Programs & Examples On #Inverse kinematics

Inverse kinematics refers to a set of algorithms used to compute joint parameters necessary to move a robotic arm to a particular position, or more generally to apply geometric constraints on a mechanism (e.g. moving the center of mass of a humanoid robot).

Change default timeout for mocha

In current versions of Mocha, the timeout can be changed globally like this:


Just add the line above anywhere in your test suite, preferably at the top of your spec or in a separate test helper.

In older versions, and only in a browser, you could change the global configuration using mocha.setup.

mocha.setup({ timeout: 5000 });

The documentation does not cover the global timeout setting, but offers a few examples on how to change the timeout in other common scenarios.

Zabbix server is not running: the information displayed may not be current

I was using a special character in my DB password - wrapping the DBPassword option in /etc/zabbix/zabbix_server.conf and doing sudo service zabbix-server restart got me back up and running.

Not Working DBPassword=MyString?

Working DBPassword='MyString?'

Can't access Eclipse marketplace

And also check with your antivirus, in case of me its avast, its blocking me from accessing market place, so i disabled it for few mins and tried accessing market place from eclipse , it worked!!!

Change hover color on a button with Bootstrap customization

or can do this...
set all btn ( class name like : .btn- + $theme-colors: map-merge ) styles at one time :

@each $color, $value in $theme-colors {
  .btn-#{$color} {
    @include button-variant($value, $value,
    // modify
    $hover-background: lighten($value, 7.5%),
    $hover-border: lighten($value, 10%),
    $active-background: lighten($value, 10%),
    $active-border: lighten($value, 12.5%)
    // /modify

// code from "node_modules/bootstrap/scss/_buttons.scss"

should add into your customization scss file.

App not setup: This app is still in development mode

This is an answer I haven't seen much around (this it was in a comment somewhere) although yes taking the app off development mode will work this can be bad for security or really annoying if the app isn't ready yet but you need to submit the app for review on account of needing access to special permissions (e.g. user_birthday).

What I did instead to fix the error was go to{appId}/roles/ or from the app dashboard click roles on the left side

Then add the user account(s) to either developer or tester. Developers will need to be verified by mobile and will get access to the app to make changes but a tester will only need to be verified by email (not sure if even this is necessary but it probably is) and will only be able to use the API instead of make changes to settings.

If the app is ready for the public, obviously just take the app off development mode.

sql primary key and index

Making it a primary key should also automatically create an index for it.

Custom bullet symbol for <li> elements in <ul> that is a regular character, and not an image

This is the W3C solution. Works in Firefox and Chrome.

ul { list-style-type: ""; }
/* Sets the marker to a  emoji character */

ul { list-style-type: " "; }

input checkbox true or checked or yes

Accordingly to W3C checked input's attribute can be absent/ommited or have "checked" as its value. This does not invalidate other values because there's no restriction to the browser implementation to allow values like "true", "on", "yes" and so on. To guarantee that you'll write a cross-browser checkbox/radio use checked="checked", as recommended by W3C.

disabled, readonly and ismap input's attributes go on the same way.


empty is not a valid value for checked, disabled, readonly and ismap input's attributes, as warned by @Quentin

How to find cube root using Python?

def cube(x):
    if 0<=x: return x**(1./3.)
    return -(-x)**(1./3.)
print (cube(8))
print (cube(-8))

Here is the full answer for both negative and positive numbers.


Or here is a one-liner;

root_cube = lambda x: x**(1./3.) if 0<=x else -(-x)**(1./3.)

:after and :before pseudo-element selectors in Sass

Use ampersand to specify the parent selector.

SCSS syntax:

p {
    margin: 2em auto;

    > a {
        color: red;

    &:before {
        content: "";

    &:after {
        content: "* * *";

How can I make a button redirect my page to another page?

Just add an onclick event to the button:

<button onclick="location.href = '';" id="myButton" class="float-left submit-button" >Home</button>

But you shouldn't really have it inline like that, instead, put it in a JS block and give the button an ID:

<button id="myButton" class="float-left submit-button" >Home</button>

<script type="text/javascript">
    document.getElementById("myButton").onclick = function () {
        location.href = "";

Execute a SQL Stored Procedure and process the results

My Stored Procedure Requires 2 Parameters and I needed my function to return a datatable here is 100% working code

Please make sure that your procedure return some rows

Public Shared Function Get_BillDetails(AccountNumber As String) As DataTable
        debug.print("Look up account number " & AccountNumber)
        Dim DP As New SqlDataAdapter("EXEC SP_GET_ACCOUNT_PAYABLES_GROUP  '" & AccountNumber & "' , '" & 08/28/2013 &"'", connection.Con)
        Dim DST As New DataSet
        Return DST.Tables(0)      
    Catch ex As Exception
        Return Nothing
    End Try
End Function

Git pull - Please move or remove them before you can merge

Apparently the files were added in remote repository, no matter what was the content of .gitignore file in the origin.

As the files exist in the remote repository, git has to pull them to your local work tree as well and therefore complains that the files already exist.

.gitignore is used only for scanning for the newly added files, it doesn't have anything to do with the files which were already added.

So the solution is to remove the files in your work tree and pull the latest version. Or the long-term solution is to remove the files from the repository if they were added by mistake.

A simple example to remove files from the remote branch is to

$git checkout <brachWithFiles>
$git rm -r *.extension
$git commit -m "fixin...."
$git push

Then you can try the $git merge again

typescript - cloning object

In typeScript I test with angular, and it's doing OK

deepCopy(obj) {

        var copy;

        // Handle the 3 simple types, and null or undefined
        if (null == obj || "object" != typeof obj) return obj;

        // Handle Date
        if (obj instanceof Date) {
            copy = new Date();
            return copy;

        // Handle Array
        if (obj instanceof Array) {
            copy = [];
            for (var i = 0, len = obj.length; i < len; i++) {
                copy[i] = this.deepCopy(obj[i]);
            return copy;

        // Handle Object
        if (obj instanceof Object) {
            copy = {};
            for (var attr in obj) {
                if (obj.hasOwnProperty(attr)) copy[attr] = this.deepCopy(obj[attr]);
            return copy;

        throw new Error("Unable to copy obj! Its type isn't supported.");

Multi-statement Table Valued Function vs Inline Table Valued Function

There is another difference. An inline table-valued function can be inserted into, updated, and deleted from - just like a view. Similar restrictions apply - can't update functions using aggregates, can't update calculated columns, and so on.

Cannot deserialize instance of object out of START_ARRAY token in Spring Webservice

Taking for granted that the JSON you posted is actually what you are seeing in the browser, then the problem is the JSON itself.

The JSON snippet you have posted is malformed.

You have posted:

        "name" : "shopqwe",
        "mobiles" : [],
        "address" : {
            "town" : "city",
            "street" : "streetqwe",
            "streetNumber" : "59",
            "cordX" : 2.229997,
            "cordY" : 1.002539
                "shoeName" : "addidas",
                "number" : "631744030",
                "producent" : "nike",
                "price" : 999.0,
                "sizes" : [30.0, 35.0, 38.0]

while the correct JSON would be:

        "name" : "shopqwe",
        "mobiles" : [],
        "address" : {
            "town" : "city",
            "street" : "streetqwe",
            "streetNumber" : "59",
            "cordX" : 2.229997,
            "cordY" : 1.002539
        "shoe" : [{
                "shoeName" : "addidas",
                "number" : "631744030",
                "producent" : "nike",
                "price" : 999.0,
                "sizes" : [30.0, 35.0, 38.0]

How to connect wireless network adapter to VMWare workstation?

Change your network adapter to a bridged connection, this will directly connect to your computers physical network.

How to find substring from string?

As user1511510 has identified, there's an unusual case when abc is at the end of the file name. We need to look for either /abc/ or /abc followed by a string-terminator '\0'. A naive way to do this would be to check if either /abc/ or /abc\0 are substrings:

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

int main() {
    const char *str = "/user/desktop/abc";
    const int exists = strstr(str, "/abc/") || strstr(str, "/abc\0");
    return 0;

but exists will be 1 even if abc is not followed by a null-terminator. This is because the string literal "/abc\0" is equivalent to "/abc". A better approach is to test if /abc is a substring, and then see if the character after this substring (indexed using the pointer returned by strstr()) is either a / or a '\0':

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

int main() {
    const char *str = "/user/desktop/abc", *substr;
    const int exists = (substr = strstr(str, "/abc")) && (substr[4] == '\0' || substr[4] == '/');
    return 0;

This should work in all cases.

Get single listView SelectedItem

Usually SelectedItems returns either a collection, an array or an IQueryable.

Either way you can access items via the index as with an array:

String text = listView1.SelectedItems[0].Text; 

By the way, you can save an item you want to look at into a variable, and check its structure in the locals after setting a breakpoint.

T-SQL datetime rounded to nearest minute and nearest hours with using functions

Select convert(char(8), DATEADD(MINUTE, DATEDIFF(MINUTE, 0, getdate), 0), 108) as Time

will round down seconds to 00

How to implement a read only property

The second method is preferred because of the encapsulation. You can certainly have the readonly field be public, but that goes against C# idioms in which you have data access occur through properties and not fields.

The reasoning behind this is that the property defines a public interface and if the backing implementation to that property changes, you don't end up breaking the rest of the code because the implementation is hidden behind an interface.

Forking / Multi-Threaded Processes | Bash

Here's my thread control function:

# This function just checks jobs in background, don't do more things.
# if jobs number is lower than MAX, then return to get more jobs;
# if jobs number is greater or equal to MAX, then wait, until someone finished.

# Usage:
#   thread_max 8
#   thread_max 0    # wait, until all jobs completed

thread_max() {
    local CHECK_INTERVAL="3s"
    local CUR_THREADS=
    local MAX=
    [[ $1 ]] && MAX=$1 || return 127

    # reset MAX value, 0 is easy to remember
    [ $MAX -eq 0 ] && {
        DEBUG "waiting for all tasks finish"

    while true; do
        CUR_THREADS=`jobs -p | wc -w`

        # workaround about jobs bug. If don't execute it explicitily,
        # CUR_THREADS will stick at 1, even no jobs running anymore.
        jobs &>/dev/null

        DEBUG "current thread amount: $CUR_THREADS"
        if [ $CUR_THREADS -ge $MAX ]; then
            sleep $CHECK_INTERVAL
            return 0

How do I generate random integers within a specific range in Java?

Following code could be used:

ThreadLocalRandom.current().nextInt(rangeStart, rangeEndExclusive)

Difference between numeric, float and decimal in SQL Server

Decimal has a fixed precision while float has variable precision.

EDIT (failed to read entire question): Float(53) (aka real) is a double-precision (64-bit) floating point number in SQL Server. Regular Float is a single-precision (32-bit) floating point number. Double is a good combination of precision and simplicty for a lot of calculations. You can create a very high precision number with decimal -- up to 136-bit -- but you also have to be careful that you define your precision and scale correctly so that it can contain all your intermediate calculations to the necessary number of digits.

HTML5 Dynamically create Canvas

 <canvas id="canvas" width="300" height="300"></canvas>
  var sun = new Image();
  var moon = new Image();
  var earth = new Image();
  function init() {
  sun.src = '';
  moon.src = '';
  earth.src = '';

  function draw() {
  var ctx = document.getElementById('canvas').getContext('2d');

  ctx.globalCompositeOperation = 'destination-over';
  ctx.clearRect(0, 0, 300, 300);

  ctx.fillStyle = 'rgba(0, 0, 0, 0.4)';
  ctx.strokeStyle = 'rgba(0, 153, 255, 0.4)';;
  ctx.translate(150, 150);

  // Earth
  var time = new Date();
  ctx.rotate(((2 * Math.PI) / 60) * time.getSeconds() + ((2 * Math.PI) / 60000) * 
  ctx.translate(105, 0);
  ctx.fillRect(10, -19, 55, 31); 
  ctx.drawImage(earth, -12, -12);

   // Moon;
  ctx.rotate(((2 * Math.PI) / 6) * time.getSeconds() + ((2 * Math.PI) / 6000) * 
  ctx.translate(0, 28.5);
  ctx.drawImage(moon, -3.5, -3.5);


   ctx.arc(150, 150, 105, 0, Math.PI * 2, false);

   ctx.drawImage(sun, 0, 0, 300, 300);



How can I retrieve the remote git address of a repo?

The long boring solution, which is not involved with CLI, you can manually navigate to:

your local repo folder ? .git folder (hidden) ? config file

then choose your text editor to open it and look for url located under the [remote "origin"] section.

Close Android Application

As per my knowledge, finish function close the current displayed screen only.

Refer this example (where see the answer given by 'plusminus'), it will sure help you to close your application.

Get the difference between two dates both In Months and days in sql

Find out Year - Month- Day between two Days in Orale Sql

trunc(trunc(months_between(To_date('20120101', 'YYYYMMDD'),to_date('19910228','YYYYMMDD')))/12) years ,
trunc(months_between(To_date('20120101', 'YYYYMMDD'),to_date('19910228','YYYYMMDD'))) 
(trunc(trunc(months_between(To_date('20120101', 'YYYYMMDD'),to_date('19910228','YYYYMMDD')))/12))*12
             round(To_date('20120101', 'YYYYMMDD')-add_months(to_date('19910228','YYYYMMDD'),
                           trunc(months_between(To_date('20120101', 'YYYYMMDD'),to_date('19910228','YYYYMMDD'))))) days
        from dual;

Using form input to access camera and immediately upload photos using web app

It's really easy to do this, simply send the file via an XHR request inside of the file input's onchange handler.

<input id="myFileInput" type="file" accept="image/*;capture=camera">

var myInput = document.getElementById('myFileInput');

function sendPic() {
    var file = myInput.files[0];

    // Send file here either by adding it to a `FormData` object 
    // and sending that via XHR, or by simply passing the file into 
    // the `send` method of an XHR instance.

myInput.addEventListener('change', sendPic, false);

min and max value of data type in C

Maximum value of any unsigned integral type:

  • ((t)~(t)0) // Generic expression that would work in almost all circumstances.

  • (~(t)0) // If you know your type t have equal or larger size than unsigned int. (This cast forces type promotion.)

  • ((t)~0U) // If you know your type t have smaller size than unsigned int. (This cast demotes type after the unsigned int-type expression ~0U is evaluated.)

Maximum value of any signed integral type:

  • If you have an unsigned variant of type t, ((t)(((unsigned t)~(unsigned t)0)>>1)) would give you the fastest result you need.

  • Otherwise, use this (thanks to @vinc17 for suggestion): (((1ULL<<(sizeof(t)*CHAR_BIT-2))-1)*2+1)

Minimum value of any signed integral type:

You have to know the signed number representation of your machine. Most machines use 2's complement, and so -(((1ULL<<(sizeof(t)*CHAR_BIT-2))-1)*2+1)-1 will work for you.

To detect whether your machine uses 2's complement, detect whether (~(t)0U) and (t)(-1) represent the same thing.

So, combined with above:


will give you the minimum value of any signed integral type.

As an example: Maximum value of size_t (a.k.a. the SIZE_MAX macro) can be defined as (~(size_t)0). Linux kernel source code define SIZE_MAX macro this way.

One caveat though: All of these expressions use either type casting or sizeof operator and so none of these would work in preprocessor conditionals (#if ... #elif ... #endif and like).

(Answer updated for incorpoating suggestions from @chux and @vinc17. Thank you both.)

Android button with different background colors

In the URL you pointed to, the button_text.xml is being used to set the textColor attribute.That it is reason they had the button_text.xml in res/color folder and therefore they used @color/button_text.xml

But you are trying to use it for background attribute. The background attribute looks for something in res/drawable folder.

check this i got this selector custom button from the internet.I dont have the link.but i thank the poster for this.It helped me.have this in the drawable folder

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="">
    <item android:state_pressed="true" >
                android:angle="270" />
                android:color="@color/grey05" />
                android:radius="3dp" />
                android:bottom="10dp" />

    <item android:state_focused="true" >
                android:angle="270" />
                android:color="@color/grey05" />
                android:radius="3dp" />
                android:bottom="10dp" />

                android:angle="270" />
                android:color="@color/grey05" />
                android:radius="3dp" />
                android:bottom="10dp" />


And i used in my main.xml layout like this

<Button android:id="@+id/button1"

Hope this helps. Vik is correct.

EDIT : Here is the colors.xml

<?xml version="1.0" encoding="utf-8"?>
   <color name="yellow1">#F9E60E</color>
   <color name="yellow2">#F9F89D</color>
   <color name="orange4">#F7BE45</color>
   <color name="orange5">#F7D896</color>
   <color name="blue2">#19FCDA</color>
   <color name="blue25">#D9F7F2</color>
   <color name="grey05">#ACA899</color>
   <color name="white1">#FFFFFF</color>
   <color name="white2">#DDDDDD</color>

Pandas/Python: Set value of one column based on value in another column


df['c2'] = df['c1'].apply(lambda x: 10 if x == 'Value' else x)

What is the easiest way to remove the first character from a string?

Using regex:

str = 'string'
n = 1  #to remove first n characters

str[/.{#{str.size-n}}\z/] #=> "tring"

How can I get Git to follow symlinks?

NOTE: This advice is now out-dated as per comment since Git 1.6.1. Git used to behave this way, and no longer does.

Git by default attempts to store symlinks instead of following them (for compactness, and it's generally what people want).

However, I accidentally managed to get it to add files beyond the symlink when the symlink is a directory.


  /bar/foo --> /foo

by doing

 git add /bar/foo/baz

it appeared to work when I tried it. That behavior was however unwanted by me at the time, so I can't give you information beyond that.

how to add or embed CKEditor in php page

If you have downloaded the latest Version 4.3.4 then just follow these steps.

  • Download the package, unzip and place in your web directory or root folder.
  • Provide the read write permissions to that folder (preferably Ubuntu machines )
  • Create view page test.php
  • Paste the below mentioned code it should work fine.

Load the mentioned js file

<script type="text/javascript" src="/ckeditor/ckeditor.js"></script>
<textarea class="ckeditor" name="editor"></textarea>

javascript: detect scroll end

The accepted answer was fundamentally flawed, it has since been deleted. The correct answer is:

function scrolled(e) {
  if (myDiv.offsetHeight + myDiv.scrollTop >= myDiv.scrollHeight) {

Tested this in Firefox, Chrome and Opera. It works.

Replacing .NET WebBrowser control with a better browser, like Chrome?

Checkout CefSharp .Net bindings, a project I started a while back that thankfully got picked up by the community and turned into something wonderful.

The project wraps the Chromium Embedded Framework and has been used in a number of major projects including Rdio's Windows client, Facebook Messenger for Windows and Github for Windows.

It features browser controls for WPF and Winforms and has tons of features and extension points. Being based on Chromium it's blisteringly fast too.

Grab it from NuGet: Install-Package CefSharp.Wpf or Install-Package CefSharp.WinForms

Check out examples and give your thoughts/feedback/pull-requests:

BSD Licensed

Make REST API call in Swift

Swift 3.0

let request = NSMutableURLRequest(url: NSURL(string: "")! as URL)
let session = URLSession.shared
request.httpMethod = "GET"
request.addValue("application/json", forHTTPHeaderField: "Content-Type")
request.addValue("application/json", forHTTPHeaderField: "Accept")

let task = session.dataTask(with: request as URLRequest, completionHandler: {data, response, error -> Void in
      if error != nil {
          print("Error: \(String(describing: error))")
      } else {
          print("Response: \(String(describing: response))")


How to pass a single object[] to a params object[]

Another way to solve this problem (it's not so good practice but looks beauty):

static class Helper
    public static object AsSingleParam(this object[] arg)
       return (object)arg;


f(new object[] { 1, 2, 3 }.AsSingleParam());

How to change the default message of the required field in the popover of form-control in bootstrap?

And for all input and select:

$("input[required], select[required]").attr("oninvalid", "this.setCustomValidity('Required!')");
$("input[required], select[required]").attr("oninput", "setCustomValidity('')");

Use .corr to get the correlation between two columns

I ran into the same issue. It appeared Citable Documents per Person was a float, and python skips it somehow by default. All the other columns of my dataframe were in numpy-formats, so I solved it by converting the columnt to np.float64

Top15['Citable Documents per Person']=np.float64(Top15['Citable Documents per Person'])

Remember it's exactly the column you calculated yourself

Bootstrap 4 dropdown with search

As of version 1.13.1 there is support for Bootstrap 4:

The implementation remains exactly the same as it was in Bootstrap 3:

  • add class="selectpicker" and data-live-search="true"to your select
  • add data-tokens to your options. The live search will look into these data-token element when performing the search.

This is an example, taken from the site of the link above:

<select class="selectpicker" data-live-search="true">
  <option data-tokens="ketchup mustard">Hot Dog, Fries and a Soda</option>
  <option data-tokens="mustard">Burger, Shake and a Smile</option>
  <option data-tokens="frosting">Sugar, Spice and all things nice</option>

Live search for the search term 'fro' will only leave the third option visible (because of the data-tokens "frosting").

Don't forget to include the bootstrap-select CDN .css and .js in your project. I am very glad to see this live search become available again, because it comes in very handy when presenting large dropdown lists to the user.

How to call Stored Procedure in Entity Framework 6 (Code-First)?

You are using MapToStoredProcedures() which indicates that you are mapping your entities to stored procedures, when doing this you need to let go of the fact that there is a stored procedure and use the context as normal. Something like this (written into the browser so not tested)

using(MyContext context = new MyContext())
    Department department = new Department()
        Name = txtDepartment.text.trim()

If all you really trying to do is call a stored procedure directly then use SqlQuery

Best font for coding

Funny, I was just researching this yesterday!

I personally use Monaco 10 or 11 for the Mac, but a good cross platform font would have to be Droid Sans Mono: Or DejaVu sans mono is another great one (goes under a lot of different names, will be Menlo on SNow leopard and is really just a repackaged Prima/Vera) check it out here: Prima/Vera... Check it out here:

Using variable in SQL LIKE statement

We can write directly too...

DECLARE @SearchLetter CHAR(1) 

SET @SearchLetter = 'A' 

WHERE  CONTACTNAME LIKE @SearchLetter + '%' 
       AND REGION = 'WY' 

or the following way as well if we have to append all the search characters then,

DECLARE @SearchLetter CHAR(1) 

SET @SearchLetter = 'A' + '%' 

       AND REGION = 'WY' 

Both these will work

Reload child component when variables on parent component changes. Angular2

On Angular to update a component including its template, there is a straight forward solution to this, having an @Input property on your ChildComponent and add to your @Component decorator changeDetection: ChangeDetectionStrategy.OnPush as follows:

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

    selector: 'master',
    templateUrl: templateUrl,
    changeDetection: ChangeDetectionStrategy.OnPush    

export class ChildComponent{
  @Input() data: MyData;

This will do all the work of check if Input data have changed and re-render the component

REST, HTTP DELETE and parameters

It's an old question, but here are some comments...

  1. In SQL, the DELETE command accepts a parameter "CASCADE", which allows you to specify that dependent objects should also be deleted. This is an example of a DELETE parameter that makes sense, but 'man rm' could provide others. How would these cases possibly be implemented in REST/HTTP without a parameter?
  2. @Jan, it seems to be a well-established convention that the path part of the URL identifies a resource, whereas the querystring does not (at least not necessarily). Examples abound: getting the same resource but in a different format, getting specific fields of a resource, etc. If we consider the querystring as part of the resource identifier, it is impossible to have a concept of "different views of the same resource" without turning to non-RESTful mechanisms such as HTTP content negotiation (which can be undesirable for many reasons).

Dictionary of dictionaries in Python?

Using collections.defaultdict is a big time-saver when you're building dicts and don't know beforehand which keys you're going to have.

Here it's used twice: for the resulting dict, and for each of the values in the dict.

import collections

def aggregate_names(errors):
    result = collections.defaultdict(lambda: collections.defaultdict(list))
    for real_name, false_name, location in errors:
    return result

Combining this with your code:

dictionary = aggregate_names(previousFunction(string))

Or to test:

    ('Fred', 'Frad', 123),
    ('Jim', 'Jam', 100),
    ('Fred', 'Frod', 200),
    ('Fred', 'Frad', 300)]
print aggregate_names(EXAMPLES)

How to scroll to top of page with JavaScript/jQuery?

I remember seeing this posted somewhere else (I couldn't find where), but this works really well:

setTimeout(() => {
    window.scrollTo(0, 0);
}, 0);

It's weird, but the way it works is based off of the way JavaScript's stack queue works. The full explanation is found here in the Zero Delays section.

The basic idea is that the time for setTimeout doesn't actually specify the set amount of time it will wait, but the minimum amount of time it will wait. So when you tell it to wait 0ms, the browser runs all the other queued processes (like scrolling the window to where you were last) and then executes the callback.

Hidden Features of Xcode

Right click on any word and select 'Find Selected Text in API Reference' to search the API for that word. This is very helpful if you need to look up the available properties and/or methods for a class. Instead of heading to or Google you will get a popup window of what you were looking for (or what was found).

Efficiently checking if arbitrary object is NaN in Python / numpy / pandas?

Is your type really arbitrary? If you know it is just going to be a int float or string you could just do

 if val.dtype == float and np.isnan(val):

assuming it is wrapped in numpy , it will always have a dtype and only float and complex can be NaN

How to count lines of Java code using IntelliJ IDEA?

Although it is not an IntelliJ option, you could use a simple Bash command (if your operating system is Linux/Unix). Go to your source directory and type:

find . -type f -name '*.java' | xargs cat | wc -l

SQL Row_Number() function in Where Clause

Using CTE (SQL Server 2005+):

WITH employee_rows AS (
  SELECT t.employee_id,
         ROW_NUMBER() OVER ( ORDER BY t.employee_id ) 'rownum'
SELECT er.employee_id
  FROM employee_rows er
 WHERE er.rownum > 1

Using Inline view/Non-CTE Equivalent Alternative:

SELECT er.employee_id
  FROM (SELECT t.employee_id,
               ROW_NUMBER() OVER ( ORDER BY t.employee_id ) 'rownum'
          FROM V_EMPLOYEE t) er
 WHERE er.rownum > 1

Oracle 10g: Extract data (select) from XML (CLOB Type)

You can try creating DBMS_XMLPARSER.parser object from the CLOB XML and get a DBMS_XMLDOM.DOMDocument object from it. Then use DBMS_XMLDOM package methods to get the value of any node.

   xml_            CLOB := 'X';
   p               DBMS_XMLPARSER.parser;
   doc_            DBMS_XMLDOM.DOMDocument;

      -- Convert the CLOB into a XML-document
      P := DBMS_XMLPARSER.newparser();
      -- Parse the clob and get the XML-document
      DBMS_XMLPARSER.parseclob(p, xml_);
      doc_ := DBMS_XMLPARSER.getDocument(p);

Then use the below methods to extract node value

DBMS_XMLDOM.getElementsByTagName(doc_, 'NodeName'); DBMS_XMLDOM.GetNodeValue(node_obj_);

Refer more about DBMS_XMLDOM methods here.

Remove scroll bar track from ScrollView in Android

Solved my problem by adding this to my ListView:


adding text to an existing text element in javascript via DOM

remove .textContent from var t = document.getElementById("p").textContent;

var t = document.getElementById("p");_x000D_
var y = document.createTextNode("This just got added");_x000D_
<p id ="p">This is some text</p>

javascript how to create a validation error message without using alert


<script language="javascript">
        var flag=0;
        function username()
                document.getElementById("error0").innerHTML="Enter UserID";
        function password()
                document.getElementById("error1").innerHTML="Enter password";   

        function check(form)
                return false;
                return true;



<form name="loginform" action="Login" method="post" class="form-signin" onSubmit="return check(this)">

                    <div id="error0"></div>
                    <input type="text" id="inputEmail" name="username" placeholder="UserID" onBlur="username()">
                    <div id="error1"></div>
                    <input type="password" id="inputPassword" name="password" placeholder="Password" onBlur="password()" onclick="make_blank()">

                    <button type="submit" class="btn">Sign in</button>

How to save select query results within temporary table?

select *
into #TempTable
from SomeTale

select *
from #TempTable

How to set up java logging using a properties file? (java.util.logging)

I have tried your code in above code don't use [preferences.load(configFile);] statement and it will is running sample code

public static void main(String[]s)

    Logger log = Logger.getLogger("MyClass");
    try {
    FileInputStream fis =  new FileInputStream("");
    log.addHandler(new java.util.logging.ConsoleHandler());
    log.setUseParentHandlers(false);"starting myApp");

    catch(IOException e) {

Understanding dispatch_async

Swift version

This is the Swift version of David's Objective-C answer. You use the global queue to run things in the background and the main queue to update the UI. .background).async {
    // Background Thread
    DispatchQueue.main.async {
        // Run UI Updates

How to create .pfx file from certificate and private key?

I know a few users have talked about installing this and that and adding command lines programmes and downloading...

Personally I am lazy and find all these methods cumbersome and slow, plus I don't want to download anything and find the correct cmd lines if I don't have to.

Best way for me on my personal IIS server is to use RapidSSLOnline. This is a tool that's on a server allows you to upload your certificate and private key and is able to generate a pfx file for you that you can directly import into IIS.

The link is here:

Below is the steps used for the scenario requested.

  1. Select Current Type = PEM
  2. Change for = PFX
  3. Upload your certificate
  4. Upload your private key
  5. If you have ROOT CA cert or intermediate certs upload them too
  6. Set a password of your choosing, used in IIS
  7. Click the reCaptcha to prove you're not a bot
  8. Click Convert

And that's it you should have a PFX downloaded and use this in your Import process on IIS.

Hope this helps other like minded, lazy tech people.

NPM vs. Bower vs. Browserify vs. Gulp vs. Grunt vs. Webpack

Update October 2018

If you are still uncertain about Front-end dev, you can take a quick look into an excellent resource here.

Update June 2018

Learning modern JavaScript is tough if you haven’t been there since the beginning. If you are the newcomer, remember to check this excellent written to have a better overview.

Update July 2017

Recently I found a comprehensive guide from Grab team about how to approach front-end development in 2017. You can check it out as below.

I've been also searching for this quite some time since there are a lot of tools out there and each of them benefits us in a different aspect. The community is divided across tools like Browserify, Webpack, jspm, Grunt and Gulp. You might also hear about Yeoman or Slush. That’s not a problem, it’s just confusing for everyone trying to understand a clear path forward.

Anyway, I would like to contribute something.

Table Of Content

  • Table Of Content
  • 1. Package Manager
    • NPM
    • Bower
    • Difference between Bower and NPM
    • Yarn
    • jspm
  • 2. Module Loader/Bundling
    • RequireJS
    • Browserify
    • Webpack
    • SystemJS
  • 3. Task runner
    • Grunt
    • Gulp
  • 4. Scaffolding tools
    • Slush and Yeoman

1. Package Manager

Package managers simplify installing and updating project dependencies, which are libraries such as: jQuery, Bootstrap, etc - everything that is used on your site and isn't written by you.

Browsing all the library websites, downloading and unpacking the archives, copying files into the projects — all of this is replaced with a few commands in the terminal.


It stands for: Node JS package manager helps you to manage all the libraries your software relies on. You would define your needs in a file called package.json and run npm install in the command line... then BANG, your packages are downloaded and ready to use. It could be used both for front-end and back-end libraries.


For front-end package management, the concept is the same with NPM. All your libraries are stored in a file named bower.json and then run bower install in the command line.

Bower is recommended their user to migrate over to npm or yarn. Please be careful

Difference between Bower and NPM

The biggest difference between Bower and NPM is that NPM does nested dependency tree while Bower requires a flat dependency tree as below.

Quoting from What is the difference between Bower and npm?


project root
[node_modules] // default directory for dependencies
 -> dependency A
 -> dependency B
    -> dependency A

 -> dependency C
    -> dependency B
       -> dependency A
    -> dependency D


project root
[bower_components] // default directory for dependencies
 -> dependency A
 -> dependency B // needs A
 -> dependency C // needs B and D
 -> dependency D

There are some updates on npm 3 Duplication and Deduplication, please open the doc for more detail.


A new package manager for JavaScript published by Facebook recently with some more advantages compared to NPM. And with Yarn, you still can use both NPMand Bower registry to fetch the package. If you've installed a package before, yarn creates a cached copy which facilitates offline package installs.


JSPM is a package manager for the SystemJS universal module loader, built on top of the dynamic ES6 module loader. It is not an entirely new package manager with its own set of rules, rather it works on top of existing package sources. Out of the box, it works with GitHub and npm. As most of the Bower based packages are based on GitHub, we can install those packages using jspm as well. It has a registry that lists most of the commonly used front-end packages for easier installation.

See the different between Bower and jspm: Package Manager: Bower vs jspm

2. Module Loader/Bundling

Most projects of any scale will have their code split between several files. You can just include each file with an individual <script> tag, however, <script> establishes a new HTTP connection, and for small files – which is a goal of modularity – the time to set up the connection can take significantly longer than transferring the data. While the scripts are downloading, no content can be changed on the page.

  • The problem of download time can largely be solved by concatenating a group of simple modules into a single file and minifying it.


    <script src=“build/wagon-bundle.js”></script>
  • The performance comes at the expense of flexibility though. If your modules have inter-dependency, this lack of flexibility may be a showstopper.


    <script src=“connectors/axle.js”></script>
    <script src=“frames/board.js”></script>
    <!-- skateboard-wheel and ball-bearing both depend on abstract-rolling-thing -->
    <script src=“rolling-things/abstract-rolling-thing.js”></script>
    <script src=“rolling-things/wheels/skateboard-wheel.js”></script>
    <!-- but if skateboard-wheel also depends on ball-bearing -->
    <!-- then having this script tag here could cause a problem -->
    <script src=“rolling-things/ball-bearing.js”></script>
    <!-- connect wheels to axle and axle to frame -->
    <script src=“vehicles/skateboard/our-sk8bd-init.js”></script>

Computers can do that better than you can, and that is why you should use a tool to automatically bundle everything into a single file.

Then we heard about RequireJS, Browserify, Webpack and SystemJS


It is a JavaScript file and module loader. It is optimized for in-browser use, but it can be used in other JavaScript environments, like Node.

E.g: myModule.js

// package/lib is a dependency we require
define(["package/lib"], function (lib) {
  // behavior for our module
  function foo() {
    lib.log("hello world!");

  // export (expose) foo to other modules as foobar
  return {
    foobar: foo,

In main.js, we can import myModule.js as a dependency and use it.

require(["package/myModule"], function(myModule) {

And then in our HTML, we can refer to use with RequireJS.

<script src=“app/require.js” data-main=“main.js” ></script>

Read more about CommonJS and AMD to get understanding easily. Relation between CommonJS, AMD and RequireJS?


Set out to allow the use of CommonJS formatted modules in the browser. Consequently, Browserify isn’t as much a module loader as a module bundler: Browserify is entirely a build-time tool, producing a bundle of code that can then be loaded client-side.

Start with a build machine that has node & npm installed, and get the package:

npm install -g –save-dev browserify

Write your modules in CommonJS format

var foo = require("../foo.js");

And when happy, issue the command to bundle:

browserify entry-point.js -o bundle-name.js

Browserify recursively finds all dependencies of entry-point and assembles them into a single file:

<script src="”bundle-name.js”"></script>


It bundles all of your static assets, including JavaScript, images, CSS, and more, into a single file. It also enables you to process the files through different types of loaders. You could write your JavaScript with CommonJS or AMD modules syntax. It attacks the build problem in a fundamentally more integrated and opinionated manner. In Browserify you use Gulp/Grunt and a long list of transforms and plugins to get the job done. Webpack offers enough power out of the box that you typically don’t need Grunt or Gulp at all.

Basic usage is beyond simple. Install Webpack like Browserify:

npm install -g –save-dev webpack

And pass the command an entry point and an output file:

webpack ./entry-point.js bundle-name.js


It is a module loader that can import modules at run time in any of the popular formats used today (CommonJS, UMD, AMD, ES6). It is built on top of the ES6 module loader polyfill and is smart enough to detect the format being used and handle it appropriately. SystemJS can also transpile ES6 code (with Babel or Traceur) or other languages such as TypeScript and CoffeeScript using plugins.

Want to know what is the node module and why it is not well adapted to in-browser.

More useful article:

Why jspm and SystemJS?

One of the main goals of ES6 modularity is to make it really simple to install and use any Javascript library from anywhere on the Internet (Github, npm, etc.). Only two things are needed:

  • A single command to install the library
  • One single line of code to import the library and use it

So with jspm, you can do it.

  1. Install the library with a command: jspm install jquery
  2. Import the library with a single line of code, no need to external reference inside your HTML file.


var $ = require('jquery');

$('body').append("I've imported jQuery!");
  1. Then you configure these things within System.config({ ... }) before importing your module. Normally when run jspm init, there will be a file named config.js for this purpose.

  2. To make these scripts run, we need to load system.js and config.js on the HTML page. After that, we will load the display.js file using the SystemJS module loader.


<script src="jspm_packages/system.js"></script>
<script src="config.js"></script>

Noted: You can also use npm with Webpack as Angular 2 has applied it. Since jspm was developed to integrate with SystemJS and it works on top of the existing npm source, so your answer is up to you.

3. Task runner

Task runners and build tools are primarily command-line tools. Why we need to use them: In one word: automation. The less work you have to do when performing repetitive tasks like minification, compilation, unit testing, linting which previously cost us a lot of times to do with command line or even manually.


You can create automation for your development environment to pre-process codes or create build scripts with a config file and it seems very difficult to handle a complex task. Popular in the last few years.

Every task in Grunt is an array of different plugin configurations, that simply get executed one after another, in a strictly independent, and sequential fashion.

    clean: {
    src: ['build/app.js', 'build/vendor.js']

    copy: {
    files: [{
        src: 'build/app.js',
        dest: 'build/dist/app.js'

    concat: {
    'build/app.js': ['build/vendors.js', 'build/app.js']

    // ... other task configurations ...


grunt.registerTask('build', ['clean', 'bower', 'browserify', 'concat', 'copy']);


Automation just like Grunt but instead of configurations, you can write JavaScript with streams like it's a node application. Prefer these days.

This is a Gulp sample task declaration.

//import the necessary gulp plugins
var gulp = require("gulp");
var sass = require("gulp-sass");
var minifyCss = require("gulp-minify-css");
var rename = require("gulp-rename");

//declare the task
gulp.task("sass", function (done) {
        keepSpecialComments: 0,
    .pipe(rename({ extname: ".min.css" }))
    .on("end", done);

See more:

4. Scaffolding tools

Slush and Yeoman

You can create starter projects with them. For example, you are planning to build a prototype with HTML and SCSS, then instead of manually create some folder like scss, css, img, fonts. You can just install yeoman and run a simple script. Then everything here for you.

Find more here.

npm install -g yo
npm install --global generator-h5bp
yo h5bp

See more:

My answer is not matched with the content of the question but when I'm searching for this knowledge on Google, I always see the question on top so that I decided to answer it in summary. I hope you guys found it helpful.

If you like this post, you can read more on my blog at Thanks for visiting :)

Copy folder structure (without files) from one location to another

This copy the directories and files attributes, but not the files data:

cp -R --attributes-only SOURCE DEST

Then you can delete the files attributes if you are not interested in them:

find DEST -type f -exec rm {} \;

changing minDate option in JQuery DatePicker not working

There is no need to destroy current instance, just refresh.

    .datepicker('option', 'minDate', new Date)

Programmatically trigger "select file" dialog box

The best solution, works in all browsers.. even on mobile.

<div class="btn" id="s_photo">Upload</div>

<input type="file" name="s_file" id="s_file" style="opacity: 0;">';


    $("#s_photo").click(function() {

Hiding the input file type causes problems with browsers, opacity is the best solution because it isn't hiding, just not showing. :)

Entity Framework - "An error occurred while updating the entries. See the inner exception for details"

In my case.. following steps resolved:

There was a column value which was set to "Update" - replaced it with Edit (non sql keyword) There was a space in one of the column names (removed the extra space or trim)

How to do a "Save As" in vba code, saving my current Excel workbook with datestamp?

I know this is an old post but I was looking up something similar... I think your issue was that when you use Now(), the output will be "6/20/2014"... This an issue for a file name as it has "/" in it. As you may know, you cannot use certain symbols in a file name.


Deserialize Java 8 LocalDateTime with JacksonMapper

This worked for me:

 @JsonFormat(pattern = "yyyy-MM-dd'T'HH:mm:ss.SSSZ", shape = JsonFormat.Shape.STRING)
 private LocalDateTime startDate;

How do you create vectors with specific intervals in R?

In R the equivalent function is seq and you can use it with the option by:

seq(from = 5, to = 100, by = 5)
# [1]   5  10  15  20  25  30  35  40  45  50  55  60  65  70  75  80  85  90  95 100

In addition to by you can also have other options such as length.out and along.with.

length.out: If you want to get a total of 10 numbers between 0 and 1, for example:

seq(0, 1, length.out = 10)
# gives 10 equally spaced numbers from 0 to 1

along.with: It takes the length of the vector you supply as input and provides a vector from 1:length(input).

# [1] 1 2 3

Although, instead of using the along.with option, it is recommended to use seq_along in this case. From the documentation for ?seq

seq is generic, and only the default method is described here. Note that it dispatches on the class of the first argument irrespective of argument names. This can have unintended consequences if it is called with just one argument intending this to be taken as along.with: it is much better to use seq_along in that case.

seq_along: Instead of seq(along.with(.))

# [1] 1 2 3

Hope this helps.

Fixing a systemd service 203/EXEC failure (no such file or directory)

If that is a copy/paste from your script, you've permuted this line:

#!/usr/env/bin bash

There's no #!/usr/env/bin, you meant #!/usr/bin/env.

Font Awesome 5 font-family issue

Since FontAwesome 5, you have to enable a new "searchPseudoElements" option to use FontAwesome icons this way:

  window.FontAwesomeConfig = {
    searchPseudoElements: true

See also this question: Font awesome 5 on pseudo elements and the new Font Awesome API:

Additionaly, change font-family in your CSS code to

font-family: "Font Awesome 5 Regular";

C# Connecting Through Proxy

Foole's code worked perfectly for me, but in .NET 4.0, don't forget to check if Proxy is NULL, which means no proxy configured (outside corporate environment)

So here's the code that solved my problem with our corporate proxy

WebClient web = new WebClient();
if (web.Proxy != null)
    web.Proxy.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;

Python spacing and aligning strings

You should be able to use the format method:

"Location: {0:20} Revision {1}".format(Location,Revision)

You will have to figure out the of the format length for each line depending on the length of the label. The User line will need a wider format width than the Location or District lines.

TypeError: can't use a string pattern on a bytes-like object in re.findall()

You want to convert html (a byte-like object) into a string using .decode, e.g. html ='utf-8').

See Convert bytes to a Python String

Create a asmx web service in C# using visual studio 2013

  1. Create Empty ASP.NET Project enter image description here
  2. Add Web Service(asmx) to your project
    enter image description here

How to read multiple text files into a single RDD?

There is a straight forward clean solution available. Use the wholeTextFiles() method. This will take a directory and forms a key value pair. The returned RDD will be a pair RDD. Find below the description from Spark docs:

SparkContext.wholeTextFiles lets you read a directory containing multiple small text files, and returns each of them as (filename, content) pairs. This is in contrast with textFile, which would return one record per line in each file

"Cannot allocate an object of abstract type" error

You must have some virtual function declared in one of the parent classes and never implemented in any of the child classes. Make sure that all virtual functions are implemented somewhere in the inheritence chain. If a class's definition includes a pure virtual function that is never implemented, an instance of that class cannot ever be constructed.

Is it possible to change the speed of HTML's <marquee> tag?

<marquee behavior=scroll direction="left" scrollamount="5">Your message here</marquee>

scrollamount controls the speed of text: higher the value higher is the scrolling speed

position fixed header in html

The position :fixed is differ from the other layout. Once you fixed the position for your header, keep in mind that you have to set the margin-top for the content div.

Constructor overload in TypeScript

Regarding constructor overloads one good alternative would be to implement the additional overloads as static factory methods. I think its more readable and simple than checking for all possible argument combinations at the constructor. Here is a simple example:

function calculateAge(birthday): number {
  return new Date().getFullYear() - birthday;

class Person {
  static fromData(data: PersonData): Person {
    const { first, last, birthday, gender = 'M' } = data;
    return new this(
      `${last}, ${first}`,

    public fullName: string,
    public age: number,
    public gender: 'M' | 'F',
  ) {}

  toString(): string {
    return `Hello, my name is ${this.fullName} and I'm a ${this.age}yo ${this.gender}`;

interface PersonData {
  first: string;
  last: string;
  birthday: string;
  gender?: 'M' | 'F';

const personA = new Person('Doe, John', 31, 'M');
const personB = Person.fromData({
  first: 'Jane',
  last: 'Smith',
  birthday: '1986',
  gender: 'F',

Method overloading in TypeScript isn't for real, let's say, as it would require too much compiler-generated code and the core team try to avoid that at all costs. Currently the main reason for method overloading to be present on the language is to provide a way to write declarations for libraries with magic arguments in their API. Since you'll need to do all the heavy-lifting by yourself to handle different sets of arguments I don't see much advantage in using overloads instead of separated methods.

Conditional WHERE clause with CASE statement in Oracle

You can write the where clause as:

where (case when (:stateCode = '') then (1)
            when (:stateCode != '') and (vw.state_cd in (:stateCode)) then 1
            else 0)
       end) = 1;

Alternatively, remove the case entirely:

where (:stateCode = '') or
      ((:stateCode != '') and vw.state_cd in (:stateCode));

Or, even better:

where (:stateCode = '') or vw.state_cd in (:stateCode)

JUnit Testing private variables?

Yeah you can use reflections to access private variables. Altough not a good idea.

Check this out:

Laravel Eloquent - Get one Row

Simply use this:

$user = User::whereEmail($email)->first();

Call PHP function from jQuery?

Thanks all. I took bits of each of your solutions and made my own.

The final working solution is:

<script type="text/javascript">
            url: '<?php bloginfo('template_url'); ?>/functions/twitter.php',
            data: "tweets=<?php echo $ct_tweets; ?>&account=<?php echo $ct_twitter; ?>",
            success: function(data) {

Excel tab sheet names vs. Visual Basic sheet names

You should be able to reference sheets by the user-supplied name. Are you sure you're referencing the correct Workbook? If you have more than one workbook open at the time you refer to a sheet, that could definitely cause the problem.

If this is the problem, using ActiveWorkbook (the currently active workbook) or ThisWorkbook (the workbook that contains the macro) should solve it.

For example,

Set someSheet = ActiveWorkbook.Sheets("Custom Sheet")

How to configure Docker port mapping to use Nginx as an upstream proxy?

AJB's "Option B" can be made to work by using the base Ubuntu image and setting up nginx on your own. (It didn't work when I used the Nginx image from Docker Hub.)

Here is the Docker file I used:

FROM ubuntu
RUN apt-get update && apt-get install -y nginx
RUN ln -sf /dev/stdout /var/log/nginx/access.log
RUN ln -sf /dev/stderr /var/log/nginx/error.log
RUN rm -rf /etc/nginx/sites-enabled/default
EXPOSE 80 443
COPY conf/ /etc/nginx/sites-enabled/
CMD ["nginx", "-g", "daemon off;"]

My nginx config (aka: conf/

server {
    listen 80 default;

    location / {
        proxy_pass http://website;

upstream website {
    server website:3000;

And finally, how I start my containers:

$ docker run -dP --name website website
$ docker run -dP --name nginx --link website:website nginx

This got me up and running so my nginx pointed the upstream to the second docker container which exposed port 3000.

What is the max size of localStorage values?

Quoting from the Wikipedia article on Web Storage:

Web storage can be viewed simplistically as an improvement on cookies, providing much greater storage capacity (10 MB per origin in Google Chrome(, Mozilla Firefox, and Opera; 10 MB per storage area in Internet Explorer) and better programmatic interfaces.

And also quoting from a John Resig article [posted January 2007]:

Storage Space

It is implied that, with DOM Storage, you have considerably more storage space than the typical user agent limitations imposed upon Cookies. However, the amount that is provided is not defined in the specification, nor is it meaningfully broadcast by the user agent.

If you look at the Mozilla source code we can see that 5120KB is the default storage size for an entire domain. This gives you considerably more space to work with than a typical 2KB cookie.

However, the size of this storage area can be customized by the user (so a 5MB storage area is not guaranteed, nor is it implied) and the user agent (Opera, for example, may only provide 3MB - but only time will tell.)

CSS hover vs. JavaScript mouseover

Use CSS, it makes for much easier management of the style itself.

Python Checking a string's first and last character

You should either use

if str1[0] == '"' and str1[-1] == '"'


if str1.startswith('"') and str1.endswith('"')

but not slice and check startswith/endswith together, otherwise you'll slice off what you're looking for...

TypeError : Unhashable type


- You can't hash a list, a set, nor a dict to put that into sets

- You can hash a tuple to put it into a set.


>>> {1, 2, [3, 4]}
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'

>>> {1, 2, (3, 4)}
set([1, 2, (3, 4)])

Note that hashing is somehow recursive and the above holds true for nested items:

>>> {1, 2, 3, (4, [2, 3])}
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'

Dict keys also are hashable, so the above holds for dict keys too.

SQL Server: Maximum character length of object names

128 characters. This is the max length of the sysname datatype (nvarchar(128)).

What's the difference between abstraction and encapsulation?

A program has mainly two parts : DATA and PROCESS. abstraction hides data in process so that no one can change. Encapsulation hides data everywhere so that it cannot be displayed. I hope this clarifies your doubt.

Anaconda / Python: Change Anaconda Prompt User Path

Just Type the Drive Location you want to work with: This worked for me! For example you want to change to D drive in windows:


If you want to change to particular folder in the drive:

cd D:\Newfolder

Best approach to converting Boolean object to string in java

If you are sure that your value is not null you can use third option which is

String str3 = b.toString();

and its code looks like

public String toString() {
    return value ? "true" : "false";

If you want to be null-safe use String.valueOf(b) which code looks like

public static String valueOf(Object obj) {
    return (obj == null) ? "null" : obj.toString();

so as you see it will first test for null and later invoke toString() method on your object.

Calling Boolean.toString(b) will invoke

public static String toString(boolean b) {
    return b ? "true" : "false";

which is little slower than b.toString() since JVM needs to first unbox Boolean to boolean which will be passed as argument to Boolean.toString(...), while b.toString() reuses private boolean value field in Boolean object which holds its state.

Creating a dynamic choice field

Underneath working solution with normal choice field. my problem was that each user have their own CUSTOM choicefield options based on few conditions.

class SupportForm(BaseForm):

    affiliated = ChoiceField(required=False, label='Fieldname', choices=[], widget=Select(attrs={'onchange': 'sysAdminCheck();'}))

    def __init__(self, *args, **kwargs):

        self.request = kwargs.pop('request', None)
        grid_id = get_user_from_request(self.request)
        for l in get_all_choices().filter(user=user_id):
            admin = 'y' if l in self.core else 'n'
            choice = (('%s_%s' % (, admin)), ('%s' %
        super(SupportForm, self).__init__(*args, **kwargs)
        self.fields['affiliated'].choices = self.affiliated_choice

How do I check for a network connection?

You can check for a network connection in .NET 2.0 using GetIsNetworkAvailable():


To monitor changes in IP address or changes in network availability use the events from the NetworkChange class:


Detect if an element is visible with jQuery

There's no need, just use fadeToggle() on the element:


Here's a demo.

form_for with nested resources

Be sure to have both objects created in controller: @post and @comment for the post, eg:

@post = Post.find params[:post_id]
@comment =>@post)

Then in view:

<%= form_for([@post, @comment]) do |f| %>

Be sure to explicitly define the array in the form_for, not just comma separated like you have above.

How to generate a random integer number from within a range

Following on from @Ryan Reich's answer, I thought I'd offer my cleaned up version. The first bounds check isn't required given the second bounds check, and I've made it iterative rather than recursive. It returns values in the range [min, max], where max >= min and 1+max-min < RAND_MAX.

unsigned int rand_interval(unsigned int min, unsigned int max)
    int r;
    const unsigned int range = 1 + max - min;
    const unsigned int buckets = RAND_MAX / range;
    const unsigned int limit = buckets * range;

    /* Create equal size buckets all in a row, then fire randomly towards
     * the buckets until you land in one of them. All buckets are equally
     * likely. If you land off the end of the line of buckets, try again. */
        r = rand();
    } while (r >= limit);

    return min + (r / buckets);

Git: How configure KDiff3 as merge tool and diff tool

Well, the problem is that Git can't find KDiff3 in the %PATH%.

In a typical Unix installation all executables reside in several well-known locations (/bin/, /usr/bin/, /usr/local/bin/, etc.), and one can invoke a program by simply typing its name in a shell processor (e.g. cmd.exe :) ).

In Microsoft Windows, programs are usually installed in dedicated paths so you can't simply type kdiff3 in a cmd session and get KDiff3 running.

The hard solution: you should tell Git where to find KDiff3 by specifying the full path to kdiff3.exe. Unfortunately, Git doesn't like spaces in the path specification in its config, so the last time I needed this, I ended up with those ancient "C:\Progra~1...\kdiff3.exe" as if it was late 1990s :)

The simple solution: Edit your computer settings and include the directory with kdiff3.exe in %PATH%. Then test if you can invoke it from cmd.exe by its name and then run Git.

How to set a parameter in a HttpServletRequest?

If you really want to do this, create an HttpServletRequestWrapper.

public class AddableHttpRequest extends HttpServletRequestWrapper {

   private HashMap params = new HashMap();

   public AddableingHttpRequest(HttpServletRequest request) {

   public String getParameter(String name) {
           // if we added one, return that one
           if ( params.get( name ) != null ) {
                 return params.get( name );
           // otherwise return what's in the original request
           HttpServletRequest req = (HttpServletRequest) super.getRequest();
           return validate( name, req.getParameter( name ) );

   public void addParameter( String name, String value ) {
           params.put( name, value );


How to exclude subdirectories in the destination while using /mir /xd switch in robocopy

When i tried the solution with /XD i found, that the path to exclude should be the source path - not the destination.

e.g. this Works

robocopy c:\test\a c:\test\b /MIR /XD c:\test\a\leavethisdiralone\

How to make asynchronous HTTP requests in PHP

ReactPHP async http client

Install via Composer

$ composer require shuchkin/react-http-client


// get.php
$loop = \React\EventLoop\Factory::create();

$http = new \Shuchkin\ReactHTTP\Client( $loop );

$http->get( '' )->then(
    function( $content ) {
        echo $content;
    function ( \Exception $ex ) {
        echo 'HTTP error '.$ex->getCode().' '.$ex->getMessage();


Run php in CLI-mode

$ php get.php target _self v window.location.href?

Definitely the second method is preferred because you don't have the overhead of another function invocation:

window.location.href = "webpage.htm";

How to make bootstrap 3 fluid layout without horizontal scrollbar

Summarizing the most relevant comments in one answer:

  • this is a known bug
  • there are workarounds but you might not need them (read on)
  • it happens when elements are placed directly inside the body, rather than inside a container-fluid div or another containing div. Placing them directly in the body is exactly what most people do when testing stuff locally. Once you place your code in the complete page (so within a container-fluid or another container div) you will not face this problem (no need to change anything).

Selenium WebDriver findElement(By.xpath()) not working for me

element = findElement(By.xpath("//*[@test-id='test-username']");
element = findElement(By.xpath("//input[@test-id='test-username']");

(*) - any tagname

org.xml.sax.SAXParseException: Content is not allowed in prolog

Try with BOMInputStream in

public static <T> T getContent(Class<T> instance, SchemaType schemaType, InputStream stream) throws JAXBException, SAXException, IOException {

    JAXBContext context = JAXBContext.newInstance(instance);
    Unmarshaller unmarshaller = context.createUnmarshaller();
    Reader reader = new InputStreamReader(new BOMInputStream(stream), "UTF-8");

    JAXBElement<T> entry = unmarshaller.unmarshal(new StreamSource(reader), instance);

    return entry.getValue();

How to download source in ZIP format from GitHub?

Updated July 2016

As of July 2016, the Download ZIP button has moved under Clone or download to extreme-right of header under the Code tab:

Download ZIP (2013)

If you don't see the button:

  • Make sure you've selected <> Code tab from right side navigation menu, or
  • Repo may not have a zip prepared. Add /archive/ to the end of the repository URL and to generate a zipfile of the master branch: -to->

to get the master branch source code in a zip file. You can do the same with tags and branch names, by replacing master in the URL above with the name of the branch or tag.

Load arrayList data into JTable

"The problem is that i cant find a way to set a fixed number of rows"

You don't need to set the number of rows. Use a TableModel. A DefaultTableModel in particular.

String col[] = {"Pos","Team","P", "W", "L", "D", "MP", "GF", "GA", "GD"};

DefaultTableModel tableModel = new DefaultTableModel(col, 0);
                                            // The 0 argument is number rows.

JTable table = new JTable(tableModel);

Then you can add rows to the tableModel with an Object[]

Object[] objs = {1, "Arsenal", 35, 11, 2, 2, 15, 30, 11, 19};


You can loop to add your Object[] arrays.

Note: JTable does not currently allow instantiation with the input data as an ArrayList. It must be a Vector or an array.

See JTable and DefaultTableModel. Also, How to Use JTable tutorial

"I created an arrayList from it and I somehow can't find a way to store this information into a JTable."

You can do something like this to add the data

ArrayList<FootballClub> originalLeagueList = new ArrayList<FootballClub>();

originalLeagueList.add(new FootballClub(1, "Arsenal", 35, 11, 2, 2, 15, 30, 11, 19));
originalLeagueList.add(new FootballClub(2, "Liverpool", 30, 9, 3, 3, 15, 34, 18, 16));
originalLeagueList.add(new FootballClub(3, "Chelsea", 30, 9, 2, 2, 15, 30, 11, 19));
originalLeagueList.add(new FootballClub(4, "Man City", 29, 9, 2, 4, 15, 41, 15, 26));
originalLeagueList.add(new FootballClub(5, "Everton", 28, 7, 1, 7, 15, 23, 14, 9));
originalLeagueList.add(new FootballClub(6, "Tottenham", 27, 8, 4, 3, 15, 15, 16, -1));
originalLeagueList.add(new FootballClub(7, "Newcastle", 26, 8, 5, 2, 15, 20, 21, -1));
originalLeagueList.add(new FootballClub(8, "Southampton", 23, 6, 4, 5, 15, 19, 14, 5));

for (int i = 0; i < originalLeagueList.size(); i++){
   int position = originalLeagueList.get(i).getPosition();
   String name = originalLeagueList.get(i).getName();
   int points = originalLeagueList.get(i).getPoinst();
   int wins = originalLeagueList.get(i).getWins();
   int defeats = originalLeagueList.get(i).getDefeats();
   int draws = originalLeagueList.get(i).getDraws();
   int totalMatches = originalLeagueList.get(i).getTotalMathces();
   int goalF = originalLeagueList.get(i).getGoalF();
   int goalA = originalLeagueList.get(i).getGoalA();
   in ttgoalD = originalLeagueList.get(i).getTtgoalD();

   Object[] data = {position, name, points, wins, defeats, draws, 
                               totalMatches, goalF, goalA, ttgoalD};



How to set different colors in HTML in one statement?

.rainbow {_x000D_
  background-image: -webkit-gradient( linear, left top, right top, color-stop(0, #f22), color-stop(0.15, #f2f), color-stop(0.3, #22f), color-stop(0.45, #2ff), color-stop(0.6, #2f2),color-stop(0.75, #2f2), color-stop(0.9, #ff2), color-stop(1, #f22) );_x000D_
  background-image: gradient( linear, left top, right top, color-stop(0, #f22), color-stop(0.15, #f2f), color-stop(0.3, #22f), color-stop(0.45, #2ff), color-stop(0.6, #2f2),color-stop(0.75, #2f2), color-stop(0.9, #ff2), color-stop(1, #f22) );_x000D_
  -webkit-background-clip: text;_x000D_
  background-clip: text;_x000D_
<h2><span class="rainbow">Rainbows are colorful and scalable and lovely</span></h2>

Typescript Type 'string' is not assignable to type

All the above answers are valid, however, there are some cases that the String Literal Type is part of another complex type. Consider the following example:

  // in foo.ts
  export type ToolbarTheme = {
    size: 'large' | 'small',

  // in bar.ts
  import { ToolbarTheme } from './foo.ts';
  function useToolbarTheme(theme: ToolbarTheme) {/* ... */}

  // Here you will get the following error: 
  // Type 'string' is not assignable to type '"small" | "large"'.ts(2322)
  ['large', 'small'].forEach(size => (
    useToolbarTheme({ size })

You have multiple solutions to fix this. Each solution is valid and has its own use cases.

1) The first solution is to define a type for the size and export it from the foo.ts. This is good if when you need to work with the size parameter by its own. For example, you have a function that accepts or returns a parameter of type size and you want to type it.

  // in foo.ts
  export type ToolbarThemeSize = 'large' | 'small';
  export type ToolbarTheme = {
    size: ToolbarThemeSize

  // in bar.ts
  import { ToolbarTheme, ToolbarThemeSize } from './foo.ts';
  function useToolbarTheme(theme: ToolbarTheme) {/* ... */}
  function getToolbarSize(): ToolbarThemeSize  {/* ... */}

  ['large', 'small'].forEach(size => (
    useToolbarTheme({ size: size as ToolbarThemeSize })

2) The second option is to just cast it to the type ToolbarTheme. In this case, you don't need to expose the internal of ToolbarTheme if you don't need.

  // in foo.ts
  export type ToolbarTheme = {
    size: 'large' | 'small'

  // in bar.ts
  import { ToolbarTheme } from './foo.ts';
  function useToolbarTheme(theme: ToolbarTheme) {/* ... */}

  ['large', 'small'].forEach(size => (
    useToolbarTheme({ size } as ToolbarTheme)

Elasticsearch difference between MUST and SHOULD bool query

Since this is a popular question, I would like to add that in Elasticsearch version 2 things changed a bit.

Instead of filtered query, one should use bool query in the top level.

If you don't care about the score of must parts, then put those parts into filter key. No scoring means faster search. Also, Elasticsearch will automatically figure out, whether to cache them, etc. must_not is equally valid for caching.


Also, mind that "gte": "now" cannot be cached, because of millisecond granularity. Use two ranges in a must clause: one with now/1h and another with now so that the first can be cached for a while and the second for precise filtering accelerated on a smaller result set.

How can I set the request header for curl?

Just use the -H parameter several times:

curl -H "Accept-Charset: utf-8" -H "Content-Type: application/x-www-form-urlencoded"

Writing List of Strings to Excel CSV File in Python

I know I'm a little late, but something I found that works (and doesn't require using csv) is to write a for loop that writes to your file for every element in your list.

# Define Data
RESULTS = ['apple','cherry','orange','pineapple','strawberry']

# Open File
resultFyle = open("output.csv",'w')

# Write data to file
for r in RESULTS:
    resultFyle.write(r + "\n")

I don't know if this solution is any better than the ones already offered, but it more closely reflects your original logic so I thought I'd share.

sqlalchemy: how to join several tables by one query?

Expanding on Abdul's answer, you can obtain a KeyedTuple instead of a discrete collection of rows by joining the columns:

q = Session.query(*User.__table__.columns + Document.__table__.columns).\
        join(Document, ==\
        filter( == 'someemail').all()

How to access a dictionary key value present inside a list?

You haven't provided enough context to provide an accurate answer (i.e. how do you want to handle identical keys in multiple dicts?)

One answer is to iterate the list, and attempt to get 'd'

mylist = [{'a': 1, 'b': 2}, {'c': 3, 'd': 4}, {'e': 5, 'f': 6}]
myvalues = [i['d'] for i in mylist if 'd' in i]

Another answer is to access the dict directly (by list index), though you have to know that the key is present


Hexadecimal To Decimal in Shell Script

Shortest way yet:

$ echo $[0x3F]

gcloud command not found - while installing Google Cloud SDK

I know this question has been answered, but here are my two cent. After installing gcloud, you need to restart the shell before you able to gcloud command.

How you do this, mostly depends on the file you keep your shell configuration. Most files are .bashrc_profile, .bashrc, .zshrc.

You can now restart with

source ~/.bashrc_profile

You can replace the file to the file you have.

Or if you don't care the file you have, on Mac or linux you can restart the shell .

exec -l $SHELL

How to refresh Gridview after pressed a button in

All you have to do is In your bLoanButton_Click , add a line to rebind the Grid to the SqlDataSource :

protected void bLoanButton_Click(object sender, EventArgs e)

//your same code




What is the difference between `new Object()` and object literal notation?

Everyone here is talking about the similarities of the two. I am gonna point out the differences.

  1. Using new Object() allows you to pass another object. The obvious outcome is that the newly created object will be set to the same reference. Here is a sample code:

    var obj1 = new Object();
    obj1.a = 1;
    var obj2 = new Object(obj1);
    obj2.a // 1
  2. The usage is not limited to objects as in OOP objects. Other types could be passed to it too. The function will set the type accordingly. For example if we pass integer 1 to it, an object of type number will be created for us.

    var obj = new Object(1);
    typeof obj // "number"
  3. The object created using the above method (new Object(1)) would be converted to object type if a property is added to it.

    var obj = new Object(1);
    typeof obj // "number"
    obj.a = 2;
    typeof obj // "object"
  4. If the object is a copy of a child class of object, we could add the property without the type conversion.

    var obj = new Object("foo");
    typeof obj // "object"
    obj === "foo" // true
    obj.a = 1;
    obj === "foo" // true
    obj.a // 1
    var str = "foo";
    str.a = 1;
    str.a // undefined

How to query SOLR for empty fields?

Try this:

?q=-id:["" TO *]

How to convert a list of numbers to jsonarray in Python

import json
row = [1L,[0.1,0.2],[[1234L,1],[134L,2]]]
row_json = json.dumps(row)

java.math.BigInteger cannot be cast to java.lang.Integer

java.lang.Integer is not a super class of BigInteger. Both BigInteger and Integer do inherit from java.lang.Number, so you could cast to a java.lang.Number.

See the java docs

What is the difference between g++ and gcc?

I was testing gcc and g++ in a linux system. By using MAKEFILE, I can define the compliler used by "GNU make". I tested with the so called "dynamic memory" locating feature of "C plus plus" by :

int main(){

int * myptr = new int;
* myptr = 1;
printf("myptr[0] is %i\n",*myptr);
return 0;

Only g++ can successfully compile on my computer while gcc will report error

undefined reference to `operator new(unsigned long)'

So my own conclusion is gcc does not fully support "C plus plus". It seems that choosing g++ for C++ source files is a better option.

error "Could not get BatchedBridge, make sure your bundle is packaged properly" on start of app

I came across this issue as well. What I did was force kill the app on my device, then I opened up another console and ran

react-native start

and then I opened the app again from my device and it started working again.

EDIT: If you are using an android device via USB and have unplugged it or your computer went to sleep, you may have to first run

adb reverse tcp:8081 tcp:8081

Finding the median of an unsorted array

Quickselect works in O(n), this is also used in the partition step of Quicksort.

JavaScript alert not working in Android WebView

Check this link , and last comment , You have to use WebChromeClient for your purpose.

How to split the filename from a full path in batch?

Parse a filename from the fully qualified path name (e.g., c:\temp\my.bat) to any component (e.g., File.ext).

Single line of code:

For %%A in ("C:\Folder1\Folder2\File.ext") do (echo %%~fA)

You can change out "C:\Folder1\Folder2\File.ext" for any full path and change "%%~fA" for any of the other options you will find by running "for /?" at the command prompt.

Elaborated Code

set "filename=C:\Folder1\Folder2\File.ext"
For %%A in ("%filename%") do (
    echo full path: %%~fA
    echo drive: %%~dA
    echo path: %%~pA
    echo file name only: %%~nA
    echo extension only: %%~xA
    echo expanded path with short names: %%~sA
    echo attributes: %%~aA
    echo date and time: %%~tA
    echo size: %%~zA
    echo drive + path: %%~dpA
    echo name.ext: %%~nxA
    echo full path + short name: %%~fsA)

Standalone Batch Script
Save as C:\cmd\ParseFn.cmd.

Add C:\cmd to your PATH environment variable and use it to store all of you reusable batch scripts.

@echo off
@echo ::___________________________________________________________________::
@echo ::                                                                   ::
@echo ::                              ParseFn                              ::
@echo ::                                                                   ::
@echo ::                           Chris Advena                            ::
@echo ::___________________________________________________________________::

:: Process arguements
if "%~1%"=="/?" goto help
if "%~1%"=="" goto help
if "%~2%"=="/?" goto help
if "%~2%"=="" (
    echo !!! Error: ParseFn requires two inputs. !!!
    goto help)

set in=%~1%
set out=%~2%
:: echo "%in:~3,1%"   "%in:~0,1%"
if "%in:~3,1%"=="" (
    if "%in:~0,1%"=="/" (
    set in=%~2%
    set out=%~1%)

:: Parse filename
set "ret="
For %%A in ("%in%") do (
    if "%out%"=="/f" (set ret=%%~fA)
    if "%out%"=="/d" (set ret=%%~dA)
    if "%out%"=="/p" (set ret=%%~pA)
    if "%out%"=="/n" (set ret=%%~nA)
    if "%out%"=="/x" (set ret=%%~xA)
    if "%out%"=="/s" (set ret=%%~sA)
    if "%out%"=="/a" (set ret=%%~aA)
    if "%out%"=="/t" (set ret=%%~tA)
    if "%out%"=="/z" (set ret=%%~zA)
    if "%out%"=="/dp" (set ret=%%~dpA)
    if "%out%"=="/nx" (set ret=%%~nxA)
    if "%out%"=="/fs" (set ret=%%~fsA)
echo ParseFn result: %ret%

goto end
@echo off
:: @echo ::___________________________________________________________________::
:: @echo ::                                                                   ::
:: @echo ::                           ParseFn Help                            ::
:: @echo ::                                                                   ::
:: @echo ::                           Chris Advena                            ::
:: @echo ::___________________________________________________________________::
@echo ParseFn parses a fully qualified path name (e.g., c:\temp\my.bat)
@echo into the requested component, such as drive, path, filename, 
@echo extenstion, etc.
@echo Syntax: /switch filename
@echo where,
@echo   filename is a fully qualified path name including drive, 
@echo   folder(s), file name, and extension
@echo   Select only one switch:
@echo       /f - fully qualified path name
@echo       /d - drive letter only
@echo       /p - path only
@echo       /n - file name only
@echo       /x - extension only
@echo       /s - expanded path contains short names only
@echo       /a - attributes of file
@echo       /t - date/time of file
@echo       /z - size of file
@echo      /dp - drive + path
@echo      /nx - file name + extension
@echo      /fs - full path + short name

:: @echo ::___________________________________________________________________::
:: @echo ::                                                                   ::
:: @echo ::                         ParseFn finished                          ::
:: @echo ::___________________________________________________________________::
:: @echo.

Convert file path to a file URI?

The workaround is simple. Just use the Uri().ToString() method and percent-encode white-spaces, if any, afterwards.

string path = new Uri("C:\my example?.txt").ToString().Replace(" ", "%20");

properly returns file:///C:/my%20example?.txt

error, string or binary data would be truncated when trying to insert

on sql server you can use SET ANSI_WARNINGS OFF like this:

        using (SqlConnection conn = new SqlConnection("Data Source=XRAYGOAT\\SQLEXPRESS;Initial Catalog='Healthy Care';Integrated Security=True"))

            using (var trans = conn.BeginTransaction())
                    using cmd = new SqlCommand("", conn, trans))

                    cmd.CommandText = "SET ANSI_WARNINGS OFF";

                    cmd.CommandText = "YOUR INSERT HERE";


                    cmd.CommandText = "SET ANSI_WARNINGS ON";

                catch (Exception)





C program to check little vs. big endian

The following will do.

unsigned int x = 1;
printf ("%d", (int) (((char *)&x)[0]));

And setting &x to char * will enable you to access the individual bytes of the integer, and the ordering of bytes will depend on the endianness of the system.

How to handle command-line arguments in PowerShell

You are reinventing the wheel. Normal PowerShell scripts have parameters starting with -, like script.ps1 -server http://devserver

Then you handle them in param section in the beginning of the file.

You can also assign default values to your params, read them from console if not available or stop script execution:

 param (
    [string]$server = "http://defaultserver",
    [string]$password = $( Read-Host "Input password, please" )

Inside the script you can simply

write-output $server

since all parameters become variables available in script scope.

In this example, the $server gets a default value if the script is called without it, script stops if you omit the -username parameter and asks for terminal input if -password is omitted.

Update: You might also want to pass a "flag" (a boolean true/false parameter) to a PowerShell script. For instance, your script may accept a "force" where the script runs in a more careful mode when force is not used.

The keyword for that is [switch] parameter type:

 param (
    [string]$server = "http://defaultserver",
    [string]$password = $( Read-Host "Input password, please" ),
    [switch]$force = $false

Inside the script then you would work with it like this:

if ($force) {
  //deletes a file or does something "bad"

Now, when calling the script you'd set the switch/flag parameter like this:

.\yourscript.ps1 -server "http://otherserver" -force

If you explicitly want to state that the flag is not set, there is a special syntax for that

.\yourscript.ps1 -server "http://otherserver" -force:$false

Links to relevant Microsoft documentation (for PowerShell 5.0; tho versions 3.0 and 4.0 are also available at the links):

Python, HTTPS GET with basic authentication

In Python 3 the following will work. I am using the lower level http.client from the standard library. Also check out section 2 of rfc2617 for details of basic authorization. This code won't check the certificate is valid, but will set up a https connection. See the http.client docs on how to do that.

from http.client import HTTPSConnection
from base64 import b64encode
#This sets up the https connection
c = HTTPSConnection("")
#we need to base 64 encode it 
#and then decode it to acsii as python 3 stores it as a byte string
userAndPass = b64encode(b"username:password").decode("ascii")
headers = { 'Authorization' : 'Basic %s' %  userAndPass }
#then connect
c.request('GET', '/', headers=headers)
#get the response back
res = c.getresponse()
# at this point you could check the status etc
# this gets the page text
data =  

How do I get the time difference between two DateTime objects using C#?

 var startDate = new DateTime(2007, 3, 24);

 var endDate = new DateTime(2009, 6, 26);

 var dateDiff = endDate.Subtract(startDate);

 var date = string.Format("{0} years {1} months {2} days", (int)dateDiff.TotalDays / 365, 
 (int)(dateDiff.TotalDays % 365) / 30, (int)(dateDiff.TotalDays % 365) / 30);


Add centered text to the middle of a <hr/>-like line


<div style="display: grid; grid-template-columns: 1fr 1fr 1fr;" class="add-heading">
    <hr class="add-hr">
    <h2>Add Employer</h2>
    <hr class="add-hr">


.add-hr { 
    display: block; height: 1px;
    border: 0; border-top: 4px solid #000;
    margin: 1em 0; padding: 0; 

.add-heading h2{
  text-align: center;

How to change collation of database, table, column?

I was surprised to learn, and so I had to come back here and report, that the excellent and well maintained Interconnect/it SAFE SEARCH AND REPLACE ON DATABASE script has some options for converting tables to utf8 / unicode, and even to convert to innodb. It's a script commonly used to migrate a database driven website (Wordpress, Drupal, Joomla, etc) from one domain to another.

interconnect script buttons

How to read from stdin line by line in Node

You can use the readline module to read from stdin line by line:

var readline = require('readline');
var rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false

rl.on('line', function(line){

grep's at sign caught as whitespace

No -P needed; -E is sufficient:

grep -E '(^|\s)abc(\s|$)' 

or even without -E:

grep '\(^\|\s\)abc\(\s\|$\)' 

Visual Studio Error: (407: Proxy Authentication Required)

I was trying to connect Visual Studio 2013 to Visual Studio Team Services, and am behind a corporate proxy. I made VS use the default proxy settings (as specified in IE's connection settings) by adding:

<> <defaultProxy useDefaultCredentials="true" enabled="true"> <proxy usesystemdefault="True" /> </defaultProxy> <settings> <ipv6 enabled="true"/> </settings> </>

to ..\Program Files\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe.config (running notepad as admin and opening the file from within there)

font-family is inherit. How to find out the font-family in chrome developer pane?

I think op wants to know what the font that is used on a webpage is, and hoped that info might be findable in the 'inspect' pane.

Try adding the Whatfont Chrome extension.

PHP: How do I display the contents of a textfile on my page?

I have to display files of computer code. If special characters are inside the file like less than or greater than, a simple "include" will not display them. Try:

$file = 'code.ino';
$orig = file_get_contents($file);
$a = htmlentities($orig);

echo '<code>';
echo '<pre>';

echo $a;

echo '</pre>';
echo '</code>';

How do you explicitly set a new property on `window` in TypeScript?

Global are "evil" :), i think the best way to have also the portability is:

First you export the interface: (eg: ./custom.window.ts)

export interface CustomWindow extends Window {
    customAttribute: any;

Second you import

import {CustomWindow} from './custom.window.ts';

Third cast global var window with CustomWindow

declare let window: CustomWindow;

In this way you don't have also red line in different IDE if you use with existent attributes of window object, so at the end try:

window.customAttribute = 'works';
window.location.href = '/works';

Tested with Typescript 2.4.x and newest!

Should I use scipy.pi, numpy.pi, or math.pi?

>>> import math
>>> import numpy as np
>>> import scipy
>>> math.pi == np.pi == scipy.pi

So it doesn't matter, they are all the same value.

The only reason all three modules provide a pi value is so if you are using just one of the three modules, you can conveniently have access to pi without having to import another module. They're not providing different values for pi.

The action or event has been blocked by Disabled Mode

On the ribbon,Go to Database Tools under "Show/Hide", make sure the Message bar is checked (turned on) Then click on the gray message bar, click database options. From there you can modify your security options. Just enable these types of content.

You should be good to go after this.

How to provide user name and password when connecting to a network share

I searched lots of methods and i did it my own way. You have to open a connection between two machine via command prompt NET USE command and after finishing your work clear the connection with command prompt NET USE "myconnection" /delete.

You must use Command Prompt process from code behind like this:

var savePath = @"\\servername\foldername\myfilename.jpg";
var filePath = @"C:\\temp\myfileTosave.jpg";

Usage is simple:

SaveACopyfileToServer(filePath, savePath);

Here is functions:

using System.IO
using System.Diagnostics;

public static void SaveACopyfileToServer(string filePath, string savePath)
        var directory = Path.GetDirectoryName(savePath).Trim();
        var username = "loginusername";
        var password = "loginpassword";
        var filenameToSave = Path.GetFileName(savePath);

        if (!directory.EndsWith("\\"))
            filenameToSave = "\\" + filenameToSave;

        var command = "NET USE " + directory + " /delete";
        ExecuteCommand(command, 5000);

        command = "NET USE " + directory + " /user:" + username + " " + password;
        ExecuteCommand(command, 5000);

        command = " copy \"" + filePath + "\"  \"" + directory + filenameToSave + "\"";

        ExecuteCommand(command, 5000);

        command = "NET USE " + directory + " /delete";
        ExecuteCommand(command, 5000);

And also ExecuteCommand function is:

public static int ExecuteCommand(string command, int timeout)
        var processInfo = new ProcessStartInfo("cmd.exe", "/C " + command)
                                  CreateNoWindow = true, 
                                  UseShellExecute = false, 
                                  WorkingDirectory = "C:\\",

        var process = Process.Start(processInfo);
        var exitCode = process.ExitCode;
        return exitCode;

This functions worked very fast and stable for me.

Waiting till the async task finish its work

Although optimally it would be nice if your code can run parallel, it can be the case you're simply using a thread so you do not block the UI thread, even if your app's usage flow will have to wait for it.

You've got pretty much 2 options here;

  1. You can execute the code you want waiting, in the AsyncTask itself. If it has to do with updating the UI(thread), you can use the onPostExecute method. This gets called automatically when your background work is done.

  2. If you for some reason are forced to do it in the Activity/Fragment/Whatever, you can also just make yourself a custom listener, which you broadcast from your AsyncTask. By using this, you can have a callback method in your Activity/Fragment/Whatever which only gets called when you want it: aka when your AsyncTask is done with whatever you had to wait for.

How to convert ISO8859-15 to UTF8?

You can use ISO-8859-9 encoding:

iconv -f ISO-8859-9 Agreement.txt -t UTF-8 -o agreement.txt

Types in MySQL: BigInt(20) vs Int(20)


  • INT is a four-byte signed integer.

  • BIGINT is an eight-byte signed integer.

They each accept no more and no fewer values than can be stored in their respective number of bytes. That means 232 values in an INT and 264 values in a BIGINT.

The 20 in INT(20) and BIGINT(20) means almost nothing. It's a hint for display width. It has nothing to do with storage, nor the range of values that column will accept.

Practically, it affects only the ZEROFILL option:

INSERT INTO foo (bar) VALUES (1234);
SELECT bar from foo;

| bar                  |
| 00000000000000001234 |

It's a common source of confusion for MySQL users to see INT(20) and assume it's a size limit, something analogous to CHAR(20). This is not the case.

How to increase Heap size of JVM

Start the program with -Xms=[size] -Xmx -XX:MaxPermSize=[size] -XX:MaxNewSize=[size]

For example -

-Xms512m -Xmx1152m -XX:MaxPermSize=256m -XX:MaxNewSize=256m

Print commit message of a given commit in git

I use shortlog for this:

$ git shortlog master..
Username (3):
      Write something
      Add something
      Bump to 1.3.8 

Sorting a DropDownList? - C#, ASP.NET

If you get a DataTable with the data, you can create a DataView off of this and then bind the drop down list to that. Your code would look something like...

DataView dvOptions = new DataView(DataTableWithOptions);
dvOptions.Sort = "Description";

ddlOptions.DataSource = dvOptions;
ddlOptions.DataTextField = "Description";
ddlOptions.DataValueField = "Id";

Your text field and value field options are mapped to the appropriate columnns in the data table you are receiving.

Ruby optional parameters

1) You cannot overload the method (Why doesn't ruby support method overloading?) so why not write a new method altogether?

2) I solved a similar problem using the splat operator * for an array of zero or more length. Then, if I want to pass a parameter(s) I can, it is interpreted as an array, but if I want to call the method without any parameter then I don't have to pass anything. See Ruby Programming Language pages 186/187

Magento - How to add/remove links on my account navigation?

My solution was to completely remove the block in local.xml and create it with the blocks I needed, so, for example

        <reference name="left">
            <action method="unsetChild">
            <block type="customer/account_navigation" name="customer_account_navigation" before="-" template="customer/account/navigation.phtml">
                <action method="addLink" translate="label" module="customer">
                    <label>Account Dashboard</label>
                <action method="addLink" translate="label" module="customer">
                    <label>Account Information</label>

plot is not defined

If you want to use a function form a package or module in python you have to import and reference them. For example normally you do the following to draw 5 points( [1,5],[2,4],[3,3],[4,2],[5,1]) in the space:

import matplotlib.pyplot

In your solution

from matplotlib import*

This imports the package matplotlib and "plot is not defined" means there is no plot function in matplotlib you can access directly, but instead if you import as

from matplotlib.pyplot import *

Now you can use any function in matplotlib.pyplot without referencing them with matplotlib.pyplot.

I would recommend you to name imports you have, in this case you can prevent disambiguation and future problems with the same function names. The last and clean version of above example looks like:

import matplotlib.pyplot as plt

Make multiple-select to adjust its height to fit options without scroll bar

You can do this with simple javascript...

<select multiple="multiple" size="return this.length();">

...or limit height until number-of-records...

<select multiple="multiple" size="return this.length() > 10 ? this.length(): 10;">

Android device chooser - My device seems offline

Happened to me with a Motorola MZ 601 (Xoom). I tried everything suggested in other answers, but the only thing that fixed the issue for me in the end was to use a different USB port. Mind you, the same device had been connected to the other USB port before and it worked. So, if all else fails, consider using a different port.

What do hjust and vjust do when making a plot using ggplot?

Probably the most definitive is Figure B.1(d) of the ggplot2 book, the appendices of which are available at

enter image description here

However, it is not quite that simple. hjust and vjust as described there are how it works in geom_text and theme_text (sometimes). One way to think of it is to think of a box around the text, and where the reference point is in relation to that box, in units relative to the size of the box (and thus different for texts of different size). An hjust of 0.5 and a vjust of 0.5 center the box on the reference point. Reducing hjust moves the box right by an amount of the box width times 0.5-hjust. Thus when hjust=0, the left edge of the box is at the reference point. Increasing hjust moves the box left by an amount of the box width times hjust-0.5. When hjust=1, the box is moved half a box width left from centered, which puts the right edge on the reference point. If hjust=2, the right edge of the box is a box width left of the reference point (center is 2-0.5=1.5 box widths left of the reference point. For vertical, less is up and more is down. This is effectively what that Figure B.1(d) says, but it extrapolates beyond [0,1].

But, sometimes this doesn't work. For example

DF <- data.frame(x=c("a","b","cdefghijk","l"),y=1:4)
p <- ggplot(DF, aes(x,y)) + geom_point()

p + opts(axis.text.x=theme_text(vjust=0))
p + opts(axis.text.x=theme_text(vjust=1))
p + opts(axis.text.x=theme_text(vjust=2))

The three latter plots are identical. I don't know why that is. Also, if text is rotated, then it is more complicated. Consider

p + opts(axis.text.x=theme_text(hjust=0, angle=90))
p + opts(axis.text.x=theme_text(hjust=0.5 angle=90))
p + opts(axis.text.x=theme_text(hjust=1, angle=90))
p + opts(axis.text.x=theme_text(hjust=2, angle=90))

The first has the labels left justified (against the bottom), the second has them centered in some box so their centers line up, and the third has them right justified (so their right sides line up next to the axis). The last one, well, I can't explain in a coherent way. It has something to do with the size of the text, the size of the widest text, and I'm not sure what else.

What is the most efficient/elegant way to parse a flat table into a tree?

You can emulate any other data structure with a hashmap, so that's not a terrible limitation. Scanning from the top to the bottom, you create a hashmap for each row of the database, with an entry for each column. Add each of these hashmaps to a "master" hashmap, keyed on the id. If any node has a "parent" that you haven't seen yet, create an placeholder entry for it in the master hashmap, and fill it in when you see the actual node.

To print it out, do a simple depth-first pass through the data, keeping track of indent level along the way. You can make this easier by keeping a "children" entry for each row, and populating it as you scan the data.

As for whether there's a "better" way to store a tree in a database, that depends on how you're going to use the data. I've seen systems that had a known maximum depth that used a different table for each level in the hierarchy. That makes a lot of sense if the levels in the tree aren't quite equivalent after all (top level categories being different than the leaves).

Download File to server from URL

prodigitalson's answer didn't work for me. I got missing fopen in CURLOPT_FILE more details.

This worked for me, including local urls:

function downloadUrlToFile($url, $outFileName)
    if(is_file($url)) {
        copy($url, $outFileName); 
    } else {
        $options = array(
          CURLOPT_FILE    => fopen($outFileName, 'w'),
          CURLOPT_TIMEOUT =>  28800, // set this to 8 hours so we dont timeout on big files
          CURLOPT_URL     => $url

        $ch = curl_init();
        curl_setopt_array($ch, $options);

Perform a Shapiro-Wilk Normality Test

You are applying shapiro.test() to a data.frame instead of the column. Try the following:


Is there a way to list open transactions on SQL Server 2000 database?

DBCC OPENTRAN helps to identify active transactions that may be preventing log truncation. DBCC OPENTRAN displays information about the oldest active transaction and the oldest distributed and nondistributed replicated transactions, if any, within the transaction log of the specified database. Results are displayed only if there is an active transaction that exists in the log or if the database contains replication information.

An informational message is displayed if there are no active transactions in the log.


SQL Server Script to create a new user

You can use:

CREATE LOGIN <login name> WITH PASSWORD = '<password>' ; GO 

To create the login (See here for more details).

Then you may need to use:

CREATE USER user_name 

To create the user associated with the login for the specific database you want to grant them access too.

(See here for details)

You can also use:

GRANT permission  [ ,...n ] ON SCHEMA :: schema_name

To set up the permissions for the schema's that you assigned the users to.

(See here for details)

Two other commands you might find useful are ALTER USER and ALTER LOGIN.

C-like structures in Python

NamedTuple is comfortable. but there no one shares the performance and storage.

from typing import NamedTuple
import guppy  # pip install guppy
import timeit

class User:
    def __init__(self, name: str, uid: int): = name
        self.uid = uid

class UserSlot:
    __slots__ = ('name', 'uid')

    def __init__(self, name: str, uid: int): = name
        self.uid = uid

class UserTuple(NamedTuple):
    # __slots__ = ()  # AttributeError: Cannot overwrite NamedTuple attribute __slots__
    name: str
    uid: int

def get_fn(obj, attr_name: str):
    def get():
        getattr(obj, attr_name)
    return get
if 'memory test':
    obj = [User('Carson', 1) for _ in range(1000000)]      # Cumulative: 189138883
    obj_slot = [UserSlot('Carson', 1) for _ in range(1000000)]          # 77718299  <-- winner
    obj_namedtuple = [UserTuple('Carson', 1) for _ in range(1000000)]   # 85718297
    print(guppy.hpy().heap())  # Run this function individually. 
    Index  Count   %     Size   % Cumulative  % Kind (class / dict of class)
     0 1000000    24 112000000 34 112000000  34 dict of __main__.User
     1 1000000    24 64000000  19 176000000  53 __main__.UserTuple
     2 1000000    24 56000000  17 232000000  70 __main__.User
     3 1000000    24 56000000  17 288000000  87 __main__.UserSlot

if 'performance test':
    obj = User('Carson', 1)
    obj_slot = UserSlot('Carson', 1)
    obj_tuple = UserTuple('Carson', 1)

    time_normal = min(timeit.repeat(get_fn(obj, 'name'), repeat=20))
    print(time_normal)  # 0.12550550000000005

    time_slot = min(timeit.repeat(get_fn(obj_slot, 'name'), repeat=20))
    print(time_slot)  # 0.1368690000000008

    time_tuple = min(timeit.repeat(get_fn(obj_tuple, 'name'), repeat=20))
    print(time_tuple)  # 0.16006120000000124

    print(time_tuple/time_slot)  # 1.1694481584580898  # The slot is almost 17% faster than NamedTuple on Windows. (Python 3.7.7)

If your __dict__ is not using, please choose between __slots__ (higher performance and storage) and NamedTuple (clear for reading and use)

You can review this link(Usage of slots ) to get more __slots__ information.

How to make a Generic Type Cast function

Something like this?

public static T ConvertValue<T>(string value)
    return (T)Convert.ChangeType(value, typeof(T));

You can then use it like this:

int val = ConvertValue<int>("42");


You can even do this more generic and not rely on a string parameter provided the type U implements IConvertible - this means you have to specify two type parameters though:

public static T ConvertValue<T,U>(U value) where U : IConvertible
    return (T)Convert.ChangeType(value, typeof(T));

I considered catching the InvalidCastException exception that might be raised by Convert.ChangeType() - but what would you return in this case? default(T)? It seems more appropriate having the caller deal with the exception.

How to get the values of a ConfigurationSection of type NameValueSectionHandler

This is an old question, but I use the following class to do the job. It's based on Scott Dorman's blog:

public class NameValueCollectionConfigurationSection : ConfigurationSection
    private const string COLLECTION_PROP_NAME = "";

    public IEnumerable<KeyValuePair<string, string>> GetNameValueItems()
        foreach ( string key in this.ConfigurationCollection.AllKeys )
            NameValueConfigurationElement confElement = this.ConfigurationCollection[key];
            yield return new KeyValuePair<string, string>
                (confElement.Name, confElement.Value);

    [ConfigurationProperty(COLLECTION_PROP_NAME, IsDefaultCollection = true)]
    protected NameValueConfigurationCollection ConfCollection
            return (NameValueConfigurationCollection) base[COLLECTION_PROP_NAME];

The usage is straightforward:

Configuration configuration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
NameValueCollectionConfigurationSection config = 
    (NameValueCollectionConfigurationSection) configuration.GetSection("MyParams");

NameValueCollection myParamsCollection = new NameValueCollection();
config.GetNameValueItems().ToList().ForEach(kvp => myParamsCollection.Add(kvp));

Calculate MD5 checksum for a file

I know that I am late to party but performed test before actually implement the solution.

I did perform test against inbuilt MD5 class and also md5sum.exe. In my case inbuilt class took 13 second where md5sum.exe too around 16-18 seconds in every run.

    DateTime current = DateTime.Now;
    string file = @"C:\text.iso";//It's 2.5 Gb file
    string output;
    using (var md5 = MD5.Create())
        using (var stream = File.OpenRead(file))
            byte[] checksum = md5.ComputeHash(stream);
            output = BitConverter.ToString(checksum).Replace("-", String.Empty).ToLower();
            Console.WriteLine("Total seconds : " + (DateTime.Now - current).TotalSeconds.ToString() + " " + output);

How can I start PostgreSQL server on Mac OS X?

I had almost the exact same issue, and you cited the initdb command as being the fix. This was also the solution for me, but I didn't see that anyone posted it here, so for those who are looking for it:

initdb /usr/local/var/postgres -E utf8

Using Google Translate in C#

I found this code works for me:

public String Translate(String word)
    var toLanguage = "en";//English
    var fromLanguage = "de";//Deutsch
    var url = $"{fromLanguage}&tl={toLanguage}&dt=t&q={HttpUtility.UrlEncode(word)}";
    var webClient = new WebClient
        Encoding = System.Text.Encoding.UTF8
    var result = webClient.DownloadString(url);
        result = result.Substring(4, result.IndexOf("\"", 4, StringComparison.Ordinal) - 4);
        return result;
        return "Error";

Easiest way to split a string on newlines in .NET?

You should be able to split your string pretty easily, like so:


Start ssh-agent on login

Please go through this article. You may find this very useful:

Just in case the above link vanishes some day, I am capturing the main piece of the solution below:

This solution from Joseph M. Reagle by way of Daniel Starin:

Add this following to your .bash_profile


function start_agent {
    echo "Initialising new SSH agent..."
    /usr/bin/ssh-agent | sed 's/^echo/#echo/' > "${SSH_ENV}"
    echo succeeded
    chmod 600 "${SSH_ENV}"
    . "${SSH_ENV}" > /dev/null

# Source SSH settings, if applicable

if [ -f "${SSH_ENV}" ]; then
    . "${SSH_ENV}" > /dev/null
    #ps ${SSH_AGENT_PID} doesn't work under cywgin
    ps -ef | grep ${SSH_AGENT_PID} | grep ssh-agent$ > /dev/null || {

This version is especially nice since it will see if you've already started ssh-agent and, if it can't find it, will start it up and store the settings so that they'll be usable the next time you start up a shell.

Console app arguments, how arguments are passed to Main method

All answers are awesome and explained everything very well

but I just want to point out different way for passing args to main method

in visual studio

  1. right click on Project then choose Properties
  2. go to Debug tab then on the Start Options section provide the app with your args

like this image

Properties window

and happy knowing secrets

Extract a substring from a string in Ruby using a regular expression

You can use a regular expression for that pretty easily…

Allowing spaces around the word (but not keeping them):

str.match(/< ?([^>]+) ?>\Z/)[1]

Or without the spaces allowed:


XMLHttpRequest module not defined/found

Since the last update of the xmlhttprequest module was around 2 years ago, in some cases it does not work as expected.

So instead, you can use the xhr2 module. In other words:

var XMLHttpRequest = require("xmlhttprequest").XMLHttpRequest;
var xhr = new XMLHttpRequest();


var XMLHttpRequest = require('xhr2');
var xhr = new XMLHttpRequest();

But ... of course, there are more popular modules like Axios, because -for example- uses promises:

// Make a request for a user with a given ID
axios.get('/user?ID=12345').then(function (response) {
}).catch(function (error) {

Clear back stack using fragments

Accepted answer was not enough for me. I had to use :

FragmentManager fm = getSupportFragmentManager();
int count = fm.getBackStackEntryCount();
for(int i = 0; i < count; ++i) {

Running Node.Js on Android

I just had a jaw-drop moment - Termux allows you to install NodeJS on an Android device!

It seems to work for a basic Websocket Speed Test I had on hand. The http served by it can be accessed both locally and on the network.

There is a medium post that explains the installation process

Basically: 1. Install termux 2. apt install nodejs 3. node it up!

One restriction I've run into - it seems the shared folders don't have the necessary permissions to install modules. It might just be a file permission thing. The private app storage works just fine.

Finding version of Microsoft C++ compiler from command-line (for makefiles)

Just run it without options.

Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8168 for 80x86
Copyright (C) Microsoft Corp 1984-1998. All rights reserved.

usage: cl [ option... ] filename... [ /link linkoption... ]

How to change current Theme at runtime in Android

recreate() (as mentioned by TPReal) will only restart current activity, but the previous activities will still be in back stack and theme will not be applied to them.

So, another solution for this problem is to recreate the task stack completely, like this:

            .addNextIntent(new Intent(getActivity(), MainActivity.class))


Just put the code above after you perform changing of theme on the UI or somewhere else. All your activities should have method setTheme() called before onCreate(), probably in some parent activity. It is also a normal approach to store the theme chosen in SharedPreferences, read it and then set using setTheme() method.

How to show current user name in a cell?

This displays the name of the current user:

Function Username() As String
    Username = Application.Username
End Function

The property Application.Username holds the name entered with the installation of MS Office.

Enter this formula in a cell:


Why does Git tell me "No such remote 'origin'" when I try to push to origin?

I faced this issue when I was tring to link a locally created repo with a blank repo on github. Initially I was trying git remote set-url but I had to do git remote add instead.

git remote add origin

Docker container not starting (docker start)

What I need is to use Docker with MariaDb on different port /3301/ on my Ubuntu machine because I already had MySql installed and running on 3306.

To do this after half day searching did it using:

docker run -it -d -p 3301:3306 -v ~/mdbdata/mariaDb:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=root --name mariaDb mariadb

This pulls the image with latest MariaDb, creates container called mariaDb, and run mysql on port 3301. All data of which is located in home directory in /mdbdata/mariaDb.

To login in mysql after that can use:

mysql -u root -proot -h -P3301

Used sources are:

The answer of Iarks in this article /using -it -d was the key :) /




Good luck all!

Setting a property by reflection with a string value

I notice a lot of people are recommending Convert.ChangeType - This does work for some cases however as soon as you start involving nullable types you will start receiving InvalidCastExceptions:

A wrapper was written a few years ago to handle this but that isn't perfect either.

How to install a specific JDK on Mac OS X?

JDK is the Java Development Kit (used to develop Java software).

JRE is the Java Runtime Environment (used to run any .jar file 'Java software').

The JDK contains a JRE inside it.

On Windows when you update Java, it updates the JRE automatically.

On Mac you do not have a JRE separated you have it, but inside the JDK, so when you update Java it will update your JRE which is inside your JDK; it doesn't install an JDK for you. You need to get it from somewhere else.

How do I download a file using VBA (without Internet Explorer)

I was struggling for hours on this until I figured out it can be done in one line of powershell:

invoke-webrequest -Uri "http://myserver/Reports/Pages/ReportViewer.aspx?%2fClients%2ftest&rs:Format=PDF&rs:ClearSession=true&CaseCode=12345678" -OutFile "C:\Temp\test.pdf" -UseDefaultCredentials

I looked into doing it purely in VBA but it runs to several pages, so I just call my powershell script from VBA every time I want to download a file.


Select first 4 rows of a data.frame in R

If you have less than 4 rows, you can use the head function ( head(data, 4) or head(data, n=4)) and it works like a charm. But, assume we have the following dataset with 15 rows

>data <- data <- read.csv("./data.csv", sep = ";", header=TRUE)

 LungCap Age Height Smoke Gender Caesarean
1    6.475   6   62.1    no   male        no
2   10.125  18   74.7   yes female        no
3    9.550  16   69.7    no female       yes
4   11.125  14   71.0    no   male        no
5    4.800   5   56.9    no   male        no
6    6.225  11   58.7    no female        no
7    4.950   8   63.3    no   male       yes
8    7.325  11   70.4    no  male         no
9    8.875  15   70.5    no   male        no
10   6.800  11   59.2    no   male        no
11   6.900  12   59.3    no   male        no
12   6.100  13   59.4    no   male        no
13   6.110  14   59.5    no   male        no
14   6.120  15   59.6    no   male        no
15   6.130  16   59.7    no   male        no

Let's say, you want to select the first 10 rows. The easiest way to do it would be data[1:10, ].

> data[1:10,]
   LungCap Age Height Smoke Gender Caesarean
1    6.475   6   62.1    no   male        no
2   10.125  18   74.7   yes female        no
3    9.550  16   69.7    no female       yes
4   11.125  14   71.0    no   male        no
5    4.800   5   56.9    no   male        no
6    6.225  11   58.7    no female        no
7    4.950   8   63.3    no   male       yes
8    7.325  11   70.4    no  male         no
9    8.875  15   70.5    no   male        no
10   6.800  11   59.2    no   male        no

However, let's say you try to retrieve the first 19 rows and see the what happens - you will have missing values

> data[1:19,]
     LungCap Age Height Smoke Gender Caesarean
1      6.475   6   62.1    no   male        no
2     10.125  18   74.7   yes female        no
3      9.550  16   69.7    no female       yes
4     11.125  14   71.0    no   male        no
5      4.800   5   56.9    no   male        no
6      6.225  11   58.7    no female        no
7      4.950   8   63.3    no   male       yes
8      7.325  11   70.4    no  male         no
9      8.875  15   70.5    no   male        no
10     6.800  11   59.2    no   male        no
11     6.900  12   59.3    no   male        no
12     6.100  13   59.4    no   male        no
13     6.110  14   59.5    no   male        no
14     6.120  15   59.6    no   male        no
15     6.130  16   59.7    no   male        no
NA        NA  NA     NA  <NA>   <NA>      <NA>
NA.1      NA  NA     NA  <NA>   <NA>      <NA>
NA.2      NA  NA     NA  <NA>   <NA>      <NA>
NA.3      NA  NA     NA  <NA>   <NA>      <NA>

and with the head() function,

> head(data, 19) # or head(data, n=19)
   LungCap Age Height Smoke Gender Caesarean
1    6.475   6   62.1    no   male        no
2   10.125  18   74.7   yes female        no
3    9.550  16   69.7    no female       yes
4   11.125  14   71.0    no   male        no
5    4.800   5   56.9    no   male        no
6    6.225  11   58.7    no female        no
7    4.950   8   63.3    no   male       yes
8    7.325  11   70.4    no  male         no
9    8.875  15   70.5    no   male        no
10   6.800  11   59.2    no   male        no
11   6.900  12   59.3    no   male        no
12   6.100  13   59.4    no   male        no
13   6.110  14   59.5    no   male        no
14   6.120  15   59.6    no   male        no
15   6.130  16   59.7    no   male        no

Hope this help!

How do I find the version of Apache running without access to the command line?

Telnet to the host at port 80.


get / http1.1

It is kind of an HTTP request, but it's not valid so the 500 error it gives you will probably give you the information you want. The blank lines at the end are important otherwise it will just seem to hang.

Download a file by jQuery.Ajax

Noone posted this @Pekka's solution... so I'll post it. It can help someone.

You don't need to do this through Ajax. Just use


What is the difference between Class.getResource() and ClassLoader.getResource()?

Had to look it up in the specs:

Class's getResource() - documentation states the difference:

This method delegates the call to its class loader, after making these changes to the resource name: if the resource name starts with "/", it is unchanged; otherwise, the package name is prepended to the resource name after converting "." to "/". If this object was loaded by the bootstrap loader, the call is delegated to ClassLoader.getSystemResource.

When and how should I use a ThreadLocal variable?

[For Reference]ThreadLocal cannot solve update problems of shared object. It is recommended to use a staticThreadLocal object which is shared by all operations in the same thread. [Mandatory]remove() method must be implemented by ThreadLocal variables, especially when using thread pools in which threads are often reused. Otherwise, it may affect subsequent business logic and cause unexpected problems such as memory leak.

Code Sign error: The identity 'iPhone Developer' doesn't match any valid certificate/private key pair in the default keychain

When I had this problem, the issue was I did not have the private key necessary for the developer certificate to be valid.

The solution was:

  1. Have the developer who created the certificate export their private key matching the iOS developer public key. see

  2. Open this file (Certificates.p12) on your machine (with KeyChain), and enter the password the other developer used when exporting. It is now imported into your KeyChain.

  3. Now connect iOS device and rebuild targeting the iOS device.

Convert utf8-characters to iso-88591 and back in PHP

Have a look at iconv() or mb_convert_encoding(). Just by the way: why don't utf8_encode() and utf8_decode() work for you?

utf8_decode — Converts a string with ISO-8859-1 characters encoded with UTF-8 to single-byte ISO-8859-1

utf8_encode — Encodes an ISO-8859-1 string to UTF-8

So essentially

$utf8 = 'ÄÖÜ'; // file must be UTF-8 encoded
$iso88591_1 = utf8_decode($utf8);
$iso88591_2 = iconv('UTF-8', 'ISO-8859-1', $utf8);
$iso88591_2 = mb_convert_encoding($utf8, 'ISO-8859-1', 'UTF-8');

$iso88591 = 'ÄÖÜ'; // file must be ISO-8859-1 encoded
$utf8_1 = utf8_encode($iso88591);
$utf8_2 = iconv('ISO-8859-1', 'UTF-8', $iso88591);
$utf8_2 = mb_convert_encoding($iso88591, 'UTF-8', 'ISO-8859-1');

all should do the same - with utf8_en/decode() requiring no special extension, mb_convert_encoding() requiring ext/mbstring and iconv() requiring ext/iconv.

How to embed image or picture in jupyter notebook, either from a local machine or from a web resource?

I'm surprised no one here has mentioned the html cell magic option. from the docs (IPython, but same for Jupyter)


Render the cell as a block of HTML

Rename multiple files in a directory in Python

I was originally looking for some GUI which would allow renaming using regular expressions and which had a preview of the result before applying changes.

On Linux I have successfully used krename, on Windows Total Commander does renaming with regexes, but I found no decent free equivalent for OSX, so I ended up writing a python script which works recursively and by default only prints the new file names without making any changes. Add the '-w' switch to actually modify the file names.

# -*- coding: utf-8 -*-

import os
import fnmatch
import sys
import shutil
import re

def usage():
    print """
        %s <work_dir> <search_regex> <replace_regex> [-w|--write]

        By default no changes are made, add '-w' or '--write' as last arg to actually rename files
        after you have previewed the result.
        """ % (os.path.basename(sys.argv[0]))

def rename_files(directory, search_pattern, replace_pattern, write_changes=False):

    pattern_old = re.compile(search_pattern)

    for path, dirs, files in os.walk(os.path.abspath(directory)):

        for filename in fnmatch.filter(files, "*.*"):

            if pattern_old.findall(filename):
                new_name = pattern_old.sub(replace_pattern, filename)

                filepath_old = os.path.join(path, filename)
                filepath_new = os.path.join(path, new_name)

                if not filepath_new:
                    print 'Replacement regex {} returns empty value! Skipping'.format(replace_pattern)

                print new_name

                if write_changes:
                    shutil.move(filepath_old, filepath_new)
                print 'Name [{}] does not match search regex [{}]'.format(filename, search_pattern)

if __name__ == '__main__':
    if len(sys.argv) < 4:

    work_dir = sys.argv[1]
    search_regex = sys.argv[2]
    replace_regex = sys.argv[3]
    write_changes = (len(sys.argv) > 4) and sys.argv[4].lower() in ['--write', '-w']
    rename_files(work_dir, search_regex, replace_regex, write_changes)

Example use case

I want to flip parts of a file name in the following manner, i.e. move the bit m7-08 to the beginning of the file name:

# Before:

# After:

This will perform a dry run, and print the new file names without actually renaming any files: . "([^\.]+?)-(m\\d+-\\d+)" "\\2_\\1"

This will do the actual renaming (you can use either -w or --write): . "([^\.]+?)-(m\\d+-\\d+)" "\\2_\\1" --write

set font size in jquery


$("#"+styleTarget).css({ 'font-size': $(this).val() });

By putting the value in quotes, it becomes a string, and "+$(this).val()+"px is definitely not close to a font value. There are a couple of ways of setting the style properties of an element:

Using a map:

    fontSize: 20

Using key and value parameters:

All of these are valid.

$("#elem").css("fontSize", 20);
$("#elem").css("fontSize", "20px");
$("#elem").css("font-size", "20");
$("#elem").css("font-size", "20px");

You can replace "fontSize" with "font-size" but it will have to be quoted then.

Shorthand for if-else statement

Most answers here will work fine if you have just two conditions in your if-else. For more which is I guess what you want, you'll be using arrays. Every names corresponding element in names array you'll have an element in the hasNames array with the exact same index. Then it's a matter of these four lines.

names = "true";
var names = ["true","false","1","2"];
var hasNames = ["Y","N","true","false"];
var intIndex = names.indexOf(name);
hasName = hasNames[intIndex ];

This method could also be implemented using Objects and properties as illustrated by Benjamin.

PostgreSQL : cast string to date DD/MM/YYYY

A DATE column does not have a format. You cannot specify a format for it.

You can use DateStyle to control how PostgreSQL emits dates, but it's global and a bit limited.

Instead, you should use to_char to format the date when you query it, or format it in the client application. Like:

SELECT to_char("date", 'DD/MM/YYYY') FROM mytable;


regress=> SELECT to_char(DATE '2014-04-01', 'DD/MM/YYYY');
(1 row)

write multiple lines in a file in python

this also works:

target.write("{}" "\n" "{}" "\n" "{}" "\n".format(line1, line2, line3))