Programs & Examples On #Software estimation

Can I invoke an instance method on a Ruby module without including it?

To invoke a module instance method without including the module (and without creating intermediary objects):

class UsefulWorker
  def do_work

apache ProxyPass: how to preserve original IP address

This has a more elegant explanation and more than one possible solutions.

The post describes how to use one popular and one lesser known Apache modules to preserve host/ip while in a setup involving proxying.

Use mod_rpaf module, install and enable it in the backend server and add following directives in the module’s configuration. RPAFenable On
RPAFsethostname On

(2017 edit) Current location of mod_rpaf:

Can I make a phone call from HTML on Android?

Yes you can; it works on Android too:

tel: phone_number
Calls the entered phone number. Valid telephone numbers as defined in the IETF RFC 3966 are accepted. Valid examples include the following:

* tel:2125551212
* tel: (212) 555 1212

The Android browser uses the Phone app to handle the “tel” scheme, as defined by RFC 3966.
Clicking a link like:

<a href="tel:2125551212">2125551212</a>

on Android will bring up the Phone app and pre-enter the digits for 2125551212 without autodialing.

Have a look to RFC3966

iOS 7 - Failing to instantiate default view controller

I get this error when I change the the storyboard file name "Main.storyboard" TO: "XXX.storyboard"

The solution for me was:

  • Product->Clean
  • CHANGE: Supporting Files -> info.plist -> Main storyboard file base name -> Main TO: XXX

Good Luck

Error : No resource found that matches the given name (at 'icon' with value '@drawable/icon')

Trying to build HelloWorld app on Ubuntu 16.04. Got error with drawable/icon. Solution could be:

cp ./platforms/android/build/intermediates/exploded-aar/    ./platforms/android/build/intermediates/exploded-aar/

So, it look like icon.xml file missed.

iPhone UIView Animation Best Practice

In the UIView docs, have a read about this function for ios4+

+ (void)transitionFromView:(UIView *)fromView toView:(UIView *)toView duration:(NSTimeInterval)duration options:(UIViewAnimationOptions)options completion:(void (^)(BOOL finished))completion

git ahead/behind info between master and branch?

You can also use awk to make it a little bit prettier:

git rev-list --left-right --count  origin/develop...feature-branch | awk '{print "Behind "$1" - Ahead "$2""}'

You can even make an alias that always fetches origin first and then compares the branches

commit-diff = !"git fetch &> /dev/null && git rev-list --left-right --count"

Simple way to read single record from MySQL

Easy way to Fetch Single Record from MySQL Database by using PHP List

The SQL Query is SELECT user_name from user_table WHERE user_id = 6

The PHP Code for the above Query is

$sql_select = "";
$sql_select .= "SELECT ";
$sql_select .= "  user_name ";
$sql_select .= "FROM user_table ";
$sql_select .= "WHERE user_id = 6" ;

$rs_id = mysql_query($sql_select, $link) or die(mysql_error());
list($userName) = mysql_fetch_row($rs_id);

Note: The List Concept should be applicable for Single Row Fetching not for Multiple Rows

Is there any good dynamic SQL builder library in Java?

You can use the following library:

The library is built on the top of the Hibernate "create sql query" so it supports all databases supported by Hibernate (the Hibernate session and JPA providers are supported). The builder patter is available and so on (object mappers, result mappers).

You can find the examples on github page, the library is available at Maven central of course.

NativeCriteria c = new NativeCriteria(new HibernateQueryProvider(hibernateSession), "table_name", "alias");
c.addJoin(NativeExps.innerJoin("table_name_to_join", "alias2", "alias.left_column", "alias2.right_column"));

How to retrieve form values from HTTPPOST, dictionary or?

Simply, you can use FormCollection like:

public ActionResult SubmitAction(FormCollection collection)
     // Get Post Params Here
 string var1 = collection["var1"];

You can also use a class, that is mapped with Form values, and mvc engine automagically fills it:

//Defined in another file
class MyForm
  public string var1 { get; set; }

public ActionResult SubmitAction(MyForm form)
  string var1 = form1.Var1;

Storing Python dictionaries

My use case was to save multiple JSON objects to a file and marty's answer helped me somewhat. But to serve my use case, the answer was not complete as it would overwrite the old data every time a new entry was saved.

To save multiple entries in a file, one must check for the old content (i.e., read before write). A typical file holding JSON data will either have a list or an object as root. So I considered that my JSON file always has a list of objects and every time I add data to it, I simply load the list first, append my new data in it, and dump it back to a writable-only instance of file (w):

def saveJson(url,sc): # This function writes the two values to the file
    newdata = {'url':url,'sc':sc}
    json_path = "db/file.json"

    old_list= []
    with open(json_path) as myfile:  # Read the contents first
        old_list = json.load(myfile)

    with open(json_path,"w") as myfile:  # Overwrite the whole content
        json.dump(old_list, myfile, sort_keys=True, indent=4)

    return "success"

The new JSON file will look something like this:

        "sc": "a11",
        "url": ""
        "sc": "a12",
        "url": ""
        "sc": "a13",
        "url": ""

NOTE: It is essential to have a file named file.json with [] as initial data for this approach to work

PS: not related to original question, but this approach could also be further improved by first checking if our entry already exists (based on one or multiple keys) and only then append and save the data.

How to set button click effect in Android?

just wanna add another easy way to do this: If your ImageButton remains its background and you don't set it to null, it will work like a normal button and will show the click animation while clicking exactly like other buttons.The way to hide the background while it is still there:

    android:src="@drawable/squareicon" />

The paddings won't let the background be visible and make the button act like other buttons.

Python 2: AttributeError: 'list' object has no attribute 'strip'

strip() is a method for strings, you are calling it on a list, hence the error.

>>> 'strip' in dir(str)
>>> 'strip' in dir(list)

To do what you want, just do

>>> l = ['Facebook;Google+;MySpace', 'Apple;Android']
>>> l1 = [elem.strip().split(';') for elem in l]
>>> print l1
[['Facebook', 'Google+', 'MySpace'], ['Apple', 'Android']]

Since, you want the elements to be in a single list (and not a list of lists), you have two options.

  1. Create an empty list and append elements to it.
  2. Flatten the list.

To do the first, follow the code:

>>> l1 = []
>>> for elem in l:
>>> l1
['Facebook', 'Google+', 'MySpace', 'Apple', 'Android']

To do the second, use itertools.chain

>>> l1 = [elem.strip().split(';') for elem in l]
>>> print l1
[['Facebook', 'Google+', 'MySpace'], ['Apple', 'Android']]
>>> from itertools import chain
>>> list(chain(*l1))
['Facebook', 'Google+', 'MySpace', 'Apple', 'Android']

How to return only 1 row if multiple duplicate rows and still return rows that are not duplicates?

Try this if you want to display one of duplicate rows based on RequestID and CreatedDate and show the latest HistoryStatus.

with t as (select row_number()over(partition by RequestID,CreatedDate order by RequestID) as rnum,* from tbltmp)
Select RequestID,CreatedDate,HistoryStatus from t a where  rnum in (SELECT Max(rnum) FROM t GROUP BY RequestID,CreatedDate having t.RequestID=a.RequestID)

or if you want to select one of duplicate rows considering CreatedDate only and show the latest HistoryStatus then try the query below.

with t as (select row_number()over(partition by CreatedDate order by RequestID) as rnum,* from tbltmp)
Select RequestID,CreatedDate,HistoryStatus from t  where  rnum = (SELECT Max(rnum) FROM t)

Or if you want to select one of duplicate rows considering Request ID only and show the latest HistoryStatus then use the query below

with t as (select row_number()over(partition by RequestID order by RequestID) as rnum,* from tbltmp)
Select RequestID,CreatedDate,HistoryStatus from t a where  rnum in (SELECT Max(rnum) FROM t GROUP BY RequestID,CreatedDate having t.RequestID=a.RequestID)

All the above queries I have written in sql server 2005.

MySQL foreign key constraints, cascade delete

I think (I'm not certain) that foreign key constraints won't do precisely what you want given your table design. Perhaps the best thing to do is to define a stored procedure that will delete a category the way you want, and then call that procedure whenever you want to delete a category.

CREATE PROCEDURE `DeleteCategory` (IN category_ID INT)

    `id` IN (
        SELECT `products_id`
        FROM `categories_products`
        WHERE `categories_id` = category_ID

DELETE FROM `categories`
WHERE `id` = category_ID;


You also need to add the following foreign key constraints to the linking table:

ALTER TABLE `categories_products` ADD
    CONSTRAINT `Constr_categoriesproducts_categories_fk`
    FOREIGN KEY `categories_fk` (`categories_id`) REFERENCES `categories` (`id`)
    CONSTRAINT `Constr_categoriesproducts_products_fk`
    FOREIGN KEY `products_fk` (`products_id`) REFERENCES `products` (`id`)

The CONSTRAINT clause can, of course, also appear in the CREATE TABLE statement.

Having created these schema objects, you can delete a category and get the behaviour you want by issuing CALL DeleteCategory(category_ID) (where category_ID is the category to be deleted), and it will behave how you want. But don't issue a normal DELETE FROM query, unless you want more standard behaviour (i.e. delete from the linking table only, and leave the products table alone).

Gulp error: The following tasks did not complete: Did you forget to signal async completion?

Basically v3.X was simpler but v4.x is strict in these means of synchronous & asynchronous tasks.

The async/await is pretty simple & helpful way to understand the workflow & issue.

Use this simple approach

const gulp = require('gulp')

gulp.task('message',async function(){
return console.log('Gulp is running...')

Hive cast string to date dd-MM-yyyy


from_unixtime(unix_timestamp('12-03-2010' , 'dd-MM-yyyy'))

Ruby's gives "No such file or directory - text.txt (Errno::ENOENT)" error

Ditto Casper's answer:

puts Dir.pwd

As soon as you know current working directory, specify the file path relatively to that directory.

For example, if your working directory is project root, you can open a file under it directly like this

json_file =

Dynamic classname inside ngClass in angular 2

You can use <i [className]="'fa fa-' + data?.icon"> </i>

How do I loop through children objects in javascript?

The trick is that the DOM Element.children attribute is not an array but an array-like collection which has length and can be indexed like an array, but it is not an array:

var children = tableFields.children;
for (var i = 0; i < children.length; i++) {
  var tableChild = children[i];
  // Do stuff

Incidentally, in general it is a better practice to iterate over an array using a basic for-loop instead of a for-in-loop.

How to print / echo environment variables?

These need to go as different commands e.g.:

NAME=sam; echo "$NAME"
NAME=sam && echo "$NAME"

The expansion $NAME to empty string is done by the shell earlier, before running echo, so at the time the NAME variable is passed to the echo command's environment, the expansion is already done (to null string).

To get the same result in one command:

NAME=sam printenv NAME

git: can't push (unpacker error) related to permission issues

For what it worth, I had the same problem over my own VPS and it was caused by my low hard disk space on VPS. Confirmed by df -h command and after i cleaned up my VPS' hard disk; the problem was gone.


Code for a simple JavaScript countdown timer?

// Javascript Countdown_x000D_
// Version 1.01 6/7/07 (1/20/2000)_x000D_
// by TDavid at
var now = new Date();_x000D_
var theevent = new Date("Nov 13 2017 22:05:01");_x000D_
var seconds = (theevent - now) / 1000;_x000D_
var minutes = seconds / 60;_x000D_
var hours = minutes / 60;_x000D_
var days = hours / 24;_x000D_
ID = window.setTimeout("update();", 1000);_x000D_
function update() {_x000D_
  now = new Date();_x000D_
  seconds = (theevent - now) / 1000;_x000D_
  seconds = Math.round(seconds);_x000D_
  minutes = seconds / 60;_x000D_
  minutes = Math.round(minutes);_x000D_
  hours = minutes / 60;_x000D_
  hours = Math.round(hours);_x000D_
  days = hours / 24;_x000D_
  days = Math.round(days);_x000D_
  document.form1.days.value = days;_x000D_
  document.form1.hours.value = hours;_x000D_
  document.form1.minutes.value = minutes;_x000D_
  document.form1.seconds.value = seconds;_x000D_
  ID = window.setTimeout("update();", 1000);_x000D_
<p><font face="Arial" size="3">Countdown To January 31, 2000, at 12:00: </font>_x000D_
<form name="form1">_x000D_
    <input type="text" name="days" value="0" size="3">Hours_x000D_
    <input type="text" name="hours" value="0" size="4">Minutes_x000D_
    <input type="text" name="minutes" value="0" size="7">Seconds_x000D_
    <input type="text" name="seconds" value="0" size="7">_x000D_

How to check if object property exists with a variable holding the property name?

For own property :

var loan = { amount: 150 };
if(, "amount")) 
   //will execute

Note: using Object.prototype.hasOwnProperty is better than loan.hasOwnProperty(..), in case a custom hasOwnProperty is defined in the prototype chain (which is not the case here), like

var foo = {
      hasOwnProperty: function() {
        return false;
      bar: 'Here be dragons'


To include inherited properties in the finding use the in operator: (but you must place an object at the right side of 'in', primitive values will throw error, e.g. 'length' in 'home' will throw error, but 'length' in new String('home') won't)

const yoshi = { skulk: true };
const hattori = { sneak: true };
const kuma = { creep: true };
if ("skulk" in yoshi) 
    console.log("Yoshi can skulk");

if (!("sneak" in yoshi)) 
    console.log("Yoshi cannot sneak");

if (!("creep" in yoshi)) 
    console.log("Yoshi cannot creep");

Object.setPrototypeOf(yoshi, hattori);

if ("sneak" in yoshi)
    console.log("Yoshi can now sneak");
if (!("creep" in hattori))
    console.log("Hattori cannot creep");

Object.setPrototypeOf(hattori, kuma);

if ("creep" in hattori)
    console.log("Hattori can now creep");
if ("creep" in yoshi)
    console.log("Yoshi can also creep");


Note: One may be tempted to use typeof and [ ] property accessor as the following code which doesn't work always ...

var loan = { amount: 150 };

loan.installment = undefined;

if("installment" in loan) // correct
    // will execute

if(typeof loan["installment"] !== "undefined") // incorrect
    // will not execute

When should I use Kruskal as opposed to Prim (and vice versa)?

I found a very nice thread on the net that explains the difference in a very straightforward way :

Kruskal's algorithm will grow a solution from the cheapest edge by adding the next cheapest edge, provided that it doesn't create a cycle.

Prim's algorithm will grow a solution from a random vertex by adding the next cheapest vertex, the vertex that is not currently in the solution but connected to it by the cheapest edge.

Here attached is an interesting sheet on that topic.enter image description hereenter image description here

If you implement both Kruskal and Prim, in their optimal form : with a union find and a finbonacci heap respectively, then you will note how Kruskal is easy to implement compared to Prim.

Prim is harder with a fibonacci heap mainly because you have to maintain a book-keeping table to record the bi-directional link between graph nodes and heap nodes. With a Union Find, it's the opposite, the structure is simple and can even produce directly the mst at almost no additional cost.

Proxy Error 502 : The proxy server received an invalid response from an upstream server

I had this issue once. It turned out to be database query issue. After re-create tables and index it has been fixed.

Although it says proxy error, when you look at server log, it shows execute query timeout. This is what I had before and how I solved it.

what is this value means 1.845E-07 in excel?

1.84E-07 is the exact value, represented using scientific notation, also known as exponential notation.

1.845E-07 is the same as 0.0000001845. Excel will display a number very close to 0 as 0, unless you modify the formatting of the cell to display more decimals.

C# however will get the actual value from the cell. The ToString method use the e-notation when converting small numbers to a string.

You can specify a format string if you don't want to use the e-notation.

JMS Topic vs Queues

TOPIC:: topic is one to many communication... (multipoint or publish/subscribe) EX:-imagine a publisher publishes the movie in the youtub then all its subscribers will gets notification.... QUEVE::queve is one-to-one communication ... Ex:-When publish a request for recharge it will go to only one qreciever ... always remember if request goto all qreceivers then multiple recharge happened so while developing analyze which is fit for a application

Measuring execution time of a function in C++

It is a very easy-to-use method in C++11. You have to use std::chrono::high_resolution_clock from <chrono> header.

Use it like so:

#include <iostream>
#include <chrono>

void function()
    long long number = 0;

    for( long long i = 0; i != 2000000; ++i )
       number += 5;

int main()
    auto t1 = std::chrono::high_resolution_clock::now();
    auto t2 = std::chrono::high_resolution_clock::now();

    auto duration = std::chrono::duration_cast<std::chrono::microseconds>( t2 - t1 ).count();

    std::cout << duration;
    return 0;

This will measure the duration of the function.

NOTE: You will not always get the same timing for a function. This is because the CPU of your machine can be less or more used by other processes running on your computer, just as your mind can be more or less concentrated when you solve a math exercise. In the human mind, we can remember the solution of a math problem, but for a computer the same process will always be something new; thus, as I said, you will not always get the same result!

git checkout all the files

If you want to checkout all the files 'anywhere'

git checkout -- $(git rev-parse --show-toplevel)

Cannot make file No such file or directory

You may want to use Apache Commons IO's FileUtils.openOutputStream(File) method. It has good Exception messages when something went wrong and also creates necessary parent dirs. If everything was right then you directly get your OutputStream - very neat.

If you just want to touch the file then use FileUtils.touch(File) instead.

How to monitor network calls made from iOS Simulator

FLEX is a great tool to monitor network traffic from your iOS app.

FLEX iOS Screenshot 1

On clicking on any of the requests listed in the above screenshot, I will be redirected to another screen where I can see more details about that request. FLEX iOS Screenshot 2

However, I had a use case where the app which I was working on would redirect the user to Safari. I wanted to monitor the network traffic in Safari as well, but FLEX could only monitor the traffic from your iOS app, not from any other app ( at the time of writing this answer ).

Then I switched to Proxyman to monitor network traffic from the iOS simulator.

  • It has a clear set of instructions on how to set it up with both iOS simulators and Android emulators.
  • It has a simple, intuitive UI, which makes it easy to work with.

enter image description here

Plotting 4 curves in a single plot, with 3 y-axes

This is a great chance to introduce you to the File Exchange. Though the organization of late has suffered from some very unfortunately interface design choices, it is still a great resource for pre-packaged solutions to common problems. Though many here have given you the gory details of how to achieve this (@prm!), I had a similar need a few years ago and found that addaxis worked very well. (It was a File Exchange pick of the week at one point!) It has inspired later, probably better mods. Here is some example output:

addaxis example

I just searched for "plotyy" at File Exchange.

Though understanding what's going on in important, sometimes you just need to get things done, not do them yourself. Matlab Central is great for that.

How to checkout in Git by date?

Andy's solution does not work for me. Here I found another way:

git checkout `git rev-list -n 1 --before="2009-07-27 13:37" master`

Git: checkout by date

Form Submit jQuery does not work

Alright, this doesn't apply to the OP's exact situation, but for anyone like myself who comes here facing a similar issue, figure I should throw this out there-- maybe save a headache or two.

If you're using an non-standard "button" to ensure the submit event isn't called:

  <input type="hidden" name="hide" value="1">
  <a href="#" onclick="submitWithChecked(this.form)">Hide Selected</a>

Then, when you try to access this.form in the script, it's going to come up undefined. As I discovered, apparently anchor elements don't have same access to a parent form element the way your standard form elements do.

In such cases, (again, assuming you are intentionally avoiding the submit event for the time-being), you can use a button with type="button"

  <input type="hidden" name="hide" value="1">
  <button type="button" onclick="submitWithChecked(this.form)">Hide Selected</a>

(Addendum 2020: All these years later, I think the more important lesson to take away from this is to check your input. If my function had bothered to check that the argument it received was actually a form element, the problem would have been much easier to catch.)

Getting "Lock wait timeout exceeded; try restarting transaction" even though I'm not using a transaction

Had this same error, even though I was only updating one table with one entry, but after restarting mysql, it was resolved.

Set a Fixed div to 100% width of the parent container

Remove Padding: 10%; or use px instead of percent for .wrap

see the example :


<div id="wrapper">
    <div id="wrap">
    Some relative item placed item
    <div id="fixed"></div>


body{ height:20000px }
#wrapper {padding:10%;}
    float: left;
    position: relative;
    width: 200px; 


Trying to check if username already exists in MySQL database using PHP

$firstname = $_POST["firstname"];
$lastname = $_POST["lastname"];
$email = $_POST["email"];
$pass = $_POST["password"];

$check_email = mysqli_query($conn, "SELECT Email FROM crud where Email = '$email' ");
if(mysqli_num_rows($check_email) > 0){
    echo('Email Already exists');
    if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $result = mysqli_query($conn, "INSERT INTO crud (Firstname, Lastname, Email, Password) VALUES ('$firstname', '$lastname', '$email', '$pass')");
    echo('Record Entered Successfully');

PyLint "Unable to import" error - how to set PYTHONPATH?

The key is to add your project directory to sys.path without considering about the env variable.

For someone who use VSCode, here's a one-line solution for you if there's a base directory of your project:

init-hook='base_dir="my_spider"; import sys,os,re;".+\/" + base_dir, os.getcwd()); project_dir = if _re else os.path.join(os.getcwd(), base_dir); sys.path.append(project_dir)'

Let me explain it a little bit:

  •".+\/" + base_dir, os.getcwd()).group(): find base directory according to the editing file

  • os.path.join(os.getcwd(), base_dir): add cwd to sys.path to meet command line environment

FYI, here's my .pylintrc:

PHP: Calling another class' method

If they are separate classes you can do something like the following:

class A
    private $name;

    public function __construct()
        $this->name = 'Some Name';

    public function getName()
        return $this->name;

class B
    private $a;

    public function __construct(A $a)
        $this->a = $a;

    function getNameOfA()
        return $this->a->getName();

$a = new A();
$b = new B($a);


What I have done in this example is first create a new instance of the A class. And after that I have created a new instance of the B class to which I pass the instance of A into the constructor. Now B can access all the public members of the A class using $this->a.

Also note that I don't instantiate the A class inside the B class because that would mean I tighly couple the two classes. This makes it hard to:

  1. unit test your B class
  2. swap out the A class for another class

How to rotate a div using jQuery

EDIT: Updated for jQuery 1.8

Since jQuery 1.8 browser specific transformations will be added automatically. jsFiddle Demo

var rotation = 0;

jQuery.fn.rotate = function(degrees) {
    $(this).css({'transform' : 'rotate('+ degrees +'deg)'});
    return $(this);

$('.rotate').click(function() {
    rotation += 5;

EDIT: Added code to make it a jQuery function.

For those of you who don't want to read any further, here you go. For more details and examples, read on. jsFiddle Demo.

var rotation = 0;

jQuery.fn.rotate = function(degrees) {
    $(this).css({'-webkit-transform' : 'rotate('+ degrees +'deg)',
                 '-moz-transform' : 'rotate('+ degrees +'deg)',
                 '-ms-transform' : 'rotate('+ degrees +'deg)',
                 'transform' : 'rotate('+ degrees +'deg)'});
    return $(this);

$('.rotate').click(function() {
    rotation += 5;

EDIT: One of the comments on this post mentioned jQuery Multirotation. This plugin for jQuery essentially performs the above function with support for IE8. It may be worth using if you want maximum compatibility or more options. But for minimal overhead, I suggest the above function. It will work IE9+, Chrome, Firefox, Opera, and many others.

Bobby... This is for the people who actually want to do it in the javascript. This may be required for rotating on a javascript callback.

Here is a jsFiddle.

If you would like to rotate at custom intervals, you can use jQuery to manually set the css instead of adding a class. Like this! I have included both jQuery options at the bottom of the answer.


<div class="rotate">
    <h1>Rotatey text</h1>


/* Totally for style */
.rotate {
    background: #F02311;
    color: #FFF;
    width: 200px;
    height: 200px;
    text-align: center;
    font: normal 1em Arial;
    position: relative;
    top: 50px;
    left: 50px;

/* The real code */
.rotated {
    -webkit-transform: rotate(45deg);  /* Chrome, Safari 3.1+ */
    -moz-transform: rotate(45deg);  /* Firefox 3.5-15 */
    -ms-transform: rotate(45deg);  /* IE 9 */
    -o-transform: rotate(45deg);  /* Opera 10.50-12.00 */
    transform: rotate(45deg);  /* Firefox 16+, IE 10+, Opera 12.10+ */


Make sure these are wrapped in $(document).ready

$('.rotate').click(function() {

Custom intervals

var rotation = 0;
$('.rotate').click(function() {
    rotation += 5;
    $(this).css({'-webkit-transform' : 'rotate('+ rotation +'deg)',
                 '-moz-transform' : 'rotate('+ rotation +'deg)',
                 '-ms-transform' : 'rotate('+ rotation +'deg)',
                 'transform' : 'rotate('+ rotation +'deg)'});

html5 localStorage error with Safari: "QUOTA_EXCEEDED_ERR: DOM Exception 22: An attempt was made to add something to storage that exceeded the quota."

Here is an Angular2+ service version for memory storage alternative, you can just inject into your components, based on Pierre Le Roux' answer.

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

// Alternative to localstorage, memory
// storage for certain browsers in private mode
export class LocalStorageAlternative {
    private  structureLocalStorage = {};

    setItem(key: string, value: string): void {
        this.structureLocalStorage[key] = value;

    getItem(key: string): string {
        if (typeof this.structureLocalStorage[key] !== 'undefined' ) {
            return this.structureLocalStorage[key];
        return null;

    removeItem(key: string): void {
        this.structureLocalStorage[key] = undefined;

export class StorageService {
    private storageEngine;

    constructor() {
        try {
            localStorage.setItem('storage_test', '');
            this.storageEngine = localStorage;
        } catch (err) {
            this.storageEngine = new LocalStorageAlternative();

    setItem(key: string, value: string): void {
        this.storageEngine.setItem(key, value);

    getItem(key: string): string {
        return this.storageEngine.getItem(key);

    removeItem(key: string): void {


delete word after or around cursor in VIM

I think it's just daw

daw - delete a word

Do you (really) write exception safe code?

  • Do you really write exception safe code?

Well, I certainly intend to.

  • Are you sure your last "production ready" code is exception safe?

I'm sure that my 24/7 servers built using exceptions run 24/7 and don't leak memory.

  • Can you even be sure, that it is?

It's very difficult to be sure that any code is correct. Typically, one can only go by results

  • Do you know and/or actually use alternatives that work?

No. Using exceptions is cleaner and easier than any of the alternatives I've used over the last 30 years in programming.

How/When does Execute Shell mark a build as failure in Jenkins?

First things first, hover the mouse over the grey area below. Not part of the answer, but absolutely has to be said:

If you have a shell script that does "checkout, build, deploy" all by itself, then why are you using Jenkins? You are foregoing all the features of Jenkins that make it what it is. You might as well have a cron or an SVN post-commit hook call the script directly. Jenkins performing the SVN checkout itself is crucial. It allows the builds to be triggered only when there are changes (or on timer, or manual, if you prefer). It keeps track of changes between builds. It shows those changes, so you can see which build was for which set of changes. It emails committers when their changes caused successful or failed build (again, as configured as you prefer). It will email committers when their fixes fixed the failing build. And more and more. Jenkins archiving the artifacts also makes them available, per build, straight off Jenkins. While not as crucial as the SVN checkout, this is once again an integral part of what makes it Jenkins. Same with deploying. Unless you have a single environment, deployment usually happens to multiple environments. Jenkins can keep track of which environment a specific build (with specific set of SVN changes) is deployed it, through the use of Promotions. You are foregoing all of this. It sounds like you are told "you have to use Jenkins" but you don't really want to, and you are doing it just to get your bosses off your back, just to put a checkmark "yes, I've used Jenkins"

The short answer is: the exit code of last command of the Jenkin's Execute Shell build step is what determines the success/failure of the Build Step. 0 - success, anything else - failure. Note, this is determining the success/failure of the build step, not the whole job run. The success/failure of the whole job run can further be affected by multiple build steps, and post-build actions and plugins.

You've mentioned Build step 'Execute shell' marked build as failure, so we will focus just on a single build step. If your Execute shell build step only has a single line that calls your shell script, then the exit code of your shell script will determine the success/failure of the build step. If you have more lines, after your shell script execution, then carefully review them, as they are the ones that could be causing failure.

Finally, have a read here Jenkins Build Script exits after Google Test execution. It is not directly related to your question, but note that part about Jenkins launching the Execute Shell build step, as a shell script with /bin/sh -xe

The -e means that the shell script will exit with failure, even if just 1 command fails, even if you do error checking for that command (because the script exits before it gets to your error checking). This is contrary to normal execution of shell scripts, which usually print the error message for the failed command (or redirect it to null and handle it by other means), and continue.

To circumvent this, add set +e to the top of your shell script.

Since you say your script does all it is supposed to do, chances are the failing command is somewhere at the end of the script. Maybe a final echo? Or copy of artifacts somewhere? Without seeing the full console output, we are just guessing.

Please post the job run's console output, and preferably the shell script itself too, and then we could tell you exactly which line is failing.

Android Studio : unmappable character for encoding UTF-8

1/ Convert the file encoding
File -> Settings -> Editor -> File encodings -> set UTF-8 for

  • IDE Encoding
  • Project Encoding
  • Default encoding propertie file

Press OK

2/ Rebuild Project

Build -> Rebuild project

How to obtain the start time and end time of a day?


LocalDate                       // Represents an entire day, without time-of-day and without time zone.
.now(                           // Capture the current date.
    ZoneId.of( "Asia/Tokyo" )   // Returns a `ZoneId` object.
)                               // Returns a `LocalDate` object.
.atStartOfDay(                  // Determines the first moment of the day as seen on that date in that time zone. Not all days start at 00:00!
    ZoneId.of( "Asia/Tokyo" ) 
)                               // Returns a `ZonedDateTime` object.

Start of day

Get the full length of the today as seen in a time zone.

Using Half-Open approach, where the beginning is inclusive while the ending is exclusive. This approach solves the flaw in your code that fails to account for the very last second of the day.

ZoneId zoneId = ZoneId.of( "Africa/Tunis" ) ;
LocalDate today = zoneId  ) ;

ZonedDateTime zdtStart = today.atStartOfDay( zoneId ) ;
ZonedDateTime zdtStop = today.plusDays( 1 ).atStartOfDay( zoneId ) ;

zdtStart.toString() = 2020-01-30T00:00+01:00[Africa/Tunis]

zdtStop.toString() = 2020-01-31T00:00+01:00[Africa/Tunis]

See the same moments in UTC.

Instant start = zdtStart.toInstant() ;
Instant stop = zdtStop.toInstant() ;

start.toString() = 2020-01-29T23:00:00Z

stop.toString() = 2020-01-30T23:00:00Z

If you want the entire day of a date as seen in UTC rather than in a time zone, use OffsetDateTime.

LocalDate today = ZoneOffset.UTC  ) ;

OffsetDateTime odtStart = today.atTime( OffsetTime.MIN ) ;
OffsetDateTime odtStop = today.plusDays( 1 ).atTime( OffsetTime.MIN ) ;

odtStart.toString() = 2020-01-30T00:00+18:00

odtStop.toString() = 2020-01-31T00:00+18:00

These OffsetDateTime objects will already be in UTC, but you can call toInstant if you need such objects which are always in UTC by definition.

Instant start = odtStart.toInstant() ;
Instant stop = odtStop.toInstant() ;

start.toString() = 2020-01-29T06:00:00Z

stop.toString() = 2020-01-30T06:00:00Z

Tip: You may be interested in adding the ThreeTen-Extra library to your project to use its Interval class to represent this pair of Instant objects. This class offers useful methods for comparison such as abuts, overlaps, contains, and more.

Interval interval = Interval.of( start , stop ) ;

interval.toString() = 2020-01-29T06:00:00Z/2020-01-30T06:00:00Z


The answer by mprivat is correct. His point is to not try to obtain end of a day, but rather compare to "before start of next day". His idea is known as the "Half-Open" approach where a span of time has a beginning that is inclusive while the ending is exclusive.

  • The current date-time frameworks of Java (java.util.Date/Calendar and Joda-Time) both use milliseconds from the epoch. But in Java 8, the new JSR 310 java.time.* classes use nanoseconds resolution. Any code you wrote based on forcing the milliseconds count of last moment of day would be incorrect if switched to the new classes.
  • Comparing data from other sources becomes faulty if they employ other resolutions. For example, Unix libraries typically employ whole seconds, and databases such as Postgres resolve date-time to microseconds.
  • Some Daylight Saving Time changes happen over midnight which might further confuse things.

enter image description here

Joda-Time 2.3 offers a method for this very purpose, to obtain first moment of the day: withTimeAtStartOfDay(). Similarly in java.time, LocalDate::atStartOfDay.

Search StackOverflow for "joda half-open" to see more discussion and examples.

See this post, Time intervals and other ranges should be half-open, by Bill Schneider.

Avoid legacy date-time classes

The java.util.Date and .Calendar classes are notoriously troublesome. Avoid them.

Use java.time classes. The java.time framework is the official successor of the highly successful Joda-Time library.


The java.time framework is built into Java 8 and later. Back-ported to Java 6 & 7 in the ThreeTen-Backport project, further adapted to Android in the ThreeTenABP project.

An Instant is a moment on the timeline in UTC with a resolution of nanoseconds.

Instant instant =;

Apply a time zone to get the wall-clock time for some locality.

ZoneId zoneId = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = ZonedDateTime.ofInstant( instant , zoneId );

To get the first moment of the day go through the LocalDate class and its atStartOfDay method.

ZonedDateTime zdtStart = zdt.toLocalDate().atStartOfDay( zoneId );

Using Half-Open approach, get first moment of following day.

ZonedDateTime zdtTomorrowStart = zdtStart.plusDays( 1 );

Table of all date-time types in Java, both modern and legacy

Currently the java.time framework lacks an Interval class as described below for Joda-Time. However, the ThreeTen-Extra project extends java.time with additional classes. This project is the proving ground for possible future additions to java.time. Among its classes is Interval. Construct an Interval by passing a pair of Instant objects. We can extract an Instant from our ZonedDateTime objects.

Interval today = Interval.of( zdtStart.toInstant() , zdtTomorrowStart.toInstant() );

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes. Hibernate 5 & JPA 2.2 support java.time.

Where to obtain the java.time classes?


UPDATE: The Joda-Time project is now in maintenance-mode, and advises migration to the java.time classes. I am leaving this section intact for history.

Joda-Time has three classes to represent a span of time in various ways: Interval, Period, and Duration. An Interval has a specific beginning and ending on the timeline of the Universe. This fits our need to represent "a day".

We call the method withTimeAtStartOfDay rather than set time of day to zeros. Because of Daylight Saving Time and other anomalies the first moment of the day may not be 00:00:00.

Example code using Joda-Time 2.3.

DateTimeZone timeZone = DateTimeZone.forID( "America/Montreal" );
DateTime now = timeZone );
DateTime todayStart = now.withTimeAtStartOfDay();
DateTime tomorrowStart = now.plusDays( 1 ).withTimeAtStartOfDay();
Interval today = new Interval( todayStart, tomorrowStart );

If you must, you can convert to a java.util.Date.

java.util.Date date = todayStart.toDate();

Scrolling to an Anchor using Transition/CSS3

Here is a pure css solution using viewport units and variables that automatically scales to the device (and works on window resize). I added the following to Alex's solution:

        html,body {
            width: 100%;
            height: 100%;
            position: fixed;/* prevents scrolling */
            --innerheight: 100vh;/* variable 100% of viewport height */

        body {
            overflow: hidden; /* prevents scrolling */

        .panel {
            width: 100%;
            height: var(--innerheight); /* viewport height */

        a[ id= "galeria" ]:target ~ #main article.panel {
            -webkit-transform: translateY( calc(-1*var(--innerheight)) );
            transform: translateY( calc(-1*var(--innerheight)) );

        a[ id= "contacto" ]:target ~ #main article.panel {
            -webkit-transform: translateY( calc(-2*var(--innerheight)) );
            transform: translateY( calc(-2*var(--innerheight)) );

Connect to sqlplus in a shell script and run SQL scripts

If you want to redirect the output to a log file to look for errors or something. You can do something like this.

sqlplus -s <<EOF>> LOG_FILE_NAME user/passwd@host/db
#Your SQL code

Begin, Rescue and Ensure in Ruby?

This is why we need ensure:

def hoge
    raise # raise again
    puts 'ensure' # will be executed
  puts 'end of func' # never be executed

SSRS Conditional Formatting Switch or IIF

To dynamically change the color of a text box goto properties, goto font/Color and set the following expression

=SWITCH(Fields!CurrentRiskLevel.Value = "Low", "Green",
Fields!CurrentRiskLevel.Value = "Moderate", "Blue",
Fields!CurrentRiskLevel.Value = "Medium", "Yellow",
Fields!CurrentRiskLevel.Value = "High", "Orange",
Fields!CurrentRiskLevel.Value = "Very High", "Red"

Same way for tolerance

=SWITCH(Fields!Tolerance.Value = "Low", "Red",
Fields!Tolerance.Value = "Moderate", "Orange",
Fields!Tolerance.Value = "Medium", "Yellow",
Fields!Tolerance.Value = "High", "Blue",
Fields!Tolerance.Value = "Very High", "Green")

Uploading multiple files using formData()

Adding [] when appending to fd works, but if you prefer to have your data grouped by file then I'd suggest doing it this way:

var files= document.getElementById('inpFile').files
var fd = new FormData()

for (let i = 0; i < files.length; i++) {
  fd.append(i, files[i])

Now your data will be sent grouped by file instead of grouped by attribute.

ASP.Net Download file to client browser

Just a slight addition to the above solution if you are having problem with downloaded file's name...

Response.AddHeader("Content-Disposition", "attachment; filename=\"" + file.Name + "\"");

This will return the exact file name even if it contains spaces or other characters.

Can I have onScrollListener for a ScrollView?

you can define a custom ScrollView class, & add an interface be called when scrolling like this:

public class ScrollChangeListenerScrollView extends HorizontalScrollView {

private MyScrollListener mMyScrollListener;

public ScrollChangeListenerScrollView(Context context) {

public ScrollChangeListenerScrollView(Context context, AttributeSet attrs) {
    super(context, attrs);

public ScrollChangeListenerScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);

public void setOnMyScrollListener(MyScrollListener myScrollListener){
    this.mMyScrollListener = myScrollListener;

protected void onScrollChanged(int l, int t, int oldl, int oldt) {
    super.onScrollChanged(l, t, oldl, oldt);


public interface MyScrollListener {
    void onScrollChange(View view,int scrollX,int scrollY,int oldScrollX, int oldScrollY);


How can I set a css border on one side only?

You can specify border separately for all borders, for example:

  border-left: 1px solid #000;
  border-right: 2px solid #FF0;

You can also specify the look of the border, and use separate style for the top, right, bottom and left borders. for example:

  border: 1px #000;
  border-style: none solid none solid;

Add leading zeroes/0's to existing Excel values to certain length


However the TEXT function is able to do other fancy stuff like date formating, aswell.

CSS how to make scrollable list

Another solution would be as below where the list is placed under a drop-down button.

  <button class="btn dropdown-toggle btn-primary btn-sm" data-toggle="dropdown"
    >Markets<span class="caret"></span></button>

    <ul class="dropdown-menu", style="height:40%; overflow:hidden; overflow-y:scroll;">
      {{ }}

Asynchronously wait for Task<T> to complete with timeout

This is a slightly enhanced version of previous answers.

  • In addition to Lawrence's answer, it cancels the original task when timeout occurs.
  • In addtion to sjb's answer variants 2 and 3, you can provide CancellationToken for the original task, and when timeout occurs, you get TimeoutException instead of OperationCanceledException.
async Task<TResult> CancelAfterAsync<TResult>(
    Func<CancellationToken, Task<TResult>> startTask,
    TimeSpan timeout, CancellationToken cancellationToken)
    using (var timeoutCancellation = new CancellationTokenSource())
    using (var combinedCancellation = CancellationTokenSource
        .CreateLinkedTokenSource(cancellationToken, timeoutCancellation.Token))
        var originalTask = startTask(combinedCancellation.Token);
        var delayTask = Task.Delay(timeout, timeoutCancellation.Token);
        var completedTask = await Task.WhenAny(originalTask, delayTask);
        // Cancel timeout to stop either task:
        // - Either the original task completed, so we need to cancel the delay task.
        // - Or the timeout expired, so we need to cancel the original task.
        // Canceling will not affect a task, that is already completed.
        if (completedTask == originalTask)
            // original task completed
            return await originalTask;
            // timeout
            throw new TimeoutException();


InnerCallAsync may take a long time to complete. CallAsync wraps it with a timeout.

async Task<int> CallAsync(CancellationToken cancellationToken)
    var timeout = TimeSpan.FromMinutes(1);
    int result = await CancelAfterAsync(ct => InnerCallAsync(ct), timeout,
    return result;

async Task<int> InnerCallAsync(CancellationToken cancellationToken)
    return 42;

Do I need <class> elements in persistence.xml?

You can provide for jar-file element path to a folder with compiled classes. For example I added something like that when I prepared persistence.xml to some integration tests:


Difference between SRC and HREF

From W3:

When the A element's href attribute is set, the element defines a source anchor for a link that may be activated by the user to retrieve a Web resource. The source anchor is the location of the A instance and the destination anchor is the Web resource.


This attribute specifies the location of the image resource. Examples of widely recognized image formats include GIF, JPEG, and PNG.


Selenium WebDriver: Wait for complex page with JavaScript to load

If anyone actually knew a general and always-applicable answer, it would have been implemented everywhere ages ago and would make our lives SO much easier.

There are many things you can do, but every single one of them has a problem:

  1. As Ashwin Prabhu said, if you know the script well, you can observe its behaviour and track some of its variables on window or document etc. This solution, however, is not for everyone and can be used only by you and only on a limited set of pages.

  2. Your solution by observing the HTML code and whether it has or hasn't been changed for some time is not bad (also, there is a method to get the original and not-edited HTML directly by WebDriver), but:

    • It takes a long time to actually assert a page and could prolong the test significantly.
    • You never know what the right interval is. The script might be downloading something big that takes more than 500 ms. There are several scripts on our company's internal page that take several seconds in IE. Your computer may be temporarily short on resources - say that an antivirus will make your CPU work fully, then 500 ms may be too short even for a noncomplex scripts.
    • Some scripts are never done. They call themselves with some delay (setTimeout()) and work again and again and could possibly change the HTML every time they run. Seriously, every "Web 2.0" page does it. Even Stack Overflow. You could overwrite the most common methods used and consider the scripts that use them as completed, but ... you can't be sure.
    • What if the script does something other than changing the HTML? It could do thousands of things, not just some innerHTML fun.
  3. There are tools to help you on this. Namely Progress Listeners together with nsIWebProgressListener and some others. The browser support for this, however, is horrible. Firefox began to try to support it from FF4 onwards (still evolving), IE has basic support in IE9.

And I guess I could come up with another flawed solution soon. The fact is - there's no definite answer on when to say "now the page is complete" because of the everlasting scripts doing their work. Pick the one that serves you best, but beware of its shortcomings.

Format Instant to String

Time Zone

To format an Instant a time-zone is required. Without a time-zone, the formatter does not know how to convert the instant to human date-time fields, and therefore throws an exception.

The time-zone can be added directly to the formatter using withZone().

DateTimeFormatter formatter =
    DateTimeFormatter.ofLocalizedDateTime( FormatStyle.SHORT )
                     .withLocale( Locale.UK )
                     .withZone( ZoneId.systemDefault() );

If you specifically want an ISO-8601 format with no explicit time-zone (as the OP asked), with the time-zone implicitly UTC, you need


Generating String

Now use that formatter to generate the String representation of your Instant.

Instant instant =;
String output = formatter.format( instant );

Dump to console.

System.out.println("formatter: " + formatter + " with zone: " + formatter.getZone() + " and Locale: " + formatter.getLocale() );
System.out.println("instant: " + instant );
System.out.println("output: " + output );

When run.

formatter: Localized(SHORT,SHORT) with zone: US/Pacific and Locale: en_GB
instant: 2015-06-02T21:34:33.616Z
output: 02/06/15 14:34

How to pick just one item from a generator?

Create a generator using

g = myfunct()

Everytime you would like an item, use


(or in Python 2.5 or below).

If the generator exits, it will raise StopIteration. You can either catch this exception if necessary, or use the default argument to next():

next(g, default_value)

How to declare or mark a Java method as deprecated?

Take a look at the @Deprecated annotation.

pandas groupby sort descending order

Similar to one of the answers above, but try adding .sort_values() to your .groupby() will allow you to change the sort order. If you need to sort on a single column, it would look like this:


ascending=False will sort from high to low, the default is to sort from low to high.

*Careful with some of these aggregations. For example .size() and .count() return different values since .size() counts NaNs.

What is the difference between size and count in pandas?

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

All you need is a bit of black magic!

>>> a = ["cherry.bad","pear.good", "apple.good"]
>>> a = list(map(lambda x: x.replace('.good','').replace('.bad',''),a))
>>> a
['cherry', 'pear', 'apple']

Uninstall Eclipse under OSX?

Eclipse has no impact on Mac OS beyond it directory, so there is no problem uninstalling.

I think that What you are facing is the result of Eclipse switching the plugin distribution system recently. There are now two redundant and not very compatible means of installing plugins. It's a complete mess. You may be better off (if possible) installing a more recent version of Eclipse (maybe even the 3.5 milestones) as they seem to be more stable in that regard.

How do I setup the dotenv file in Node.js?

My code structure using is as shown below


I have required .env at the top of my app.js

import express = require('express');
import bodyParser from 'body-parser';
import mongoose = require('mongoose');

The process.env.PORT works in my app.listen function. However, on my userController file not sure how this is happening but my problem was I was getting the secretKey value and type as string when I checked using console.log() but getting undefined when trying it on jwt.sign() e.g.

console.log('Type: '+ process.env.ACCESS_TOKEN_SECRET)



jwt.sign giving error

let accessToken = jwt.sign(userObj, process.env.ACCESS_TOKEN_SECRET); //not working 

Error was

    Argument of type 'string | undefined' is not assignable to parameter of type 'Secret'.
  Type 'undefined' is not assignable to type 'Secret'.

My Solution: After reading the documentation. I required the env again in my file( which I probably should have in the first place ) and saved it to variable 'environment'

let environment = require('dotenv').config();

console logging environment this gives:

parsed: {
    DB_HOST: 'localhost',
    DB_USER: 'root',
    DB_PASS: 'pass',
    PORT: '3000',
    ACCESS_TOKEN_SECRET: 'secretKey',

Using it on jwt.sign not works

let accessToken = jwt.sign(userObj, environment.parsed.ACCESS_TOKEN_SECRET);

Hope this helps, I was stuck on it for hours. Please feel free to add anything to my answer which may help explain more on this.

Numpy: Creating a complex array from 2 real ones?

If your real and imaginary parts are the slices along the last dimension and your array is contiguous along the last dimension, you can just do


If you are using single precision floats, this would be


Here is a fuller example

import numpy as np
from numpy.random import rand
# Randomly choose real and imaginary parts.
# Treat last axis as the real and imaginary parts.
A = rand(100, 2)
# Cast the array as a complex array
# Note that this will now be a 100x1 array
A_comp = A.view(dtype=np.complex128)
# To get the original array A back from the complex version
A = A.view(dtype=np.float64)

If you want to get rid of the extra dimension that stays around from the casting, you could do something like

A_comp = A.view(dtype=np.complex128)[...,0]

This works because, in memory, a complex number is really just two floating point numbers. The first represents the real part, and the second represents the imaginary part. The view method of the array changes the dtype of the array to reflect that you want to treat two adjacent floating point values as a single complex number and updates the dimension accordingly.

This method does not copy any values in the array or perform any new computations, all it does is create a new array object that views the same block of memory differently. That makes it so that this operation can be performed much faster than anything that involves copying values. It also means that any changes made in the complex-valued array will be reflected in the array with the real and imaginary parts.

It may also be a little trickier to recover the original array if you remove the extra axis that is there immediately after the type cast. Things like A_comp[...,np.newaxis].view(np.float64) do not currently work because, as of this writing, NumPy doesn't detect that the array is still C-contiguous when the new axis is added. See this issue. A_comp.view(np.float64).reshape(A.shape) seems to work in most cases though.

How to verify if nginx is running or not?

The modern (systemctl) way of doing it:

systemctl is-active nginx

You can use the exit value in your shell scripts as follows:

systemctl -q is-active nginx && echo "It is active, do something"

Download data url file


  • Try a <a href="data:...." target="_blank"> (Untested)

  • Use downloadify instead of data URLs (would work for IE as well)

error: (-215) !empty() in function detectMultiScale

the error may be due to, the required xml files has not been loaded properly. Search for the file haarcascade_frontalface_default.xml by using the search engine of ur OS get the full path and put it as the argument to cv2.CascadeClassifier as string

Assign pandas dataframe column dtypes

Since 0.17, you have to use the explicit conversions:

pd.to_datetime, pd.to_timedelta and pd.to_numeric

(As mentioned below, no more "magic", convert_objects has been deprecated in 0.17)

df = pd.DataFrame({'x': {0: 'a', 1: 'b'}, 'y': {0: '1', 1: '2'}, 'z': {0: '2018-05-01', 1: '2018-05-02'}})


x    object
y    object
z    object
dtype: object


   x  y           z
0  a  1  2018-05-01
1  b  2  2018-05-02

You can apply these to each column you want to convert:

df["y"] = pd.to_numeric(df["y"])
df["z"] = pd.to_datetime(df["z"])    

   x  y          z
0  a  1 2018-05-01
1  b  2 2018-05-02


x            object
y             int64
z    datetime64[ns]
dtype: object

and confirm the dtype is updated.

OLD/DEPRECATED ANSWER for pandas 0.12 - 0.16: You can use convert_objects to infer better dtypes:

In [21]: df
   x  y
0  a  1
1  b  2

In [22]: df.dtypes
x    object
y    object
dtype: object

In [23]: df.convert_objects(convert_numeric=True)
   x  y
0  a  1
1  b  2

In [24]: df.convert_objects(convert_numeric=True).dtypes
x    object
y     int64
dtype: object

Magic! (Sad to see it deprecated.)

Read only the first line of a file?

f1 = open("input1.txt", "r")

How do I break a string in YAML over multiple lines?

You might not believe it, but YAML can do multi-line keys too:


PHP Header redirect not working

If I understand correctly, something has already sent out from header.php (maybe some HTML) so the headers have been set. You may need to recheck your header.php file for any part that may output HTML or spaces before your first

EDIT: I am now sure that it is caused from header.php since you have those HTML output. You can fix this by remove the "include('header.php');" line and copy the following code to your file instead.


        $date = date('Y-m-j');

MySql ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

Comment by @Niagaradad helped me. I was entering the wrong password the whole time.

Notice the error message

ERROR 1045 (28000): Access denied for user 'ayaz'@'localhost' (using password: YES)

It says, Password: Yes. That means I am sending the password to SQL and that is wrong.

Usually root account doesn't have password if you haven't set one. If you have installed mysql via homebrew then root account won't have a password.

Here is the comment.

so, not exactly the same then. NO means you are not sending a password to MySQL. YES means you are sending a password to MySQL but the incorrect one. Did you specifically set a password for the mysql root user when you installed MySQL? By default there is no password so you can use mysql -u root -p and hit enter.

The POST method is not supported for this route. Supported methods: GET, HEAD. Laravel

I've seen your code in web.php as follows: Route::post('/edit/{id}','ProjectController@update');

Step 1: remove the {id} random parameter so it would be like this: Route::post('/edit','ProjectController@update');

Step 2: Then remove the @method('PUT') in your form, so let's say we'll just plainly use the POST method

Then how can I pass the ID to my method?

Step 1: make an input field in your form with the hidden attribute for example

<input type="hidden" value="{{$project->id}}" name="id">

Step 2: in your update method in your controller, fetch that ID for example:

$id = $request->input('id');

then you may not use it to find which project to edit

$project = Project::find($id)
$project = Project::where('id',$id);

Angular no provider for NameService

You should be injecting NameService inside providers array of your AppModule's NgModule metadata.

   providers: [MyService]

and be sure import in your component by same name (case sensitive),becouse SystemJs is case sensitive (by design). If you use different path name in your project files like this:


import { MyService } from './MyService';


import { MyService } from './Myservice';

then System js will make double imports

What is thread Safe in java?

As Seth stated thread safe means that a method or class instance can be used by multiple threads at the same time without any problems occuring.

Consider the following method:

private int myInt = 0;
public int AddOne()
    int tmp = myInt;
    tmp = tmp + 1;
    myInt = tmp;
    return tmp;

Now thread A and thread B both would like to execute AddOne(). but A starts first and reads the value of myInt (0) into tmp. Now for some reason the scheduler decides to halt thread A and defer execution to thread B. Thread B now also reads the value of myInt (still 0) into it's own variable tmp. Thread B finishes the entire method, so in the end myInt = 1. And 1 is returned. Now it's Thread A's turn again. Thread A continues. And adds 1 to tmp (tmp was 0 for thread A). And then saves this value in myInt. myInt is again 1.

So in this case the method AddOne() was called two times, but because the method was not implemented in a thread safe way the value of myInt is not 2, as expected, but 1 because the second thread read the variable myInt before the first thread finished updating it.

Creating thread safe methods is very hard in non trivial cases. And there are quite a few techniques. In Java you can mark a method as synchronized, this means that only one thread can execute that method at a given time. The other threads wait in line. This makes a method thread safe, but if there is a lot of work to be done in a method, then this wastes a lot of time. Another technique is to 'mark only a small part of a method as synchronized' by creating a lock or semaphore, and locking this small part (usually called the critical section). There are even some methods that are implemented as lockless thread safe, which means that they are built in such a way that multiple threads can race through them at the same time without ever causing problems, this can be the case when a method only executes one atomic call. Atomic calls are calls that can't be interrupted and can only be done by one thread at a time.

Exception: Unexpected end of ZLIB input stream

You have to call close() on the GZIPOutputStream before you attempt to read it. The final bytes of the file will only be written when the file is actually closed. (This is irrespective of any explicit buffering in the output stack. The stream only knows to compress and write the last bytes when you tell it to close. A flush() probably won't help ... though calling finish() instead of close() should work. Look at the javadocs.)

Here's the correct code (in Java);

package test;


public class GZipTest {

    public static void main(String[] args) throws
                FileNotFoundException, IOException {
        String name = "/tmp/test";
        GZIPOutputStream gz = new GZIPOutputStream(new FileOutputStream(name));
        gz.close();       // Remove this to reproduce the reported bug
        System.out.println(new GZIPInputStream(new FileInputStream(name)).read());

(I've not implemented resource management or exception handling / reporting properly as they are not relevant to the purpose of this code. Don't treat this as an example of "good code".)

Why is my power operator (^) not working?

Instead of using ^, use 'pow' function which is a predefined function which performs the Power operation and it can be used by including math.h header file.

^ This symbol performs BIT-WISE XOR operation in C, C++.

Replace a^i with pow(a,i).

ECMAScript 6 class destructor

"A destructor wouldn't even help you here. It's the event listeners themselves that still reference your object, so it would not be able to get garbage-collected before they are unregistered."

Not so. The purpose of a destructor is to allow the item that registered the listeners to unregister them. Once an object has no other references to it, it will be garbage collected.

For instance, in AngularJS, when a controller is destroyed, it can listen for a destroy event and respond to it. This isn't the same as having a destructor automatically called, but it's close, and gives us the opportunity to remove listeners that were set when the controller was initialized.

// Set event listeners, hanging onto the returned listener removal functions
function initialize() {
    $scope.listenerCleanup = [];
    $scope.listenerCleanup.push( $scope.$on( EVENTS.DESTROY, instance.onDestroy) );
    $scope.listenerCleanup.push( $scope.$on( AUTH_SERVICE_RESPONSES.CREATE_USER.SUCCESS, instance.onCreateUserResponse ) );
    $scope.listenerCleanup.push( $scope.$on( AUTH_SERVICE_RESPONSES.CREATE_USER.FAILURE, instance.onCreateUserResponse ) );

// Remove event listeners when the controller is destroyed
function onDestroy(){
    $scope.listenerCleanup.forEach( remove => remove() );

Run Batch File On Start-up

To start the batch file at the start of your system, you can also use a registry key.


Here you can create a string. As name you can choose anything and the data is the full path to your file.

There is also the registry key


to run something at only the next start of your system.

PHP executable not found. Install PHP 7 and add it to your PATH or set the php.executablePath setting

Try this !!!. This will solve your problem for sure!

Method 1 -

Step 1 - Go to 'Environmental Variables'.

Step 2 - Find PATH variable and add the path to your PHP folder.

Step 3 - For 'XAMPP' users put 'C:\xampp\php' and 'WAMP' users put 'C:\wamp64\bin\php\php7.1.9' ) and save.

Method 2-

In VS Code

File -> Preferences -> Settings.

enter image description here

Open 'settings.json' file and put the below codes.

If you are using WAMP put this code and Save.

  "php.validate.executablePath": "C:\\wamp64\\bin\\php\\php7.1.9\\php.exe",
  "php.executablePath": "C:\\wamp64\\bin\\php\\php7.1.9\\php.exe"

If you are using XAMPP put this code and Save.

  "php.validate.executablePath": "C:\\xampp\\php\\php.exe",
  "php.executablePath": "C:\\xampp\\php\\php.exe"

Note - Replace php7.1.9 with your PHP version.

LEFT INNER JOIN vs. LEFT OUTER JOIN - Why does the OUTER take longer?

The fact that the same number of rows is returned is an after fact, the query optimizer cannot know in advance that every row in Accepts has a matching row in Marker, can it?

If you join two tables A and B, say A has 1 million rows and B has 1 row. If you say A LEFT INNER JOIN B it means only rows that match both A and B can result, so the query plan is free to scan B first, then use an index to do a range scan in A, and perhaps return 10 rows. But if you say A LEFT OUTER JOIN B then at least all rows in A have to be returned, so the plan must scan everything in A no matter what it finds in B. By using an OUTER join you are eliminating one possible optimization.

If you do know that every row in Accepts will have a match in Marker, then why not declare a foreign key to enforce this? The optimizer will see the constraint, and if is trusted, will take it into account in the plan.

Re-ordering factor levels in data frame

Assuming your dataframe is mydf:

mydf$task <- factor(mydf$task, levels = c("up", "down", "left", "right", "front", "back"))

How can I run dos2unix on an entire directory?

I have had the same problem and thanks to the posts here I have solved it. I knew that I have around a hundred files and I needed to run it for *.js files only. find . -type f -name '*.js' -print0 | xargs -0 dos2unix

Thank you all for your help.

Cell color changing in Excel using C#

For text:

[RangeObject].Font.Color = System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.Red);

For cell background

[RangeObject].Interior.Color = System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.Red);

Split by comma and strip whitespace in Python

map(lambda s: s.strip(), mylist) would be a little better than explicitly looping.
Or for the whole thing at once:

map(lambda s:s.strip(), string.split(','))

That's basically everything you need.

MySQL Error 1093 - Can't specify target table for update in FROM clause

try this

DELETE FROM story_category 
WHERE category_id NOT IN (
FROM (SELECT * FROM STORY_CATEGORY) sc; - Add blank item at top of dropdownlist

Like "Whisk" Said, the trick is in "AppendDataBoundItems" property

protected void Page_Load(object sender, EventArgs e)
    if (!IsPostBack)
        DropDownList1.AppendDataBoundItems = true;
        DropDownList1.Items.Insert(0, new ListItem(String.Empty, String.Empty));
        DropDownList1.SelectedIndex = 0;

Thanks "Whisk"

Windows- Pyinstaller Error "failed to execute script " When App Clicked

I got the same error and figured out that i wrote my script using Anaconda but pyinstaller tries to pack script on pure python. So, modules not exist in pythons library folder cause this problem.

Creating watermark using html and css

Other solutions are great but they didn't take care of the fact that watermark shouldn't get selected on selection from the mouse. This fiddle takes care or that:

This will be better option for pdf or static html.


#watermark {
  opacity: 0.2;
  font-size: 52px;
  color: 'black';
  background: '#ccc';
  position: absolute;
  cursor: default;
  user-select: none;
  -webkit-user-select: none;
  -khtml-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  right: 5px;
  bottom: 5px;

Iterating through all the cells in Excel VBA or VSTO 2005

My VBA skills are a little rusty, but this is the general idea of what I'd do.
The easiest way to do this would be to iterate through a loop for every column:

public sub CellProcessing()
on error goto errHandler

    dim MAX_ROW as Integer   'how many rows in the spreadsheet
    dim i as Integer
    dim cols as String

    for i = 1 to MAX_ROW
        'perform checks on the cell here
        'access the cell with Range("A" & i) to get cell A1 where i = 1
    next i

    exit sub
    msgbox "Error " & err.Number & ": " & err.Description
    resume exitHandler
end sub

it seems that the color syntax highlighting doesn't like vba, but hopefully this will help somewhat (at least give you a starting point to work from).

  • Brisketeer

Get changes from master into branch in Git

You can also do this by running a single line.
git merge aq master

This is equivalent to

git checkout aq
git merge master

JPA and Hibernate - Criteria vs. JPQL or HQL

I also prefer Criteria Queries for dynamic queries. But I prefer hql for delete queries, for example if delete all records from child table for parent id 'xyz', It is easily achieved by HQL, but for criteria API first we must fire n number of delete query where n is number of child table records.

Big-O summary for Java Collections Framework implementations?

The book Java Generics and Collections has this information (pages: 188, 211, 222, 240).

List implementations:

                      get  add  contains next remove(0) iterator.remove
ArrayList             O(1) O(1) O(n)     O(1) O(n)      O(n)
LinkedList            O(n) O(1) O(n)     O(1) O(1)      O(1)
CopyOnWrite-ArrayList O(1) O(n) O(n)     O(1) O(n)      O(n)

Set implementations:

                      add      contains next     notes
HashSet               O(1)     O(1)     O(h/n)   h is the table capacity
LinkedHashSet         O(1)     O(1)     O(1) 
CopyOnWriteArraySet   O(n)     O(n)     O(1) 
EnumSet               O(1)     O(1)     O(1) 
TreeSet               O(log n) O(log n) O(log n)
ConcurrentSkipListSet O(log n) O(log n) O(1)

Map implementations:

                      get      containsKey next     Notes
HashMap               O(1)     O(1)        O(h/n)   h is the table capacity
LinkedHashMap         O(1)     O(1)        O(1) 
IdentityHashMap       O(1)     O(1)        O(h/n)   h is the table capacity 
EnumMap               O(1)     O(1)        O(1) 
TreeMap               O(log n) O(log n)    O(log n) 
ConcurrentHashMap     O(1)     O(1)        O(h/n)   h is the table capacity 
ConcurrentSkipListMap O(log n) O(log n)    O(1)

Queue implementations:

                      offer    peek poll     size
PriorityQueue         O(log n) O(1) O(log n) O(1)
ConcurrentLinkedQueue O(1)     O(1) O(1)     O(n)
ArrayBlockingQueue    O(1)     O(1) O(1)     O(1)
LinkedBlockingQueue   O(1)     O(1) O(1)     O(1)
PriorityBlockingQueue O(log n) O(1) O(log n) O(1)
DelayQueue            O(log n) O(1) O(log n) O(1)
LinkedList            O(1)     O(1) O(1)     O(1)
ArrayDeque            O(1)     O(1) O(1)     O(1)
LinkedBlockingDeque   O(1)     O(1) O(1)     O(1)

The bottom of the javadoc for the java.util package contains some good links:

Adding calculated column(s) to a dataframe in pandas

The exact code will vary for each of the columns you want to do, but it's likely you'll want to use the map and apply functions. In some cases you can just compute using the existing columns directly, since the columns are Pandas Series objects, which also work as Numpy arrays, which automatically work element-wise for usual mathematical operations.

>>> d
    A   B  C
0  11  13  5
1   6   7  4
2   8   3  6
3   4   8  7
4   0   1  7
>>> (d.A + d.B) / d.C
0    4.800000
1    3.250000
2    1.833333
3    1.714286
4    0.142857
>>> d.A > d.C
0     True
1     True
2     True
3    False
4    False

If you need to use operations like max and min within a row, you can use apply with axis=1 to apply any function you like to each row. Here's an example that computes min(A, B)-C, which seems to be like your "lower wick":

>>> d.apply(lambda row: min([row['A'], row['B']])-row['C'], axis=1)
0    6
1    2
2   -3
3   -3
4   -7

Hopefully that gives you some idea of how to proceed.

Edit: to compare rows against neighboring rows, the simplest approach is to slice the columns you want to compare, leaving off the beginning/end, and then compare the resulting slices. For instance, this will tell you for which rows the element in column A is less than the next row's element in column C:

d['A'][:-1] < d['C'][1:]

and this does it the other way, telling you which rows have A less than the preceding row's C:

d['A'][1:] < d['C'][:-1]

Doing ['A"][:-1] slices off the last element of column A, and doing ['C'][1:] slices off the first element of column C, so when you line these two up and compare them, you're comparing each element in A with the C from the following row.

How to get english language word database?

You didn't say what you needed this list for. If something used as a blacklist for password checks is enough cracklib might be good for you. It contains over 1.5M words.

Chart.js - Formatting Y axis

As Nevercom said the scaleLable should contain javascript so to manipulate the y value just apply the required formatting.

Note the the value is a string.

var options = {      
    scaleLabel : "<%= value + ' + two = ' + (Number(value) + 2)   %>"

jsFiddle example

if you wish to set a manual y scale you can use scaleOverride

var options = {      
    scaleLabel : "<%= value + ' + two = ' + (Number(value) + 2)   %>",

    scaleOverride: true,
    scaleSteps: 10,
    scaleStepWidth: 10,
    scaleStartValue: 0


jsFiddle example

Error LNK2019: Unresolved External Symbol in Visual Studio

When you have everything #included, an unresolved external symbol is often a missing * or & in the declaration or definition of a function.

Android Studio not showing modules in project structure

Check settings.gradle. You'll find this : include ':app'

Just add your own module name and it should look like this :

include ':app', ':yourModuleName'


That's it.

Serialize Class containing Dictionary member

There is a solution at Paul Welter's Weblog - XML Serializable Generic Dictionary

For some reason, the generic Dictionary in .net 2.0 is not XML serializable. The following code snippet is a xml serializable generic dictionary. The dictionary is serialzable by implementing the IXmlSerializable interface.

using System;
using System.Collections.Generic;
using System.Text;
using System.Xml.Serialization;

public class SerializableDictionary<TKey, TValue>
    : Dictionary<TKey, TValue>, IXmlSerializable
    public SerializableDictionary() { }
    public SerializableDictionary(IDictionary<TKey, TValue> dictionary) : base(dictionary) { }
    public SerializableDictionary(IDictionary<TKey, TValue> dictionary, IEqualityComparer<TKey> comparer) : base(dictionary, comparer) { }
    public SerializableDictionary(IEqualityComparer<TKey> comparer) : base(comparer) { }
    public SerializableDictionary(int capacity) : base(capacity) { }
    public SerializableDictionary(int capacity, IEqualityComparer<TKey> comparer) : base(capacity, comparer) { }

    #region IXmlSerializable Members
    public System.Xml.Schema.XmlSchema GetSchema()
        return null;

    public void ReadXml(System.Xml.XmlReader reader)
        XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
        XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));

        bool wasEmpty = reader.IsEmptyElement;

        if (wasEmpty)

        while (reader.NodeType != System.Xml.XmlNodeType.EndElement)

            TKey key = (TKey)keySerializer.Deserialize(reader);

            TValue value = (TValue)valueSerializer.Deserialize(reader);

            this.Add(key, value);


    public void WriteXml(System.Xml.XmlWriter writer)
        XmlSerializer keySerializer = new XmlSerializer(typeof(TKey));
        XmlSerializer valueSerializer = new XmlSerializer(typeof(TValue));

        foreach (TKey key in this.Keys)

            keySerializer.Serialize(writer, key);

            TValue value = this[key];
            valueSerializer.Serialize(writer, value);


How to Display Selected Item in Bootstrap Button Dropdown Title

Here is my version of this which I hope can save some of your time :)

enter image description here jQuery PART:

$(".dropdown-menu").on('click', 'li a', function(){
  var selText = $(this).children("h4").html();



<div class="container">
  <div class="btn-group">
    <a class="btn btn-default dropdown-toggle btn-blog " data-toggle="dropdown" href="#" id="dropdownMenu1" style="width:200px;"><span class="selection pull-left">Select an option </span> 
      <span class="pull-right glyphiconglyphicon-chevron-down caret" style="float:right;margin-top:10px;"></span></a>

     <ul class="dropdown-menu" role="menu" aria-labelledby="dropdownMenu1">
       <li><a href="#" class="" data-value=1><p> HER Can you write extra text or <b>HTLM</b></p> <h4> <span class="glyphicon glyphicon-plane"></span>  <span> Your Option 1</span> </h4></a>  </li>
       <li><a href="#" class="" data-value=2><p> HER Can you write extra text or <i>HTLM</i> or some long long long long long long long long long long text </p><h4> <span class="glyphicon glyphicon-briefcase"></span> <span>Your Option 2</span>  </h4></a>
      <li class="divider"></li>
   <li><a href="#" class="" data-value=3><p> HER Can you write extra text or <b>HTLM</b> or some </p><h4> <span class="glyphicon glyphicon-heart text-danger"></span> <span>Your Option 3</span>  </h4></a>
  <input type="text" id="vl" />

Convert String with Dot or Comma as decimal separator to number in JavaScript

All the other solutions require you to know the format in advance. I needed to detect(!) the format in every case and this is what I end up with.

function detectFloat(source) {
    let float = accounting.unformat(source);
    let posComma = source.indexOf(',');
    if (posComma > -1) {
        let posDot = source.indexOf('.');
        if (posDot > -1 && posComma > posDot) {
            let germanFloat = accounting.unformat(source, ',');
            if (Math.abs(germanFloat) > Math.abs(float)) {
                float = germanFloat;
        } else {
            // source = source.replace(/,/g, '.');
            float = accounting.unformat(source, ',');
    return float;

This was tested with the following cases:

        const cases = {
            "0": 0,
            "10.12": 10.12,
            "222.20": 222.20,
            "-222.20": -222.20,
            "+222,20": 222.20,
            "-222,20": -222.20,
            "-2.222,20": -2222.20,
            "-11.111,20": -11111.20,

Suggestions welcome.

Common HTTPclient and proxy

Although this question is very old, but I see still there are no exact answer. I will try to answer the question here.

I believe the question in short here is how to set the proxy settings for the Apache commons HttpClient (org.apache.commons.httpclient.HttpClient).

Code snippet below should work :

HttpClient client = new HttpClient();
HostConfiguration hostConfiguration = client.getHostConfiguration();
hostConfiguration.setProxy("localhost", 8080);

Debugging WebSocket in Google Chrome

I'm just posting this since Chrome changes alot, and none of the answers were quite up to date.

  1. Open dev tools
  2. REFRESH YOUR PAGE (so that the WS connection is captured by the network tab)
  3. Click your request
  4. Click the "Frames" sub-tab
  5. You should see somthing like this:

enter image description here

How can you represent inheritance in a database?

Alternatively, consider using a document databases (such as MongoDB) which natively support rich data structures and nesting.

How to use ArrayList's get() method

ArrayList get(int index) method is used for fetching an element from the list. We need to specify the index while calling get method and it returns the value present at the specified index.

public Element get(int index)

Example : In below example we are getting few elements of an arraylist by using get method.

import java.util.ArrayList;
public class GetMethodExample {
   public static void main(String[] args) {
       ArrayList<String> al = new ArrayList<String>();
       al.add("white board");

       System.out.println("First element of the ArrayList: "+al.get(0));
       System.out.println("Third element of the ArrayList: "+al.get(2));
       System.out.println("Sixth element of the ArrayList: "+al.get(5));
       System.out.println("Fourth element of the ArrayList: "+al.get(3));


First element of the ArrayList: pen
Third element of the ArrayList: ink
Sixth element of the ArrayList: books
Fourth element of the ArrayList: notebook

How can I hide the Adobe Reader toolbar when displaying a PDF in the .NET WebBrowser control?

It appears the default setting for Adobe Reader X is for the toolbars not to be shown by default unless they are explicitly turned on by the user. And even when I turn them back on during a session, they don't show up automatically next time. As such, I suspect you have a preference set contrary to the default.

The state you desire, with the top and left toolbars not shown, is called "Read Mode". If you right-click on the document itself, and then click "Page Display Preferences" in the context menu that is shown, you'll be presented with the Adobe Reader Preferences dialog. (This is the same dialog you can access by opening the Adobe Reader application, and selecting "Preferences" from the "Edit" menu.) In the list shown in the left-hand column of the Preferences dialog, select "Internet". Finally, on the right, ensure that you have the "Display in Read Mode by default" box checked:

   Adobe Reader Preferences dialog

You can also turn off the toolbars temporarily by clicking the button at the right of the top toolbar that depicts arrows pointing to opposing corners:

   Adobe Reader Read Mode toolbar button

Finally, if you have "Display in Read Mode by default" turned off, but want to instruct the page you're loading not to display the toolbars (i.e., override the user's current preferences), you can append the following to the URL:


So, for example, the following code will disable both the top toolbar (called "toolbar") and the left-hand toolbar (called "navpane"). However, if the user knows the keyboard combination (F8, and perhaps other methods as well), they will still be able to turn them back on.

string url = @"";

You can read more about the parameters that are available for customizing the way PDF files open here on Adobe's developer website.

Reading Space separated input in python

Assuming you are on Python 3, you can use this syntax

inputs = list(map(str,input().split()))

if you want to access individual element you can do it like that

m, n = map(str,input().split())

Best way to get identity of inserted row?

I can't speak to other versions of SQL Server, but in 2012, outputting directly works just fine. You don't need to bother with a temporary table.

VALUES (...)

By the way, this technique also works when inserting multiple rows.




Laravel 4 with Sentry 2 add user to a group on Registration

Somehow, where you are using Sentry, you're not using its Facade, but the class itself. When you call a class through a Facade you're not really using statics, it's just looks like you are.

Do you have this:

use Cartalyst\Sentry\Sentry; 

In your code?

Ok, but if this line is working for you:

$user = $this->sentry->register(array(     'username' => e($data['username']),     'email' => e($data['email']),      'password' => e($data['password'])     )); 

So you already have it instantiated and you can surely do:

$adminGroup = $this->sentry->findGroupById(5); 

How to install Python package from GitHub?

You need to use the proper git URL:

pip install git+

Also see the VCS Support section of the pip documentation.

Don’t forget to include the egg=<projectname> part to explicitly name the project; this way pip can track metadata for it without having to have run the script.

Declaring functions in JSP?

You need to enclose that in <%! %> as follows:


public String getQuarter(int i){
String quarter;
        case 1: quarter = "Winter";

        case 2: quarter = "Spring";

        case 3: quarter = "Summer I";

        case 4: quarter = "Summer II";

        case 5: quarter = "Fall";

        default: quarter = "ERROR";

return quarter;


You can then invoke the function within scriptlets or expressions:



<%= getQuarter(17) %>

Get pixel's RGB using PIL

Not PIL, but imageio.imread might still be interesting:

import imageio
im = scipy.misc.imread('um_000000.png', flatten=False, mode='RGB')
im = imageio.imread('Figure_1.png', pilmode='RGB')


(480, 640, 3)

so it is (height, width, channels). So the pixel at position (x, y) is

color = tuple(im[y][x])
r, g, b = color


scipy.misc.imread is deprecated in SciPy 1.0.0 (thanks for the reminder, fbahr!)

How to install popper.js with Bootstrap 4?

Bootstrap 4 has two dependencies: jQuery 1.9.1 and popper.js 1.12.3. When you install Bootstrap 4, you need to install these two dependencies.

For Bootstrap 4.1

Explicit vs implicit SQL joins

Performance wise, it should not make any difference. The explicit join syntax seems cleaner to me as it clearly defines relationships between tables in the from clause and does not clutter up the where clause.

how to get the one entry from hashmap without iterating

This would get a single entry from the map, which about as close as one can get, given 'first' doesn't really apply.

import java.util.*;

public class Friday {
    public static void main(String[] args) {
        Map<String, Integer> map = new HashMap<String, Integer>();

        map.put("code", 10);
        map.put("to", 11);
        map.put("joy", 12);

        if (! map.isEmpty()) {
            Map.Entry<String, Integer> entry = map.entrySet().iterator().next();

Center content vertically on Vuetify

For me, align="center" was enough to center FOO vertically:

<v-row align="center">

How to hide form code from view code/inspect element browser?

You simply can't.

Code inspectors are designed for debugging HTML and Javascript. They do so by showing the live DOM object of the web page. That means it reveals HTML code of everything you see on the page, even if they're generated by Javascript. Some inspectors even shows the code inside iframes.

How about some javascript to disable keyboard / mouse interaction...

There are some javascript tricks to disable some keyboard, mouse interaction on the page. But there always are work around to those tricks. For instance, you can use the browser top menu to enable DOM inspector without a problem.

Try theses:

They are outside the control of Javascripts.

Big Picture

Think about this:

  1. Everything on a web page is rendered by the browser, so they are of a lower abstraction level than your Javascripts. They are "guarding all the doors and holding all the keys".
  2. Browsers want web sites to properly work on them or their users would despise them.
  3. As a result, browsers want to expose the lower level ticks of everything to the web developers with tools like code inspectors.

Basically, browsers are god to your Javascript. And they want to grant the web developer super power with code inspectors. Even if your trick works for a while, the browsers would want to undo it in the future.

You're waging war against god and you're doomed to fail.


To put it simple, if you do not want people to get something in their browser, you should never send it to their browser in the first place.


CLOCK_REALTIME is affected by NTP, and can move forwards and backwards. CLOCK_MONOTONIC is not, and advances at one tick per tick.

Cannot instantiate the type List<Product>

Use a concrete list type, e.g. ArrayList instead of just List.

PHP fwrite new line

fwrite($handle, "<br>"."\r\n");

Add this under

$password = $_POST['password'].PHP_EOL;

this. .

Specifying an Index (Non-Unique Key) Using JPA

In JPA 2.1 you need to do the following

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Index;
import javax.persistence.Table;

    indexes = {
       @Index(name = "PERSON_INDX_0", columnList = "age"),
       @Index(name = "PERSON_INDX_1", columnList = "fName"),
       @Index(name = "PERSON_INDX_1", columnList = "sName")  })
public class TestPerson {

    @Column(name = "age", nullable = false)
    private int age;

    @Column(name = "fName", nullable = false)
    private String firstName;

    @Column(name = "sName", nullable = false)
    private String secondName;

    private long id;

    public TestPerson() {

In the above example the table TEST_PERSON will have 3 indexes:

  • unique index on the primary key ID

  • index on AGE

  • compound index on FNAME, SNAME

Note 1: You get the compound index by having two @Index annotations with the same name

Note 2: You specify the column name in the columnList not the fieldName

Output array to CSV in Ruby

To a file:

require 'csv'"myfile.csv", "w") do |csv|
  csv << ["row", "of", "CSV", "data"]
  csv << ["another", "row"]
  # ...

To a string:

require 'csv'
csv_string = CSV.generate do |csv|
  csv << ["row", "of", "CSV", "data"]
  csv << ["another", "row"]
  # ...

Here's the current documentation on CSV:

python-How to set global variables in Flask?


global index_add_counter

You are not defining, just declaring so it's like saying there is a global index_add_counter variable elsewhere, and not create a global called index_add_counter. As you name don't exists, Python is telling you it can not import that name. So you need to simply remove the global keyword and initialize your variable:

index_add_counter = 0

Now you can import it with:

from app import index_add_counter

The construction:

global index_add_counter

is used inside modules' definitions to force the interpreter to look for that name in the modules' scope, not in the definition one:

index_add_counter = 0
def test():
  global index_add_counter # means: in this scope, use the global name

Cannot connect to repo with TortoiseSVN

SVN is case-sensitive. Make sure that you're spelling it properly. If it got renamed, you can relocate the working folder to the new URL. See

Execute a file with arguments in Python shell

import sys
import subprocess[sys.executable, '', 'argument1', 'argument2'])

Install mysql-python (Windows)

If you encounter the problem with missing MS VC 14 Build tools while trying pip install mysqlclient a possible solution for this may be

How to develop a soft keyboard for Android?

Some tips:

About your questions:

An inputMethod is basically an Android Service, so yes, you can do HTTP and all the stuff you can do in a Service.

You can open Activities and dialogs from the InputMethod. Once again, it's just a Service.

I've been developing an IME, so ask again if you run into an issue.

JavaScript - Get Browser Height

var winWidth = window.screen.width;
var winHeight = window.screen.height;

document.write(winWidth, winHeight);

Is it possible to reference one CSS rule within another?

You can't unless you're using some kind of extended CSS such as SASS. However it is very reasonable to apply those two extra classes to .someDiv.

If .someDiv is unique I would also choose to give it an id and referencing it in css using the id.

Starting iPhone app development in Linux?

The answer to this really depends on whether or not you want to develop apps that are then distributed through the iPhone store. If you don't, and don't mind developing for the "jailbroken" iPhone crowd - then it's possible to develop from Linux.

Check this chap's page for a comprehensive (if a little complex) guide on what to do :

How to sign in kubernetes dashboard?

Combining two answers: 49992698 and 47761914 :

# Create service account
kubectl create serviceaccount -n kube-system cluster-admin-dashboard-sa

# Bind ClusterAdmin role to the service account
kubectl create clusterrolebinding -n kube-system cluster-admin-dashboard-sa \
  --clusterrole=cluster-admin \

# Parse the token
TOKEN=$(kubectl describe secret -n kube-system $(kubectl get secret -n kube-system | awk '/^cluster-admin-dashboard-sa-token-/{print $1}') | awk '$1=="token:"{print $2}')

How to upgrade rubygems

You can update all gems by just performing:

sudo gem update

How to upgrade PowerShell version from 2.0 to 3.0

Download and install from You need Windows 7 SP1 though.

It's worth keeping in mind that PowerShell 3 on Windows 7 does not have all the cmdlets as PowerShell 3 on Windows 8. So you may still encounter cmdlets that are not present on your system.

"pip install unroll": "python egg_info" failed with error code 1

I had this problem using virtualenvs (with pipenv) on my new development setup.

I could only solve it by upgrading the psycopg2 version from 2.6.2 to 2.7.3. More information is at

How to use BufferedReader in Java

Try this to read a file:

BufferedReader reader = null;

try {
    File file = new File("sample-file.dat");
    reader = new BufferedReader(new FileReader(file));

    String line;
    while ((line = reader.readLine()) != null) {

} catch (IOException e) {
} finally {
    try {
    } catch (IOException e) {

Apple Cover-flow effect using jQuery or other library?

Try Jquery Interface Elements here -

Here's a sample.

I looked around for a Jquery image carousel a few months ago and didn't find a good one so I gave up. This one was the best I could find.

Which ChromeDriver version is compatible with which Chrome Browser version?

In case of mine, I solved it just by npm install protractor@latest -g and npm install webdriver-manager@latest. I am using chrome 80.x version. It worked for me in both Angular 4 & 6

ASP.NET MVC Razor: How to render a Razor Partial View's HTML inside the controller action

You could also use the RenderView Controller extension from here (source)

and use it like this:

public ActionResult Do() {
var html = this.RenderView("index", theModel);

it works for razor and web-forms viewengines

An implementation of the fast Fourier transform (FFT) in C#

For a multi-threaded implementation tuned for Intel processors I'd check out Intel's MKL library. It's not free, but it's afforable (less than $100) and blazing fast - but you'd need to call it's C dll's via P/Invokes. The Exocortex project stopped development 6 years ago, so I'd be careful using it if this is an important project.

Retaining file permissions with Git

I am running on FreeBSD 11.1, the freebsd jail virtualization concept makes the operating system optimal. The current version of Git I am using is 2.15.1, I also prefer to run everything on shell scripts. With that in mind I modified the suggestions above as followed:

git push: .git/hooks/pre-commit

#! /bin/sh -
# A hook script called by "git commit" with no arguments. The hook should
# exit with non-zero status after issuing an appropriate message if it wants
# to stop the commit.

SELF_DIR=$(git rev-parse --show-toplevel);

# Clear the permissions database file

printf "Backing-up file permissions...\n";

for FILE in $(git ls-files);
   # Save the permissions of all the files in the index
    printf "%s;%s\n" $FILE $(stat -f "%Lp;%u;%g" $FILE) >> $DATABASE;

# Add the permissions database file to the index
git add $DATABASE;

printf "OK\n";

git pull: .git/hooks/post-merge

#! /bin/sh -

SELF_DIR=$(git rev-parse --show-toplevel);

printf "Restoring file permissions...\n";

while read -r LINE || [ -n "$LINE" ];
   FILE=$(printf "%s" $LINE | cut -d ";" -f 1);
   PERMISSIONS=$(printf "%s" $LINE | cut -d ";" -f 2);
   USER=$(printf "%s" $LINE | cut -d ";" -f 3);
   GROUP=$(printf "%s" $LINE | cut -d ";" -f 4);

   # Set the file permissions

   # Set the file owner and groups
   chown $USER:$GROUP $FILE;

done < $DATABASE

pritnf "OK\n";

exit 0;

If for some reason you need to recreate the script the .permissions file output should have the following format:


For a .gitignore file with 644 permissions given to root:wheel

Notice I had to make a few changes to the stat options.


Where can I find the TypeScript version installed in Visual Studio?

As far as I understand VS has nothing to do with TS installed by NPM. (You may notice after you install TS using NPM, there is no tsc.exe file). VS targets only tsc.exe installed by TS for VS extension, which installes TS to c:\Program Files (x86)\Microsoft SDKs\TypeScript\X.Y. You may have multiple folders under c:\Program Files (x86)\Microsoft SDKs\TypeScript. Set TypeScriptToolsVersion to the highest version installed. In my case I had folders "1.0", "1.7", "1.8", so I set TypeScriptToolsVersion = 1.8, and if you run tsc - v inside that folder you will get 1.8.3 or something, however, when u run tsc outside that folder, it will use PATH variable pointing to TS version installed by NPM, which is in my case 1.8.10. I believe TS for VS will always be a little behind the latest version of TS you install using NPM. But as far as I understand, VS doesnt know anything about TS installed by NPM, it only targets whateve versions installed by TS for VS extensions, and the version specified in TypeScriptToolsVersion in your project file.

How to get the selected radio button’s value?

I like to use brackets to get value from input, its way more clear than using dots.


How to use ADB to send touch events to device using sendevent command?

Android comes with an input command-line tool that can simulate miscellaneous input events. To simulate tapping, it's:

input tap x y

You can use the adb shell ( > 2.3.5) to run the command remotely:

adb shell input tap x y

How to pass in password to pg_dump?

Correct me if I'm wrong, but if the system user is the same as the database user, PostgreSQL won't ask for the password - it relies on the system for authentication. This might be a matter of configuration.

Thus, when I wanted the database owner postgres to backup his databases every night, I could create a crontab for it: crontab -e -u postgres. Of course, postgres would need to be allowed to execute cron jobs; thus it must be listed in /etc/cron.allow, or /etc/cron.deny must be empty.

Find the min/max element of an array in JavaScript

if you have complex object, you could use sort....such as: if I want get item which contains MAX/MIN value of below objs.

var objs= [

I will do a sort:

objs.sort(function(a, b){return a.value-b.value});

Then: objs[0] is the MIN, objs[objs.length-1] is the MAX.

Hashing a file in Python

I have programmed a module wich is able to hash big files with different algorithms.

pip3 install py_essentials

Use the module like this:

from py_essentials import hashing as hs
hash = hs.fileChecksum("path/to/the/file.txt", "sha256")

Better way to set distance between flexbox items

You can use & > * + * as a selector to emulate a flex-gap (for a single line):

#box { display: flex; width: 230px; outline: 1px solid blue; }_x000D_
.item { background: gray; width: 50px; height: 100px; }_x000D_
/* ----- Flexbox gap: ----- */_x000D_
#box > * + * {_x000D_
  margin-left: 10px;_x000D_
<div id='box'>_x000D_
    <div class='item'></div>_x000D_
    <div class='item'></div>_x000D_
    <div class='item'></div>_x000D_
    <div class='item'></div>_x000D_

If you need to support flex wrapping, you can use a wrapper element:

.flex { display: flex; flex-wrap: wrap;  }_x000D_
.box { background: gray; height: 100px; min-width: 100px; flex: auto; }_x000D_
.flex-wrapper {outline: 1px solid red; }_x000D_
/* ----- Flex gap 10px: ----- */_x000D_
.flex > * {_x000D_
  margin: 5px;_x000D_
.flex {_x000D_
  margin: -5px;_x000D_
.flex-wrapper {_x000D_
  width: 400px; /* optional */_x000D_
  overflow: hidden; /* optional */_x000D_
<div class='flex-wrapper'>_x000D_
  <div class='flex'>_x000D_
    <div class='box'></div>_x000D_
    <div class='box'></div>_x000D_
    <div class='box'></div>_x000D_
    <div class='box'></div>_x000D_
    <div class='box'></div>_x000D_

Missing MVC template in Visual Studio 2015

I don't think the accepted answer works anymore. According to Microsoft here, here, and here, has been re-branded to ASP.Net Core. It looks like they've taken down the templates from the general ASP.Net Web Application project type. But now there's a new project type of ASP.Net Core Web Application. enter image description hereI don't see an MVC template for this project type, but I don't think the Core framework has been completely released yet.

UIView Infinite 360 degree rotation animation?

I has developed a shiny animation framework which can save you tone of time! Using it this animation can be created very easily:

private var endlessRotater: EndlessAnimator!
override func viewDidAppear(animated: Bool) 
    let rotationAnimation = AdditiveRotateAnimator(M_PI).to(targetView).duration(2.0).baseAnimation(.CurveLinear)
    endlessRotater = EndlessAnimator(rotationAnimation)

to stop this animation simply set nil to endlessRotater.

If you are interested, please take a look:

Cannot read property 'getContext' of null, using canvas

Put your JavaScript code after your tag <canvas></canvas>

HTML encoding issues - "Â" character showing up instead of "&nbsp;"

In my case this (a with caret) occurred in code I generated from visual studio using my own tool for generating code. It was easy to solve:

Select single spaces ( ) in the document. You should be able to see lots of single spaces that are looking different from the other single spaces, they are not selected. Select these other single spaces - they are the ones responsible for the unwanted characters in the browser. Go to Find and Replace with single space ( ). Done.

PS: It's easier to see all similar characters when you place the cursor on one or if you select it in VS2017+; I hope other IDEs may have similar features

Angularjs on page load call function

<section ng-controller="testController as ctrl" class="test_cls"  data-ng-init="fn_load()">

$scope.fn_load = function () {
  console.log("page load")

Get URL of ASP.Net Page in code-behind

Request.Url.GetLeftPart(UriPartial.Authority) + Request.FilePath + "?theme=blue";

that will give you the full path to the page you are sitting on. I added in the querystring.

$(document).click() not working correctly on iPhone. jquery

Adding in the following code works.

The problem is iPhones dont raise click events. They raise "touch" events. Thanks very much apple. Why couldn't they just keep it standard like everyone else? Anyway thanks Nico for the tip.

Credit to:

$(document).ready(function () {
  $(document).click(function (e) {

function fire(e) { alert('hi'); }

function touchHandler(event)
    var touches = event.changedTouches,
        first = touches[0],
        type = "";

       case "touchstart": type = "mousedown"; break;
       case "touchmove":  type = "mousemove"; break;        
       case "touchend":   type = "mouseup"; break;
       default: return;

    //initMouseEvent(type, canBubble, cancelable, view, clickCount, 
    //           screenX, screenY, clientX, clientY, ctrlKey, 
    //           altKey, shiftKey, metaKey, button, relatedTarget);

    var simulatedEvent = document.createEvent("MouseEvent");
    simulatedEvent.initMouseEvent(type, true, true, window, 1, 
                          first.screenX, first.screenY, 
                          first.clientX, first.clientY, false, 
                          false, false, false, 0/*left*/, null);;

function init() 
    document.addEventListener("touchstart", touchHandler, true);
    document.addEventListener("touchmove", touchHandler, true);
    document.addEventListener("touchend", touchHandler, true);
    document.addEventListener("touchcancel", touchHandler, true);    

Is there a minlength validation attribute in HTML5?

I wrote this JavaScript code, [minlength.js]:

window.onload = function() {
    function testaFunction(evt) {
        var elementos = this.elements;
        for (var j = 0; j < elementos.length; j++) {
            if (elementos[j].tagName == "TEXTAREA" && elementos[j].hasAttribute("minlength")) {
                if (elementos[j].value.length < elementos[j].getAttribute("minlength")) {
                    alert("The textarea control must be at least " + elementos[j].getAttribute("minlength") + " characters.");
    var forms = document.getElementsByTagName("form");
    for(var i = 0; i < forms.length; i++) {
        forms[i].addEventListener('submit', testaFunction, true);

Mockito : doAnswer Vs thenReturn

You should use thenReturn or doReturn when you know the return value at the time you mock a method call. This defined value is returned when you invoke the mocked method.

thenReturn(T value) Sets a return value to be returned when the method is called.

public void test_return() throws Exception {
    Dummy dummy = mock(Dummy.class);
    int returnValue = 5;

    // choose your preferred way

Answer is used when you need to do additional actions when a mocked method is invoked, e.g. when you need to compute the return value based on the parameters of this method call.

Use doAnswer() when you want to stub a void method with generic Answer.

Answer specifies an action that is executed and a return value that is returned when you interact with the mock.

public void test_answer() throws Exception {
    Dummy dummy = mock(Dummy.class);
    Answer<Integer> answer = new Answer<Integer>() {
        public Integer answer(InvocationOnMock invocation) throws Throwable {
            String string = invocation.getArgumentAt(0, String.class);
            return string.length() * 2;

    // choose your preferred way

SQL Server Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >=

The select statement in the cost part of your select is returning more than one value. You need to add more where clauses, or use an aggregation. Is there a way to auto indent / format <html>

I found an add-on for that uses auto-indent called Indentator.
It uses shortcut keys Ctrl + Alt + I

Reporting Services export to Excel with Multiple Worksheets

As @huttelihut pointed out, this is now possible as of SQL Server 2008 R2 - Read More Here

Prior to 2008 R2 it does't appear possible but MSDN Social has some suggested workarounds.

How to get the size of a varchar[n] field in one SQL statement?

For SQL Server (2008 and above):


COLUMNPROPERTY returns information for a column or parameter (id, column/parameter, property). The PRECISION property returns the length of the data type of the column or parameter.

COLUMNPROPERTY documentation

Oracle timestamp data type

Quite simply the number is the precision of the timestamp, the fraction of a second held in the column:

SQL> create table t23
  2  (ts0 timestamp(0)
  3   , ts3 timestamp(3)
  4  , ts6 timestamp(6)
  5  )
  6  /

Table created.

SQL> insert into t23 values (systimestamp, systimestamp, systimestamp)
  2  /

1 row created.

SQL> select * from t23
  2  /

24-JAN-12 05.57.12 AM
24-JAN-12 AM
24-JAN-12 AM


If we don't specify a precision then the timestamp defaults to six places.

SQL> alter table t23 add ts_def timestamp;

Table altered.

SQL> update t23      
  2  set ts_def = systimestamp
  3  /

1 row updated.

SQL> select * from t23
  2  /

24-JAN-12 05.57.12 AM
24-JAN-12 AM
24-JAN-12 AM
24-JAN-12 AM


Note that I'm running on Linux so my TIMESTAMP column actually gives me precision to six places i.e. microseconds. This would also be the case on most (all?) flavours of Unix. On Windows the limit is three places i.e. milliseconds. (Is this still true of the most modern flavours of Windows - citation needed).

As might be expected, the documentation covers this. Find out more.

"when you create timestamp(9) this gives you nanos right"

Only if the OS supports it. As you can see, my OEL appliance does not:

SQL> alter table t23 add ts_nano timestamp(9)
  2  /

Table altered.

SQL> update t23 set ts_nano = systimestamp(9)
  2  /

1 row updated.

SQL> select * from t23
  2  /

24-JAN-12 05.57.12 AM
24-JAN-12 AM
24-JAN-12 AM
24-JAN-12 AM
24-JAN-12 AM


(Those trailing zeroes could be a coincidence but they aren't.)

Convert Pandas column containing NaNs to dtype `int`

Assuming your DateColumn formatted 3312018.0 should be converted to 03/31/2018 as a string. And, some records are missing or 0.

df['DateColumn'] = df['DateColumn'].astype(int)
df['DateColumn'] = df['DateColumn'].astype(str)
df['DateColumn'] = df['DateColumn'].apply(lambda x: x.zfill(8))
df.loc[df['DateColumn'] == '00000000','DateColumn'] = '01011980'
df['DateColumn'] = pd.to_datetime(df['DateColumn'], format="%m%d%Y")
df['DateColumn'] = df['DateColumn'].apply(lambda x: x.strftime('%m/%d/%Y'))

Get battery level and state in Android

Here is a code sample that explains how to get battery information.

To sum it up, a broadcast receiver for the ACTION_BATTERY_CHANGED intent is set up dynamically, because it can not be received through components declared in manifests, only by explicitly registering for it with Context.registerReceiver().

public class Main extends Activity {
  private TextView batteryTxt;
  private BroadcastReceiver mBatInfoReceiver = new BroadcastReceiver(){
    public void onReceive(Context ctxt, Intent intent) {
      int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
      int scale = intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
      float batteryPct = level * 100 / (float)scale;
      batteryTxt.setText(String.valueOf(batteryPct) + "%");

  public void onCreate(Bundle b) {
    batteryTxt = (TextView) this.findViewById(;
    this.registerReceiver(this.mBatInfoReceiver, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));

dropdownlist set selected value in MVC3 Razor

For anyone that dont want to or dont make sense to use dropdownlistfor, here is how I did it in jQuery with .NET MVC set up.

  1. Front end Javascript -> getting data from model:
    var settings = @Html.Raw(Json.Encode(Model.GlobalSetting.NotificationFrequencySettings)); 


    function SelectNotificationSettings(settings) {
                $.each(settings, function (i, value) {
                    $("#" + value.NotificationItemTypeId + " option[value=" + value.NotificationFrequencyTypeId + "]").prop("selected", true);
  1. In razor html, you going to have few dropdownlist
    notificationFrequencyOptions, optionLabel:=DbRes.T("Default", "CommonLabels"),
    htmlAttributes:=New With {.class = "form-control notification-item-type", .id = Convert.ToInt32(NotificationItemTypeEnum.GenerateSubscriptionNotification)})

And when page load, you js function is going to set the selected option based on value that's stored in @model.


Is it possible to create a temporary table in a View and drop it after select?

Try creating another SQL view instead of a temporary table and then referencing it in the main SQL view. In other words, a view within a view. You can then drop the first view once you are done creating the main view.

HTML5 Email Validation

A bit late for the party, but this regular expression helped me to validate email type input in the client side. Though, we should always do verification in server side also.

<input type="email" pattern="^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$">

You can find more regex of all kinds here.

How to change font size in html?

You can do this by setting a style in your paragraph tag. For example if you wanted to change the font size to 28px.

<p style="font-size: 28px;"> Hello, World! </p>

You can also set the color by setting:

<p style="color: blue;"> Hello, World! </p>

However, if you want to preview font sizes and colors (which I recommend doing) before you add them to your website and use them. I recommend testing them out beforehand so you pick a good font size and color that contrasts well with the background. I recommend using this site if you wish to do so, couldn't find anything else:

javascript create array from for loop

Remove obj and just do this inside your for loop:


Also, the i < yearEnd condition will not include the final year, so change it to i <= yearEnd.

Create new project on Android, Error: Studio Unknown host ''

I have same problem after update android studio to 1.5, and i fix it by update the gradle location,

  1. Go to File->Setting->Build, Execution, Deployment->Build Tools->Gradle
  2. Under Project level Setting find gradle directory

Hope this method works for you,

Using SVG as background image

You can try removing the width and height attributes on the svg root element, adding preserveAspectRatio="none" viewBox="0 0 1024 800" instead. It makes a difference in Opera at least, assuming you wanted the svg to stretch to fill the entire region defined by the CSS styles.

How to test if a string contains one of the substrings in a list, in pandas?

You can use str.contains alone with a regex pattern using OR (|):


Or you could add the series to a dataframe then use str.contains:

df = pd.DataFrame(s)


0 cat
1 hat
2 dog
3 fog 

psql: server closed the connection unexepectedly

Solved by setting a password for the user first.

In terminal

sudo -u <username> psql

ALTER USER <username> PASSWORD 'SetPassword';


In pgAdmin


Host name/address:
Port: 5432
Maintenance database: postgres
username: postgres
password: XXXXXX

Return current date plus 7 days

Here is how you can do it using strtotime(),

    $date = strtotime("3 October 2005");
    $d = strtotime("+7 day", $date);
    echo "Created date is " . date("Y-m-d h:i:sa", $d) . "<br>";

How can I plot with 2 different y-axes?

update: Copied material that was on the R wiki at, link now broken: also available from the wayback machine

Two different y axes on the same plot

(some material originally by Daniel Rajdl 2006/03/31 15:26)

Please note that there are very few situations where it is appropriate to use two different scales on the same plot. It is very easy to mislead the viewer of the graphic. Check the following two examples and comments on this issue (example1, example2 from Junk Charts), as well as this article by Stephen Few (which concludes “I certainly cannot conclude, once and for all, that graphs with dual-scaled axes are never useful; only that I cannot think of a situation that warrants them in light of other, better solutions.”) Also see point #4 in this cartoon ...

If you are determined, the basic recipe is to create your first plot, set par(new=TRUE) to prevent R from clearing the graphics device, creating the second plot with axes=FALSE (and setting xlab and ylab to be blank – ann=FALSE should also work) and then using axis(side=4) to add a new axis on the right-hand side, and mtext(...,side=4) to add an axis label on the right-hand side. Here is an example using a little bit of made-up data:

x <- 1:10
y <- rnorm(10)
## second data set on a very different scale
z <- runif(10, min=1000, max=10000) 
par(mar = c(5, 4, 4, 4) + 0.3)  # Leave space for z axis
plot(x, y) # first plot
par(new = TRUE)
plot(x, z, type = "l", axes = FALSE, bty = "n", xlab = "", ylab = "")
axis(side=4, at = pretty(range(z)))
mtext("z", side=4, line=3)

twoord.plot() in the plotrix package automates this process, as does doubleYScale() in the latticeExtra package.

Another example (adapted from an R mailing list post by Robert W. Baer):

## set up some fake test data
time <- seq(0,72,12)
betagal.abs <- c(0.05,0.18,0.25,0.31,0.32,0.34,0.35)
cell.density <- c(0,1000,2000,3000,4000,5000,6000)

## add extra space to right margin of plot within frame
par(mar=c(5, 4, 4, 6) + 0.1)

## Plot first set of data and draw its axis
plot(time, betagal.abs, pch=16, axes=FALSE, ylim=c(0,1), xlab="", ylab="", 
   type="b",col="black", main="Mike's test data")
axis(2, ylim=c(0,1),col="black",las=1)  ## las=1 makes horizontal labels
mtext("Beta Gal Absorbance",side=2,line=2.5)

## Allow a second plot on the same graph

## Plot the second plot and put axis scale on right
plot(time, cell.density, pch=15,  xlab="", ylab="", ylim=c(0,7000), 
    axes=FALSE, type="b", col="red")
## a little farther out (line=4) to make room for labels
mtext("Cell Density",side=4,col="red",line=4) 
axis(4, ylim=c(0,7000), col="red",col.axis="red",las=1)

## Draw the time axis
mtext("Time (Hours)",side=1,col="black",line=2.5)  

## Add Legend
legend("topleft",legend=c("Beta Gal","Cell Density"),

enter image description here

Similar recipes can be used to superimpose plots of different types – bar plots, histograms, etc..

RegEx match open tags except XHTML self-contained tags

Here is a PHP based parser that parses HTML using some ungodly regex. As the author of this project, I can tell you it is possible to parse HTML with regex, but not efficient. If you need a server-side solution (as I did for my wp-Typography WordPress plugin), this works.

How to stop mongo DB in one command

mongod --dbpath /path/to/your/db --shutdown

More info at official:

Clear MySQL query cache without restarting server

I believe you can use...


...if the user you're running as has reload rights. Alternatively, you can defragment the query cache via...


See the Query Cache Status and Maintenance section of the MySQL manual for more information.

Get Bitmap attached to ImageView

Bitmap bitmap = ((BitmapDrawable)image.getDrawable()).getBitmap();

How do I create the small icon next to the website tab for my site?

It is called favicon.ico and you can generate it from this site.

SDK location not found. Define location with sdk.dir in the file or with an ANDROID_HOME environment variable

In my case I was using linux and putting double quote around the path inside like

sdk.dir = "/root/Android/Sdk/"
export ANDROID_SDK_ROOT = "/root/Android/Sdk/"

So it should be

sdk.dir = /root/Android/Sdk/
export ANDROID_SDK_ROOT = /root/Android/Sdk/

and .bash_profile

enter image description here

How to use IntelliJ IDEA to find all unused code?

After you've run the Inspect by Name, select all the locations, and make use of the Apply quick fixes to all the problems drop-down, and use either (or both) of Delete unused parameter(s) and Safe Delete.

Don't forget to hit Do Refactor afterwards.

Then you'll need to run another analysis, as the refactored code will no doubt reveal more unused declarations.

Apply quick fixes to all the problems

Adding blank spaces to layout

Just add weightSum tag to linearlayout to 1 and for the corresponding view beneath it give layout_weight as .9 it will create a space between the views. You can experiment with the values to get appropriate value for you.

ORA-00972 identifier is too long alias column name

The error is also caused by quirky handling of quotes and single qutoes. To include single quotes inside the query, use doubled single quotes.

This won't work

select dbms_xmlgen.getxml("Select ....") XML from dual;

or this either

select dbms_xmlgen.getxml('Select .. where something='red'..') XML from dual;

but this DOES work

select dbms_xmlgen.getxml('Select .. where something=''red''..') XML from dual;

NumPy ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

try this=> numpy.array(yourvariable) followed by the command to compare, whatever you wish to.

Taking pictures with camera on Android programmatically

Intent takePhoto = new Intent("");
startActivityForResult(takePhoto, CAMERA_PIC_REQUEST)

and set CAMERA_PIC_REQUEST= 1 or 0

How large should my recv buffer be when calling recv in the socket library

For streaming protocols such as TCP, you can pretty much set your buffer to any size. That said, common values that are powers of 2 such as 4096 or 8192 are recommended.

If there is more data then what your buffer, it will simply be saved in the kernel for your next call to recv.

Yes, you can keep growing your buffer. You can do a recv into the middle of the buffer starting at offset idx, you would do:

recv(socket, recv_buffer + idx, recv_buffer_size - idx, 0);

Creating a singleton in Python

You probably never need a singleton in Python. Just define all your data and functions in a module and you have a de facto singleton:

import datetime

def set_file_name(new_file_name: str):
    global file_name

def write(message: str):
    global file_name
    if file_name:
        with open(file_name, 'a+') as f:
            f.write("{} {}\n".format(, message))
        print("LOG: {}", message)

To use:

    import log
    log.write("System starting")

If you really absolutely have to have a singleton class then I'd go with:

    class My_Singleton(object):
        def foo(self):

    my_singleton = My_Singleton()

To use:

    from mysingleton import my_singleton

where is your filename that My_Singleton is defined in. This works because after the first time a file is imported, Python doesn't re-execute the code.

How to solve Notice: Undefined index: id in C:\xampp\htdocs\invmgt\manufactured_goods\change.php on line 21

You are not getting value of $id=$_GET['id'];

And you are using it (before it gets initialised).

Use php's in built isset() function to check whether the variable is defied or not.

So, please update the line to:

$id = isset($_GET['id']) ? $_GET['id'] : '';

Regular expression for decimal number


It allows:




?: ?? Operators Instead Of IF|ELSE

The ternary operator RETURNS one of two values. Or, it can execute one of two statements based on its condition, but that's generally not a good idea, as it can lead to unintended side-effects.

bar ? () : baz();

In this case, the () does nothing, while baz does something. But you've only made the code less clear. I'd go for more verbose code that's clearer and easier to maintain.

Further, this makes little sense at all:

var foo = bar ? () : baz();

since () has no return type (it's void) and baz has a return type that's unknown at the point of call in this sample. If they don't agree, the compiler will complain, and loudly.

An invalid XML character (Unicode: 0xc) was found

There are a few characters that are dissallowed in XML documents, even when you encapsulate data in CDATA-blocks.

If you generated the document you will need to entity encode it or strip it out. If you have an errorneous document, you should strip away these characters before trying to parse it.

See dolmens answer in this thread: Invalid Characters in XML

Where he links to this article:

Basically, all characters below 0x20 is disallowed, except 0x9 (TAB), 0xA (CR?), 0xD (LF?)