settings/under signing, code signing identity, and select both as iOS Developer, not Distribution.

Go to the menu: Product/Archive again, then the issue will be fixed.

How can I create a blank/hardcoded column in a sql query?

Thank you, in PostgreSQL this works for boolean

false as placeholder

Convert char to int in C and C++

It sort of depends on what you mean by "convert".

If you have a series of characters that represents an integer, like "123456", then there are two typical ways to do that in C: Use a special-purpose conversion like atoi() or strtol(), or the general-purpose sscanf(). C++ (which is really a different language masquerading as an upgrade) adds a third, stringstreams.

If you mean you want the exact bit pattern in one of your int variables to be treated as a char, that's easier. In C the different integer types are really more of a state of mind than actual separate "types". Just start using it where chars are asked for, and you should be OK. You might need an explicit conversion to make the compiler quit whining on occasion, but all that should do is drop any extra bits past 256.

what does it mean "(include_path='.:/usr/share/pear:/usr/share/php')"?

If you look at the PHP constant PATH_SEPARATOR, you will see it being ":" for you.

If you break apart your string ".:/usr/share/pear:/usr/share/php" using that character, you will get 3 parts.

  • . (this means the current directory your code is in)
  • /usr/share/pear
  • /usr/share/php

Any attempts to include()/require() things, will look in these directories, in this order.

It is showing you that in the error message to let you know where it could NOT find the file you were trying to require()

For your first require, if that is being included from your index.php, then you dont need the dir stuff, just do...

require_once ( 'db/config.php');

How do I get a substring of a string in Python?

Maybe I missed it, but I couldn't find a complete answer on this page to the original question(s) because variables are not further discussed here. So I had to go on searching.

Since I'm not yet allowed to comment, let me add my conclusion here. I'm sure I was not the only one interested in it when accessing this page:

 >>>myString = 'Hello World'
 >>>end = 5


If you leave the first part, you get


And if you left the : in the middle as well you got the simplest substring, which would be the 5th character (count starting with 0, so it's the blank in this case):

 ' '

How to disable action bar permanently

  protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState); actionBar = getSupportActionBar();
    if (actionBar != null) {

Can you write nested functions in JavaScript?

Is this really possible.


function a(x) {    // <-- function_x000D_
  function b(y) { // <-- inner function_x000D_
    return x + y; // <-- use variables from outer scope_x000D_
  return b;       // <-- you can even return a function._x000D_

check if variable is dataframe

Use the built-in isinstance() function.

import pandas as pd

def f(var):
    if isinstance(var, pd.DataFrame):
        print("do stuff")

Spring data jpa- No bean named 'entityManagerFactory' is defined; Injection of autowired dependencies failed

In my specific case I seemed to have been missing the dependency

 <!-- -->

Dynamically set value of a file input

I ended up doing something like this for AngularJS in case someone stumbles across this question:

const imageElem = angular.element('#awardImg');

if (imageElem[0].files[0])
    vm.award.imageElem = imageElem;
    vm.award.image = imageElem[0].files[0];

And then:

if (vm.award.imageElem)
    delete vm.award.imageElem;

How do I make Git ignore file mode (chmod) changes?


git config core.fileMode false

From git-config(1):

    Tells Git if the executable bit of files in the working tree
    is to be honored.

    Some filesystems lose the executable bit when a file that is
    marked as executable is checked out, or checks out a
    non-executable file with executable bit on. git-clone(1)
    or git-init(1) probe the filesystem to see if it handles the 
    executable bit correctly and this variable is automatically
    set as necessary.

    A repository, however, may be on a filesystem that handles
    the filemode correctly, and this variable is set to true when
    created, but later may be made accessible from another
    environment that loses the filemode (e.g. exporting ext4
    via CIFS mount, visiting a Cygwin created repository with Git
    for Windows or Eclipse). In such a case it may be necessary
    to set this variable to false. See git-update-index(1).

    The default is true (when core.filemode is not specified
    in the config file).

The -c flag can be used to set this option for one-off commands:

git -c core.fileMode=false diff

And the --global flag will make it be the default behavior for the logged in user.

git config --global core.fileMode false

Changes of the global setting won't be applied to existing repositories. Additionally, git clone and git init explicitly set core.fileMode to true in the repo config as discussed in Git global core.fileMode false overridden locally on clone


core.fileMode is not the best practice and should be used carefully. This setting only covers the executable bit of mode and never the read/write bits. In many cases you think you need this setting because you did something like chmod -R 777, making all your files executable. But in most projects most files don't need and should not be executable for security reasons.

The proper way to solve this kind of situation is to handle folder and file permission separately, with something like:

find . -type d -exec chmod a+rwx {} \; # Make folders traversable and read/write
find . -type f -exec chmod a+rw {} \;  # Make files read/write

If you do that, you'll never need to use core.fileMode, except in very rare environment.

Changing factor levels with dplyr mutate

From my understanding, the currently accepted answer only changes the order of the factor levels, not the actual labels (i.e., how the levels of the factor are called). To illustrate the difference between levels and labels, consider the following example:

Turn cyl into factor (specifying levels would not be necessary as they are coded in alphanumeric order):

    mtcars2 <- mtcars %>% mutate(cyl = factor(cyl, levels = c(4, 6, 8))) 
    #[1] 6 6 4 6 8
    #Levels: 4 6 8

Change the order of levels (but not the labels itself: cyl is still the same column)

    mtcars3 <- mtcars2 %>% mutate(cyl = factor(cyl, levels = c(8, 6, 4))) 
    #[1] 6 6 4 6 8
    #Levels: 8 6 4
    #[1] TRUE

Assign new labels to cyl The order of the labels was: c(8, 6, 4), hence we specify new labels as follows:

    mtcars4 <- mtcars3 %>% mutate(cyl = factor(cyl, labels = c("new_value_for_8", 
                                                               "new_value_for_4" )))
    #[1] new_value_for_6 new_value_for_6 new_value_for_4 new_value_for_6 new_value_for_8
    #Levels: new_value_for_8 new_value_for_6 new_value_for_4

Note how this column differs from our first columns:

    #[1] TRUE 
    #Note: TRUE here indicates that all values are unequal because I used != instead of ==
    #as.character() was required as the levels were numeric and thus not comparable to a character vector

More details:

If we were to change the levels of cyl using mtcars2 instead of mtcars3, we would need to specify the labels differently to get the same result. The order of labels for mtcars2 was: c(4, 6, 8), hence we specify new labels as follows

    #change labels of mtcars2 (order used to be: c(4, 6, 8)
    mtcars5 <- mtcars2 %>% mutate(cyl = factor(cyl, labels = c("new_value_for_4", 
                                                               "new_value_for_8" )))

Unlike mtcars3$cyl and mtcars4$cyl, the labels of mtcars4$cyl and mtcars5$cyl are thus identical, even though their levels have a different order.

    #[1] new_value_for_6 new_value_for_6 new_value_for_4 new_value_for_6 new_value_for_8
    #Levels: new_value_for_8 new_value_for_6 new_value_for_4

    #[1] new_value_for_6 new_value_for_6 new_value_for_4 new_value_for_6 new_value_for_8
    #Levels: new_value_for_4 new_value_for_6 new_value_for_8

    #[1] TRUE

    levels(mtcars4$cyl) == levels(mtcars5$cyl)

WPF TabItem Header Styling

Try this style instead, it modifies the template itself. In there you can change everything you need to transparent:

<Style TargetType="{x:Type TabItem}">
  <Setter Property="Template">
      <ControlTemplate TargetType="{x:Type TabItem}">
          <Border Name="Border" Margin="0,0,0,0" Background="Transparent"
                  BorderBrush="Black" BorderThickness="1,1,1,1" CornerRadius="5">
            <ContentPresenter x:Name="ContentSite" VerticalAlignment="Center"
                              ContentSource="Header" Margin="12,2,12,2"
            <RotateTransform Angle="270" />
          <Trigger Property="IsSelected" Value="True">
            <Setter Property="Panel.ZIndex" Value="100" />
            <Setter TargetName="Border" Property="Background" Value="Red" />
            <Setter TargetName="Border" Property="BorderThickness" Value="1,1,1,0" />
          <Trigger Property="IsEnabled" Value="False">
            <Setter TargetName="Border" Property="Background" Value="DarkRed" />
            <Setter TargetName="Border" Property="BorderBrush" Value="Black" />
            <Setter Property="Foreground" Value="DarkGray" />

How to hide action bar before activity is created, and then show it again?

For Splashscreen you should use this line in manifest and don't use getActionBar()

<item name="android:windowActionBar">false</item>

and once when Splash Activity is finished in the main Activity use below or nothing

<item name="android:windowActionBar">true</item>

Redirect from web api post action


public HttpResponseMessage Post()
    // ... do the job

    // now redirect
    var response = Request.CreateResponse(HttpStatusCode.Moved);
    response.Headers.Location = new Uri("");
    return response;

How to Compare a long value is equal to Long value

I will share that How do I do it since Java 7 -

Long first = 12345L, second = 123L;

output returned : false

and second example of match is -

Long first = 12345L, second = 12345L;

output returned : true

So, I believe in equals method for comparing Object's value, Hope it helps you, thanks.

Minimum 6 characters regex expression

Something along the lines of this?

<asp:TextBox id="txtUsername" runat="server" />

    ErrorMessage="Field not valid!"
    ValidationExpression="[0-9a-zA-Z]{6,}" />

How to output oracle sql result into a file in windows?

Use the spool:

spool myoutputfile.txt
select * from users;
spool off;

Note that this will create myoutputfile.txt in the directory from which you ran SQL*Plus.

If you need to run this from a SQL file (e.g., "tmp.sql") when SQLPlus starts up and output to a file named "output.txt":


select * from users;


sqlplus -s username/password@sid @tmp.sql > output.txt

Mind you, I don't have an Oracle instance in front of me right now, so you might need to do some of your own work to debug what I've written from memory.

How to copy a row and insert in same table with a autoincrement field in MySQL?

Dump the row you want to sql and then use the generated SQL, less the ID column to import it back in.

Use FontAwesome or Glyphicons with css :before

This is the easiest way to do what you are trying to do:

 ul {
   list-style-type: none;

<ul class="icons">
 <li><i class="fa fa-bomb"></i> Lists</li>
 <li><i class="fa fa-bomb"></i> Buttons</li>
 <li><i class="fa fa-bomb"></i> Button groups</li>
 <li><i class="fa fa-bomb"></i> Navigation</li>
 <li><i class="fa fa-bomb"></i> Prepended form inputs</li>

Determine command line working directory when running node bin script

path.resolve('.') is also a reliable and clean option, because we almost always require('path'). It will give you absolute path of the directory from where it is called.

How to get JSON data from the URL (REST API) to UI using jQuery or plain JavaScript?

You can use us jquery function getJson :

    $.getJSON('/api/rest/abc', function(data) {

Exponentiation in Python - should I prefer ** operator instead of math.pow and math.sqrt?

Even in base Python you can do the computation in generic form

result = sum(x**2 for x in some_vector) ** 0.5

x ** 2 is surely not an hack and the computation performed is the same (I checked with cpython source code). I actually find it more readable (and readability counts).

Using instead x ** 0.5 to take the square root doesn't do the exact same computations as math.sqrt as the former (probably) is computed using logarithms and the latter (probably) using the specific numeric instruction of the math processor.

I often use x ** 0.5 simply because I don't want to add math just for that. I'd expect however a specific instruction for the square root to work better (more accurately) than a multi-step operation with logarithms.

Python: How to ignore an exception and proceed?

Try this:


Error occurred during initialization of VM (java/lang/NoClassDefFoundError: java/lang/Object)

please try to execute java from

C:\Program Files\Java\jdk1.7.0_10\bin

i.e from the location where java is installed.

If it is successful, it means that the error lies somewhere in the classpath.

Also, this guy seems to have had the same problem as yours, check it out

In UML class diagrams, what are Boundary Classes, Control Classes, and Entity Classes?

Robustness diagrams are written after use cases and before class diagrams. They help to identify the roles of use case steps. You can use them to ensure your use cases are sufficiently robust to represent usage requirements for the system you're building.

They involve:

  1. Actors
  2. Use Cases
  3. Entities
  4. Boundaries
  5. Controls

Whereas the Model-View-Controller pattern is used for user interfaces, the Entity-Control-Boundary Pattern (ECB) is used for systems. The following aspects of ECB can be likened to an abstract version of MVC, if that's helpful:

UML notation

Entities (model)
Objects representing system data, often from the domain model.

Boundaries (view/service collaborator)
Objects that interface with system actors (e.g. a user or external service). Windows, screens and menus are examples of boundaries that interface with users.

Controls (controller)
Objects that mediate between boundaries and entities. These serve as the glue between boundary elements and entity elements, implementing the logic required to manage the various elements and their interactions. It is important to understand that you may decide to implement controllers within your design as something other than objects – many controllers are simple enough to be implemented as a method of an entity or boundary class for example.

Four rules apply to their communication:

  1. Actors can only talk to boundary objects.
  2. Boundary objects can only talk to controllers and actors.
  3. Entity objects can only talk to controllers.
  4. Controllers can talk to boundary objects and entity objects, and to other controllers, but not to actors

Communication allowed:

         Entity    Boundary   Control
Entity     X                     X
Boundary                         X
Control    X          X          X

Setting Oracle 11g Session Timeout

I came to this question looking for a way to enable oracle session pool expiration based on total session lifetime instead of idle time. Another goal is to avoid force closes unexpected to application.

It seems it's possible by setting pool validation query to

select 1 from V$SESSION 
where AUDSID = userenv('SESSIONID') and sysdate-LOGON_TIME < 30/24/60

This would close sessions aging over 30 minutes in predictable manner that doesn't affect application.

C++ - struct vs. class

The other difference is that

template<class T> ...

is allowed, but

template<struct T> ...

is not.

How to initialize all members of an array to the same value?

I know the original question explicitly mentions C and not C++, but if you (like me) came here looking for a solution for C++ arrays, here's a neat trick:

If your compiler supports fold expressions, you can use template magic and std::index_sequence to generate an initializer list with the value that you want. And you can even constexpr it and feel like a boss:

#include <array>

/// [3]
/// This functions's only purpose is to ignore the index given as the second
/// template argument and to always produce the value passed in.
template<class T, size_t /*ignored*/>
constexpr T identity_func(const T& value) {
    return value;

/// [2]
/// At this point, we have a list of indices that we can unfold
/// into an initializer list using the `identity_func` above.
template<class T, size_t... Indices>
constexpr std::array<T, sizeof...(Indices)>
make_array_of_impl(const T& value, std::index_sequence<Indices...>) {
    return {identity_func<T, Indices>(value)...};

/// [1]
/// This is the user-facing function.
/// The template arguments are swapped compared to the order used
/// for std::array, this way we can let the compiler infer the type
/// from the given value but still define it explicitly if we want to.
template<size_t Size, class T>
constexpr std::array<T, Size> 
make_array_of(const T& value) {
    using Indices = std::make_index_sequence<Size>;
    return make_array_of_impl(value, Indices{});

// std::array<int, 4>{42, 42, 42, 42}
constexpr auto test_array = make_array_of<4/*, int*/>(42);
static_assert(test_array[0] == 42);
static_assert(test_array[1] == 42);
static_assert(test_array[2] == 42);
static_assert(test_array[3] == 42);
// static_assert(test_array[4] == 42); out of bounds

You can take a look at the code at work (at Wandbox)

How to check if command line tools is installed


Below are a few extra steps on a fresh Mac that some people might need. This adds a little to @jnovack's excellent answer.

Update: A few other notes when setting this up:

Make sure your admin user has a password. A blank password won't work when trying to enable a root user.

System Preferences > Users and Groups > (select user) > Change password

Then to enable root, run dsenableroot in a terminal:

$ dsenableroot
username = mac_admin_user
user password:
root password:
verify root password:

dsenableroot:: ***Successfully enabled root user.

Type in the admin user's password, then the new enabled root password twice.

Next type:

sudo gcc


sudo make

It will respond with something like the following:

WARNING: Improper use of the sudo command could lead to data loss
or the deletion of important system files. Please double-check your
typing when using sudo. Type "man sudo" for more information.

To proceed, enter your password, or type Ctrl-C to abort.


You have not agreed to the Xcode license agreements. You must agree to 
both license agreements below in order to use Xcode.

Press enter when it prompts to show you the license agreement.

Hit the Enter key to view the license agreements at 



Press q to exit the license agreement view.

By typing 'agree' you are agreeing to the terms of the software license 
agreements. Type 'print' to print them or anything else to cancel, 
[agree, print, cancel]

Type agree. And then it will end with:

clang: error: no input files 

Which basically means that you didn't give make or gcc any input files.

Here is what the check looked like:

$ xcode-select -p


With Mavericks, it is a little different now.

When the tools were NOT found, this is what the command pkgutil command returned:

$ pkgutil
No receipt for '' found at '/'.

To install the command line tools, this works nicely from the Terminal, with a nice gui and everything.

$ xcode-select --install

When they were found, this is what the pkgutil command returned:

$ pkgutil
volume: /
location: /
install-time: 1384149984

This command returned the same before and after the install.

$ pkgutil
No receipt for '' found at '/'.

Also I had the component for the CLT selected and installed in xcode's downloads section before, but it seems like it didn't make it to the terminal...

Hope that helps.

Twitter Bootstrap: Print content of modal window

you can download printThis lib from this source and include it into your html page

Call the following jquery to print all the content including the content that is not viewable. You may include your css files in an array if you have multiple css files.

    debug: false,              
    importCSS: true,             
    importStyle: true,         
    printContainer: true,       
    loadCSS: "../css/style.css", 
    pageTitle: "My Modal",             
    removeInline: false,        
    printDelay: 333,            
    header: null,             
    formValues: true          

PHP - Check if two arrays are equal

If you want to check non associative arrays, here is the solution:

$a = ['blog', 'company'];
$b = ['company', 'blog'];

(count(array_unique(array_merge($a, $b))) === count($a)) ? 'Equals' : 'Not Equals';
// Equals

Grouped bar plot in ggplot

First you need to get the counts for each category, i.e. how many Bads and Goods and so on are there for each group (Food, Music, People). This would be done like so:

raw <- read.csv("",sep=",")
raw[,2]<-factor(raw[,2],levels=c("Very Bad","Bad","Good","Very Good"),ordered=FALSE)
raw[,3]<-factor(raw[,3],levels=c("Very Bad","Bad","Good","Very Good"),ordered=FALSE)
raw[,4]<-factor(raw[,4],levels=c("Very Bad","Bad","Good","Very Good"),ordered=FALSE)

raw=raw[,c(2,3,4)] # getting rid of the "people" variable as I see no use for it

freq=table(col(raw), as.matrix(raw)) # get the counts of each factor level

Then you need to create a data frame out of it, melt it and plot it:

Names=c("Food","Music","People")     # create list of names
data=data.frame(cbind(freq),Names)   # combine them into a data frame
data=data[,c(5,3,1,2,4)]             # sort columns

# melt the data frame for plotting
data.m <- melt(data, id.vars='Names')

# plot everything
ggplot(data.m, aes(Names, value)) +   
  geom_bar(aes(fill = variable), position = "dodge", stat="identity")

Is this what you're after?

enter image description here

To clarify a little bit, in ggplot multiple grouping bar you had a data frame that looked like this:

> head(df)
1  1    A  1980   450   338   154    36    13     9
2  2    A  2000   288   407   212    54    16    23
3  3    A  2020   196   434   246    68    19    36
4  4    B  1980   111   326   441    90    21    11
5  5    B  2000    63   298   443   133    42    21
6  6    B  2020    36   257   462   162    55    30

Since you have numerical values in columns 4-9, which would later be plotted on the y axis, this can be easily transformed with reshape and plotted.

For our current data set, we needed something similar, so we used freq=table(col(raw), as.matrix(raw)) to get this:

> data
   Names Very.Bad Bad Good Very.Good
1   Food        7   6    5         2
2  Music        5   5    7         3
3 People        6   3    7         4

Just imagine you have Very.Bad, Bad, Good and so on instead of X1PCE, X2PCE, X3PCE. See the similarity? But we needed to create such structure first. Hence the freq=table(col(raw), as.matrix(raw)).

PHP Converting Integer to Date, reverse of strtotime

The time() function displays the seconds between now and the unix epoch , 01 01 1970 (00:00:00 GMT). The strtotime() transforms a normal date format into a time() format. So the representation of that date into seconds will be : 1388516401


Checkout one file from Subversion

An update in case what you really need can be covered by having the file included in a checkout of another folder.

Since SVN 1.6 you can make file externals, a kind of svn links. It means that you can have another versioned folder that includes a single file. Committing changes to the file in a checkout of this folder is also possible.

It's very simple, checkout the folder you want to include the file, and simply add a property to the folder

svn propedit svn:externals .

with content like this:

file.txt /repos/path/to/file.txt

After you commit this, the file will appear in future checkouts of the folder. Basically it works, but there are some limitations as described in the documentation linked above.

Xpath: select div that contains class AND whose specific child element contains text

You can use ancestor. I find that this is easier to read because the element you are actually selecting is at the end of the path.

//span[contains(text(),'someText')]/ancestor::div[contains(@class, 'measure-tab')]

What is the easiest way to initialize a std::vector with hardcoded elements?

In C++0x you will be able to do it in the same way that you did with an array, but not in the current standard.

With only language support you can use:

int tmp[] = { 10, 20, 30 };
std::vector<int> v( tmp, tmp+3 ); // use some utility to avoid hardcoding the size here

If you can add other libraries you could try boost::assignment:

vector<int> v = list_of(10)(20)(30);

To avoid hardcoding the size of an array:

// option 1, typesafe, not a compile time constant
template <typename T, std::size_t N>
inline std::size_t size_of_array( T (&)[N] ) {
   return N;
// option 2, not typesafe, compile time constant
#define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))

// option 3, typesafe, compile time constant
template <typename T, std::size_t N>
char (&sizeof_array( T(&)[N] ))[N];    // declared, undefined
#define ARRAY_SIZE(x) sizeof(sizeof_array(x))

how to load url into div tag

You need to use an iframe.

<script type="text/javascript">
<iframe id="content" src="about:blank"></iframe>

Changing capitalization of filenames in Git

File names under OS X are not case sensitive (by default). This is more of an OS problem than a Git problem. If you remove and readd the file, you should get what you want, or rename it to something else and then rename it back.

What is the default Precision and Scale for a Number in Oracle?

I believe the default precision is 38, default scale is zero. However the actual size of an instance of this column, is dynamic. It will take as much space as needed to store the value, or max 21 bytes.

AmazonS3 putObject with InputStream length example

adding log4j-1.2.12.jar file has resolved the issue for me Broken pipe

I agree with @arcy, the problem is on client side, on my case it was because of nginx, let me elaborate I am using nginx as the frontend (so I can distribute load, ssl, etc ...) and using proxy_pass to forward the appropiate requests to tomcat.

There is a default value for the nginx variable proxy_read_timeout of 60s that should be enough, but on some peak moments my setup would error with the Broken pipe changing the value will help until the root cause (60s should be enough) can be fixed.

NOTE: I made a new answer so I could expand a bit more with my case (it was the only mention I found about this error on internet after looking quite a lot)

How to iterate through XML in Powershell?

You can also do it without the [xml] cast. (Although xpath is a world unto itself.

$xml = (select-xml -xpath / -path stack.xml).node

Or just this, xpath is case sensitive. Both have the same output:

$xml = (select-xml -xpath /Objects/Object/Property -path stack.xml).node

Name         Type                                                #text
----         ----                                                -----
DisplayName  System.String                                       SQL Server (MSSQLSERVER)
ServiceState Microsoft.SqlServer.Management.Smo.Wmi.ServiceState Running
DisplayName  System.String                                       SQL Server Agent (MSSQLSERVER)
ServiceState Microsoft.SqlServer.Management.Smo.Wmi.ServiceState Stopped

New to unit testing, how to write great tests?

It's worth noting that retro-fitting unit tests into existing code is far more difficult than driving the creation of that code with tests in the first place. That's one of the big questions in dealing with legacy applications... how to unit test? This has been asked many times before (so you may be closed as a dupe question), and people usually end up here:

Moving existing code to Test Driven Development

I second the accepted answer's book recommendation, but beyond that there's more information linked in the answers there.

Create an Android GPS tracking application

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

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

Debugging the source code will surely help you.

Set NA to 0 in R

A solution using mutate_all from dplyr in case you want to add that to your dplyr pipeline:

df %>%
  mutate_all(funs(ifelse(, 0, .)))


   A B C
1  0 0 0
2  1 0 0
3  2 0 2
4  3 0 5
5  0 0 2
6  0 0 1
7  1 0 1
8  2 0 5
9  3 0 2
10 0 0 4
11 0 0 3
12 1 0 5
13 2 0 5
14 3 0 0
15 0 0 1

If in any case you only want to replace the NA's in numeric columns, which I assume it might be the case in modeling, you can use mutate_if:

df %>%
  mutate_if(is.numeric, funs(ifelse(, 0, .)))

or in base R:

replace(, 0)


   A    B C
1  0    0 0
2  1 <NA> 0
3  2    0 2
4  3 <NA> 5
5  0    0 2
6  0 <NA> 1
7  1    0 1
8  2 <NA> 5
9  3    0 2
10 0 <NA> 4
11 0    0 3
12 1 <NA> 5
13 2    0 5
14 3 <NA> 0
15 0    0 1


with dplyr 1.0.0, across is introduced:

# Replace `NA` for all columns
df %>%
  mutate(across(everything(), ~ ifelse(, 0, .)))

# Replace `NA` for numeric columns
df %>%
  mutate(across(where(is.numeric), ~ ifelse(, 0, .)))


df <- data.frame(A=rep(c(0:3, NA), 3), 
                 B=rep(c("0", NA), length.out = 15), 
                 C=sample(c(0:5, NA), 15, replace = TRUE))

java.text.ParseException: Unparseable date

Check your Pattern (DD-MMM-YYYY) and the input for the parse("29-11-2018") method. Input to the parse method should follow : DD-MMM-YYYY i,e. 21-AUG-2019

In My Code:

String pattern = "DD-MMM-YYYY";
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(pattern);

    try {
        startDate = simpleDateFormat.parse("29-11-2018");// here no pattern match 
        endDate = simpleDateFormat.parse("28-AUG-2019");// Ok 
    } catch (ParseException e) {
        // TODO Auto-generated catch block

For vs. while in C programming?

/* while loop

5 bucks

1 chocolate = 1 bucks

while my money is greater than 1 bucks 
  select chocolate
  pay 1 bucks to the shopkeeper
  money = money - 1

come to home and cant go to while shop because my money = 0 bucks */

int main(){
  int money = 5;

  while( money >= 1){   
    printf("inside the shopk and selecting chocolate\n");
    printf("after selecting chocolate paying 1 bucks\n");
    money = money - 1 ;  
    printf("my remaining moeny = %d\n", money);

  printf("dont have money cant go inside the shop, money = %d",  money);

  return 0;

infinite money

while( codition ){ // condition will always true ....infinite loop

please visit this video for better understanding

/* for loop

5 bucks

for my money is greater than equal to 1 bucks   0      money >= 1
  select chocolate
  pay 1 bucks to the shopkeeper
  money = money - 1  1-1 => 0


int main(){

  int money = 5;
  for( ; money >= 1; ){     0>=1  false 
    printf("select chocolate \n");
    printf("paying 1 bucks to the shopkeeper\n");
    money = money - 1;    1-1 = 0
    printf(" remaining money =%d\n", money);

  return 0;

For better understanding please visit

`getchar()` gives the same output as the input string

There is an underlying buffer/stream that getchar() and friends read from. When you enter text, the text is stored in a buffer somewhere. getchar() can stream through it one character at a time. Each read returns the next character until it reaches the end of the buffer. The reason it's not asking you for subsequent characters is that it can fetch the next one from the buffer.

If you run your script and type directly into it, it will continue to prompt you for input until you press CTRL+D (end of file). If you call it like ./program < myInput where myInput is a text file with some data, it will get the EOF when it reaches the end of the input. EOF isn't a character that exists in the stream, but a sentinel value to indicate when the end of the input has been reached.

As an extra warning, I believe getchar() will also return EOF if it encounters an error, so you'll want to check ferror(). Example below (not tested, but you get the idea).

main() {
    int c;
    do {
        c = getchar();
        if (c == EOF && ferror()) {
        else {
    while(c != EOF);

How to execute python file in linux

Add to top of the code,


Then, run the following command on the terminal,

chmod +x yourScriptFile

Java Enum return Int

In my opinion the most readable version

    PULL_UP {
        public int getValue() {
            return 1;
        public int getValue() {
            return 0;

    public abstract int getValue();

How do I draw a shadow under a UIView?

Sketch Shadow Using IBDesignable and IBInspectable in Swift 4




Shadow Exampl


@IBDesignable class ShadowView: UIView {

    @IBInspectable var shadowColor: UIColor? {
        get {
            if let color = layer.shadowColor {
                return UIColor(cgColor: color)
            return nil
        set {
            if let color = newValue {
                layer.shadowColor = color.cgColor
            } else {
                layer.shadowColor = nil

    @IBInspectable var shadowOpacity: Float {
        get {
            return layer.shadowOpacity
        set {
            layer.shadowOpacity = newValue

    @IBInspectable var shadowOffset: CGPoint {
        get {
            return CGPoint(x: layer.shadowOffset.width, y:layer.shadowOffset.height)
        set {
            layer.shadowOffset = CGSize(width: newValue.x, height: newValue.y)


    @IBInspectable var shadowBlur: CGFloat {
        get {
            return layer.shadowRadius
        set {
            layer.shadowRadius = newValue / 2.0

    @IBInspectable var shadowSpread: CGFloat = 0 {
        didSet {
            if shadowSpread == 0 {
                layer.shadowPath = nil
            } else {
                let dx = -shadowSpread
                let rect = bounds.insetBy(dx: dx, dy: dx)
                layer.shadowPath = UIBezierPath(rect: rect).cgPath



How can I create a product key for my C# application?

One simple method is using a Globally Unique Identifier (GUID). GUIDs are usually stored as 128-bit values and are commonly displayed as 32 hexadecimal digits with groups separated by hyphens, such as {21EC2020-3AEA-4069-A2DD-08002B30309D}.

Use the following code in C# by System.Guid.NewGuid().

getKey = System.Guid.NewGuid().ToString().Substring(0, 8).ToUpper(); //Will generate a random 8 digit hexadecimal string.

_key = Convert.ToString(Regex.Replace(getKey, ".{4}", "$0/")); // And use this to separate every four digits with a "/".

I hope it helps.

How do you create a dictionary in Java?

There's an Abstract Class Dictionary

However this requires implementation.

Java gives us a nice implementation called a Hashtable

Which version of MVC am I using?

Select the System.Web.Mvc assembly in the "References" folder in the solution explorer. Bring up the properties window (F4) and check the Version

Reference Properties

Create nice column output in python

A slight variation on a previous answer (I don't have enough rep to comment on it). The format library lets you specify the width and alignment of an element but not where it starts, ie, you can say "be 20 columns wide" but not "start in column 20". Which leads to this issue:

table_data = [
    ['a', 'b', 'c'],
    ['aaaaaaaaaa', 'b', 'c'], 
    ['a', 'bbbbbbbbbb', 'c']

print("first row: {: >20} {: >20} {: >20}".format(*table_data[0]))
print("second row: {: >20} {: >20} {: >20}".format(*table_data[1]))
print("third row: {: >20} {: >20} {: >20}".format(*table_data[2]))


first row:                    a                    b                    c
second row:           aaaaaaaaaa                    b                    c
third row:                    a           bbbbbbbbbb                    c

The answer of course is to format the literal strings as well, which combines slightly weirdly with the format:

table_data = [
    ['a', 'b', 'c'],
    ['aaaaaaaaaa', 'b', 'c'], 
    ['a', 'bbbbbbbbbb', 'c']

print(f"{'first row:': <20} {table_data[0][0]: >20} {table_data[0][1]: >20} {table_data[0][2]: >20}")
print("{: <20} {: >20} {: >20} {: >20}".format(*['second row:', *table_data[1]]))
print("{: <20} {: >20} {: >20} {: >20}".format(*['third row:', *table_data[1]]))


first row:                              a                    b                    c
second row:                    aaaaaaaaaa                    b                    c
third row:                     aaaaaaaaaa                    b                    c

JavaScript get window X/Y position for scroll

Using pure javascript you can use Window.scrollX and Window.scrollY

window.addEventListener("scroll", function(event) {
    var top = this.scrollY,
        left =this.scrollX;
}, false);


The pageXOffset property is an alias for the scrollX property, and The pageYOffset property is an alias for the scrollY property:

window.pageXOffset == window.scrollX; // always true
window.pageYOffset == window.scrollY; // always true

Here is a quick demo

window.addEventListener("scroll", function(event) {_x000D_
    var top = this.scrollY,_x000D_
        left = this.scrollX;_x000D_
    var horizontalScroll = document.querySelector(".horizontalScroll"),_x000D_
        verticalScroll = document.querySelector(".verticalScroll");_x000D_
    horizontalScroll.innerHTML = "Scroll X: " + left + "px";_x000D_
      verticalScroll.innerHTML = "Scroll Y: " + top + "px";_x000D_
}, false);
*{box-sizing: border-box}_x000D_
:root{height: 200vh;width: 200vw}_x000D_
    position: fixed;_x000D_
    background: black;_x000D_
    color: green;_x000D_
    height: 64px;_x000D_
.wrapper div{_x000D_
    display: inline;_x000D_
    width: 50%;_x000D_
    float: left;_x000D_
    text-align: center;_x000D_
    line-height: 64px_x000D_
.horizontalScroll{color: orange}
<div class=wrapper>_x000D_
    <div class=horizontalScroll>Scroll (x,y) to </div>_x000D_
    <div class=verticalScroll>see me in action</div>_x000D_

Populate one dropdown based on selection in another

Could you please have a look at:

Basically, the data is stored in an Array and the options are added accordingly. I think the code says more than a thousand words.

var data = [ // The data
    ['ten', [
    ['twenty', [
        'twentyone', 'twentytwo'

$a = $('#a'); // The dropdowns
$b = $('#b');

for(var i = 0; i < data.length; i++) {
    var first = data[i][0];
    $a.append($("<option>"). // Add options
       data("sel", i).

$a.change(function() {
    var index = $(this).children('option:selected').data('sel');
    var second = data[index][1]; // The second-choice data

    $b.html(''); // Clear existing options in second dropdown

    for(var j = 0; j < second.length; j++) {
        $b.append($("<option>"). // Add options
           data("sel", j).
}).change(); // Trigger once to add options at load of first choice

Cannot find Microsoft.Office.Interop Visual Studio

If you're using Visual Studio 2015 and you're encountering this problem, you can install MS Office Developer Tools for VS2015 here.

How can I install an older version of a package via NuGet?

Now, it's very much simplified in Visual Studio 2015 and later. You can do downgrade / upgrade within the User interface itself, without executing commands in the Package Manager Console.

  1. Right click on your project and *go to Manage NuGet Packages.

  2. Look at the below image.

    • Select your Package and Choose the Version, which you wanted to install.

NuGet Package Manager window of Project

Very very simple, isn't it? :)

Getting HTTP code in PHP using curl

First make sure if the URL is actually valid (a string, not empty, good syntax), this is quick to check server side. For example, doing this first could save a lot of time:

if(!$url || !is_string($url) || ! preg_match('/^http(s)?:\/\/[a-z0-9-]+(.[a-z0-9-]+)*(:[0-9]+)?(\/.*)?$/i', $url)){
    return false;

Make sure you only fetch the headers, not the body content:

@curl_setopt($ch, CURLOPT_HEADER  , true);  // we want headers
@curl_setopt($ch, CURLOPT_NOBODY  , true);  // we don't need body

For more details on getting the URL status http code I refer to another post I made (it also helps with following redirects):

As a whole:

$url = '';
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_HEADER, true);    // we want headers
curl_setopt($ch, CURLOPT_NOBODY, true);    // we don't need body
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_TIMEOUT,10);
$output = curl_exec($ch);
$httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);

echo 'HTTP code: ' . $httpcode;

DB2 Query to retrieve all table names for a given schema

You should try this:

select TABNAME from syscat.tables where tabschema = 'yourschemaname'";

How to ignore whitespace in a regular expression subject string?

Addressing Steven's comment to Sam Dufel's answer

Thanks, sounds like that's the way to go. But I just realized that I only want the optional whitespace characters if they follow a newline. So for example, "c\n ats" or "ca\n ts" should match. But wouldn't want "c ats" to match if there is no newline. Any ideas on how that might be done?

This should do the trick:


See this page for all the different variations of 'cats' that this matches.

You can also solve this using conditionals, but they are not supported in the javascript flavor of regex.

Android ListView Divider

The problem you're having stems from the fact that you're missing android:dividerHeight, which you need, and the fact that you're trying to specify a line weight in your drawable, which you can't do with dividers for some odd reason. Essentially to get your example to work you could do something like the following:

Create your drawable as either a rectangle or a line, either works you just can't try to set any dimensions on it, so either:

<shape xmlns:android="" android:shape="line">
     <stroke android:color="#8F8F8F" android:dashWidth="1dp" android:dashGap="1dp" />


<shape xmlns:android=""  android:shape="rectangle">
     <solid android:color="#8F8F8F"/>

Then create a custom style (just a preference but I like to be able to reuse stuff)

<style name="dividedListStyle" parent="@android:style/Widget.ListView">
    <item name="android:cacheColorHint">@android:color/transparent</item>
    <item name="android:divider">@drawable/list_divider</item>
    <item name="android:dividerHeight">1dp</item>

Finally declare your list view using the custom style:


I'm assuming you know how to use these snippets, if not let me know. Basically the answer to your question is that you can't set the divider thickness in the drawable, you have to leave the width undefined there and use android:dividerHeight to set it instead.

Unable to load script from assets on windows


first time, I created new app with react-native init project-name. I got the same error. so i do the following steps to resolve this in my case.

  1. Firstly run sudo chown user-name-of-pc /dev/kvm in my case.
  2. While debugging from your Android phone, select Use USB to Transfer photos (PTP).

  3. Create Folder assets in project-name/android/app/src/main

  4. make sure index.js be avaiable into your project root directory and then run below command from console after cd project-name directory.

react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/ --assets-dest android/app/src/main/res

or for then

react-native bundle --platform android --dev false --entry-file --bundle-output android/app/src/main/assets/ --assets-dest android/app/src/main/res

  1. run command ./ in android-studio/bin directory. It will opens up Android Studio.

  2. run command react-native run-android.

enter image description here

How to check if all of the following items are in a list?

Not OP's case, but - for anyone who wants to assert intersection in dicts and ended up here due to poor googling (e.g. me) - you need to work with dict.items:

>>> a = {'key': 'value'}
>>> b = {'key': 'value', 'extra_key': 'extra_value'}
>>> all(item in a.items() for item in b.items())
>>> all(item in b.items() for item in a.items())

That's because dict.items returns tuples of key/value pairs, and much like any object in Python, they're interchangeably comparable

C free(): invalid pointer

You're attempting to free something that isn't a pointer to a "freeable" memory address. Just because something is an address doesn't mean that you need to or should free it.

There are two main types of memory you seem to be confusing - stack memory and heap memory.

  • Stack memory lives in the live span of the function. It's temporary space for things that shouldn't grow too big. When you call the function main, it sets aside some memory for your variables you've declared (p,token, and so on).

  • Heap memory lives from when you malloc it to when you free it. You can use much more heap memory than you can stack memory. You also need to keep track of it - it's not easy like stack memory!

You have a few errors:

  • You're trying to free memory that's not heap memory. Don't do that.

  • You're trying to free the inside of a block of memory. When you have in fact allocated a block of memory, you can only free it from the pointer returned by malloc. That is to say, only from the beginning of the block. You can't free a portion of the block from the inside.

For your bit of code here, you probably want to find a way to copy relevant portion of memory to somewhere else...say another block of memory you've set aside. Or you can modify the original string if you want (hint: char value 0 is the null terminator and tells functions like printf to stop reading the string).

EDIT: The malloc function does allocate heap memory*.

"9.9.1 The malloc and free Functions

The C standard library provides an explicit allocator known as the malloc package. Programs allocate blocks from the heap by calling the malloc function."

~Computer Systems : A Programmer's Perspective, 2nd Edition, Bryant & O'Hallaron, 2011

EDIT 2: * The C standard does not, in fact, specify anything about the heap or the stack. However, for anyone learning on a relevant desktop/laptop machine, the distinction is probably unnecessary and confusing if anything, especially if you're learning about how your program is stored and executed. When you find yourself working on something like an AVR microcontroller as H2CO3 has, it is definitely worthwhile to note all the differences, which from my own experience with embedded systems, extend well past memory allocation.

How to check if any value is NaN in a Pandas DataFrame

df.isnull().any().any() should do it.

How can I set the PATH variable for javac so I can manually compile my .java works?

You don't need to do any complex command-line stuff or edit any system code. You simply have to open Computer, showing all of your disks and open properties. From there, go to Advanced System Settings and click Environment Variables. Scroll down in the lower list box and edit Path. Do not erase anything already there. Put a ; after it and then type in your path. To test, open command prompt and do "javac", it should list around 20 programs. You would be finished at that point.

By the way, the command to compile is javac -g not just javac.

Happy coding!

org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'customerService' is defined

Please make sure that your applicationContext.xml file is loaded by specifying it in your web.xml file:


Remove all unused resources from an android project

There really excellent answers in here suggesting good tools

But if you are intending to remove png-drawables (or other image files), you should also consider moving all the drawable-xxxx folders out of your project into a temporary folder, then do a rebuild all, and take a look at the build message list which will tell you which ones are missing.

This can be specially useful if you want to get an overview of which resources you are effectively using and maybe replace them with an icon font or svg resources, possibly with the help of the Android Iconics library.

Adding a new value to an existing ENUM Type

Simplest: get rid of enums. They are not easily modifiable, and thus should very rarely be used.

Laravel view not found exception

Create the index.blade.php file in the views folder, that should be all

Node Version Manager install - nvm command not found

For the issue was fixed when I moved

export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/" ] && \. "$NVM_DIR/"  # This loads nvm
[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion

to the end of .zshrc

Listing all extras of an Intent

private TextView tv;

protected void onCreate(Bundle savedInstanceState) {

    tv = new TextView(this);
    tv.setText("Extras: \n\r");


    StringBuilder str = new StringBuilder();
    Bundle bundle = getIntent().getExtras();
    if (bundle != null) {
        Set<String> keys = bundle.keySet();
        Iterator<String> it = keys.iterator();
        while (it.hasNext()) {
            String key =;

How to format a QString?

Use QString::arg() for the same effect.

Is there a way to check if a file is in use?

You can return a task which gives you a stream as soon as it becomes available. It's a simplified solution, but it is a good starting point. It's thread safe.

private async Task<Stream> GetStreamAsync()
        return new FileStream("sample.mp3", FileMode.Open, FileAccess.Write);
    catch (IOException)
        await Task.Delay(TimeSpan.FromSeconds(1));
        return await GetStreamAsync();

You can use this stream as usual:

using (var stream = await FileStreamGetter.GetStreamAsync())

How to automatically convert strongly typed enum into int?

An extension to the answers from R. Martinho Fernandes and Class Skeleton: Their answers show how to use typename std::underlying_type<EnumType>::type or std::underlying_type_t<EnumType> to convert your enumeration value with a static_cast to a value of the underlying type. Compared to a static_cast to some specific integer type, like, static_cast<int> this has the benefit of being maintenance friendly, because when the underlying type changes, the code using std::underlying_type_t will automatically use the new type.

This, however, is sometimes not what you want: Assume you wanted to print out enumeration values directly, for example to std::cout, like in the following example:

enum class EnumType : int { Green, Blue, Yellow };
std::cout << static_cast<std::underlying_type_t<EnumType>>(EnumType::Green);

If you later change the underlying type to a character type, like, uint8_t, then the value of EnumType::Green will not be printed as a number, but as a character, which is most probably not what you want. Thus, you sometimes would rather convert the enumeration value into something like "underlying type, but with integer promotion where necessary".

It would be possible to apply the unary operator+ to the result of the cast to force integer promotion if necessary. However, you can also use std::common_type_t (also from header file <type_traits>) to do the following:

enum class EnumType : int { Green, Blue, Yellow };
std::cout << static_cast<std::common_type_t<int, std::underlying_type_t<EnumType>>>(EnumType::Green);

Preferrably you would wrap this expression in some helper template function:

template <class E>
constexpr std::common_type_t<int, std::underlying_type_t<E>>
enumToInteger(E e) {
    return static_cast<std::common_type_t<int, std::underlying_type_t<E>>>(e);

Which would then be more friendly to the eyes, be maintenance friendly with respect to changes to the underlying type, and without need for tricks with operator+:

std::cout << enumToInteger(EnumType::Green);

How to wrap text of HTML button with fixed width?

If we have some inner divisions inside <button> tag like this-

<button class="top-container">
    <div class="classA">
       <div class="classB">
           puts " some text to get print." 
     <div class="class1">
       <div class="class2">
           puts " some text to get print." 

Sometime Text of class A get overlap on class1 data because these both are in a single button tag. I try to break the tex using-

 word-wrap: break-word;         /* All browsers since IE 5.5+ */
 overflow-wrap: break-word;     /* Renamed property in CSS3 draft spec */ 

But this won't worked then I try this-

white-space: normal;

after removing above css properties and got my task done.

Hope will work for all !!!

How do you wait for input on the same Console.WriteLine() line?

Use Console.Write instead, so there's no newline written:

Console.Write("What is your name? ");
var name = Console.ReadLine();

Converting a float to a string without rounding it

I know this is too late but for those who are coming here for the first time, I'd like to post a solution. I have a float value index and a string imgfile and I had the same problem as you. This is how I fixed the issue

index = 1.0
imgfile = 'data/2.jpg'
out = '%.1f,%s' % (index,imgfile)
print out

The output is


You may modify this formatting example as per your convenience.

How to set button click effect in Android?

Step: set a button in XML with onClick Action:

android:textSize="@dimen/login_textSize" />

Step: on button clicked show animation point
//pgrm mark ---- ---- ----- ---- ---- ----- ---- ---- -----  ---- ---- -----

    public void edit_user_info(View view) {

        // show click effect on button pressed
        final AlphaAnimation buttonClick = new AlphaAnimation(1F, 0.8F);

        Intent intent = new Intent(getApplicationContext(),  EditUserInfo.class);

    }// end edit_user_info

MySQL timestamp select date range

This SQL query will extract the data for you. It is easy and fast.

  FROM table_name
  WHERE extract( YEAR_MONTH from timestamp)="201010";

What does "var" mean in C#?

It means the data type is derived (implied) from the context.


Beginning in Visual C# 3.0, variables that are declared at method scope can have an implicit type var. An implicitly typed local variable is strongly typed just as if you had declared the type yourself, but the compiler determines the type. The following two declarations of i are functionally equivalent:

var i = 10; // implicitly typed
int i = 10; //explicitly typed

var is useful for eliminating keyboard typing and visual noise, e.g.,

MyReallyReallyLongClassName x = new MyReallyReallyLongClassName();


var x = new MyReallyReallyLongClassName();

but can be overused to the point where readability is sacrificed.

How to create a HTML Cancel button that redirects to a URL

<input class="button" type="button" onclick="window.location.replace('your_url')" value="Cancel" />

Returning IEnumerable<T> vs. IQueryable<T>

In addition to first 2 really good answers (by driis & by Jacob) :

IEnumerable interface is in the System.Collections namespace.

The IEnumerable object represents a set of data in memory and can move on this data only forward. The query represented by the IEnumerable object is executed immediately and completely, so the application receives data quickly.

When the query is executed, IEnumerable loads all the data, and if we need to filter it, the filtering itself is done on the client side.

IQueryable interface is located in the System.Linq namespace.

The IQueryable object provides remote access to the database and allows you to navigate through the data either in a direct order from beginning to end, or in the reverse order. In the process of creating a query, the returned object is IQueryable, the query is optimized. As a result, less memory is consumed during its execution, less network bandwidth, but at the same time it can be processed slightly more slowly than a query that returns an IEnumerable object.

What to choose?

If you need the entire set of returned data, then it's better to use IEnumerable, which provides the maximum speed.

If you DO NOT need the entire set of returned data, but only some filtered data, then it's better to use IQueryable.

How to use linux command line ftp with a @ sign in my username?

Try to define the account in a ~/.netrc file like this:

machine host login [email protected] password mypassword

Check man netrc for details.

T-SQL How to select only Second row from a table?

In SQL Server 2012+, you can use OFFSET...FETCH:

   <sort column(s)>
OFFSET 1 ROWS   -- Skip this number of rows
FETCH NEXT 1 ROWS ONLY;  -- Return this number of rows

Difference between Width:100% and width:100vw?

You can solve this issue be adding max-width:

#element {
   width: 100vw;
   height: 100vw;
   max-width: 100%;

When you using CSS to make the wrapper full width using the code width: 100vw; then you will notice a horizontal scroll in the page, and that happened because the padding and margin of html and body tags added to the wrapper size, so the solution is to add max-width: 100%

Switch: Multiple values in one case?

You can use ifelse instead.but if you want to know how to use switch in this is an example.

int age = Convert.ToInt32(txtBoxAge.Text);`
int flag;
if(age >= 1 && age <= 8) {
flag = 1;
} else if (age >= 9 && age <= 15) {
 flag = 2;
} else if (age >= 16 && age <= 100) {
 flag = 3;
} else {
 flag = 4;   
switch (flag) 

 case 1:
  MessageBox.Show("You are only " + age + " years old\n You must be kidding right.\nPlease fill in your *real* age.");
case 2:
  MessageBox.Show("You are only " + age + " years old\n That's too young!");
case 3:
  MessageBox.Show("You are " + age + " years old\n Perfect.");
  MessageBox.Show("You an old person.");

hope that helps ! :)

Copy table from one database to another


select * into <destination table> from <source table>

How to put a Scanner input into an array... for example a couple of numbers

List<Double> numbers = new ArrayList<Double>();
double sum = 0;

Scanner scan = new Scanner(;
    double value = scan.nextDouble();
    sum += value;

double average = sum / numbers.size();

SQL Server FOR EACH Loop

You could use a variable table, like this:

declare @num int

set @num = 1

declare @results table ( val int )

while (@num < 6)
  insert into @results ( val ) values ( @num )
  set @num = @num + 1

select val from @results

Creating a Custom Event

Declare the class containing the event:

class MyClass {
    public event EventHandler MyEvent;

    public void Method() {

    private void OnEvent() {
        if (MyEvent != null) {
            MyEvent(this, EventArgs.Empty);

Use it like this:

MyClass myObject = new MyClass();
myObject.MyEvent += new EventHandler(myObject_MyEvent);

How to respond to clicks on a checkbox in an AngularJS directive?

This is the way I've been doing this sort of stuff. Angular tends to favor declarative manipulation of the dom rather than a imperative one(at least that's the way I've been playing with it).

The markup

<table class="table">
        <input type="checkbox" 
    <tr ng-repeat="e in entities" ng-class="getSelectedClass(e)">
        <input type="checkbox" name="selected"

And in the controller

var updateSelected = function(action, id) {
  if (action === 'add' && $scope.selected.indexOf(id) === -1) {
  if (action === 'remove' && $scope.selected.indexOf(id) !== -1) {
    $scope.selected.splice($scope.selected.indexOf(id), 1);

$scope.updateSelection = function($event, id) {
  var checkbox = $;
  var action = (checkbox.checked ? 'add' : 'remove');
  updateSelected(action, id);

$scope.selectAll = function($event) {
  var checkbox = $;
  var action = (checkbox.checked ? 'add' : 'remove');
  for ( var i = 0; i < $scope.entities.length; i++) {
    var entity = $scope.entities[i];

$scope.getSelectedClass = function(entity) {
  return $scope.isSelected( ? 'selected' : '';

$scope.isSelected = function(id) {
  return $scope.selected.indexOf(id) >= 0;

//something extra I couldn't resist adding :)
$scope.isSelectedAll = function() {
  return $scope.selected.length === $scope.entities.length;

EDIT: getSelectedClass() expects the entire entity but it was being called with the id of the entity only, which is now corrected

How do you uninstall a python package that was installed using distutils?

The three things that get installed that you will need to delete are:

  1. Packages/modules
  2. Scripts
  3. Data files

Now on my linux system these live in:

  1. /usr/lib/python2.5/site-packages
  2. /usr/bin
  3. /usr/share

But on a windows system they are more likely to be entirely within the Python distribution directory. I have no idea about OSX except it is more likey to follow the linux pattern.

How to find count of Null and Nan values for each column in a PySpark dataframe efficiently?

Here is my one liner. Here 'c' is the name of the column'c').withColumn('isNull_c',F.col('c').isNull()).where('isNull_c = True').count()

How to implement infinity in Java?

For the numeric wrapper types.


Hope this might help you.

Checking that a List is not empty in Hamcrest

If you're after readable fail messages, you can do without hamcrest by using the usual assertEquals with an empty list:

assertEquals(new ArrayList<>(0), yourList);

E.g. if you run

assertEquals(new ArrayList<>(0), Arrays.asList("foo", "bar");

you get

Expected :[]
Actual   :[foo, bar]

C#: HttpClient with POST parameters

A cleaner alternative would be to use a Dictionary to handle parameters. They are key-value pairs after all.

private static readonly HttpClient httpclient;

static MyClassName()
    // HttpClient is intended to be instantiated once and re-used throughout the life of an application. 
    // Instantiating an HttpClient class for every request will exhaust the number of sockets available under heavy loads. 
    // This will result in SocketException errors.
    httpclient = new HttpClient();    

var url = "http://myserver/method";
var parameters = new Dictionary<string, string> { { "param1", "1" }, { "param2", "2" } };
var encodedContent = new FormUrlEncodedContent (parameters);

var response = await httpclient.PostAsync (url, encodedContent).ConfigureAwait (false);
if (response.StatusCode == HttpStatusCode.OK) {
    // Do something with response. Example get content:
    // var responseContent = await response.Content.ReadAsStringAsync ().ConfigureAwait (false);

Also dont forget to Dispose() httpclient, if you dont use the keyword using

As stated in the Remarks section of the HttpClient class in the Microsoft docs, HttpClient should be instantiated once and re-used.


You may want to look into response.EnsureSuccessStatusCode(); instead of if (response.StatusCode == HttpStatusCode.OK).

You may want to keep your httpclient and dont Dispose() it. See: Do HttpClient and HttpClientHandler have to be disposed?


Do not worry about using .ConfigureAwait(false) in .NET Core. For more details look at

How to check if array is empty or does not exist?

You want to do the check for undefined first. If you do it the other way round, it will generate an error if the array is undefined.

if (array === undefined || array.length == 0) {
    // array empty or does not exist


This answer is getting a fair amount of attention, so I'd like to point out that my original answer, more than anything else, addressed the wrong order of the conditions being evaluated in the question. In this sense, it fails to address several scenarios, such as null values, other types of objects with a length property, etc. It is also not very idiomatic JavaScript.

The foolproof approach
Taking some inspiration from the comments, below is what I currently consider to be the foolproof way to check whether an array is empty or does not exist. It also takes into account that the variable might not refer to an array, but to some other type of object with a length property.

if (!Array.isArray(array) || !array.length) {
  // array does not exist, is not an array, or is empty
  // ? do not attempt to process array

To break it down:

  1. Array.isArray(), unsurprisingly, checks whether its argument is an array. This weeds out values like null, undefined and anything else that is not an array.
    Note that this will also eliminate array-like objects, such as the arguments object and DOM NodeList objects. Depending on your situation, this might not be the behavior you're after.

  2. The array.length condition checks whether the variable's length property evaluates to a truthy value. Because the previous condition already established that we are indeed dealing with an array, more strict comparisons like array.length != 0 or array.length !== 0 are not required here.

The pragmatic approach
In a lot of cases, the above might seem like overkill. Maybe you're using a higher order language like TypeScript that does most of the type-checking for you at compile-time, or you really don't care whether the object is actually an array, or just array-like.

In those cases, I tend to go for the following, more idiomatic JavaScript:

if (!array || !array.length) {
    // array or array.length are falsy
    // ? do not attempt to process array

Or, more frequently, its inverse:

if (array && array.length) {
    // array and array.length are truthy
    // ? probably OK to process array

With the introduction of the optional chaining operator (Elvis operator) in ECMAScript 2020, this can be shortened even further:

if (!array?.length) {
    // array or array.length are falsy
    // ? do not attempt to process array

Or the opposite:

if (array?.length) {
    // array and array.length are truthy
    // ? probably OK to process array

How do you run a command as an administrator from the Windows command line?

A batch/WSH hybrid is able to call ShellExecute to display the UAC elevation dialog...

@if (1==1) @if(1==0) @ELSE
>nul 2>&1 "%SYSTEMROOT%\system32\cacls.exe" "%SYSTEMROOT%\system32\config\system"||(
    cscript //E:JScript //nologo "%~f0"
    @goto :EOF
echo.Performing admin tasks...
REM call foo.exe
@goto :EOF
@end @ELSE
ShA=new ActiveXObject("Shell.Application")
ShA.ShellExecute("cmd.exe","/c \""+WScript.ScriptFullName+"\"","","runas",5);

Efficient evaluation of a function at every cell of a NumPy array

When the 2d-array (or nd-array) is C- or F-contiguous, then this task of mapping a function onto a 2d-array is practically the same as the task of mapping a function onto a 1d-array - we just have to view it that way, e.g. via np.ravel(A,'K').

Possible solution for 1d-array have been discussed for example here.

However, when the memory of the 2d-array isn't contiguous, then the situation a little bit more complicated, because one would like to avoid possible cache misses if axis are handled in wrong order.

Numpy has already a machinery in place to process axes in the best possible order. One possibility to use this machinery is np.vectorize. However, numpy's documentation on np.vectorize states that it is "provided primarily for convenience, not for performance" - a slow python function stays a slow python function with the whole associated overhead! Another issue is its huge memory-consumption - see for example this SO-post.

When one wants to have a performance of a C-function but to use numpy's machinery, a good solution is to use numba for creation of ufuncs, for example:

# runtime generated C-function as ufunc
import numba as nb
def nb_vf(x):
    return x+2*x*x+4*x*x*x

It easily beats np.vectorize but also when the same function would be performed as numpy-array multiplication/addition, i.e.

# numpy-functionality
def f(x):
    return x+2*x*x+4*x*x*x

# python-function as ufunc
import numpy as np

See appendix of this answer for time-measurement-code:

enter image description here

Numba's version (green) is about 100 times faster than the python-function (i.e. np.vectorize), which is not surprising. But it is also about 10 times faster than the numpy-functionality, because numbas version doesn't need intermediate arrays and thus uses cache more efficiently.

While numba's ufunc approach is a good trade-off between usability and performance, it is still not the best we can do. Yet there is no silver bullet or an approach best for any task - one has to understand what are the limitation and how they can be mitigated.

For example, for transcendental functions (e.g. exp, sin, cos) numba doesn't provide any advantages over numpy's np.exp (there are no temporary arrays created - the main source of the speed-up). However, my Anaconda installation utilizes Intel's VML for vectors bigger than 8192 - it just cannot do it if memory is not contiguous. So it might be better to copy the elements to a contiguous memory in order to be able to use Intel's VML:

import numba as nb
def nb_vexp(x):
    return np.exp(x)

def np_copy_exp(x):
    copy = np.ravel(x, 'K')
    return np.exp(copy).reshape(x.shape) 

For the fairness of the comparison, I have switched off VML's parallelization (see code in the appendix):

enter image description here

As one can see, once VML kicks in, the overhead of copying is more than compensated. Yet once data becomes too big for L3 cache, the advantage is minimal as task becomes once again memory-bandwidth-bound.

On the other hand, numba could use Intel's SVML as well, as explained in this post:

from llvmlite import binding
# set before import
binding.set_option('SVML', '-vector-library=SVML')

import numba as nb

def nb_vexp_svml(x):
    return np.exp(x)

and using VML with parallelization yields:

enter image description here

numba's version has less overhead, but for some sizes VML beats SVML even despite of the additional copying overhead - which isn't a bit surprise as numba's ufuncs aren't parallelized.


A. comparison of polynomial function:

import perfplot
    setup=lambda n: np.random.rand(n,n)[::2,::2],
    n_range=[2**k for k in range(0,12)],

B. comparison of exp:

import perfplot
import numexpr as ne # using ne is the easiest way to set vml_num_threads
    setup=lambda n: np.random.rand(n,n)[::2,::2],
    n_range=[2**k for k in range(0,12)],

Cleaning `Inf` values from an R dataframe

Option 1

Use the fact that a data.frame is a list of columns, then use to recreate a data.frame.,lapply(DT, function(x) replace(x, is.infinite(x),NA)))

Option 2 -- data.table

You could use data.table and set. This avoids some internal copying.

DT <- data.table(dat)
invisible(lapply(names(DT),function(.name) set(DT, which(is.infinite(DT[[.name]])), j = .name,value =NA)))

Or using column numbers (possibly faster if there are a lot of columns):

for (j in 1:ncol(DT)) set(DT, which(is.infinite(DT[[j]])), j, NA)


# some `big(ish)` data
dat <- data.frame(a = rep(c(1,Inf), 1e6), b = rep(c(Inf,2), 1e6), 
                  c = rep(c('a','b'),1e6),d = rep(c(1,Inf), 1e6),  
                  e = rep(c(Inf,2), 1e6))
# create data.table
DT <- data.table(dat)

# replace (@mnel)
system.time(na_dat <-,lapply(dat, function(x) replace(x, is.infinite(x),NA))))
## user  system elapsed 
#  0.52    0.01    0.53 

# (@dwin)
system.time( <- sapply(dat, is.infinite))
# user  system elapsed 
# 32.96    0.07   33.12 

# modified
system.time( <-,lapply(dat, is.infinite)))
#  user  system elapsed 
# 1.22    0.38    1.60 

# data.table (@mnel)
system.time(invisible(lapply(names(DT),function(.name) set(DT, which(is.infinite(DT[[.name]])), j = .name,value =NA))))
# user  system elapsed 
# 0.29    0.02    0.31 

data.table is the quickest. Using sapply slows things down noticeably.

ubuntu "No space left on device" but there is tons of space

It's possible that you've run out of memory or some space elsewhere and it prompted the system to mount an overflow filesystem, and for whatever reason, it's not going away.

Try unmounting the overflow partition:

umount /tmp


umount overflow

Date difference in years using C#

Maybe this will be helpful for answering the question: Count of days in given year,

new DateTime(anyDate.Year, 12, 31).DayOfYear //will include leap years too

Regarding DateTime.DayOfYear Property.

git: 'credential-cache' is not a git command

For the sake of others having this issue - I landed here because I tried to get cute with how I set up a new github repository, but per the setup page credential helper doesn't work unless you clone a repository.

"Tip: The credential helper only works when you clone an HTTPS repository URL. If you use the SSH repository URL instead, SSH keys are used for authentication. This guide offers help generating and using an SSH key pair."

How do I determine k when using k-means clustering?

Look at this paper, "Learning the k in k-means" by Greg Hamerly, Charles Elkan. It uses a Gaussian test to determine the right number of clusters. Also, the authors claim that this method is better than BIC which is mentioned in the accepted answer.

Can I change the viewport meta tag in mobile safari on the fly?

This has been answered for the most part, but I will expand...

Step 1

My goal was to enable zoom at certain times, and disable it at others.

// enable pinch zoom
var $viewport = $('head meta[name="viewport"]');    
$viewport.attr('content', 'width=device-width, initial-scale=1, maximum-scale=4');

// ...later...

// disable pinch zoom
$viewport.attr('content', 'width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no');

Step 2

The viewport tag would update, but pinch zoom was still active!! I had to find a way to get the page to pick up the changes...

It's a hack solution, but toggling the opacity of body did the trick. I'm sure there are other ways to accomplish this, but here's what worked for me.

// after updating viewport tag, force the page to pick up changes   = .9999;
setTimeout(function(){ = 1;
}, 1);

Step 3

My problem was mostly solved at this point, but not quite. I needed to know the current zoom level of the page so I could resize some elements to fit on the page (think of map markers).

// check zoom level during user interaction, or on animation frame
var currentZoom = $document.width() / window.innerWidth;

I hope this helps somebody. I spent several hours banging my mouse before finding a solution.

Regex - Does not contain certain Characters


The caret in the character class ([^) means match anything but, so this means, beginning of string, then one or more of anything except < and >, then the end of the string.

PHP Call to undefined function

Presently I am working on web services where my function is defined and it was throwing an error undefined function.I just added this in autoload.php in codeigniter

$autoload['helper'] = array('common','security','url');

common is the name of my controller.

How to scroll table's "tbody" independent of "thead"?

The missing part is:

thead, tbody {
    display: block;


Add Favicon with React and Webpack

This worked for me:

Add this in index.html (inside src folder along with favicon.ico)

**<link rel="icon" href="/src/favicon.ico" type="image/x-icon" />**

webpack.config.js is like:

 plugins: [new HtmlWebpackPlugin({`enter code here`
        template: './src/index.html'

Complex CSS selector for parent of active child

Many people answered with jQuery parent, but just to add on to that I wanted to share a quick snippet of code that I use for adding classes to my navs so I can add styling to li's that only have sub-menus and not li's that don't.

$("li ul").parent().addClass('has-sub');

Postgresql column reference "id" is ambiguous

SELECT (, name) FROM v_groups vg 
INNER JOIN people2v_groups p2vg ON = p2vg.v_group_id
WHERE p2vg.people_id = 0;

What is the difference between "::" "." and "->" in c++

-> is for pointers to a class instance

. is for class instances

:: is for classnames - for example when using a static member

Peak signal detection in realtime timeseries data

Here is a Groovy (Java) implementation of the smoothed z-score algorithm (see answer above).

 * "Smoothed zero-score alogrithm" shamelessly copied from
 *  Uses a rolling mean and a rolling deviation (separate) to identify peaks in a vector
 * @param y - The input vector to analyze
 * @param lag - The lag of the moving window (i.e. how big the window is)
 * @param threshold - The z-score at which the algorithm signals (i.e. how many standard deviations away from the moving mean a peak (or signal) is)
 * @param influence - The influence (between 0 and 1) of new signals on the mean and standard deviation (how much a peak (or signal) should affect other values near it)
 * @return - The calculated averages (avgFilter) and deviations (stdFilter), and the signals (signals)

public HashMap<String, List<Object>> thresholdingAlgo(List<Double> y, Long lag, Double threshold, Double influence) {
    //init stats instance
    SummaryStatistics stats = new SummaryStatistics()

    //the results (peaks, 1 or -1) of our algorithm
    List<Integer> signals = new ArrayList<Integer>(Collections.nCopies(y.size(), 0))
    //filter out the signals (peaks) from our original list (using influence arg)
    List<Double> filteredY = new ArrayList<Double>(y)
    //the current average of the rolling window
    List<Double> avgFilter = new ArrayList<Double>(Collections.nCopies(y.size(), 0.0d))
    //the current standard deviation of the rolling window
    List<Double> stdFilter = new ArrayList<Double>(Collections.nCopies(y.size(), 0.0d))
    //init avgFilter and stdFilter
    (0..lag-1).each { stats.addValue(y[it as int]) }
    avgFilter[lag - 1 as int] = stats.getMean()
    stdFilter[lag - 1 as int] = Math.sqrt(stats.getPopulationVariance()) //getStandardDeviation() uses sample variance (not what we want)
    //loop input starting at end of rolling window
    (lag..y.size()-1).each { i ->
        //if the distance between the current value and average is enough standard deviations (threshold) away
        if (Math.abs((y[i as int] - avgFilter[i - 1 as int]) as Double) > threshold * stdFilter[i - 1 as int]) {
            //this is a signal (i.e. peak), determine if it is a positive or negative signal
            signals[i as int] = (y[i as int] > avgFilter[i - 1 as int]) ? 1 : -1
            //filter this signal out using influence
            filteredY[i as int] = (influence * y[i as int]) + ((1-influence) * filteredY[i - 1 as int])
        } else {
            //ensure this signal remains a zero
            signals[i as int] = 0
            //ensure this value is not filtered
            filteredY[i as int] = y[i as int]
        //update rolling average and deviation
        (i - lag..i-1).each { stats.addValue(filteredY[it as int] as Double) }
        avgFilter[i as int] = stats.getMean()
        stdFilter[i as int] = Math.sqrt(stats.getPopulationVariance()) //getStandardDeviation() uses sample variance (not what we want)

    return [
        signals  : signals,
        avgFilter: avgFilter,
        stdFilter: stdFilter

Below is a test on the same dataset that yields the same results as the above Python / numpy implementation.

    // Data
    def y = [1d, 1d, 1.1d, 1d, 0.9d, 1d, 1d, 1.1d, 1d, 0.9d, 1d, 1.1d, 1d, 1d, 0.9d, 1d, 1d, 1.1d, 1d, 1d,
         1d, 1d, 1.1d, 0.9d, 1d, 1.1d, 1d, 1d, 0.9d, 1d, 1.1d, 1d, 1d, 1.1d, 1d, 0.8d, 0.9d, 1d, 1.2d, 0.9d, 1d,
         1d, 1.1d, 1.2d, 1d, 1.5d, 1d, 3d, 2d, 5d, 3d, 2d, 1d, 1d, 1d, 0.9d, 1d,
         1d, 3d, 2.6d, 4d, 3d, 3.2d, 2d, 1d, 1d, 0.8d, 4d, 4d, 2d, 2.5d, 1d, 1d, 1d]

    // Settings
    def lag = 30
    def threshold = 5
    def influence = 0

    def thresholdingResults = thresholdingAlgo((List<Double>) y, (Long) lag, (Double) threshold, (Double) influence)

    println y.size()
    println thresholdingResults.signals.size()
    println thresholdingResults.signals

    thresholdingResults.signals.eachWithIndex { x, idx ->
        if (x) {
            println y[idx]

Static array vs. dynamic array in C++

Yes right the static array is created at the compile time where as the dynamic array is created on the run time. Where as the difference as far is concerned with their memory locations the static are located on the stack and the dynamic are created on the heap. Everything which gets located on heap needs the memory management until and unless garbage collector as in the case of .net framework is present otherwise there is a risk of memory leak.

How to convert a UTF-8 string into Unicode?

If you have a UTF-8 string, where every byte is correct ('Ö' -> [195, 0] , [150, 0]), you can use the following:

public static string Utf8ToUtf16(string utf8String)
     * Every .NET string will store text with the UTF-16 encoding, *
     * known as Encoding.Unicode. Other encodings may exist as     *
     * Byte-Array or incorrectly stored with the UTF-16 encoding.  *
     *                                                             *
     * UTF-8 = 1 bytes per char                                    *
     *    ["100" for the ansi 'd']                                 *
     *    ["206" and "186" for the russian '?']                    *
     *                                                             *
     * UTF-16 = 2 bytes per char                                   *
     *    ["100, 0" for the ansi 'd']                              *
     *    ["186, 3" for the russian '?']                           *
     *                                                             *
     * UTF-8 inside UTF-16                                         *
     *    ["100, 0" for the ansi 'd']                              *
     *    ["206, 0" and "186, 0" for the russian '?']              *
     *                                                             *
     * First we need to get the UTF-8 Byte-Array and remove all    *
     * 0 byte (binary 0) while doing so.                           *
     *                                                             *
     * Binary 0 means end of string on UTF-8 encoding while on     *
     * UTF-16 one binary 0 does not end the string. Only if there  *
     * are 2 binary 0, than the UTF-16 encoding will end the       *
     * string. Because of .NET we don't have to handle this.       *
     *                                                             *
     * After removing binary 0 and receiving the Byte-Array, we    *
     * can use the UTF-8 encoding to string method now to get a    *
     * UTF-16 string.                                              *
     *                                                             *

    // Get UTF-8 bytes and remove binary 0 bytes (filler)
    List<byte> utf8Bytes = new List<byte>(utf8String.Length);
    foreach (byte utf8Byte in utf8String)
        // Remove binary 0 bytes (filler)
        if (utf8Byte > 0) {

    // Convert UTF-8 bytes to UTF-16 string
    return Encoding.UTF8.GetString(utf8Bytes.ToArray());

In my case the DLL result is a UTF-8 string too, but unfortunately the UTF-8 string is interpreted with UTF-16 encoding ('Ö' -> [195, 0], [19, 32]). So the ANSI '–' which is 150 was converted to the UTF-16 '–' which is 8211. If you have this case too, you can use the following instead:

public static string Utf8ToUtf16(string utf8String)
    // Get UTF-8 bytes by reading each byte with ANSI encoding
    byte[] utf8Bytes = Encoding.Default.GetBytes(utf8String);

    // Convert UTF-8 bytes to UTF-16 bytes
    byte[] utf16Bytes = Encoding.Convert(Encoding.UTF8, Encoding.Unicode, utf8Bytes);

    // Return UTF-16 bytes as UTF-16 string
    return Encoding.Unicode.GetString(utf16Bytes);

Or the Native-Method:

private static extern Int32 MultiByteToWideChar(UInt32 CodePage, UInt32 dwFlags, [MarshalAs(UnmanagedType.LPStr)] String lpMultiByteStr, Int32 cbMultiByte, [Out, MarshalAs(UnmanagedType.LPWStr)] StringBuilder lpWideCharStr, Int32 cchWideChar);

public static string Utf8ToUtf16(string utf8String)
    Int32 iNewDataLen = MultiByteToWideChar(Convert.ToUInt32(Encoding.UTF8.CodePage), 0, utf8String, -1, null, 0);
    if (iNewDataLen > 1)
        StringBuilder utf16String = new StringBuilder(iNewDataLen);
        MultiByteToWideChar(Convert.ToUInt32(Encoding.UTF8.CodePage), 0, utf8String, -1, utf16String, utf16String.Capacity);

        return utf16String.ToString();
        return String.Empty;

If you need it the other way around, see Utf16ToUtf8. Hope I could be of help.

Removing first x characters from string?

Example to show last 3 digits of account number.

x = '1234567890'   
x.replace(x[:7], '')

o/p: '890'

Apply CSS style attribute dynamically in Angular JS

On a generic note, you can use a combination of ng-if and ng-style incorporate conditional changes with change in background image.

<span ng-if=""
                'background-size':'52px 57px',
                'background-position': 'center'}">
 <span ng-if="selectedItem!"
                'background-size':'52px 57px',
                'background-position': 'center'}">

Updates were rejected because the tip of your current branch is behind hint: its remote counterpart. Integrate the remote changes (e.g

You need to merge the remote branch into your current branch by running git pull.

If your local branch is already up-to-date, you may also need to run git pull --rebase.

A quick google search also turned up this same question asked by another SO user: Cannot push to GitHub - keeps saying need merge. More details there.

How to import large sql file in phpmyadmin

For that you will have to edit php.ini file, If you are using the ubuntu server this is link Upload large file in phpMyAdmin might help you.

How do you force a CIFS connection to unmount

I use lazy unmount: umount -l (that's a lowercase L)

Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. (Requires kernel 2.4.11 or later.)

Excel VBA function to print an array to the workbook

My tested version

Sub PrintArray(RowPrint, ColPrint, ArrayName, WorkSheetName)

Sheets(WorkSheetName).Range(Cells(RowPrint, ColPrint), _
Cells(RowPrint + UBound(ArrayName, 2) - 1, _
ColPrint + UBound(ArrayName, 1) - 1)) = _

End Sub

How to solve static declaration follows non-static declaration in GCC C code?

This error can be caused by an unclosed set of brackets.

int main {
  doSomething {}
  doSomething else {

Not so easy to spot, even in this 4 line example.

This error, in a 150 line main function, caused the bewildering error: "static declaration of ‘savePair’ follows non-static declaration". There was nothing wrong with my definition of function savePair, it was that unclosed bracket.

Java 8 lambda Void argument

The lambda:

() -> { System.out.println("Do nothing!"); };

actually represents an implementation for an interface like:

public interface Something {
    void action();

which is completely different than the one you've defined. That's why you get an error.

Since you can't extend your @FunctionalInterface, nor introduce a brand new one, then I think you don't have much options. You can use the Optional<T> interfaces to denote that some of the values (return type or method parameter) is missing, though. However, this won't make the lambda body simpler.

history.replaceState() example?

The second argument Title does not mean Title of the page - It is more of a definition/information for the state of that page

But we can still change the title using onpopstate event, and passing the title name not from the second argument, but as an attribute from the first parameter passed as object


Mysql service is missing

Go to your mysql bin directory and install mysql service again:

cd \mysql\bin
mysqld-nt.exe --install

or if mysqld-nt.exe is missing (depending on version):

mysqld.exe --install

Then go to services, start the service and set it to automatic start.

Replacing all non-alphanumeric characters with empty strings

return value.replaceAll("[^A-Za-z0-9 ]", "");

This will leave spaces intact. I assume that's what you want. Otherwise, remove the space from the regex.

How can I override the OnBeforeUnload dialog and replace it with my own?

Try placing a return; instead of a message.. this is working most browsers for me. (This only really prevents dialog's presents)

window.onbeforeunload = function(evt) {            
        //Your Extra Code

Dynamically add child components in React

Firstly a warning: you should never tinker with DOM that is managed by React, which you are doing by calling ReactDOM.render(<SampleComponent ... />);

With React, you should use SampleComponent directly in the main App.

var App = require('./App.js');
var SampleComponent = require('./SampleComponent.js');
ReactDOM.render(<App/>, document.body);

The content of your Component is irrelevant, but it should be used like this:

var App = React.createClass({
    render: function() {
        return (
                <h1>App main component! </h1>
                <SampleComponent name="SomeName"/>

You can then extend your app component to use a list.

var App = React.createClass({
    render: function() {
        var componentList = [
            <SampleComponent name="SomeName1"/>,
            <SampleComponent name="SomeName2"/>
        ]; // Change this to get the list from props or state
        return (
                <h1>App main component! </h1>

I would really recommend that you look at the React documentation then follow the "Get Started" instructions. The time you spend on that will pay off later.

echo key and value of an array without and with loop

You can try following code:

foreach ($arry as $key => $value) 
      echo $key;
      foreach ($value as  $val) 
         echo $val; 

How to dismiss AlertDialog in android

I think there's a simpler solution: Just use the DialogInterface argument that is passed to the onClick method.

AlertDialog.Builder db = new AlertDialog.Builder(context);
        db.setNegativeButton("cancel", new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface d, int arg1) {
                //here db.cancel will dismiss the builder


See, for example,

Check if a value is in an array (C#)

   string[] array = { "cat", "dot", "perls" };

// Use Array.Exists in different ways.
bool a = Array.Exists(array, element => element == "perls");
bool b = Array.Exists(array, element => element == "python");
bool c = Array.Exists(array, element => element.StartsWith("d"));
bool d = Array.Exists(array, element => element.StartsWith("x"));

// Display bools.

1)True 2)False 3)True 4)False

SSL handshake alert: unrecognized_name error since upgrade to Java 1.7.0


  • System.setProperty("jsse.enableSNIExtension", "false");
  • Restart your Tomcat (important)

Creating custom function in React component

With React Functional way

import React, { useEffect } from "react";
import ReactDOM from "react-dom";
import Button from "@material-ui/core/Button";

const App = () => {
  const saySomething = (something) => {
  useEffect(() => {
    saySomething("from useEffect");
  const handleClick = (e) => {
    saySomething("element clicked");
  return (
    <Button variant="contained" color="primary" onClick={handleClick}>
      Hello World

ReactDOM.render(<App />, document.querySelector("#app"));

"The system cannot find the file specified"

Considering that a LocalDb instance only intended for use in development. LocalDb is not available for production servers When you deploy the final result.

I think your connection string is pointing to a LocalDb instance and you need to take certain steps to turn it into the SQL Server database. It's not just a matter of copying an mdf file either. It will possibly differ from one hosting company to another, but typically, you need to create a backup of your existing database (a .bak file) and then restore that to the hosting company's SQL Server. You should ask them where you can find instructions on deploying your database into production.

How to create a zip file in Java

public static void zipFromTxt(String zipFilePath, String txtFilePath) {
    Assert.notNull(zipFilePath, "Zip file path is required");
    Assert.notNull(txtFilePath, "Txt file path is required");
    zipFromTxt(new File(zipFilePath), new File(txtFilePath));

public static void zipFromTxt(File zipFile, File txtFile) {
    ZipOutputStream out = null;
    FileInputStream in = null;
    try {
        Assert.notNull(zipFile, "Zip file is required");
        Assert.notNull(txtFile, "Txt file is required");
        out = new ZipOutputStream(new FileOutputStream(zipFile));
        in = new FileInputStream(txtFile);
        out.putNextEntry(new ZipEntry(txtFile.getName()));
        int len;
        byte[] buffer = new byte[1024];
        while ((len = > 0) {
            out.write(buffer, 0, len);
    } catch (Exception e) {"Zip from txt occur error,Detail message:{}", e.toString());
    } finally {
        try {
            if (in != null) in.close();
            if (out != null) {
        } catch (Exception e) {
  "Zip from txt close error,Detail message:{}", e.toString());

Conversion of a datetime2 data type to a datetime data type results out-of-range value

If we dont pass a date time to date time field the default date {1/1/0001 12:00:00 AM} will be passed.

But this date is not compatible with entity frame work so it will throw conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value

Just default to the date field if you are not passing any date .

movie.DateAdded = System.DateTime.Now

How to install a plugin in Jenkins manually

Yes, you can. Download the plugin (*.hpi file) and put it in the following directory:


Afterwards you will need to restart Jenkins.

How do I vertically align something inside a span tag?

Use line-height:50px; instead of height. That should do the trick ;)

How to cast Object to boolean?

Assuming that yourObject.toString() returns "true" or "false", you can try

boolean b = Boolean.valueOf(yourObject.toString())

Display milliseconds in Excel

Right click on Cell B1 and choose Format Cells. In Custom, put the following in the text box labeled Type:


To set this in code, you can do something like:

Range("A1").NumberFormat = "[h]:mm:ss.000"

That should give you what you're looking for.

NOTE: Specially formatted fields often require that the column width be wide enough for the entire contents of the formatted text. Otherwise, the text will display as ######.

how to display a javascript var in html body

<script type="text/javascript">
var number = 123;
var string = "abcd";

function docWrite(variable) {

<h1>the value for number is: <script>docWrite(number)</script></h1>

<h2>the text is: <script>docWrite(string)</script> </h2>

You can shorten document.write but can't avoid <script> tag

How to return a file using Web API?

Better to return HttpResponseMessage with StreamContent inside of it.

Here is example:

public HttpResponseMessage GetFile(string id)
    if (String.IsNullOrEmpty(id))
        return Request.CreateResponse(HttpStatusCode.BadRequest);

    string fileName;
    string localFilePath;
    int fileSize;

    localFilePath = getFileFromID(id, out fileName, out fileSize);

    HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
    response.Content = new StreamContent(new FileStream(localFilePath, FileMode.Open, FileAccess.Read));
    response.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
    response.Content.Headers.ContentDisposition.FileName = fileName;
    response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");

    return response;

UPD from comment by patridge: Should anyone else get here looking to send out a response from a byte array instead of an actual file, you're going to want to use new ByteArrayContent(someData) instead of StreamContent (see here).

How do I use variables in Oracle SQL Developer?

Use the next query:

  EmpIDVar INT;

  EmpIDVar := 1234;

  FROM Employees
  WHERE EmployeeID = EmpIDVar;

What is the total amount of public IPv4 addresses?

According to Reserved IP addresses there are 588,514,304 reserved addresses and since there are 4,294,967,296 (2^32) IPv4 addressess in total, there are 3,706,452,992 public addresses.

And too many addresses in this post.

Creating a jQuery object from a big HTML-string

You can try something like below

$($.parseHTML(<<table html string variable here>>)).find("td:contains('<<some text to find>>')").first().prev().text();

Passing command line arguments to R CMD BATCH

After trying the options described here, I found this post from Forester in r-bloggers . I think it is a clean option to consider.

I put his code here:

From command line

$ R CMD BATCH --no-save --no-restore '--args a=1 b=c(2,5,6)' test.R test.out &


##First read in the arguments listed at the command line

##args is now a list of character vectors
## First check to see if arguments are passed.
## Then cycle through each element of the list and evaluate the expressions.
    print("No arguments supplied.")
    ##supply default values
    a = 1
    b = c(1,1,1)
    for(i in 1:length(args)){


In test.out

> print(a*2)
[1] 2
> print(b*3)
[1]  6 15 18

Thanks to Forester!

console.log showing contents of array object

there are two potential simple solutions to dumping an array as string. Depending on the environment you're using:

…with modern browsers use JSON:

// returns this

…with something like node.js you can use;
// will output:
{ dvals: 
[ { brand: '1', count: '1' },
  { brand: '2', count: '2' },
  { brand: '3', count: '3' } ] }


JSON.stringify comes with two more optional parameters. The third "spaces" parameter enables pretty printing:

                obj,      // the object to stringify
                replacer, // a function or array transforming the result
                spaces    // prettyprint indentation spaces


JSON.stringify(filters, null, "  ");
// returns this
 "dvals": [
   "brand": "1",
   "count": "1"
   "brand": "2",
   "count": "2"
   "brand": "3",
   "count": "3"

Error: Failed to execute 'appendChild' on 'Node': parameter 1 is not of type 'Node'

This can happen if you accidentally are not dragging the element that does have an id assigned (for example you are dragging the surrounding element). In that case the ID is empty and the function drag() is assigning an empty value which is then passed to drop() and fails there.

Try assigning the ids to all of your elements, including the tds, divs, or whatever is around your draggable element.

Convert Pandas Series to DateTime in a DataFrame

You can't: DataFrame columns are Series, by definition. That said, if you make the dtype (the type of all the elements) datetime-like, then you can access the quantities you want via the .dt accessor (docs):

>>> df["TimeReviewed"] = pd.to_datetime(df["TimeReviewed"])
>>> df["TimeReviewed"]
205  76032930   2015-01-24 00:05:27.513000
232  76032930   2015-01-24 00:06:46.703000
233  76032930   2015-01-24 00:06:56.707000
413  76032930   2015-01-24 00:14:24.957000
565  76032930   2015-01-24 00:23:07.220000
Name: TimeReviewed, dtype: datetime64[ns]
>>> df["TimeReviewed"].dt
<pandas.tseries.common.DatetimeProperties object at 0xb10da60c>
>>> df["TimeReviewed"].dt.year
205  76032930    2015
232  76032930    2015
233  76032930    2015
413  76032930    2015
565  76032930    2015
dtype: int64
>>> df["TimeReviewed"].dt.month
205  76032930    1
232  76032930    1
233  76032930    1
413  76032930    1
565  76032930    1
dtype: int64
>>> df["TimeReviewed"].dt.minute
205  76032930     5
232  76032930     6
233  76032930     6
413  76032930    14
565  76032930    23
dtype: int64

If you're stuck using an older version of pandas, you can always access the various elements manually (again, after converting it to a datetime-dtyped Series). It'll be slower, but sometimes that isn't an issue:

>>> df["TimeReviewed"].apply(lambda x: x.year)
205  76032930    2015
232  76032930    2015
233  76032930    2015
413  76032930    2015
565  76032930    2015
Name: TimeReviewed, dtype: int64

How to determine whether a year is a leap year?

Use calendar.isleap:

import calendar

Doctrine query builder using inner join with conditions

You can explicitly have a join like this:

$qb->innerJoin('c.phones', 'p', Join::ON, ' = p.customerId');

But you need to use the namespace of the class Join from doctrine:

use Doctrine\ORM\Query\Expr\Join;

Or if you prefere like that:

$qb->innerJoin('c.phones', 'p', Doctrine\ORM\Query\Expr\Join::ON, ' = p.customerId');

Otherwise, Join class won't be detected and your script will crash...

Here the constructor of the innerJoin method:

public function innerJoin($join, $alias, $conditionType = null, $condition = null);

You can find other possibilities (not just join "ON", but also "WITH", etc...) here:


Think it should be:

    ->innerJoin('c.phones', 'p', Join::ON, ' = p.customerId')
    ->where('c.username = :username')
    ->andWhere(' = :phone');

        'username' => $username,
        'phone' => $phone->getPhone(),

Otherwise I think you are performing a mix of ON and WITH, perhaps the problem.

How to get root directory of project in core. Directory.GetCurrentDirectory() doesn't seem to work correctly on a mac

I solved the problem with this code:

using System.IO;

var path = Path.GetDirectoryName(Assembly.GetEntryAssembly().Location.Substring(0, Assembly.GetEntryAssembly().Location.IndexOf("bin\\")))

How to write to a JSON file in the correct format

To make this work on Ubuntu Linux:

  1. I installed the Ubuntu package ruby-json:

    apt-get install ruby-json
  2. I wrote the script in ${HOME}/rubybin/jsonDEMO

  3. $HOME/.bashrc included:


(On this occasion I also typed the above on the bash command line.)

Then it worked when I entered on the command line:


Render a string in HTML and preserve spaces and linebreaks

I was trying the white-space: pre-wrap; technique stated by pete but if the string was continuous and long it just ran out of the container, and didn't warp for whatever reason, didn't have much time to investigate.. but if you too are having the same problem, I ended up using the <pre> tags and the following css and everything was good to go..

pre {
font-size: inherit;
color: inherit;
border: initial;
padding: initial;
font-family: inherit;

successful/fail message pop up box after submit?

Instead of using a submit button, try using a <button type="button">Submit</button>

You can then call a javascript function in the button, and after the alert popup is confirmed, you can manually submit the form with document.getElementById("form").submit(); ... so you'll need to name and id your form for that to work.

MS SQL Date Only Without Time

DATEADD(d, 0, DATEDIFF(d, 0, [tstamp]))

Edit: While this will remove the time portion of your datetime, it will also make the condition non SARGable. If that's important for this query, an indexed view or a between clause is more appropriate.

How do I stop Notepad++ from showing autocomplete for all words in the file

Notepad++ provides 2 types of features:

  • Auto-completion that read the open file and provide suggestion of words and/or functions within the file
  • Suggestion with the arguments of functions (specific to the language)

Based on what you write, it seems what you want is auto-completion on function only + suggestion on arguments.

To do that, you just need to change a setting.

  1. Go to Settings > Preferences... > Auto-completion
  2. Check Enable Auto-completion on each input
  3. Select Function completion and not Word completion
  4. Check Function parameter hint on input (if you have this option)

On version 6.5.5 of Notepad++, I have this setting settings

Some documentation about auto-completion is available in Notepad++ Wiki.

How do I format a date in VBA with an abbreviated month?

I'm using

Sheet1.Range("E2", "E3000").NumberFormat = "dd/mm/yyyy hh:mm:ss"

to format a column

So I guess

Sheet1.Range("E2", "E3000").NumberFormat = "MMM dd yyyy"

would do the trick for you.

More: NumberFormat function.

Find element in List<> that contains a value

Using function Find is cleaner way.

MyClass item = MyList.Find(item => == "foo");
if (item != null) // check item isn't null

Upload artifacts to Nexus, without Maven

If you need a convenient command line interface or python API, look at repositorytools

Using it, you can upload artifact to nexus with command

artifact upload foo-1.2.3.ext releases com.fooware

To make it work, you will also need to set some environment variables

export REPOSITORY_USER=admin
export REPOSITORY_PASSWORD=mysecretpassword

How can I copy the content of a branch to a new local branch?

git checkout old_branch
git branch new_branch

This will give you a new branch "new_branch" with the same state as "old_branch".

This command can be combined to the following:

git checkout -b new_branch old_branch

Completely removing phpMyAdmin

Try purge

sudo aptitude purge phpmyadmin

Not sure this works with plain old apt-get though

JS strings "+" vs concat method

In JS, "+" concatenation works by creating a new String object.

For example, with...

var s = "Hello";

...we have one object s.


s = s + " World";

Now, s is a new object.

2nd method: String.prototype.concat

How to simulate key presses or a click with JavaScript?

Or even shorter, with only standard modern Javascript:

var first_link = document.getElementsByTagName('a')[0];
first_link.dispatchEvent(new MouseEvent('click'));

The new MouseEvent constructor takes a required event type name, then an optional object (at least in Chrome). So you could, for example, set some properties of the event:

first_link.dispatchEvent(new MouseEvent('click', {bubbles: true, cancelable: true}));

Map and Reduce in .NET

The classes of problem that are well suited for a mapreduce style solution are problems of aggregation. Of extracting data from a dataset. In C#, one could take advantage of LINQ to program in this style.

From the following article:

the GroupBy method is acting as the map, while the Select method does the job of reducing the intermediate results into the final list of results.

var wordOccurrences = words
                .GroupBy(w => w)
                .Select(intermediate => new
                    Word = intermediate.Key,
                    Frequency = intermediate.Sum(w => 1)
                .Where(w => w.Frequency > 10)
                .OrderBy(w => w.Frequency);

For the distributed portion, you could check out DryadLINQ:

Can you recommend a free light-weight MySQL GUI for Linux?

Why not try MySQL GUI Tools? It's light, and does its job well.

<select> HTML element with height

You can also "center" the text with:

vertical-align: middle;

How to append to a file in Node?

fd = fs.openSync(path.join(process.cwd(), 'log.txt'), 'a')
fs.writeSync(fd, 'contents to append')

Performance differences between ArrayList and LinkedList


  • ArrayList is best choice if our frequent operation is retrieval operation.
  • ArrayList is worst choice if our operation is insertion and deletion in the middle because internally several shift operations are performed.
  • In ArrayList elements will be stored in consecutive memory locations hence retrieval operation will become easy.


  • LinkedList is best choice if our frequent operation is insertion and deletion in the middle.
  • LinkedList is worst choice is our frequent operation is retrieval operation.
  • In LinkedList the elements won't be stored in consecutive memory location and hence retrieval operation will be complex.

Now coming to your questions:-

1) ArrayList saves data according to indexes and it implements RandomAccess interface which is a marker interface that provides the capability of a Random retrieval to ArrayList but LinkedList doesn't implements RandomAccess Interface that's why ArrayList is faster than LinkedList.

2) The underlying data structure for LinkedList is doubly linked list so insertion and deletion in the middle is very easy in LinkedList as it doesn't have to shift each and every element for each and every deletion and insertion operations just like ArrayList(which is not recommended if our operation is insertion and deletion in the middle because internally several shift operations are performed).