Programs & Examples On #Object literal

JavaScript Object Literal An object literal is a comma separated list of name value pairs wrapped in curly braces. In JavaScript an object literal is defined as follows: var myObject = { sProp: 'some string value', numProp: 2, bProp: false };

How to fill a Javascript object literal with many static key/value pairs efficiently?

The syntax you wrote as first is not valid. You can achieve something using the follow:

var map =  {"aaa": "rrr", "bbb": "ppp" /* etc */ };

How to use a variable for a key in a JavaScript object literal?

With ECMAScript 2015 you are now able to do it directly in object declaration with the brackets notation: 

var obj = {
  [key]: value

Where key can be any sort of expression (e.g. a variable) returning a value.

So here your code would look like:

  [thetop]: 10
}, 10)

Where thetop will be evaluated before being used as key.

How to create an array of object literals in a loop?

If you want to go even further than @tetra with ES6 you can use the Object spread syntax and do something like this:

let john = {
    firstName: "John",
    lastName: "Doe",

let people = new Array(10).fill().map((e, i) => {(...john, id: i});

Adding/removing items from a JavaScript object with jQuery

Adding an object in a json array

var arrList = [];
var arr = {};   
arr['worker_id'] = worker_id;
arr['worker_nm'] = worker_nm;

Removing an object from a json

It worker for me.

  arrList = $.grep(arrList, function (e) { 

        if(e.worker_id == worker_id) {
            return false;
        } else {
            return true;

It returns an array without that object.

Hope it helps.

JavaScript property access: dot notation vs. brackets?

Dot notation does not work with some keywords (like new and class) in internet explorer 8.

I had this code:

//app.users is a hash = {
  // some code

And this triggers the dreaded "expected indentifier" (at least on IE8 on windows xp, I havn't tried other environments). The simple fix for that is to switch to bracket notation:

app.users['new'] = {
  // some code

How can I add a key/value pair to a JavaScript object?


Today 2020.01.14 I perform tests on MacOs HighSierra 10.13.6 on Chrome v78.0.0, Safari v13.0.4 and Firefox v71.0.0, for chosen solutions. I divide solutions to mutable (first letter M) and immutable (first letter I). I also provide few immutable solutions (IB,IC,ID/IE) not yet published in answers to this question


  • fastest mutable solutions are much faster than fastest immutable (>10x)
  • classic mutable approach like obj.key3 = "abc" (MA,MB) is fastest
  • for immutable solutions the {...obj, key3:'abc'} and Object.assign (IA,IB) are fastest
  • surprisingly there are immutable solutions faster than some mutable solutions for chrome (MC-IA) and safari (MD-IB)

enter image description here


In snippet below there are presended tested solution, you can prefrom test on your machine HERE

var o = {_x000D_
    key1: true,_x000D_
    key2: 3,_x000D_
var log= (s,f)=> console.log(`${s} --> ${JSON.stringify(f({...o}))}`);_x000D_
function MA(obj) {_x000D_
  obj.key3 = "abc";_x000D_
  return obj;_x000D_
function MB(obj) {_x000D_
  obj['key3'] = "abc";_x000D_
  return obj;_x000D_
function MC(obj) {_x000D_
  Object.assign(obj, {key3:'abc'});_x000D_
  return obj;_x000D_
function MD(obj) {_x000D_
  Object.defineProperty(obj, 'key3', {_x000D_
    value: "abc",       // undefined by default_x000D_
    enumerable: true,      // false by default_x000D_
    configurable: true,    // false by default_x000D_
    writable: true         // false by default_x000D_
  return obj;_x000D_
function IA(obj) {_x000D_
  return {...obj, key3:'abc'};_x000D_
function IB(obj) {_x000D_
  return Object.assign({key3:'abc'}, obj);_x000D_
function IC(obj) {_x000D_
  let ob= JSON.parse(JSON.stringify(obj))_x000D_
  ob.key3 = 'abc';_x000D_
  return ob;_x000D_
function ID(obj) {_x000D_
 let ob= Object.fromEntries(Object.entries(obj));_x000D_
  ob.key3 = 'abc';_x000D_
  return ob;_x000D_
function IE(obj) {_x000D_
 return Object.fromEntries(Object.entries(obj).concat([['key3','abc']]))_x000D_
This snippet only presents code - it not perform tests itself!

enter image description here

Self-references in object literals / initializers

Well, the only thing that I can tell you about are getter:

var foo = {_x000D_
  a: 5,_x000D_
  b: 6,_x000D_
  get c() {_x000D_
    return this.a + this.b;_x000D_
console.log(foo.c) // 11

This is a syntactic extension introduced by the ECMAScript 5th Edition Specification, the syntax is supported by most modern browsers (including IE9).

Dynamically Add Variable Name Value Pairs to JSON Object

if my understanding of your initial JSON is correct, either of these solutions might help you loop through all ip ids & assign each one, a new object.

// initial JSON
var ips = {ipId1: {}, ipId2: {}};

// Solution1
Object.keys(ips).forEach(function(key) {
  ips[key] = {name: 'value', anotherName: 'another value'};

// Solution 2
Object.keys(ips).forEach(function(key) {
  Object.assign(ips[key],{name: 'value', anotherName: 'another value'});

To confirm:

console.log(JSON.stringify(ips, null, 2));

The above statement spits:

  "ipId1": {
    "anotherName":"another value"
  "ipId2": {
    "anotherName":"another value"

Android Studio doesn't see device

I use the Android version of Nougat API 24, I solved a device problem not detected by replacing the USB cable.

Unable to connect to SQL Express "Error: 26-Error Locating Server/Instance Specified)

Could you post the connection string you're using that's giving you trouble?
You might need to add the port number to the Data Source value, as omitting it can also produce SQL Error 26.

E.g.: Data Source=ServerHostName\SQLServerInstanceName,1433


You don't really need a sub-select:

   SUM( CASE WHEN c = 'const' THEN 1 ELSE 0 END ) as d,
   from t group by a order by b desc

SQL: Combine Select count(*) from multiple tables

select sum(counts) from (
select count(1) as counts from foo 
union all
select count(1) as counts from bar)

What does InitializeComponent() do, and how does it work in WPF?

Looking at the code always helps too. That is, you can actually take a look at the generated partial class (that calls LoadComponent) by doing the following:

  1. Go to the Solution Explorer pane in the Visual Studio solution that you are interested in.
  2. There is a button in the tool bar of the Solution Explorer titled 'Show All Files'. Toggle that button.
  3. Now, expand the obj folder and then the Debug or Release folder (or whatever configuration you are building) and you will see a file titled YourClass.g.cs.

The YourClass.g.cs ... is the code for generated partial class. Again, if you open that up you can see the InitializeComponent method and how it calls LoadComponent ... and much more.

Pick images of root folder from sub-folder

when you upload your files to the server be careful ,some tomes your images will not appear on the web page and a crashed icon will appear that means your file path is not properly arranged or coded when you have the the following file structure the code should be like this File structure: ->web(main folder) ->images(subfolder)->logo.png(image in the sub folder)the code for the above is below follow this standard

 <img src="../images/logo.jpg" alt="image1" width="50px" height="50px">

if you uploaded your files to the web server by neglecting the file structure with out creating the folder web if you directly upload the files then your images will be broken you can't see images,then change the code as following

 <img src="images/logo.jpg" alt="image1" width="50px" height="50px">

thank you->vamshi krishnan

How can I fetch all items from a DynamoDB table without specifying the primary key?

I fetch all items from dynamodb with the following query. It works fine. i create these function generic in zend framework and access these functions over the project.

        public function getQuerydata($tablename, $filterKey, $filterValue){
            return $this->getQuerydataWithOp($tablename, $filterKey, $filterValue, 'EQ');

        public function getQuerydataWithOp($tablename, $filterKey, $filterValue, $compOperator){
        $result = $this->getClientdb()->query(array(
                'TableName'     => $tablename,
                'IndexName'     => $filterKey,
                'Select'        => 'ALL_ATTRIBUTES',
                'KeyConditions' => array(
                    $filterKey => array(
                        'AttributeValueList' => array(
                            array('S' => $filterValue)
                'ComparisonOperator' => $compOperator
            return $result['Items'];

       //Below i Access these functions and get data.
       $accountsimg = $this->getQuerydataWithPrimary('accounts', 'accountID',$msgdata[0]['accountID']['S']);

Getting a 'source: not found' error when using source in a bash script

In the POSIX standard, which /bin/sh is supposed to respect, the command is . (a single dot), not source. The source command is a csh-ism that has been pulled into bash.


. $env_name/bin/activate

Or if you must have non-POSIX bash-isms in your code, use #!/bin/bash.

How to update Xcode from command line

Xcode::Install is a simple cli software that allow you to install/select a specific Xcode version.

You can install it using gem install xcode-install
Then you will be able to install a specific version with xcversion install 9.4.1
And if you have more than one version installed, you can switch version with xcversion select 9.4

You can find more information at

How to capitalize the first letter of a String in Java?

Those who search capitalize first letter of a name here..

public static String capitaliseName(String name) {
    String collect[] = name.split(" ");
    String returnName = "";
    for (int i = 0; i < collect.length; i++) {
        collect[i] = collect[i].trim().toLowerCase();
        if (collect[i].isEmpty() == false) {
            returnName = returnName + collect[i].substring(0, 1).toUpperCase() + collect[i].substring(1) + " ";
    return returnName.trim();

usase: capitaliseName("saurav khan");

output: Saurav Khan

error: This is probably not a problem with npm. There is likely additional logging output above

Deleting the package-lock.json did it for me. I'd suggest you not push package-lock.json to your repo as I wasted hours trying to npm install with the package-lock.json in the folder which gave me helluva errors.

Read file-contents into a string in C++

The most efficient is to create a buffer of the correct size and then read the file into the buffer.

#include <fstream>
#include <vector>

int main()
    std::ifstream       file("Plop");
    if (file)
         * Get the size of the file
        std::streampos          length = file.tellg();

         * Use a vector as the buffer.
         * It is exception safe and will be tidied up correctly.
         * This constructor creates a buffer of the correct length.
         * Because char is a POD data type it is not initialized.
         * Then read the whole file into the buffer.
        std::vector<char>       buffer(length);[0],length);

how to find array size in angularjs

You can find the number of members in a Javascript array by using its length property:

var number = $scope.names.length;

Docs - Array.prototype.length

The 'packages' element is not declared

Oh ok - now I get it. You can ignore this one - the XML for this is just not correct - the packages-element is indeed not declared (there is no reference to a schema or whatever). I think this is a known minor bug that won't do a thing because only NuGet will use this.

See this similar question also.

Inserting a string into a list without getting split into characters

You have to add another list:


How to read a file into vector in C++?

Just to expand on juanchopanza's answer a bit...

for (int i=0; i=((Main.size())-1); i++) {
    cout << Main[i] << '\n';

does this:

  1. Create i and set it to 0.
  2. Set i to Main.size() - 1. Since Main is empty, Main.size() is 0, and i gets set to -1.
  3. Main[-1] is an out-of-bounds access. Kaboom.

Stratified Train/Test-split in scikit-learn

You can simply do it with train_test_split() method available in Scikit learn:

from sklearn.model_selection import train_test_split 
train, test = train_test_split(X, test_size=0.25, stratify=X['YOUR_COLUMN_LABEL']) 

I have also prepared a short GitHub Gist which shows how stratify option works:

Auto-refreshing div with jQuery - setTimeout or another method?

function update() {
    type: 'GET',
    url: 'jbede.php',
    timeout: 2000,
    success: function(data) {
      window.setTimeout(update, 10000);
    error: function (XMLHttpRequest, textStatus, errorThrown) {
      $("#notice_div").html('Timeout contacting server..');
      window.setTimeout(update, 60000);
$(document).ready(function() {

This is Better Code

Select values from XML field in SQL Server 2008

/* This example uses an XML variable with a schema */

IF EXISTS (SELECT * FROM sys.xml_schema_collections 
           WHERE name = 'OrderingAfternoonTea')
    DROP XML SCHEMA COLLECTION dbo.OrderingAfternoonTea 

N'<?xml version="1.0" encoding="UTF-16" ?>
  <xsd:schema xmlns:xsd=""
    <xsd:complexType name="AfternoonTeaOrderType">
         <xsd:element name="potsOfTea" type="xsd:int"/>
         <xsd:element name="cakes" type="xsd:int"/>
         <xsd:element name="fruitedSconesWithCream" type="xsd:int"/>
         <xsd:element name="jams" type="xsd:string"/>
      <xsd:attribute name="schemaVersion" type="xsd:long" use="required"/>

    <xsd:element name="afternoonTeaOrder"

  </xsd:schema>' ;

DECLARE @potsOfTea int;
DECLARE @cakes int;
DECLARE @fruitedSconesWithCream int;
DECLARE @jams nvarchar(128);

DECLARE @RequestMsg NVARCHAR(2048);
DECLARE @RequestXml XML(dbo.OrderingAfternoonTea);

set @potsOfTea = 5;
set @cakes = 7;
set @fruitedSconesWithCream = 25;
set @jams = N'medlar jelly, quince and mulberry';

SELECT @RequestMsg = N'<?xml version="1.0" encoding="utf-16" ?>
<TFor2:afternoonTeaOrder schemaVersion="10"
    <TFor2:potsOfTea>' + CAST(@potsOfTea as NVARCHAR(20)) 
        + '</TFor2:potsOfTea>
    <TFor2:cakes>' + CAST(@cakes as NVARCHAR(20)) + '</TFor2:cakes>
        + CAST(@fruitedSconesWithCream as NVARCHAR(20))
        + '</TFor2:fruitedSconesWithCream>
    <TFor2:jams>' + @jams + '</TFor2:jams>


with xmlnamespaces(''
                    as tea)
    cast( x.Rec.value('.[1]/@schemaVersion','nvarchar(20)') as bigint )
        as schemaVersion,
    cast( x.Rec.query('./tea:potsOfTea')
               .value('.','nvarchar(20)') as bigint ) as potsOfTea,
    cast( x.Rec.query('./tea:cakes')
               .value('.','nvarchar(20)') as bigint )  as cakes,
    cast( x.Rec.query('./tea:fruitedSconesWithCream')
               .value('.','nvarchar(20)') as bigint ) 
      as fruitedSconesWithCream,
    x.Rec.query('./tea:jams').value('.','nvarchar(50)')  as jams
from @RequestXml.nodes('/tea:afternoonTeaOrder')  as x(Rec);

select @RequestXml.query('/*')

extract date only from given timestamp in oracle sql

This format worked for me, for the mentioned date format i.e. MM/DD/YYYY

SELECT to_char(query_date,'MM/DD/YYYY') as query_date 

Convert List<String> to List<Integer> directly

Using lambda:;

SQL query to check if a name begins and ends with a vowel

My simple solution :::



WHERE CITY LIKE '[a,e,i,o,u]%[a,e,i,o,u]';

How to prevent multiple definitions in C?

You actually compile the source code of test.c twice:

  • The first time when compiling test.c itself,
  • The second time when compiling main.c which includes all the test.c source.

What you need in your main.c in order to use the test() function is a simple declaration, not its definition. This is achieved by including a test.h header file which contains something like:

void test(void);

This informs the compiler that such a function with input parameters and return type exists. What this function does ( everything inside { and } ) is left in your test.c file.

In main.c, replace #include "test.c" by #include "test.h".

A last point: with your programs being more complex, you will be faced to situations when header files may be included several times. To prevent this, header sources are sometimes enclosed by specific macro definitions, like:


void test(void);


Call asynchronous method in constructor?

Try to replace this:

myLongList.ItemsSource = writings;

with this

Dispatcher.BeginInvoke(() => myLongList.ItemsSource = writings);

How to add a new line of text to an existing file in Java?

The solution with FileWriter is working, however you have no possibility to specify output encoding then, in which case the default encoding for machine will be used, and this is usually not UTF-8!

So at best use FileOutputStream:

    Writer writer = new BufferedWriter(new OutputStreamWriter(
        new FileOutputStream(file, true), "UTF-8"));

Display JSON as HTML

I think you meant something like this: JSON Visualization

Don't know if you might use it, but you might ask the author.

Fatal error: Can't open and lock privilege tables: Table '' doesn't exist

When download mysql zip version, if run mysqld directly, you'll get this error: 2016-02-18T07:23:48.318481Z 0 [ERROR] Fatal error: Can't open and lock privilege tables: Table 'mysql.user' doesn't exist 2016-02-18T07:23:48.319482Z 0 [ERROR] Aborting

You have to run below command first: mysqld --initialize

Make sure your data folder is empty before this command.

PHP: cannot declare class because the name is already in use

You should use require_once and include_once. Inside parent.php use

include_once 'database.php';

And inside child1.php and child2.php use

include_once 'parent.php';

How do I name the "row names" column in r

It sounds like you want to convert the rownames to a proper column of the data.frame. eg:

# add the rownames as a proper column
myDF <- cbind(Row.Names = rownames(myDF), myDF)

#           Row.Names id val vr2
# row_one     row_one  A   1  23
# row_two     row_two  A   2  24
# row_three row_three  B   3  25
# row_four   row_four  C   4  26

If you want to then remove the original rownames:

rownames(myDF) <- NULL
#   Row.Names id val vr2
# 1   row_one  A   1  23
# 2   row_two  A   2  24
# 3 row_three  B   3  25
# 4  row_four  C   4  26

Alternatively, if all of your data is of the same class (ie, all numeric, or all string), you can convert to Matrix and name the dimnames

myMat <- as.matrix(myDF)
names(dimnames(myMat)) <- c("Names.of.Rows", "")

# Names.of.Rows id  val vr2 
#   row_one   "A" "1" "23"
#   row_two   "A" "2" "24"
#   row_three "B" "3" "25"
#   row_four  "C" "4" "26"

ReactJS call parent method

Pass the method from Parent component down as a prop to your Child component. ie:

export default class Parent extends Component {
  state = {
    word: ''

  handleCall = () => {
    this.setState({ word: 'bar' })

  render() {
    const { word } = this.state
    return <Child handler={this.handleCall} word={word} />

const Child = ({ handler, word }) => (
<span onClick={handler}>Foo{word}</span>

Show and hide divs at a specific time interval using jQuery

here is a jQuery plugin I came up with:

$.fn.cycle = function(timeout){
    var $all_elem = $(this)

    show_cycle_elem = function(index){
        if(index == $all_elem.length) return; //you can make it start-over, if you want
        setTimeout(function(){show_cycle_elem(++index)}, timeout);

You need to have a common classname for all the divs you wan to cycle, use it like this:


Using onBackPressed() in Android Fragments

Why don't you want to use the back stack? If there is an underlying problem or confusion maybe we can clear it up for you.

If you want to stick with your requirement just override your Activity's onBackPressed() method and call whatever method you're calling when the back arrow in your ActionBar gets clicked.

EDIT: How to solve the "black screen" fragment back stack problem:

You can get around that issue by adding a backstack listener to the fragment manager. That listener checks if the fragment back stack is empty and finishes the Activity accordingly:

You can set that listener in your Activity's onCreate method:

protected void onCreate(Bundle savedInstanceState) {
    FragmentManager fm = getFragmentManager();
    fm.addOnBackStackChangedListener(new OnBackStackChangedListener() {
        public void onBackStackChanged() {
            if(getFragmentManager().getBackStackEntryCount() == 0) finish();

How to redirect siteA to siteB with A or CNAME records

You can do this a number of non-DNS ways. The landing page at can have an HTTP redirect. The webserver at can be configured to redirect (easy in Apache, not sure about IIS), etc.

How to call javascript function from code-behind

This is a way to invoke one or more JavaScript methods from the code behind. By using Script Manager we can call the methods in sequence. Consider the below code for example.

ScriptManager.RegisterStartupScript(this, typeof(Page), "UpdateMsg", 
    alert('Overrides successfully Updated.');

In this first method EnableControls() is invoked. Next the alert will be displayed. Next the DisableControls() method will be invoked.

How to run sql script using SQL Server Management Studio?

This website has a concise tutorial on how to use SQL Server Management Studio. As you will see you can open a "Query Window", paste your script and run it. It does not allow you to execute scripts by using the file path. However, you can do this easily by using the command line (cmd.exe):

sqlcmd -S .\SQLExpress -i SqlScript.sql

Where SqlScript.sql is the script file name located at the current directory. See this Microsoft page for more examples

What is the best IDE for C Development / Why use Emacs over an IDE?

Emacs is an IDE.

edit: OK, I'll elaborate. What is an IDE?

As a starting point, let's expand the acronym: Integrated Development Environment. To analyze this, I start from the end.

An environment is, generally speaking, the part of the world that surrounds the point of view. In this case, it is what we see on our monitor (perhaps hear from our speakers) and manipulate through our keyboard (and perhaps a mouse).

Development is what we want to do in this environment, its purpose, if you want. We use the environment to develop software. This defines what subparts we need: an editor, an interface to the REPL, resp. the compiler, an interface to the debugger, and access to online documentation (this list may not be exhaustive).

Integrated means that all parts of the environment are somehow under a uniform surface. In an IDE, we can access and use the different subparts with a minimum of switching; we don't have to leave our defined environment. This integration lets the different subparts interact better. For example, the editor can know about what language we write in, and give us symbol autocompletion, jump-to-definition, auto-indentation, syntax highlighting, etc.. It can get information from the compiler, automatically jump to errors, and highlight them. In most, if not all IDEs, the editor is naturally at the heart of the development process.

Emacs does all this, it does it with a wide range of languages and tasks, and it does it with excellence, since it is seamlessly expandable by the user wherever he misses anything.

Counterexample: you could develop using something like Notepad, access documentation through Firefox and XPdf, and steer the compiler and debugger from a shell. This would be a Development Environment, but it would not be integrated.

Remove Sub String by using Python

>>> import re
>>> st = " i think mabe 124 + <font color=\"black\"><font face=\"Times New Roman\">but I don't have a big experience it just how I see it in my eyes <font color=\"green\"><font face=\"Arial\">fun stuff"
>>> re.sub("<.*?>","",st)
" i think mabe 124 + but I don't have a big experience it just how I see it in my eyes fun stuff"

How to rearrange Pandas column sequence?

I would suggest you just write a function to do what you're saying probably using drop (to delete columns) and insert to insert columns at a position. There isn't an existing API function to do what you're describing.

dereferencing pointer to incomplete type

this error usually shows if the name of your struct is different from the initialization of your struct in the code, so normally, c will find the name of the struct you put and if the original struct is not found, this would usually appear, or if you point a pointer pointed into that pointer, the error will show up.

Why maven settings.xml file is not there?

Installation of Maven doesn't create the settings.xml file. You have to create it on your own. Just put it in your .m2 directory where you expected it, see for reference. The m2eclipse plugin will use the same settings file as the command line.

Quickly reading very large tables as dataframes

I didn't see this question initially and asked a similar question a few days later. I am going to take my previous question down, but I thought I'd add an answer here to explain how I used sqldf() to do this.

There's been little bit of discussion as to the best way to import 2GB or more of text data into an R data frame. Yesterday I wrote a blog post about using sqldf() to import the data into SQLite as a staging area, and then sucking it from SQLite into R. This works really well for me. I was able to pull in 2GB (3 columns, 40mm rows) of data in < 5 minutes. By contrast, the read.csv command ran all night and never completed.

Here's my test code:

Set up the test data:

bigdf <- data.frame(dim=sample(letters, replace=T, 4e7), fact1=rnorm(4e7), fact2=rnorm(4e7, 20, 50))
write.csv(bigdf, 'bigdf.csv', quote = F)

I restarted R before running the following import routine:

f <- file("bigdf.csv")
system.time(bigdf <- sqldf("select * from f", dbname = tempfile(), file.format = list(header = T, row.names = F)))

I let the following line run all night but it never completed:

system.time(big.df <- read.csv('bigdf.csv'))

Java time-based map/cache with expiring keys

You can try out my implementation of a self-expiring hash map. This implementation does not make use of threads to remove expired entries, instead it uses DelayQueue that is cleaned up at every operation automatically.

apache not accepting incoming connections from outside of localhost

Try disabling iptables: service iptables stop

If this works, enable TCP port 80 to your firewall rules: run system-config-selinux from root, and enable TCP port 80 (HTTP) on your firewall.

How to compile a static library in Linux?

Generate the object files with gcc, then use ar to bundle them into a static library.

Difference between a user and a schema in Oracle?

From WikiAnswers:

  • A schema is collection of database objects, including logical structures such as tables, views, sequences, stored procedures, synonyms, indexes, clusters, and database links.
  • A user owns a schema.
  • A user and a schema have the same name.
  • The CREATE USER command creates a user. It also automatically creates a schema for that user.
  • The CREATE SCHEMA command does not create a "schema" as it implies, it just allows you to create multiple tables and views and perform multiple grants in your own schema in a single transaction.
  • For all intents and purposes you can consider a user to be a schema and a schema to be a user.

Furthermore, a user can access objects in schemas other than their own, if they have permission to do so.

Python creating a dictionary of lists

You can build it with list comprehension like this:

>>> dict((i, range(int(i), int(i) + 2)) for i in ['1', '2'])
{'1': [1, 2], '2': [2, 3]}

And for the second part of your question use defaultdict

>>> from collections import defaultdict
>>> s = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]
>>> d = defaultdict(list)
>>> for k, v in s:

>>> d.items()
[('blue', [2, 4]), ('red', [1]), ('yellow', [1, 3])]

What do 'lazy' and 'greedy' mean in the context of regular expressions?

Greedy will consume as much as possible. From we see the example of trying to match HTML tags with <.+>. Suppose you have the following:

<em>Hello World</em>

You may think that <.+> (. means any non newline character and + means one or more) would only match the <em> and the </em>, when in reality it will be very greedy, and go from the first < to the last >. This means it will match <em>Hello World</em> instead of what you wanted.

Making it lazy (<.+?>) will prevent this. By adding the ? after the +, we tell it to repeat as few times as possible, so the first > it comes across, is where we want to stop the matching.

I'd encourage you to download RegExr, a great tool that will help you explore Regular Expressions - I use it all the time.

How can I disable a specific LI element inside a UL?

Using CSS3:

If that's not an option for any reason, you could try giving the list items classes:

<li class="one"></li>
<li class="two"></li>
<li class="three"></li>

Then in your css:{display:none}/*hide first li*/
li.three{display:none}/*hide third li*/

Check if String contains only letters

While there are many ways to skin this cat, I prefer to wrap such code into reusable extension methods that make it trivial to do going forward. When using extension methods, you can also avoid RegEx as it is slower than a direct character check. I like using the extensions in the Extensions.cs NuGet package. It makes this check as simple as:

  1. Add the package to your project.
  2. Add "using Extensions;" to the top of your code.
  3. "smith23".IsAlphabetic() will return False whereas "john smith".IsAlphabetic() will return True. By default the .IsAlphabetic() method ignores spaces, but it can also be overridden such that "john smith".IsAlphabetic(false) will return False since the space is not considered part of the alphabet.
  4. Every other check in the rest of the code is simply MyString.IsAlphabetic().

How can I change the width and height of slides on Slick Carousel?

I initialised the slider with one of the properties as

variableWidth: true

then i could set the width of the slides to anything i wanted in CSS with:

.slick-slide {
    width: 200px;

Best way to "push" into C# array

As per comment "That is not pushing to an array. It is merely assigning to it"

If you looking for the best practice to assign value to array then its only way that you can assign value.

Array[index]= value;

there is only way to assign value when you do not want to use List.

Credit card payment gateway in PHP?

The best solution we found was to team up with one of those intermediaries. Otherwise you will have to deal with a bunch of other requirements like PCI compliance. We use Verifone's IPCharge and it works quite well.

SQL Server JOIN missing NULL values

Dirty and quick hack:

SELECT Table1.Col1, Table1.Col2, Table1.Col3, Table2.Col4
FROM Table1 INNER JOIN Table2 ON Table1.Col1 = Table2.Col1
 AND ((Table1.Col2 = Table2.Col2) OR (Table1.Col2 IS NULL AND Table2.Col2 IS NULL))

How do I properly set the Datetimeindex for a Pandas datetime object in a dataframe?

To simplify Kirubaharan's answer a bit:

df['Datetime'] = pd.to_datetime(df['date'] + ' ' + df['time'])
df = df.set_index('Datetime')

And to get rid of unwanted columns (as OP did but did not specify per se in the question):

df = df.drop(['date','time'], axis=1)

Convert a list to a dictionary in Python

You can use a dict comprehension for this pretty easily:

a = ['hello','world','1','2']

my_dict = {item : a[index+1] for index, item in enumerate(a) if index % 2 == 0}

This is equivalent to the for loop below:

my_dict = {}
for index, item in enumerate(a):
    if index % 2 == 0:
        my_dict[item] = a[index+1]

Event listener for when element becomes visible?

I had this same problem and created a jQuery plugin to solve it for our site.

Here is how you would use it based on your example:

$('#contentDiv').visibilityChanged(function(element, visible) {
    alert("do something");

Oracle TNS names not showing when adding new connection to SQL Developer

You can always find out the location of the tnsnames.ora file being used by running TNSPING to check connectivity (9i or later):

C:\>tnsping dev

TNS Ping Utility for 32-bit Windows: Version - Production on 08-JAN-2009 12:48:38

Copyright (c) 1997, 2005, Oracle.  All rights reserved.

Used parameter files:

Used TNSNAMES adapter to resolve the alias
OK (30 msec)


Sometimes, the problem is with the entry you made in tnsnames.ora, not that the system can't find it. That said, I agree that having a tns_admin environment variable set is a Good Thing, since it avoids the inevitable issues that arise with determining exactly which tnsnames file is being used in systems with multiple oracle homes.

Mockito - difference between doReturn() and when()

The Mockito javadoc seems to tell why use doReturn() instead of when() Use doReturn() in those rare occasions when you cannot use Mockito.when(Object).

Beware that Mockito.when(Object) is always recommended for stubbing because it is argument type-safe and more readable (especially when stubbing consecutive calls).

Here are those rare occasions when doReturn() comes handy:

1. When spying real objects and calling real methods on a spy brings side effects

List list = new LinkedList(); List spy = spy(list);

//Impossible: real method is called so spy.get(0) throws IndexOutOfBoundsException (the list is yet empty)


//You have to use doReturn() for stubbing: doReturn("foo").when(spy).get(0);

2. Overriding a previous exception-stubbing:

when( RuntimeException());

//Impossible: the exception-stubbed foo() method is called so RuntimeException is thrown. when("bar");

//You have to use doReturn() for stubbing:

doReturn("bar").when(mock).foo(); Above scenarios shows a tradeoff of Mockito's elegant syntax. Note that the scenarios are very rare, though. Spying should be sporadic and overriding exception-stubbing is very rare. Not to mention that in general overridding stubbing is a potential code smell that points out too much stubbing.

Can I extend a class using more than 1 class in PHP?

I just solved my "multiple inheritance" problem with:

class Session {
    public $username;

class MyServiceResponsetype {
    protected $only_avaliable_in_response;

class SessionResponse extends MyServiceResponsetype {
    /** has shared $only_avaliable_in_response */

    public $session;

    public function __construct(Session $session) {
      $this->session = $session;


This way I have the power to manipulate session inside a SessionResponse which extends MyServiceResponsetype still being able to handle Session by itself.

How to reload the datatable(jquery) data?

You can use a simple approach...


It will refresh the data by making an ajax request with the same parameters. Very simple.

What is phtml, and when should I use a .phtml extension rather than .php?

.phtml files tell the webserver that those are html files with dynamic content which is generated by the server... just like .php files in a browser behave. So, in productive usage you should experience no difference from .phtml to .php files.

python numpy ValueError: operands could not be broadcast together with shapes

dot is matrix multiplication, but * does something else.

We have two arrays:

  • X, shape (97,2)
  • y, shape (2,1)

With Numpy arrays, the operation

X * y

is done element-wise, but one or both of the values can be expanded in one or more dimensions to make them compatible. This operation is called broadcasting. Dimensions, where size is 1 or which are missing, can be used in broadcasting.

In the example above the dimensions are incompatible, because:

97   2
 2   1

Here there are conflicting numbers in the first dimension (97 and 2). That is what the ValueError above is complaining about. The second dimension would be ok, as number 1 does not conflict with anything.

For more information on broadcasting rules:

(Please note that if X and y are of type numpy.matrix, then asterisk can be used as matrix multiplication. My recommendation is to keep away from numpy.matrix, it tends to complicate more than simplifying things.)

Your arrays should be fine with; if you get an error on, you must have some other bug. If the shapes are wrong for, you get a different exception:

ValueError: matrices are not aligned

If you still get this error, please post a minimal example of the problem. An example multiplication with arrays shaped like yours succeeds:

In [1]: import numpy

In [2]:[97, 2]), numpy.ones([2, 1])).shape
Out[2]: (97, 1)

What is the difference between compileSdkVersion and targetSdkVersion?

The CompileSdkVersion is the version of the SDK platform your app works with for compilation, etc DURING the development process (you should always use the latest) This is shipped with the API version you are using

enter image description here

You will see this in your build.gradle file:

enter image description here

targetSdkVersion: contains the info your app ships with AFTER the development process to the app store that allows it to TARGET the SPECIFIED version of the Android platform. Depending on the functionality of your app, it can target API versions lower than the current.For instance, you can target API 18 even if the current version is 23.

Take a good look at this official Google page.

Nested select statement in SQL Server

The answer provided by Joe Stefanelli is already correct.

SELECT name FROM (SELECT name FROM agentinformation) as a  

We need to make an alias of the subquery because a query needs a table object which we will get from making an alias for the subquery. Conceptually, the subquery results are substituted into the outer query. As we need a table object in the outer query, we need to make an alias of the inner query.

Statements that include a subquery usually take one of these forms:

  • WHERE expression [NOT] IN (subquery)
  • WHERE expression comparison_operator [ANY | ALL] (subquery)
  • WHERE [NOT] EXISTS (subquery)

Check for more subquery rules and subquery types.

More examples of Nested Subqueries.

  1. IN / NOT IN – This operator takes the output of the inner query after the inner query gets executed which can be zero or more values and sends it to the outer query. The outer query then fetches all the matching [IN operator] or non matching [NOT IN operator] rows.

  2. ANY – [>ANY or ANY operator takes the list of values produced by the inner query and fetches all the values which are greater than the minimum value of the list. The

e.g. >ANY(100,200,300), the ANY operator will fetch all the values greater than 100.

  1. ALL – [>ALL or ALL operator takes the list of values produced by the inner query and fetches all the values which are greater than the maximum of the list. The

e.g. >ALL(100,200,300), the ALL operator will fetch all the values greater than 300.

  1. EXISTS – The EXISTS keyword produces a Boolean value [TRUE/FALSE]. This EXISTS checks the existence of the rows returned by the sub query.

How do I prevent a parent's onclick event from firing when a child anchor is clicked?

you can also try this

$("#clickable").click(function(event) {
   var senderElementName =;
   if(senderElementName === 'div')
       // do something here 
      //do something with <a> tag

How can I fix the Microsoft Visual Studio error: "package did not load correctly"?

I had a similar issue (Tizen Project type package did not load correctly) with Visual Studio 2017.

After trying all the answers above, and spending a few hours searching for a solution for the errors inside ActivityLog.XML, nothing worked for me.

Eventually, the solution was a Visual Studio Repair.

I assume that the repair process overrides some configurations that caused the problem.

Repair Visual Studio 2017
Repair Visual Studio 2019

Why do I keep getting 'SVN: Working Copy XXXX locked; try performing 'cleanup'?

I had the same problem using the package.

To fix it, I first made a backup of the code changes in the model package. Then deleted model package and synchronized with the repository. It will show incoming the entire folder/package. Then updated my code.

Finally, paste the old code commit to the SVN Repository. It works fine.

taking input of a string word by word

Put the line in a stringstream and extract word by word back:

#include <iostream>
#include <sstream>
using namespace std;

int main()
    string t;

    istringstream iss(t);
    string word;
    while(iss >> word) {
        /* do stuff with word */

Of course, you can just skip the getline part and read word by word from cin directly.

And here you can read why is using namespace std considered bad practice.

Getting today's date in YYYY-MM-DD in Python?

This works:

from datetime import date

Output in this time: 2020-08-29


this_year =
this_month =
this_day =

How to update a record using sequelize for node?

Using async and await in a modern javascript Es6

const title = "title goes here";
const id = 1;

    const result = await Project.update(
          { title },
          { where: { id } }
    }.catch(err => console.log(err));

you can return result ...

Android : Capturing HTTP Requests with non-rooted android device

There is many ways to do that but one of them is fiddler

Fiddler Configuration

  1. Go to options
  2. In HTTPS tab, enable Capture HTTPS Connects and Decrypt HTTPS traffic
  3. In Connections tab, enable Allow remote computers to connect
  4. Restart fiddler

Android Configuration

  1. Connect to same network
  2. Modify network settings
  3. Add proxy for connection with your PC's IP address ( or hostname ) and default fiddler's port ( 8888 / you can change that in settings )

Now you can see full log from your device in fiddler

Also you can find a full instruction here

What's the easy way to auto create non existing dir in ansible

Right now, this is the only way

- name: Ensures {{project_root}}/conf dir exists
  file: path={{project_root}}/conf state=directory
- name: Copy file
    src: code.conf.j2
    dest: "{{project_root}}/conf/code.conf"

Print number of keys in Redis

Go to redis-cli and use below command

info keyspace

It may help someone

What does the 'export' command do?

In simple terms, environment variables are set when you open a new shell session. At any time if you change any of the variable values, the shell has no way of picking that change. that means the changes you made become effective in new shell sessions. The export command, on the other hand, provides the ability to update the current shell session about the change you made to the exported variable. You don't have to wait until new shell session to use the value of the variable you changed.

Run .php file in Windows Command Prompt (cmd)

It seems your question is very much older. But I just saw it. I searched(not in google) and found My Answer.

So I am writing its solution so that others may get help from it.

Here is my solution.

Unlike the other answers, you don't need to setup environments.

all you need is just to write php index.php if index.php is your file name.

then you will see that, the file compiled and showing it's desired output.

How do you express binary literals in Python?

As far as I can tell Python, up through 2.5, only supports hexadecimal & octal literals. I did find some discussions about adding binary to future versions but nothing definite.

Changing the Status Bar Color for specific ViewControllers using Swift in iOS8

What worked with me, in the Storyboard, go to the Navigation Controller, select the navigation bar, click on the Attributes Inspector, then change the style from default to black. That's it!

No provider for TemplateRef! (NgIf ->TemplateRef)

You missed the * in front of NgIf (like we all have, dozens of times):

<div *ngIf="answer.accepted">&#10004;</div>

Without the *, Angular sees that the ngIf directive is being applied to the div element, but since there is no * or <template> tag, it is unable to locate a template, hence the error.

If you get this error with Angular v5:

Error: StaticInjectorError[TemplateRef]:
    NullInjectorError: No provider for TemplateRef!

You may have <template>...</template> in one or more of your component templates. Change/update the tag to <ng-template>...</ng-template>.

JavaScript Number Split into individual digits

I used this simple way of doing it.

To split digits

var N = 69;
var arr = N.toString().split('').map(Number)
// outputs [6,9]
console.log( arr ); 

To add them together

console.log(arr.reduce( (a,b) => a+b )); // 15

How to detect simple geometric shapes using OpenCV

The answer depends on the presence of other shapes, level of noise if any and invariance you want to provide for (e.g. rotation, scaling, etc). These requirements will define not only the algorithm but also required pre-procesing stages to extract features.

Template matching that was suggested above works well when shapes aren't rotated or scaled and when there are no similar shapes around; in other words, it finds a best translation in the image where template is located:

double minVal, maxVal;
Point minLoc, maxLoc;
Mat image, template, result; // template is your shape
matchTemplate(image, template, result, CV_TM_CCOEFF_NORMED);
minMaxLoc(result, &minVal, &maxVal, &minLoc, &maxLoc); // maxLoc is answer

Geometric hashing is a good method to get invariance in terms of rotation and scaling; this method would require extraction of some contour points.

Generalized Hough transform can take care of invariance, noise and would have minimal pre-processing but it is a bit harder to implement than other methods. OpenCV has such transforms for lines and circles.

In the case when number of shapes is limited calculating moments or counting convex hull vertices may be the easiest solution: openCV structural analysis

How to get the clicked link's href with jquery?

$(".testClick").click(function () {
         var value = $(this).attr("href");
         alert(value );     

When you use $(".className") you are getting the set of all elements that have that class. Then when you call attr it simply returns the value of the first item in the collection.

Add x and y labels to a pandas plot

The df.plot() function returns a matplotlib.axes.AxesSubplot object. You can set the labels on that object.

ax = df2.plot(lw=2, colormap='jet', marker='.', markersize=10, title='Video streaming dropout by category')
ax.set_xlabel("x label")
ax.set_ylabel("y label")

enter image description here

Or, more succinctly: ax.set(xlabel="x label", ylabel="y label").

Alternatively, the index x-axis label is automatically set to the Index name, if it has one. so = 'x label' would work too.

Named regular expression group "(?P<group_name>regexp)": what does "P" stand for?

Since we're all guessing, I might as well give mine: I've always thought it stood for Python. That may sound pretty stupid -- what, P for Python?! -- but in my defense, I vaguely remembered this thread [emphasis mine]:

Subject: Claiming (?P...) regex syntax extensions

From: Guido van Rossum ([email protected])

Date: Dec 10, 1997 3:36:19 pm

I have an unusual request for the Perl developers (those that develop the Perl language). I hope this (perl5-porters) is the right list. I am cc'ing the Python string-sig because it is the origin of most of the work I'm discussing here.

You are probably aware of Python. I am Python's creator; I am planning to release a next "major" version, Python 1.5, by the end of this year. I hope that Python and Perl can co-exist in years to come; cross-pollination can be good for both languages. (I believe Larry had a good look at Python when he added objects to Perl 5; O'Reilly publishes books about both languages.)

As you may know, Python 1.5 adds a new regular expression module that more closely matches Perl's syntax. We've tried to be as close to the Perl syntax as possible within Python's syntax. However, the regex syntax has some Python-specific extensions, which all begin with (?P . Currently there are two of them:

(?P<foo>...) Similar to regular grouping parentheses, but the text
matched by the group is accessible after the match has been performed, via the symbolic group name "foo".

(?P=foo) Matches the same string as that matched by the group named "foo". Equivalent to \1, \2, etc. except that the group is referred
to by name, not number.

I hope that this Python-specific extension won't conflict with any future Perl extensions to the Perl regex syntax. If you have plans to use (?P, please let us know as soon as possible so we can resolve the conflict. Otherwise, it would be nice if the (?P syntax could be permanently reserved for Python-specific syntax extensions. (Is there some kind of registry of extensions?)

to which Larry Wall replied:

[...] There's no registry as of now--yours is the first request from outside perl5-porters, so it's a pretty low-bandwidth activity. (Sorry it was even lower last week--I was off in New York at Internet World.)

Anyway, as far as I'm concerned, you may certainly have 'P' with my blessing. (Obviously Perl doesn't need the 'P' at this point. :-) [...]

So I don't know what the original choice of P was motivated by -- pattern? placeholder? penguins? -- but you can understand why I've always associated it with Python. Which considering that (1) I don't like regular expressions and avoid them wherever possible, and (2) this thread happened fifteen years ago, is kind of odd.

How to get the data-id attribute?

var id = $(this)

works for me!

General error: 1364 Field 'user_id' doesn't have a default value

So, after After reviewing the code again, I found the error. I am wondering how no one notice that! In the above code I wrote

Post::create(request([  // <= the error is Here!!!
    'body' => request('body'),
    'title' => request('title'),
    'user_id' => auth()->id()

actually, there is no need for the request function warping the body of the create function.

// this is right
    'body' => request('body'),
    'title' => request('title'),
    'user_id' => auth()->id()

Execution time of C program

CLOCKS_PER_SEC is a constant which is declared in <time.h>. To get the CPU time used by a task within a C application, use:

clock_t begin = clock();

/* here, do your time-consuming job */

clock_t end = clock();
double time_spent = (double)(end - begin) / CLOCKS_PER_SEC;

Note that this returns the time as a floating point type. This can be more precise than a second (e.g. you measure 4.52 seconds). Precision depends on the architecture; on modern systems you easily get 10ms or lower, but on older Windows machines (from the Win98 era) it was closer to 60ms.

clock() is standard C; it works "everywhere". There are system-specific functions, such as getrusage() on Unix-like systems.

Java's System.currentTimeMillis() does not measure the same thing. It is a "wall clock": it can help you measure how much time it took for the program to execute, but it does not tell you how much CPU time was used. On a multitasking systems (i.e. all of them), these can be widely different.

PHP Session timeout

    session_cache_expire( 20 );
    session_start(); // NEVER FORGET TO START THE SESSION!!!
    $inactive = 1200; //20 minutes *60
    if(isset($_SESSION['start']) ) {
$session_life = time() - $_SESSION['start'];
if($session_life > $inactive){
    header("Location: user_logout.php");
    $_SESSION['start'] = time();

    if($_SESSION['valid_user'] != true){
    header('Location: ../....php');


Getting full-size profile picture

found a way:

$albums = $facebook->api('/' . $user_id . '/albums');
foreach($albums['data'] as $album){
    if ($album['name'] == "Profile Pictures"){
        $photos = $facebook->api('/' . $album['id'] . '/photos');
        $profile_pic = $photos['data'][0]['source'];

Java: how to import a jar file from command line


java -cp "your_jar.jar:lib/referenced_jar.jar" com.your.main.Main

If you are on windows, you should use ; instead of :

Adding text to a cell in Excel using VBA

Range("$A$1").Value = "'01/01/13 00:00" will do it.

Note the single quote; this will defeat automatic conversion to a number type. But is that what you really want? An alternative would be to format the cell to take a date-time value. Then drop the single quote from the string.

There are no primary or candidate keys in the referenced table that match the referencing column list in the foreign key

Another thing is - if your keys are very complicated sometimes you need to replace the places of the fields and it helps :

if this dosent work:

foreign key (ISBN, Title) references BookTitle (ISBN, Title)

Then this might work (not for this specific example but in general) :

foreign key (Title,ISBN) references BookTitle (Title,ISBN)

how to open an URL in Swift3

If you want to open inside the app itself instead of leaving the app you can import SafariServices and work it out.

import UIKit
import SafariServices

let url = URL(string: "")
let vc = SFSafariViewController(url: url!)
present(vc, animated: true, completion: nil)


I don't know why

cfg_name_unique NOT LIKE '%categories%' 

still returns those two values, but maybe exclude them explicit:

    FROM developer_configurations_cms

    WHERE developer_configurations_cms.cat_id = '1'
    AND developer_configurations_cms.cfg_variables LIKE '%parent_id=2%'
    AND developer_configurations_cms.cfg_name_unique NOT LIKE '%categories%'
    AND developer_configurations_cms.cfg_name_unique NOT IN ('categories_posts', 'categories_news')

What is Bootstrap?

Bootstrap is an open-source CSS, JavaScript framework that was originally developed for twitter application by twitter's team of designers and developers. Then they released it for open-source. Being a longtime user of twitter bootstrap I find that its one of the best for designing mobile ready responsive websites. Many CSS and Javascript plugins are available for designing your website in no time. It's kind of rapid template design framework. Some people complain that the bootstrap CSS files are heavy and take time to load but these claims are made by lazy people. You don't have to keep the complete bootstrap.css in your website. You always have the option to remove the styles for components that you do not need for your website. For example, if you are only using basic components like forms and buttons then you can remove other components like accordions etc from the main CSS file. To start dabbling in bootstrap you can download the basic templates and components from getbootstrap site and let the magic happen.

How to split string using delimiter char using T-SQL?

You need a split function:

Create Function [dbo].[udf_Split]
    @DelimitedList nvarchar(max)
    , @Delimiter nvarchar(2) = ','
    With CorrectedList As
        Select Case When Left(@DelimitedList, Len(@Delimiter)) <> @Delimiter Then @Delimiter Else '' End
            + @DelimitedList
            + Case When Right(@DelimitedList, Len(@Delimiter)) <> @Delimiter Then @Delimiter Else '' End
            As List
            , Len(@Delimiter) As DelimiterLen
        , Numbers As 
        Select TOP( Coalesce(DataLength(@DelimitedList)/2,0) ) Row_Number() Over ( Order By c1.object_id ) As Value
        From sys.columns As c1
            Cross Join sys.columns As c2
    Select CharIndex(@Delimiter, CL.list, N.Value) + CL.DelimiterLen As Position
        , Substring (
                    , CharIndex(@Delimiter, CL.list, N.Value) + CL.DelimiterLen     
                    , CharIndex(@Delimiter, CL.list, N.Value + 1)                           
                        - ( CharIndex(@Delimiter, CL.list, N.Value) + CL.DelimiterLen ) 
                    ) As Value
    From CorrectedList As CL
        Cross Join Numbers As N
    Where N.Value <= DataLength(CL.List) / 2
        And Substring(CL.List, N.Value, CL.DelimiterLen) = @Delimiter

With your split function, you would then use Cross Apply to get the data:

Select T.Col1, T.Col2
    , Substring( Z.Value, 1, Charindex(' = ', Z.Value) - 1 ) As AttributeName
    , Substring( Z.Value, Charindex(' = ', Z.Value) + 1, Len(Z.Value) ) As Value
From Table01 As T
    Cross Apply dbo.udf_Split( T.Col3, '|' ) As Z

Is it possible to override / remove background: none!important with jQuery?

Yes it is possible depending on what css you have, you simply just declare the same thing with a different background like this

ul li {
    background: none !important;

ul li{
    background: blue !important;

But you have to make sure the declaration comes after the first one seeing as it is cascading.


You can also create a style tag in jQuery like this

$('head').append('<style> #an-element li { background: inherit !important;} </style>');


You cannot see any changes because it's not inheriting any background but it is overwriting the background: none;

How to remove unused imports from Eclipse

You can direct use the shortcut by pressing Ctrl+Shift+O

How can I catch all the exceptions that will be thrown through reading and writing a file?

If you want, you can add throws clauses to your methods. Then you don't have to catch checked methods right away. That way, you can catch the exceptions later (perhaps at the same time as other exceptions).

The code looks like:

public void someMethode() throws SomeCheckedException {

    //  code


Then later you can deal with the exceptions if you don't wanna deal with them in that method.

To catch all exceptions some block of code may throw you can do: (This will also catch Exceptions you wrote yourself)

try {

    // exceptional block of code ...

    // ...

} catch (Exception e){

    // Deal with e as you please.
    //e may be any type of exception at all.


The reason that works is because Exception is the base class for all exceptions. Thus any exception that may get thrown is an Exception (Uppercase 'E').

If you want to handle your own exceptions first simply add a catch block before the generic Exception one.

}catch(MyOwnException me){
}catch(Exception e){

Why can't Python find shared objects that are in directories in sys.path?

Ensure your module is in the system library path, which is distinct and separate from the python library path.

A "quick fix" is to add this path to a LD_LIBRARY_PATH variable. However, setting that system wide (or even account wide) is a BAD IDEA, as it is possible to set it in such a way that some programs will find a library it shouldn't, or even worse, open up security holes.

If your "locally installed libraries" are installed in, for example, /usr/local/lib, add this directory to /etc/ (it's a text file) and run "ldconfig"

The command will run a caching utility, but will also create all the necessary "symbolic links" required for the loader system to function. It is surprising that the "make install" for libcurl did not do this already, but it's possible it could not if /usr/local/lib is not in /etc/ already.

PS: it's possible that your /etc/ contains nothing but "include*.conf". You can still add a directory path after it, or just create a new file inside the directory it's being included from. Dont forget to run "ldconfig" after it.

Be careful. Getting this wrong can screw up your system.

Additionally: make sure your python module is compiled against THAT version of libcurl. If you just copied some files over from another system, this wont always work. If in doubt, compile your modules on the system you intend to run them on.

Add a new item to recyclerview programmatically?

First add your item to mItems and then use:

mAdapter.notifyItemInserted(mItems.size() - 1);

this method is better than using:


in performance.

Android webview slow

I tried all the proposals to fix the render performance problem in my phonegap app. But nothing realy worked.

Finally, after a whole day of searching, I made it. I set within the tag (not the tag) of my AndroidManifest

<application android:hardwareAccelerated="false" ...

Now the app behaves in the same fast way as my webbrowser. Seems like, if hardware acceleration is not always the best feature...

The detailed problem I had:

Correct way to load a Nib for a UIView subclass

Answering my own question about 2 or something years later here but...

It uses a protocol extension so you can do it without any extra code for all classes.


- In IB set the view's class to the type hook up any IBOutlets
- In IB ensure the file's owner is blank


public protocol CreatedFromNib {
    static func createFromNib() -> Self?
    static func nibName() -> String?

extension UIView: CreatedFromNib { }

public extension CreatedFromNib where Self: UIView {

    public static func createFromNib() -> Self? {
        guard let nibName = nibName() else { return nil }
        guard let view = NSBundle.mainBundle().loadNibNamed(nibName, owner: nil, options: nil).last as? Self else { return nil }
        return view

    public static func nibName() -> String? {
        guard let n = NSStringFromClass(Self.self).componentsSeparatedByString(".").last else { return nil }
        return n

// Usage:
let myView = MyView().createFromNib()

Angular2: custom pipe could not be found

see this is working for me.

ActStatus.pipe.ts First this is my pipe

import {Pipe,PipeTransform} from "@angular/core";

export class ActStatusPipe implements PipeTransform{
    switch (status) {
      case 1:
        return "UN_PUBLISH";
      case 2:
        return "PUBLISH";
        return status

main-pipe.module.ts in pipe module, i need to declare my pipe/s and export it.

import { NgModule } from '@angular/core';
import {CommonModule} from "@angular/common";

import {ActStatusPipe} from "./ActStatusPipe.pipe"; // <---

  declarations:[ActStatusPipe], // <---
  exports:[ActStatusPipe] // <---

export class MainPipe{}

app.module.ts user this pipe module in any module.

  declarations: [...],
  imports: [..., MainPipe], // <---
  providers: [...],
  bootstrap: [AppComponent]

you can directly user pipe in this module. but if you feel that your pipe is used with in more than one component i suggest you to follow my approach.

  1. create pipe .
  2. create separate module and declare and export one or more pipe.
  3. user that pipe module.

How to use pipe totally depends on your project complexity and requirement. you might have just one pipe which used only once in the whole project. in that case you can directly use it without creating a pipe/s module (module approach).

How to remove default chrome style for select Input?

In your CSS add this:

input {-webkit-appearance: none; box-shadow: none !important; }
:-webkit-autofill { color: #fff !important; }

Only for Chrome! :)

How to select top n rows from a datatable/dataview in ASP.NET


How to delete node from XML file using C#

You can use Linq to XML to do this:

XDocument doc = XDocument.Load("input.xml");
var q = from node in doc.Descendants("Setting")
        let attr = node.Attribute("name")
        where attr != null && attr.Value == "File1"
        select node;
q.ToList().ForEach(x => x.Remove());

No @XmlRootElement generated by JAXB

@XmlRootElement is not needed for unmarshalling - if one uses the 2 parameter form of Unmarshaller#unmarshall.

So, if instead of doing:

UserType user = (UserType) unmarshaller.unmarshal(new StringReader(responseString));

one should do:

JAXBElement<UserType> userElement = unmarshaller.unmarshal(someSource, UserType.class);
UserType user = userElement.getValue();

The latter code will not require @XmlRootElement annotation at UserType class level.

Reading in from - Java

Well, you may read itself as it is a valid InputStream. Or also you can wrap it in a BufferedReader:

BufferedReader br = new BufferedReader(new InputStreamReader(;

td widths, not working?

You can try the "table-layout: fixed;" to your table

table-layout: fixed;
width: 150px;

150px or your desired width.


IndentationError: unexpected indent error

The error is pretty straightforward - the line starting with check_exists_sql isn't indented properly. From the context of your code, I'd indent it and the following lines to match the line before it:

   #open db connection
   db = MySQLdb.connect("localhost","root","str0ng","TESTDB")

   #prepare a cursor object using cursor() method
   cursor = db.cursor()

   #see if any links in the DB match the crawled link
   check_exists_sql = "SELECT * FROM LINKS WHERE link = '%s' LIMIT 1" % item['link']


And keep indenting it until the for loop ends (all the way through to and including items.append(item).

javascript: pause setTimeout();

I don't think you'll find anything better than clearTimeout. Anyway, you can always schedule another timeout later, instead 'resuming' it.

How to change text and background color?

There is no (standard) cross-platform way to do this. On windows, try using conio.h. It has the:

textcolor(); // and


For example:

// and so on.

How to repeat a string a variable number of times in C++?


You can use C++ function for doing this.

 std::string repeat(const std::string& input, size_t num)
    std::ostringstream os;
    std::fill_n(std::ostream_iterator<std::string>(os), num, input);
    return os.str();

jQuery Validation plugin: validate check box

You had several issues with your code.

1) Missing a closing brace, }, within your rules.

2) In this case, there is no reason to use a function for the required rule. By default, the plugin can handle checkbox and radio inputs just fine, so using true is enough. However, this will simply do the same logic as in your original function and verify that at least one is checked.

3) If you also want only a maximum of two to be checked, then you'll need to apply the maxlength rule.

4) The messages option was missing the rule specification. It will work, but the one custom message would apply to all rules on the same field.

5) If a name attribute contains brackets, you must enclose it within quotes.


$(document).ready(function () {

    $('#formid').validate({ // initialize the plugin
        rules: {
            'test[]': {
                required: true,
                maxlength: 2
        messages: {
            'test[]': {
                required: "You must check at least 1 box",
                maxlength: "Check no more than {0} boxes"


Random date in C#

private Random gen = new Random();
DateTime RandomDay()
    DateTime start = new DateTime(1995, 1, 1);
    int range = (DateTime.Today - start).Days;           
    return start.AddDays(gen.Next(range));

For better performance if this will be called repeatedly, create the start and gen (and maybe even range) variables outside of the function.

"SDK Platform Tools component is missing!"

Before update SDK components, check in Android SDK Manager ? Tools ? Options and set HTTP proxy and port if it is set in local LAN.

How to disable a ts rule for a specific line?


TS 3.9 introduces a new magic comment. @ts-expect-error will:

  • have same functionality as @ts-ignore
  • trigger an error, if actually no compiler error has been suppressed (= indicates useless flag)
if (false) {
  // @ts-expect-error: Let's ignore a single compiler error like this unreachable code 
  console.log("hello"); // compiles

// If @ts-expect-error didn't suppress anything at all, we now get a nice warning 
let flag = true;
// ...
if (flag) {
  // @ts-expect-error
  // ^~~~~~~~~~~~~~~^ error: "Unused '@ts-expect-error' directive.(2578)"


@ts-ignore and @ts-expect-error can be used for all sorts of compiler errors. For type issues (like in OP), I recommend one of the following alternatives due to narrower error suppression scope:

? Use any type

// type assertion for single expression
delete ($ as any).summernote.options.keyMap.pc.TAB;

// new variable assignment for multiple usages
const $$: any = $
delete $$.summernote.options.keyMap.pc.TAB;
delete $$.summernote.options.keyMap.mac.TAB;

? Augment JQueryStatic interface

// ./global.d.ts
interface JQueryStatic {
  summernote: any;

// ./main.ts
delete $.summernote.options.keyMap.pc.TAB; // works

In other cases, shorthand module declarations or module augmentations for modules with no/extendable types are handy utilities. A viable strategy is also to keep not migrated code in .js and use --allowJs with checkJs: false.

Excel VBA Run-time Error '32809' - Trying to Understand it

Ok, this might be weird. Anyway one of my colleagues had this error and we tried the edit VBA compile whatever. But the thing is, just copy the excel file to the desktop. And it worked. The Excel file was originally in a network drive. This worked, this is my answer to this issue.

Put icon inside input element in a form

This works for me for more or less standard forms:

  <button type="submit" value="Submit" name="ButtonType" id="whateveristheId" class="button-class">Submit<img src="/img/selectedImage.png" alt=""></button>

How to identify if a webpage is being loaded inside an iframe or directly into the browser window?

This ended being the simplest solution for me.

    <p id="demofsdfsdfs"></p>


if(window.self !== {

//run this code if in an iframe
document.getElementById("demofsdfsdfs").innerHTML = "in frame";


//run code if not in an iframe
document.getElementById("demofsdfsdfs").innerHTML = "no frame";


What port is a given program using?

most decent firewall programs should allow you to access this information. I know that Agnitum OutpostPro Firewall does.

Getting output of system() calls in Ruby

I didn't find this one here so adding it, I had some issues getting the full output.

You can redirect STDERR to STDOUT if you want to capture STDERR using backtick.

output = `grep hosts /private/etc/* 2>&1`


file_get_contents("php://input") or $HTTP_RAW_POST_DATA, which one is better to get the body of JSON request?

For JSON data, it's much easier to POST it as "application/json" content-type. If you use GET, you have to URL-encode the JSON in a parameter and it's kind of messy. Also, there is no size limit when you do POST. GET's size if very limited (4K at most).

Calculate the date yesterday in JavaScript

To generalize the question and make other diff calculations use:

var yesterday = new Date((new Date()).valueOf() - 1000*60*60*24);

this creates a new date object based on the value of "now" as an integer which represents the unix epoch in milliseconds subtracting one day.

Two days ago:

var twoDaysAgo = new Date((new Date()).valueOf() - 1000*60*60*24*2);

An hour ago:

var oneHourAgo = new Date((new Date()).valueOf() - 1000*60*60);

Regular expressions inside SQL Server

You can write queries like this in SQL Server:

--each [0-9] matches a single digit, this would match 5xx
SELECT * FROM YourTable WHERE SomeField LIKE '5[0-9][0-9]'

datetime dtypes in pandas read_csv

I tried using the dtypes=[datetime, ...] option, but

import pandas as pd
from datetime import datetime
headers = ['col1', 'col2', 'col3', 'col4'] 
dtypes = [datetime, datetime, str, float] 
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

I encountered the following error:

TypeError: data type not understood

The only change I had to make is to replace datetime with datetime.datetime

import pandas as pd
from datetime import datetime
headers = ['col1', 'col2', 'col3', 'col4'] 
dtypes = [datetime.datetime, datetime.datetime, str, float] 
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

RabbitMQ / AMQP: single queue, multiple consumers for same message?

The send pattern is a one-to-one relationship. If you want to "send" to more than one receiver you should be using the pub/sub pattern. See for more details.

Get the date of next monday, tuesday, etc

PHP 7.1:

$next_date = new DateTime('next Thursday');
$stamp = $next_date->getTimestamp();

PHP manual getTimestamp()

Node.js: Difference between req.query[] and req.params

Given this route

app.get('/hi/:param1', function(req,res){} );

and given this URL

You will have:


  qs1: 'you',
  qs2: 'tube'


  param1: 'there'

Express req.params >>

How to custom switch button?

you can use the following code to change color and text :


Create a xml named colors.xml in res/values folder:

<?xml version="1.0" encoding="utf-8"?>
    <color name="red">#ff0000</color>
    <color name="green">#00ff00</color>

In drawable folder, create a xml file my_btn_toggle.xml:

  <selector xmlns:android="">
        <item android:state_checked="false" android:drawable="@color/red"  />
        <item android:state_checked="true" android:drawable="@color/green"  />

and in xml section defining your toggle button add:


to change the color of textOn and textOffuse


file path Windows format to java format

String path = "C:\\Documents and Settings\\Manoj\\Desktop";
path = path.replace("\\", "/");
// or
path = path.replaceAll("\\\\", "/");

Find more details in the Docs

CSS Select box arrow style

Try to replace the

padding: 2px 30px 2px 2px;


padding: 2px 2px 2px 2px;

It should work.

How to list active / open connections in Oracle?

When I'd like to view incoming connections from our application servers to the database I use the following command:

SELECT username FROM v$session 
ORDER BY username ASC;

Simple, but effective.

How can I use inverse or negative wildcards when pattern matching in a unix/linux shell?

this would do it excluding exactly 'Music'

cp -a ^'Music' /target

this and that for excluding things like Music?* or *?Music

cp -a ^\*?'complete' /target
cp -a ^'complete'?\* /target

CSS for grabbing cursors (drag & drop)

You can create your own cursors and set them as the cursor using cursor: url('path-to-your-cursor');, or find Firefox's and copy them (bonus: a nice consistent look in every browser).

What is special about /dev/tty?

The 'c' means it's a character device. tty is a special file representing the 'controlling terminal' for the current process.

Character Devices

Unix supports 'device files', which aren't really files at all, but file-like access points to hardware devices. A 'character' device is one which is interfaced byte-by-byte (as opposed to buffered IO).


/dev/tty is a special file, representing the terminal for the current process. So, when you echo 1 > /dev/tty, your message ('1') will appear on your screen. Likewise, when you cat /dev/tty, your subsequent input gets duplicated (until you press Ctrl-C).

/dev/tty doesn't 'contain' anything as such, but you can read from it and write to it (for what it's worth). I can't think of a good use for it, but there are similar files which are very useful for simple IO operations (e.g. /dev/ttyS0 is normally your serial port)

This quote is from :

/dev/tty stands for the controlling terminal (if any) for the current process. To find out which tty's are attached to which processes use the "ps -a" command at the shell prompt (command line). Look at the "tty" column. For the shell process you're in, /dev/tty is the terminal you are now using. Type "tty" at the shell prompt to see what it is (see manual pg. tty(1)). /dev/tty is something like a link to the actually terminal device name with some additional features for C-programmers: see the manual page tty(4).

Here is the man page:

What is the difference between a mutable and immutable string in C#?


Short Answer : String is immutable – whereas StringBuilder is mutable.

What does that mean ? Wiki says : In object-oriented, an immutable object is an object whose state cannot be modified after it is created. This is in contrast to a mutable object, which can be modified after it is created.

From the StringBuilder Class documentation:

The String object is immutable. Every time you use one of the methods in the System.String class, you create a new string object in memory, which requires a new allocation of space for that new object.

In situations where you need to perform repeated modifications to a string, the overhead associated with creating a new String object can be costly.

The System.Text.StringBuilder class can be used when you want to modify a string without creating a new object. For example, using the StringBuilder class can boost performance when concatenating many strings together in a loop.

Apache server keeps crashing, "caught SIGTERM, shutting down"

Try to upgrade and install new packages

sudo apt-get update && sudo apt-get upgrade -y

How to make a div center align in HTML

<!DOCTYPE html>_x000D_
    <div style="text-align: center;">_x000D_
      <div style="width: 500px; margin: 0 auto; background: #000; color: #fff;">This DIV is centered</div>_x000D_

Tested and worked in IE, Firefox, Chrome, Safari and Opera. I did not test IE6. The outer text-align is needed for IE. Other browsers (and IE9?) will work when you give the DIV margin (left and right) value of auto. Margin "0 auto" is a shorthand for margin "0 auto 0 auto" (top right bottom left).

Note: the text is also centered inside the inner DIV, if you want it to remain on the left side just specify text-align: left; for the inner DIV.

Edit: IE 6, 7, 8 and 9 running on the Standards Mode will work with margins set to auto.

Storing image in database directly or as base64 data?

I contend that images (files) are NOT usually stored in a database base64 encoded. Instead, they are stored in their raw binary form in a binary (blob) column (or file).

Base64 is only used as a transport mechanism, not for storage. For example, you can embed a base64 encoded image into an XML document or an email message.

Base64 is also stream friendly. You can encode and decode on the fly (without knowing the total size of the data).

While base64 is fine for transport, do not store your images base64 encoded.

Base64 provides no checksum or anything of any value for storage.

Base64 encoding increases the storage requirement by 33% over a raw binary format. It also increases the amount of data that must be read from persistent storage, which is still generally the largest bottleneck in computing. It's generally faster to read less bytes and encode them on the fly. Only if your system is CPU bound instead of IO bound, and you're regularly outputting the image in base64, then consider storing in base64.

Inline images (base64 encoded images embedded in HTML) are a bottleneck themselves--you're sending 33% more data over the wire, and doing it serially (the web browser has to wait on the inline images before it can finish downloading the page HTML).

If you still wish to store images base64 encoded, please, whatever you do, make sure you don't store base64 encoded data in a UTF8 column then index it.

How can I replace every occurrence of a String in a file with PowerShell?

Credit to @rominator007

I wrapped it into a function (because you may want to use it again)

function Replace-AllStringsInFile($SearchString,$ReplaceString,$FullPathToFile)
    $content = [System.IO.File]::ReadAllText("$FullPathToFile").Replace("$SearchString","$ReplaceString")
    [System.IO.File]::WriteAllText("$FullPathToFile", $content)

NOTE: This is NOT case sensitive!!!!!

See this post: String.Replace ignoring case

Getting strings recognized as variable names in R

Subsetting the data and combining them back is unnecessary. So are loops since those operations are vectorized. From your previous edit, I'm guessing you are doing all of this to make bubble plots. If that is correct, perhaps the example below will help you. If this is way off, I can just delete the answer.

# let's look at the included dataset named trees.
# ?trees for a description
ggplot(trees,aes(Height,Volume)) + geom_point(aes(size=Girth))
# Great, now how do we color the bubbles by groups?
# For this example, I'll divide Volume into three groups: lo, med, high
trees$set[trees$Volume>22.7 & trees$Volume<=45.4]="med"

ggplot(trees,aes(Height,Volume,colour=set)) + geom_point(aes(size=Girth))

# Instead of just circles scaled by Girth, let's also change the symbol
ggplot(trees,aes(Height,Volume,colour=set)) + geom_point(aes(size=Girth,pch=set))

# Now let's choose a specific symbol for each set. Full list of symbols at ?pch
trees$symbol[trees$Volume>22.7 & trees$Volume<=45.4]=2

ggplot(trees,aes(Height,Volume,colour=set)) + geom_point(aes(size=Girth,pch=symbol))

How do I check if there are duplicates in a flat list?

I thought it would be useful to compare the timings of the different solutions presented here. For this I used my own library simple_benchmark:

enter image description here

So indeed for this case the solution from Denis Otkidach is fastest.

Some of the approaches also exhibit a much steeper curve, these are the approaches that scale quadratic with the number of elements (Alex Martellis first solution, wjandrea and both of Xavier Decorets solutions). Also important to mention is that the pandas solution from Keiku has a very big constant factor. But for larger lists it almost catches up with the other solutions.

And in case the duplicate is at the first position. This is useful to see which solutions are short-circuiting:

enter image description here

Here several approaches don't short-circuit: Kaiku, Frank, Xavier_Decoret (first solution), Turn, Alex Martelli (first solution) and the approach presented by Denis Otkidach (which was fastest in the no-duplicate case).

I included a function from my own library here: iteration_utilities.all_distinct which can compete with the fastest solution in the no-duplicates case and performs in constant-time for the duplicate-at-begin case (although not as fastest).

The code for the benchmark:

from collections import Counter
from functools import reduce

import pandas as pd
from simple_benchmark import BenchmarkBuilder
from iteration_utilities import all_distinct

b = BenchmarkBuilder()

def Keiku(l):
    return pd.Series(l).duplicated().sum() > 0

def Frank(num_list):
    unique = []
    dupes = []
    for i in num_list:
        if i not in unique:
    if len(dupes) != 0:
        return False
        return True

def wjandrea(iterable):
    seen = []
    for x in iterable:
        if x in seen:
            return True
    return False

def user(iterable):
    clean_elements_set = set()
    clean_elements_set_add = clean_elements_set.add

    for possible_duplicate_element in iterable:

        if possible_duplicate_element in clean_elements_set:
            return True

            clean_elements_set_add( possible_duplicate_element )

    return False

def Turn(l):
    return Counter(l).most_common()[0][1] > 1

def getDupes(l):
    seen = set()
    seen_add = seen.add
    for x in l:
        if x in seen or seen_add(x):
            yield x

def F1Rumors(l):
        if next(getDupes(l)): return True    # Found a dupe
    except StopIteration:
    return False

def decompose(a_list):
    return reduce(
        lambda u, o : (u[0].union([o]), u[1].union(u[0].intersection([o]))),
        (set(), set()))

def Xavier_Decoret_1(l):
    return not decompose(l)[1]

def Xavier_Decoret_2(l):
        def func(s, o):
            if o in s:
                raise Exception
            return s.union([o])
        reduce(func, l, set())
        return True
        return False

def pyrospade(xs):
    s = set()
    return any(x in s or s.add(x) for x in xs)

def Alex_Martelli_1(thelist):
    return any(thelist.count(x) > 1 for x in thelist)

def Alex_Martelli_2(thelist):
    seen = set()
    for x in thelist:
        if x in seen: return True
    return False

def Denis_Otkidach(your_list):
    return len(your_list) != len(set(your_list))

def MSeifert04(l):
    return not all_distinct(l)

And for the arguments:

# No duplicate run
@b.add_arguments('list size')
def arguments():
    for exp in range(2, 14):
        size = 2**exp
        yield size, list(range(size))

# Duplicate at beginning run
@b.add_arguments('list size')
def arguments():
    for exp in range(2, 14):
        size = 2**exp
        yield size, [0, *list(range(size)]

# Running and plotting
r =

how to write value into cell with vba code without auto type conversion?

Indeed, just as commented by Tim Williams, the way to make it work is pre-formatting as text. Thus, to do it all via VBA, just do that:

Cells(1, 1).NumberFormat = "@"
Cells(1, 1).Value = "1234,56"

HttpClient - A task was cancelled?

I ran into this issue because my Main() method wasn't waiting for the task to complete before returning, so the Task<HttpResponseMessage> myTask was being cancelled when my console program exited.

The solution was to call myTask.GetAwaiter().GetResult() in Main() (from this answer).

Excel VBA - select multiple columns not in sequential order

Range("A:B,D:E,G:H").Select can help

Edit note: I just saw you have used different column sequence, I have updated my answer

How to pass props to {this.props.children}

You no longer need {this.props.children}. Now you can wrap your child component using render in Route and pass your props as usual:

      <li><Link to="/">Home</Link></li>
      <li><Link to="/posts">Posts</Link></li>
      <li><Link to="/about">About</Link></li>


    <Route path="/" exact component={Home} />
    <Route path="/posts" render={() => (
    )} />
    <Route path="/about" component={About} />

How can I trim leading and trailing white space?

To manipulate the white space, use str_trim() in the stringr package. The package has manual dated Feb 15, 2013 and is in CRAN. The function can also handle string vectors.

install.packages("stringr", dependencies=TRUE)

(Credit goes to commenter: R. Cotton)

Directory.GetFiles: how to get only filename, not full path?

Have a look at using FileInfo.Name Property

something like

string[] files = Directory.GetFiles(dir); 

for (int iFile = 0; iFile < files.Length; iFile++)
    string fn = new FileInfo(files[iFile]).Name;

Also have a look at using DirectoryInfo Class and FileInfo Class

A table name as a variable

Use sp_executesql to execute any SQL, e.g.

DECLARE @tbl    sysname,
        @sql    nvarchar(4000),
        @params nvarchar(4000),
        @count  int

   SELECT object_name(id) FROM syscolumns WHERE name = 'LastUpdated'
   ORDER  BY 1
OPEN tblcur

WHILE 1 = 1
   FETCH tblcur INTO @tbl
   IF @@fetch_status <> 0

   SELECT @sql =
   N' SELECT @cnt = COUNT(*) FROM dbo.' + quotename(@tbl) +
   N' WHERE LastUpdated BETWEEN @fromdate AND ' +
   N'                           coalesce(@todate, ''99991231'')'
   SELECT @params = N'@fromdate datetime, ' +
                    N'@todate   datetime = NULL, ' +
                    N'@cnt      int      OUTPUT'
   EXEC sp_executesql @sql, @params, '20060101', @cnt = @count OUTPUT

   PRINT @tbl + ': ' + convert(varchar(10), @count) + ' modified rows.'


Remove multiple items from a Python list in just one statement

You can use filterfalse function from itertools module


import random
from itertools import filterfalse


data = [random.randrange(5) for _ in range(10)]
clean = [*filterfalse(lambda i: i == 0, data)]
print(f"Remove 0s\n{data=}\n{clean=}\n")

clean = [*filterfalse(lambda i: i in (0, 1), data)]
print(f"Remove 0s and 1s\n{data=}\n{clean=}")


Remove 0s
data=[0, 0, 2, 1, 1, 1, 0, 4, 0, 4]
clean=[2, 1, 1, 1, 4, 4]

Remove 0s and 1s
data=[0, 0, 2, 1, 1, 1, 0, 4, 0, 4]
clean=[2, 4, 4]

Regex not operator

You could capture the (2001) part and replace the rest with nothing.

public static string extractYearString(string input) {
    return input.replaceAll(".*\(([0-9]{4})\).*", "$1");

var subject = "(2001) (asdf) (dasd1123_asd 21.01.2011 zqge)(dzqge) name (20019)";
var result = extractYearString(subject);
System.out.println(result); // <-- "2001"

.*\(([0-9]{4})\).* means

  • .* match anything
  • \( match a ( character
  • ( begin capture
  • [0-9]{4} any single digit four times
  • ) end capture
  • \) match a ) character
  • .* anything (rest of string)

Map isn't showing on Google Maps JavaScript API v3 when nested in a div tag

I solved this problem with:

    <div id="map" style="width: 100%; height: 100%; position: absolute;">
                 <div id="map-canvas"></div>

React Native version mismatch

Just go to your android/app/build.gradle and then add to the dependencies section:

compile ("com.facebook.react:react-native:0.50.3") { force = true } 

/// the react native version can be found in package.json

Random number between 0 and 1 in python

I want a random number between 0 and 1, like 0.3452

random.random() is what you are looking for:

From python docs: random.random() Return the next random floating point number in the range [0.0, 1.0).

And, btw, Why your try didn't work?:

Your try was: random.randrange(0, 1)

From python docs: random.randrange() Return a randomly selected element from range(start, stop, step). This is equivalent to choice(range(start, stop, step)), but doesn’t actually build a range object.

So, what you are doing here, with random.randrange(a,b) is choosing a random element from range(a,b); in your case, from range(0,1), but, guess what!: the only element in range(0,1), is 0, so, the only element you can choose from range(0,1), is 0; that's why you were always getting 0 back.

Algorithm to calculate the number of divisors of a given number

This is something i came up with based on Justin answer. It might require some optimization.



def sieve(n):
    np = n + 1
    s = list(range(np)) 
    s[1] = 0
    sqrtn = int(n**0.5)
    for i in range(2, sqrtn + 1): 
        if s[i]:
            s[i*i: np: i] = [0] * len(range(i*i, np, i))
    return filter(None, s)


for i in range(len(k)):
        if n%k[i]==0:


for i in range(len(a)):
        while n%(a[i]**j)==0: 


for i in range(len(b)):

print('no.of divisors of {} = {}'.format(n,nod))

Access images inside public folder in laravel

I have created an Asset helper of my own.

First I defined the asset types and path in app/config/assets.php:

return array(

    | Assets paths
    | Location of all application assets, relative to the public folder,
    | may be used together with absolute paths or with URLs.

    'images' => '/storage/images',
    'css' => '/assets/css',
    'img' => '/assets/img',
    'js' => '/assets/js'

Then the actual Asset class:

class Asset
    private static function getUrl($type, $file)
        return URL::to(Config::get('assets.' . $type) . '/' . $file);

    public static function css($file)
        return self::getUrl('css', $file);

    public static function img($file)
        return self::getUrl('img', $file);

    public static function js($file)
        return self::getUrl('js', $file);


So in my view I can do this to show an image:

{{ HTML::image(Asset::img('logo.png'), "My logo")) }}

Or like this to implement a Java script:

{{ HTML::script(Asset::js('my_script.js')) }}

If Python is interpreted, what are .pyc files?

There is no such thing as an interpreted language. Whether an interpreter or a compiler is used is purely a trait of the implementation and has absolutely nothing whatsoever to do with the language.

Every language can be implemented by either an interpreter or a compiler. The vast majority of languages have at least one implementation of each type. (For example, there are interpreters for C and C++ and there are compilers for JavaScript, PHP, Perl, Python and Ruby.) Besides, the majority of modern language implementations actually combine both an interpreter and a compiler (or even multiple compilers).

A language is just a set of abstract mathematical rules. An interpreter is one of several concrete implementation strategies for a language. Those two live on completely different abstraction levels. If English were a typed language, the term "interpreted language" would be a type error. The statement "Python is an interpreted language" is not just false (because being false would imply that the statement even makes sense, even if it is wrong), it just plain doesn't make sense, because a language can never be defined as "interpreted."

In particular, if you look at the currently existing Python implementations, these are the implementation strategies they are using:

  • IronPython: compiles to DLR trees which the DLR then compiles to CIL bytecode. What happens to the CIL bytecode depends upon which CLI VES you are running on, but Microsoft .NET, GNU Portable.NET and Novell Mono will eventually compile it to native machine code.
  • Jython: interprets Python sourcecode until it identifies the hot code paths, which it then compiles to JVML bytecode. What happens to the JVML bytecode depends upon which JVM you are running on. Maxine will directly compile it to un-optimized native code until it identifies the hot code paths, which it then recompiles to optimized native code. HotSpot will first interpret the JVML bytecode and then eventually compile the hot code paths to optimized machine code.
  • PyPy: compiles to PyPy bytecode, which then gets interpreted by the PyPy VM until it identifies the hot code paths which it then compiles into native code, JVML bytecode or CIL bytecode depending on which platform you are running on.
  • CPython: compiles to CPython bytecode which it then interprets.
  • Stackless Python: compiles to CPython bytecode which it then interprets.
  • Unladen Swallow: compiles to CPython bytecode which it then interprets until it identifies the hot code paths which it then compiles to LLVM IR which the LLVM compiler then compiles to native machine code.
  • Cython: compiles Python code to portable C code, which is then compiled with a standard C compiler
  • Nuitka: compiles Python code to machine-dependent C++ code, which is then compiled with a standard C compiler

You might notice that every single one of the implementations in that list (plus some others I didn't mention, like tinypy, Shedskin or Psyco) has a compiler. In fact, as far as I know, there is currently no Python implementation which is purely interpreted, there is no such implementation planned and there never has been such an implementation.

Not only does the term "interpreted language" not make sense, even if you interpret it as meaning "language with interpreted implementation", it is clearly not true. Whoever told you that, obviously doesn't know what he is talking about.

In particular, the .pyc files you are seeing are cached bytecode files produced by CPython, Stackless Python or Unladen Swallow.

How to programmatically set the layout_align_parent_right attribute of a Button in Relative Layout?

For adding a RelativeLayout attribute whose value is true or false use 0 for false and RelativeLayout.TRUE for true:

RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) button.getLayoutParams()
params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT, RelativeLayout.TRUE)

It doesn't matter whether or not the attribute was already added, you still use addRule(verb, subject) to enable/disable it. However, post-API 17 you can use removeRule(verb) which is just a shortcut for addRule(verb, 0).

JavaScript object: access variable property by name as string

You don't need a function for it - simply use the bracket notation:

var side = columns['right'];

This is equal to dot notation, var side = columns.right;, except the fact that right could also come from a variable, function return value, etc., when using bracket notation.

If you NEED a function for it, here it is:

function read_prop(obj, prop) {
    return obj[prop];

To answer some of the comments below that aren't directly related to the original question, nested objects can be referenced through multiple brackets. If you have a nested object like so:

var foo = { a: 1, b: 2, c: {x: 999, y:998, z: 997}};

you can access property x of c as follows:

var cx = foo['c']['x']

If a property is undefined, an attempt to reference it will return undefined (not null or false):

foo['c']['q'] === null
// returns false

foo['c']['q'] === false
// returns false

foo['c']['q'] === undefined
// returns true

Multiple submit buttons in an HTML form

You can use Tabindex to solve this issue. Also changing the order of the buttons would be a more efficient way to achieve this.

Change the order of the buttons and add float values to assign them the desired position you want to show in your HTML view.

python pandas: apply a function with arguments to a series


  1. Create a dataframe
  2. Create a function
  3. Use the named arguments of the function in the apply statement.



def add(i1, i2):  
    return i1+i2


The outcome of this example is that each number in the dataframe will be added to the number 9.

0  10
1  11
2  12
3  13


The "add" function has two parameters: i1, i2. The first parameter is going to be the value in data frame and the second is whatever we pass to the "apply" function. In this case, we are passing "9" to the apply function using the keyword argument "i2".

Windows equivalent of OS X Keychain?

The "traditional" Windows equivalent would be the Protected Storage subsystem, used by IE (pre IE 7), Outlook Express, and a few other programs. I believe it's encrypted with your login password, which prevents some offline attacks, but once you're logged in, any program that wants to can read it. (See, for example, NirSoft's Protected Storage PassView.)

Windows also provides the CryptoAPI and Data Protection API that might help. Again, though, I don't think that Windows does anything to prevent processes running under the same account from seeing each other's passwords.

It looks like the book Mechanics of User Identification and Authentication provides more details on all of these.

Eclipse (via its Secure Storage feature) implements something like this, if you're interested in seeing how other software does it.

Modulo operator in Python

Same thing you'd expect from normal modulo .. e.g. 7 % 4 = 3, 7.3 % 4.0 = 3.3

Beware of floating point accuracy issues.

How do you handle a "cannot instantiate abstract class" error in C++?

In my case i declared a function in COM Control .idl file like

[id(1)] HRESULT MyMethod([in]INT param);

but not declared in my interface .h file like this

STDMETHOD(MyMethod)(INT param);

Problem solved by adding above line into my interface .h file

this might help some one .

XAMPP - Apache could not start - Attempting to start Apache service

Had the same issue while updating to PHP7.2

Problem: First I closed skype and then checked whether port 80 is not an issue. How you can check that? See @AlexT comment above.

In my case, port 80 wasn't an issue. So now I had to figure out what was wrong. So I checked Error Logs Control Panel > Even viewer > Windows Logs > Application and found following error against Apache2.4

httpd.exe: Syntax error on line 520 of C:/xampp/apache/conf/httpd.conf: Syntax error on line 18 of C:/xampp/apache/conf/extra/httpd-xampp.conf: Cannot load C:/xampp/php/php7ts.dll into server: The Apache service named is not a valid Win32 application.

Which means I had installed wrong PHP version. Actually I downloaded win64 version while the required version was Win32 for me.

So I downloaded correct version from: Download PHP 7.2.0 extracted it in C:/xampp/php folder, restarted the apache and it worked :)

dropping rows from dataframe based on a "not in" condition

You can use Series.isin:

df = df[~df.datecolumn.isin(a)]

While the error message suggests that all() or any() can be used, they are useful only when you want to reduce the result into a single Boolean value. That is however not what you are trying to do now, which is to test the membership of every values in the Series against the external list, and keep the results intact (i.e., a Boolean Series which will then be used to slice the original DataFrame).

You can read more about this in the Gotchas.

Remove all items from RecyclerView

Help yourself:

public void clearAdapter() {

Could someone explain this for me - for (int i = 0; i < 8; i++)

for (int i = 0; i < 8; i++) {

In simplest terms

int i = 0;
if (i < 8) //code
i = i + 1; //i = 1
if (i < 8) //code
i = i + 1;  //i = 2
if (i < 8) //code
i = i + 1;  //i = 3
if (i < 8) //code
i = i + 1; //i = 4
if (i < 8) //code
i = i + 1; //i = 5
if (i < 8) //code
i = i + 1; //i = 6
if (i < 8) //code
i = i + 1; //i = 7
if (i < 8) //code
i = i + 1; //i = 8
if (i < 8) //code - this if won't pass

Javascript variable access in HTML

It is also possible to use span tag instead of a tag:

   var simpleText = "hello_world";
   var finalSplitText = simpleText.split("_");
   var splitText = finalSplitText[0];

   document.getElementById('someId').InnerHTML = splitText;

  <span id="someId"></span>


It worked well for me

Array Index Out of Bounds Exception (Java)

for ( i = 0; i < total.length; i++ );
                                    ^-- remove the semi-colon here

With this semi-colon, the loop loops until i == total.length, doing nothing, and then what you thought was the body of the loop is executed.

Can I use conditional statements with EJS templates (in JMVC)?

Just making code shorter you can use ES6 features. The same things can be written as

app.get("/recipes", (req, res) => {
    res.render("recipes.ejs", {

And the Templeate can be render as the same!

<%if (recipes.length > 0) { %>
// Do something with more than 1 recipe
<% } %>

JQuery: 'Uncaught TypeError: Illegal invocation' at ajax request - several elements

I was getting this error while posting a FormData object because I was not setting up the ajax call correctly. Setup below fixed my issue.

var myformData = new FormData();        
myformData.append('leadid', $("#leadid").val());
myformData.append('date', $(this).val());
myformData.append('time', $(;

    method: 'post',
    processData: false,
    contentType: false,
    cache: false,
    data: myformData,
    enctype: 'multipart/form-data',
    url: 'include/ajax.php',
    success: function (response) {

Getting "net::ERR_BLOCKED_BY_CLIENT" error on some AJAX calls

As it has been explained here, beside of multiple extensions that perform ad or script blocking you may aware that this may happen by file names as below:

Particularly in the AdBlock Plus the character string "-300x600" is causing the Failed to Load Resource ERR_BLOCKED_BY_CLIENT problem.

As shown in the picture, some of the images were blocked because of the '-300x600' pattern in their name, that particular text pattern matches an expression list pattern in the AdBlock Plus.


Text was truncated or one or more characters had no match in the target code page including the primary key in an unpivot

It usually because in connection manager it may be still of 50 char , hence I have resolved the problem by going to Connection Manager--> Advanced and then change to 100 or may be 1000 if its big enough

How can I change or remove HTML5 form validation default error messages?

you can change them via constraint validation api:

if you want an easy solution, you can rock out civem.js, Custom Input Validation Error Messages JavaScript lib download here: live demo here:

How do I read a large csv file with pandas?

I want to make a more comprehensive answer based off of the most of the potential solutions that are already provided. I also want to point out one more potential aid that may help reading process.

Option 1: dtypes

"dtypes" is a pretty powerful parameter that you can use to reduce the memory pressure of read methods. See this and this answer. Pandas, on default, try to infer dtypes of the data.

Referring to data structures, every data stored, a memory allocation takes place. At a basic level refer to the values below (The table below illustrates values for C programming language):

The maximum value of UNSIGNED CHAR = 255                                    
The minimum value of SHORT INT = -32768                                     
The maximum value of SHORT INT = 32767                                      
The minimum value of INT = -2147483648                                      
The maximum value of INT = 2147483647                                       
The minimum value of CHAR = -128                                            
The maximum value of CHAR = 127                                             
The minimum value of LONG = -9223372036854775808                            
The maximum value of LONG = 9223372036854775807

Refer to this page to see the matching between NumPy and C types.

Let's say you have an array of integers of digits. You can both theoretically and practically assign, say array of 16-bit integer type, but you would then allocate more memory than you actually need to store that array. To prevent this, you can set dtype option on read_csv. You do not want to store the array items as long integer where actually you can fit them with 8-bit integer (np.int8 or np.uint8).

Observe the following dtype map.


You can pass dtype parameter as a parameter on pandas methods as dict on read like {column: type}.

import numpy as np
import pandas as pd

df_dtype = {
        "column_1": int,
        "column_2": str,
        "column_3": np.int16,
        "column_4": np.uint8,
        "column_n": np.float32

df = pd.read_csv('path/to/file', dtype=df_dtype)

Option 2: Read by Chunks

Reading the data in chunks allows you to access a part of the data in-memory, and you can apply preprocessing on your data and preserve the processed data rather than raw data. It'd be much better if you combine this option with the first one, dtypes.

I want to point out the pandas cookbook sections for that process, where you can find it here. Note those two sections there;

Option 3: Dask

Dask is a framework that is defined in Dask's website as:

Dask provides advanced parallelism for analytics, enabling performance at scale for the tools you love

It was born to cover the necessary parts where pandas cannot reach. Dask is a powerful framework that allows you much more data access by processing it in a distributed way.

You can use dask to preprocess your data as a whole, Dask takes care of the chunking part, so unlike pandas you can just define your processing steps and let Dask do the work. Dask does not apply the computations before it is explicitly pushed by compute and/or persist (see the answer here for the difference).

Other Aids (Ideas)

  • ETL flow designed for the data. Keeping only what is needed from the raw data.
    • First, apply ETL to whole data with frameworks like Dask or PySpark, and export the processed data.
    • Then see if the processed data can be fit in the memory as a whole.
  • Consider increasing your RAM.
  • Consider working with that data on a cloud platform.

Easiest way to change font and font size

Use the Font Class to set the control's font and styles.

Try Font Constructor (String, Single)

Label lab  = new Label();
lab.Text ="Font Bold at 24";
lab.Font = new Font("Arial", 20);


lab.Font = new Font(FontFamily.GenericSansSerif,
            12.0F, FontStyle.Bold);

To get installed fonts refer this - .NET System.Drawing.Font - Get Available Sizes and Styles

extract month from date in python

import datetime

a = '2010-01-31'

datee = datetime.datetime.strptime(a, "%Y-%m-%d")

Out[9]: 1

Out[10]: 2010
Out[11]: 31

Javascript string replace with regex to strip off illegal characters

You need to wrap them all in a character class. The current version means replace this sequence of characters with an empty string. When wrapped in square brackets it means replace any of these characters with an empty string.

var cleanString = dirtyString.replace(/[\|&;\$%@"<>\(\)\+,]/g, "");

disable editing default value of text input

How about disabled=disabled:

<input id="price_from" value="price from " disabled="disabled">????????????

Problem is if you don't want user to edit them, why display them in input? You can hide them even if you want to submit a form. And to display information, just use other tag instead.

How do I remove an object from an array with JavaScript?

Well splice works:

var arr = [{id:1,name:'serdar'}];
// []

Do NOT use the delete operator on Arrays. delete will not remove an entry from an Array, it will simply replace it with undefined.

var arr = [0,1,2];
delete arr[1];
// [0, undefined, 2]

But maybe you want something like this?

var removeByAttr = function(arr, attr, value){
    var i = arr.length;
       if( arr[i] 
           && arr[i].hasOwnProperty(attr) 
           && (arguments.length > 2 && arr[i][attr] === value ) ){ 


    return arr;

Just an example below.

var arr = [{id:1,name:'serdar'}, {id:2,name:'alfalfa'},{id:3,name:'joe'}];
removeByAttr(arr, 'id', 1);   
// [{id:2,name:'alfalfa'}, {id:3,name:'joe'}]

removeByAttr(arr, 'name', 'joe');
// [{id:2,name:'alfalfa'}]

Installed SSL certificate in certificate store, but it's not in IIS certificate list

I had the same in IIS 10.

I fixed it by importing the .pfx file using IIS manager.

Select server root (above the sites-node), click 'Server Certificates' in the right hand pane and import pfx there. Then I could select it from the dropdown when creating ssl binding for a website under sites

TypeScript for ... of with index / key?

for (var [key, item] of someArray.entries()) { ... }

In TS this requires targeting ES2015 since it requires the runtime to support iterators, which ES5 runtimes don't. You can of course use something like Babel to make the output work on ES5 runtimes.

Url to a google maps page to show a pin given a latitude / longitude?

From my notes:,-122.088715&spn=0.004250,0.011579&t=h&iwloc=A&hl=en

Which parses like this:

    q=latN+lonW+(label)     location of teardrop

    t=k             keyhole (satelite map)
    t=h             hybrid

    ll=lat,-lon     center of map
    spn=w.w,h.h     span of map, degrees

iwloc has something to do with the info window. hl is obviously language.

See also:

Difference between the System.Array.CopyTo() and System.Array.Clone()

Clone() is used to copy only structure of data/array it doesn't copy the actual data.

CopyTo() copies the structure as well as actual data.

How to check if user input is not an int value

Maybe you can try this:

int function(){
Scanner input = new Scanner(;   
System.out.print("Enter an integer between 1-100: ");   
int range;
    range = input.nextInt();
    if(0<=range && range <= 100)
    input.nextLine();  //Comsume the garbage value
    System.out.println("Enter an integer between 1-100:");
return range;

SSH to Elastic Beanstalk instance

If you are using elastic bean and EB CLI, just use eb ssh to login to instance. You can use options as specified in the following link

aspx page to redirect to a new page

<%@ Page Language="C#" %>
<script runat="server">
  protected override void OnLoad(EventArgs e)

Spring MVC 4: "application/json" Content Type is not being set correctly

Not exactly for this OP, but for those who encountered 404 and cannot set response content-type to "application/json" (any content-type). One possibility is a server actually responds 406 but explorer (e.g., chrome) prints it as 404.

If you do not customize message converter, spring would use It would run:

List<MediaType> requestedMediaTypes = getAcceptableMediaTypes(request);
List<MediaType> producibleMediaTypes = getProducibleMediaTypes(request, valueType, declaredType);

and if they do not have any overlapping (the same item), it would throw HttpMediaTypeNotAcceptableException and this finally causes 406. No matter if it is an ajax, or GET/POST, or form action, if the request uri ends with a .html or any suffix, the requestedMediaTypes would be "text/[that suffix]", and this conflicts with producibleMediaTypes, which is usually:


WCFTestClient The HTTP request is unauthorized with client authentication scheme 'Anonymous'

I didn't have control over the security configuration for the service I was calling into, but got the same error. I was able to fix my client as follows.

  1. In the config, set up the security mode:

    <security mode="TransportCredentialOnly">
      <transport clientCredentialType="Windows" proxyCredentialType="None" realm="" />
      <message clientCredentialType="UserName" algorithmSuite="Default" />
  2. In the code, set the proxy class to allow impersonation (I added a reference to a service called customer):

    Customer_PortClient proxy = new Customer_PortClient();
    proxy.ClientCredentials.Windows.AllowedImpersonationLevel =    

How add "or" in switch statements?

You do it by stacking case labels:

    case 2:
    case 5:

    case 7: 
    case 12:

Simple calculations for working with lat/lon and km distance?

Why not use properly formulated geospatial queries???

Here is the SQL server reference page on the STContains geospatial function:

or if you do not waant to use box and radian conversion , you cna always use the distance function to find the points that you need:

DECLARE @CurrentLocation geography; 
SET @CurrentLocation  = geography::Point(12.822222, 80.222222, 4326)

SELECT * , Round (GeoLocation.STDistance(@CurrentLocation ),0) AS Distance FROM [Landmark]
WHERE GeoLocation.STDistance(@CurrentLocation )<= 2000 -- 2 Km

There should be similar functionality for almost any database out there.

If you have implemented geospatial indexing correctly your searches would be way faster than the approach you are using

Moving Average Pandas

A moving average can also be calculated and visualized directly in a line chart by using the following code:

Example using stock price data:

import as web
import matplotlib.pyplot as plt
import datetime'ggplot')

# Input variables
start = datetime.datetime(2016, 1, 01)
end = datetime.datetime(2018, 3, 29)
stock = 'WFC'

# Extrating data
df = web.DataReader(stock,'morningstar', start, end)
df = df['Close']

print df 

plt.plot(df['WFC'],label= 'Close')
plt.plot(df['WFC'].rolling(9).mean(),label= 'MA 9 days')
plt.plot(df['WFC'].rolling(21).mean(),label= 'MA 21 days')
plt.title('Wells Fargo\nClose and Moving Averages')

Tutorial on how to do this:

How to fade changing background image

Someone pointed me to this thread because I had this same issue but it didn't work for me. After hours of searching I found a solution using this -

It has a few other options other than fade too.