Programs & Examples On #Map projections

A map-projection transforms the coordinates of the spherical earth to a flat map in cartesian (x,y) space.

pod has unbound PersistentVolumeClaims

You have to define a PersistentVolume providing disc space to be consumed by the PersistentVolumeClaim.

When using storageClass Kubernetes is going to enable "Dynamic Volume Provisioning" which is not working with the local file system.

To solve your issue:

  • Provide a PersistentVolume fulfilling the constraints of the claim (a size >= 100Mi)
  • Remove the storageClass-line from the PersistentVolumeClaim
  • Remove the StorageClass from your cluster

How do these pieces play together?

At creation of the deployment state-description it is usually known which kind (amount, speed, ...) of storage that application will need.
To make a deployment versatile you'd like to avoid a hard dependency on storage. Kubernetes' volume-abstraction allows you to provide and consume storage in a standardized way.

The PersistentVolumeClaim is used to provide a storage-constraint alongside the deployment of an application.

The PersistentVolume offers cluster-wide volume-instances ready to be consumed ("bound"). One PersistentVolume will be bound to one claim. But since multiple instances of that claim may be run on multiple nodes, that volume may be accessed by multiple nodes.

A PersistentVolume without StorageClass is considered to be static.

"Dynamic Volume Provisioning" alongside with a StorageClass allows the cluster to provision PersistentVolumes on demand. In order to make that work, the given storage provider must support provisioning - this allows the cluster to request the provisioning of a "new" PersistentVolume when an unsatisfied PersistentVolumeClaim pops up.

Example PersistentVolume

In order to find how to specify things you're best advised to take a look at the API for your Kubernetes version, so the following example is build from the API-Reference of K8S 1.17:

apiVersion: v1
kind: PersistentVolume
  name: ckan-pv-home
    type: local
    storage: 100Mi
    path: "/mnt/data/ckan"

The PersistentVolumeSpec allows us to define multiple attributes. I chose a hostPath volume which maps a local directory as content for the volume. The capacity allows the resource scheduler to recognize this volume as applicable in terms of resource needs.

Additional Resources:

How to select label for="XYZ" in CSS?

If the label immediately follows a specified input element:

input#example + label { ... }
input:checked + label { ... }

Validate email with a regex in jQuery

This : /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$/i is not working for below Gmail case

[email protected] [email protected]

Below Regex will cover all the E-mail Points: I have tried the all Possible Points and my Test case get also pass because of below regex

I found this Solution from this URL:

Regex Solution link


Vertical alignment of text and icon in button

There is one rule that is set by font-awesome.css, which you need to override.

You should set overrides in your CSS files rather than inline, but essentially, the icon-ok class is being set to vertical-align: baseline; by default and which I've corrected here:

<button id="whatever" class="btn btn-large btn-primary" name="Continue" type="submit">
    <i class="icon-ok" style="font-size:30px; vertical-align: middle;"></i>

Example here: and the output of which is:

enter image description here

I've downsized the font-size of the icon above in this instance to 30px, as it feels too big at 40px for the size of the button, but this is purely a personal viewpoint. You could increase the padding on the button to compensate if required:

<button id="whaever" class="btn btn-large btn-primary" style="padding: 20px;" name="Continue" type="submit">
    <i class="icon-ok" style="font-size:30px; vertical-align: middle;"></i>

Producing: the output of which is:

enter image description here

Zoom to fit: PDF Embedded in HTML

just in case someone need it, in firefox for me it work like this

<iframe src="filename.pdf#zoom=FitH" style="position:absolute;right:0; top:0; bottom:0; width:100%;"></iframe>

Difference between abstract class and interface in Python

What is the difference between abstract class and interface in Python?

An interface, for an object, is a set of methods and attributes on that object.

In Python, we can use an abstract base class to define and enforce an interface.

Using an Abstract Base Class

For example, say we want to use one of the abstract base classes from the collections module:

import collections
class MySet(collections.Set):

If we try to use it, we get an TypeError because the class we created does not support the expected behavior of sets:

>>> MySet()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Can't instantiate abstract class MySet with abstract methods
__contains__, __iter__, __len__

So we are required to implement at least __contains__, __iter__, and __len__. Let's use this implementation example from the documentation:

class ListBasedSet(collections.Set):
    """Alternate set implementation favoring space over speed
    and not requiring the set elements to be hashable. 
    def __init__(self, iterable):
        self.elements = lst = []
        for value in iterable:
            if value not in lst:
    def __iter__(self):
        return iter(self.elements)
    def __contains__(self, value):
        return value in self.elements
    def __len__(self):
        return len(self.elements)

s1 = ListBasedSet('abcdef')
s2 = ListBasedSet('defghi')
overlap = s1 & s2

Implementation: Creating an Abstract Base Class

We can create our own Abstract Base Class by setting the metaclass to abc.ABCMeta and using the abc.abstractmethod decorator on relevant methods. The metaclass will be add the decorated functions to the __abstractmethods__ attribute, preventing instantiation until those are defined.

import abc

For example, "effable" is defined as something that can be expressed in words. Say we wanted to define an abstract base class that is effable, in Python 2:

class Effable(object):
    __metaclass__ = abc.ABCMeta
    def __str__(self):
        raise NotImplementedError('users must define __str__ to use this base class')

Or in Python 3, with the slight change in metaclass declaration:

class Effable(object, metaclass=abc.ABCMeta):
    def __str__(self):
        raise NotImplementedError('users must define __str__ to use this base class')

Now if we try to create an effable object without implementing the interface:

class MyEffable(Effable): 

and attempt to instantiate it:

>>> MyEffable()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Can't instantiate abstract class MyEffable with abstract methods __str__

We are told that we haven't finished the job.

Now if we comply by providing the expected interface:

class MyEffable(Effable): 
    def __str__(self):
        return 'expressable!'

we are then able to use the concrete version of the class derived from the abstract one:

>>> me = MyEffable()
>>> print(me)

There are other things we could do with this, like register virtual subclasses that already implement these interfaces, but I think that is beyond the scope of this question. The other methods demonstrated here would have to adapt this method using the abc module to do so, however.


We have demonstrated that the creation of an Abstract Base Class defines interfaces for custom objects in Python.

How to create a sticky left sidebar menu using bootstrap 3?

I used this way in my code


How can building a heap be O(n) time complexity?

I think there are several questions buried in this topic:

  • How do you implement buildHeap so it runs in O(n) time?
  • How do you show that buildHeap runs in O(n) time when implemented correctly?
  • Why doesn't that same logic work to make heap sort run in O(n) time rather than O(n log n)?

How do you implement buildHeap so it runs in O(n) time?

Often, answers to these questions focus on the difference between siftUp and siftDown. Making the correct choice between siftUp and siftDown is critical to get O(n) performance for buildHeap, but does nothing to help one understand the difference between buildHeap and heapSort in general. Indeed, proper implementations of both buildHeap and heapSort will only use siftDown. The siftUp operation is only needed to perform inserts into an existing heap, so it would be used to implement a priority queue using a binary heap, for example.

I've written this to describe how a max heap works. This is the type of heap typically used for heap sort or for a priority queue where higher values indicate higher priority. A min heap is also useful; for example, when retrieving items with integer keys in ascending order or strings in alphabetical order. The principles are exactly the same; simply switch the sort order.

The heap property specifies that each node in a binary heap must be at least as large as both of its children. In particular, this implies that the largest item in the heap is at the root. Sifting down and sifting up are essentially the same operation in opposite directions: move an offending node until it satisfies the heap property:

  • siftDown swaps a node that is too small with its largest child (thereby moving it down) until it is at least as large as both nodes below it.
  • siftUp swaps a node that is too large with its parent (thereby moving it up) until it is no larger than the node above it.

The number of operations required for siftDown and siftUp is proportional to the distance the node may have to move. For siftDown, it is the distance to the bottom of the tree, so siftDown is expensive for nodes at the top of the tree. With siftUp, the work is proportional to the distance to the top of the tree, so siftUp is expensive for nodes at the bottom of the tree. Although both operations are O(log n) in the worst case, in a heap, only one node is at the top whereas half the nodes lie in the bottom layer. So it shouldn't be too surprising that if we have to apply an operation to every node, we would prefer siftDown over siftUp.

The buildHeap function takes an array of unsorted items and moves them until they all satisfy the heap property, thereby producing a valid heap. There are two approaches one might take for buildHeap using the siftUp and siftDown operations we've described.

  1. Start at the top of the heap (the beginning of the array) and call siftUp on each item. At each step, the previously sifted items (the items before the current item in the array) form a valid heap, and sifting the next item up places it into a valid position in the heap. After sifting up each node, all items satisfy the heap property.

  2. Or, go in the opposite direction: start at the end of the array and move backwards towards the front. At each iteration, you sift an item down until it is in the correct location.

Which implementation for buildHeap is more efficient?

Both of these solutions will produce a valid heap. Unsurprisingly, the more efficient one is the second operation that uses siftDown.

Let h = log n represent the height of the heap. The work required for the siftDown approach is given by the sum

(0 * n/2) + (1 * n/4) + (2 * n/8) + ... + (h * 1).

Each term in the sum has the maximum distance a node at the given height will have to move (zero for the bottom layer, h for the root) multiplied by the number of nodes at that height. In contrast, the sum for calling siftUp on each node is

(h * n/2) + ((h-1) * n/4) + ((h-2)*n/8) + ... + (0 * 1).

It should be clear that the second sum is larger. The first term alone is hn/2 = 1/2 n log n, so this approach has complexity at best O(n log n).

How do we prove the sum for the siftDown approach is indeed O(n)?

One method (there are other analyses that also work) is to turn the finite sum into an infinite series and then use Taylor series. We may ignore the first term, which is zero:

Taylor series for buildHeap complexity

If you aren't sure why each of those steps works, here is a justification for the process in words:

  • The terms are all positive, so the finite sum must be smaller than the infinite sum.
  • The series is equal to a power series evaluated at x=1/2.
  • That power series is equal to (a constant times) the derivative of the Taylor series for f(x)=1/(1-x).
  • x=1/2 is within the interval of convergence of that Taylor series.
  • Therefore, we can replace the Taylor series with 1/(1-x), differentiate, and evaluate to find the value of the infinite series.

Since the infinite sum is exactly n, we conclude that the finite sum is no larger, and is therefore, O(n).

Why does heap sort require O(n log n) time?

If it is possible to run buildHeap in linear time, why does heap sort require O(n log n) time? Well, heap sort consists of two stages. First, we call buildHeap on the array, which requires O(n) time if implemented optimally. The next stage is to repeatedly delete the largest item in the heap and put it at the end of the array. Because we delete an item from the heap, there is always an open spot just after the end of the heap where we can store the item. So heap sort achieves a sorted order by successively removing the next largest item and putting it into the array starting at the last position and moving towards the front. It is the complexity of this last part that dominates in heap sort. The loop looks likes this:

for (i = n - 1; i > 0; i--) {
    arr[i] = deleteMax();

Clearly, the loop runs O(n) times (n - 1 to be precise, the last item is already in place). The complexity of deleteMax for a heap is O(log n). It is typically implemented by removing the root (the largest item left in the heap) and replacing it with the last item in the heap, which is a leaf, and therefore one of the smallest items. This new root will almost certainly violate the heap property, so you have to call siftDown until you move it back into an acceptable position. This also has the effect of moving the next largest item up to the root. Notice that, in contrast to buildHeap where for most of the nodes we are calling siftDown from the bottom of the tree, we are now calling siftDown from the top of the tree on each iteration! Although the tree is shrinking, it doesn't shrink fast enough: The height of the tree stays constant until you have removed the first half of the nodes (when you clear out the bottom layer completely). Then for the next quarter, the height is h - 1. So the total work for this second stage is

h*n/2 + (h-1)*n/4 + ... + 0 * 1.

Notice the switch: now the zero work case corresponds to a single node and the h work case corresponds to half the nodes. This sum is O(n log n) just like the inefficient version of buildHeap that is implemented using siftUp. But in this case, we have no choice since we are trying to sort and we require the next largest item be removed next.

In summary, the work for heap sort is the sum of the two stages: O(n) time for buildHeap and O(n log n) to remove each node in order, so the complexity is O(n log n). You can prove (using some ideas from information theory) that for a comparison-based sort, O(n log n) is the best you could hope for anyway, so there's no reason to be disappointed by this or expect heap sort to achieve the O(n) time bound that buildHeap does.

Type or namespace name does not exist

I recently needed to do a System Restore and it caused several of my files to change/disappear that I had been working on since the restore. Some of those were DLL files. I used Source Control to retrieve the entire project but I still had a similar issue as above. I found this answer that described you may need to remove a DLL and readd it to get your errors fixed. This was the case in my scenario.

Removing WebMatrix.WebData and readding it as well as adding in WebMatrix.Data fixed my error of The type or namespace name 'Data' does not exist in the namespace 'WebMatrix' .... cannot open shared object file

Check below link: Specially "Install 32 bit libraries (if you're on 64 bit)"

What's the fastest algorithm for sorting a linked list?

As stated many times, the lower bound on comparison based sorting for general data is going to be O(n log n). To briefly resummarize these arguments, there are n! different ways a list can be sorted. Any sort of comparison tree that has n! (which is in O(n^n)) possible final sorts is going to need at least log(n!) as its height: this gives you a O(log(n^n)) lower bound, which is O(n log n).

So, for general data on a linked list, the best possible sort that will work on any data that can compare two objects is going to be O(n log n). However, if you have a more limited domain of things to work in, you can improve the time it takes (at least proportional to n). For instance, if you are working with integers no larger than some value, you could use Counting Sort or Radix Sort, as these use the specific objects you're sorting to reduce the complexity with proportion to n. Be careful, though, these add some other things to the complexity that you may not consider (for instance, Counting Sort and Radix sort both add in factors that are based on the size of the numbers you're sorting, O(n+k) where k is the size of largest number for Counting Sort, for instance).

Also, if you happen to have objects that have a perfect hash (or at least a hash that maps all values differently), you could try using a counting or radix sort on their hash functions.

how to convert string into time format and add two hours

Basic program of adding two times:
You can modify hour:min:sec as per your need using if else.
This program shows you how you can add values from two objects and return in another object.

class demo
{private int hour,min,sec;
    void input(int hour,int min,int sec)

    demo add(demo d2)//demo  because we are returning object
    {   demo obj=new demo();
    return obj;//Returning object and later on it gets allocated to demo d3                    
    void display()
    public static  void main(String args[])
        demo d1=new demo();
        demo d2=new demo();
        d1.input(2, 5, 10);
        d2.input(3, 3, 3);
        demo d3=d1.add(d2);//Note another object is created



Modified Time Addition Program

class demo {private int hour,min,sec; void input(int hour,int min,int sec) {this.hour=(hour>12&&hour<24)?(hour-12):hour; this.min=(min>60)?0:min; this.sec=(sec>60)?0:sec; } demo add(demo d2) { demo obj=new demo(); obj.hour=hour+d2.hour; obj.min=min+d2.min; obj.sec=sec+d2.sec; if(obj.sec>60) {obj.sec-=60; obj.min++; } if(obj.min>60) { obj.min-=60; obj.hour++; } return obj; } void display() { System.out.println(hour+":"+min+":"+sec); } public static void main(String args[]) { demo d1=new demo(); demo d2=new demo(); d1.input(12, 55, 55); d2.input(12, 7, 6); demo d3=d1.add(d2); d3.display(); } }

java.sql.SQLException: No suitable driver found for jdbc:microsoft:sqlserver

For someone looking to solve same by using maven. Add below dependency in POM:


And use below code for connection:

String connectionUrl = "jdbc:sqlserver://localhost:1433;databaseName=master;user=sa;password=your_password";

try {
    System.out.print("Connecting to SQL Server ... ");
    try (Connection connection = DriverManager.getConnection(connectionUrl))        {
} catch (Exception e) {

Look for this link for other CRUD type of queries.

How to display a Yes/No dialog box on Android?

All the answers here boil down to lengthy and not reader-friendly code: just what the person asking was trying to avoid. To me, was the easiest approach is to employ lambdas here:

new AlertDialog.Builder(this)
        .setTitle("Are you sure?")
        .setMessage("If you go back you will loose any changes.")
        .setPositiveButton("Yes", (dialog, which) -> {
        .setNegativeButton("No", (dialog, which) -> dialog.dismiss())

Lambdas in Android require the retrolambda plugin (, but it's hugely helpful in writing cleaner code anyways.

Get size of an Iterable in Java

Strictly speaking, Iterable does not have size. Think data structure like a cycle.

And think about following Iterable instance, No size:

    new Iterable(){

        @Override public Iterator iterator() {
            return new Iterator(){

                public boolean hasNext() {
                    return isExternalSystemAvailble();

                public Object next() {
                    return fetchDataFromExternalSystem();

Python loop counter in a for loop

I'll sometimes do this:

def draw_menu(options, selected_index):
    for i in range(len(options)):
        if i == selected_index:
            print " [*] %s" % options[i]
            print " [ ] %s" % options[i]

Though I tend to avoid this if it means I'll be saying options[i] more than a couple of times.

Volatile Vs Atomic

So what will happen if two threads attack a volatile primitive variable at same time?

Usually each one can increment the value. However sometime, both will update the value at the same time and instead of incrementing by 2 total, both thread increment by 1 and only 1 is added.

Does this mean that whosoever takes lock on it, that will be setting its value first.

There is no lock. That is what synchronized is for.

And in if meantime, some other thread comes up and read old value while first thread was changing its value, then doesn't new thread will read its old value?


What is the difference between Atomic and volatile keyword?

AtomicXxxx wraps a volatile so they are basically same, the difference is that it provides higher level operations such as CompareAndSwap which is used to implement increment.

AtomicXxxx also supports lazySet. This is like a volatile set, but doesn't stall the pipeline waiting for the write to complete. It can mean that if you read a value you just write you might see the old value, but you shouldn't be doing that anyway. The difference is that setting a volatile takes about 5 ns, bit lazySet takes about 0.5 ns.

Android - java.lang.SecurityException: Permission Denial: starting Intent

In my case, this error was due to incorrect paths used to specify intents in my preferences xml file after I renamed the project. For instance, where I had:

<PreferenceScreen xmlns:android="">
        android:title="Add/Edit Recipe">

I needed the following instead:

<PreferenceScreen xmlns:android="">
        android:title="Add/Edit Recipe">

Correcting the path names fixed the problem.

How do I download and save a file locally on iOS using objective C?

I'm not sure what wget is, but to get a file from the web and store it locally, you can use NSData:

NSString *stringURL = @"";
NSURL  *url = [NSURL URLWithString:stringURL];
NSData *urlData = [NSData dataWithContentsOfURL:url];
if ( urlData )
  NSArray       *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  NSString  *documentsDirectory = [paths objectAtIndex:0];  

  NSString  *filePath = [NSString stringWithFormat:@"%@/%@", documentsDirectory,@"filename.png"];
  [urlData writeToFile:filePath atomically:YES];

How to set a time zone (or a Kind) of a DateTime value?

You can try this as well, it is easy to implement

TimeZone time2 = TimeZone.CurrentTimeZone;
DateTime test = time2.ToUniversalTime(DateTime.Now);
var singapore = TimeZoneInfo.FindSystemTimeZoneById("Singapore Standard Time");
var singaporetime = TimeZoneInfo.ConvertTimeFromUtc(test, singapore);

Change the text to which standard time you want to change.

Use TimeZone feature of C# to implement.

How to check date of last change in stored procedure or function in SQL server

SELECT name, create_date, modify_date 
FROM sys.objects
WHERE type = 'P'
ORDER BY modify_date DESC

The type for a function is FN rather than P for procedure. Or you can filter on the name column.

Import Libraries in Eclipse?

If you want to get this library into your library and use it, follow these steps:

  1. You can create a new folder within Eclipse by right-clicking on your project, and selecting New Folder. The library folder is traditionally called lib.

  2. Drag and drop your jar folder into the new lib folder, and when prompted select Copy Files.

  3. Selecting the Project tab at the top of the screen, and click Properties.

  4. Select Java Build Path followed by the Libraries tab.

  5. Click the Add JARs… button and select your JAR file from within the lib folder.

  6. Your JAR file will now appear in both the lib and Referenced Libraries folders. You can explore the JAR's resources by clicking Referenced Libraries.

How can I define an array of objects?

Some tslint rules are disabling use of [], example message: Array type using 'T[]' is forbidden for non-simple types. Use 'Array<T>' instead.

Then you would write it like:

var userTestStatus: Array<{ id: number, name: string }> = Array(
    { "id": 0, "name": "Available" },
    { "id": 1, "name": "Ready" },
    { "id": 2, "name": "Started" }

Typescript sleep

You have to wait for TypeScript 2.0 with async/await for ES5 support as it now supported only for TS to ES6 compilation.

You would be able to create delay function with async:

function delay(ms: number) {
    return new Promise( resolve => setTimeout(resolve, ms) );

And call it

await delay(300);

Please note, that you can use await only inside async function.

If you can't (let's say you are building nodejs application), just place your code in the anonymous async function. Here is an example:

    (async () => { 
        // Do something before delay
        console.log('before delay')

        await delay(1000);

        // Do something after
        console.log('after delay')

Example TS Application:

In OLD JS you have to use

setTimeout(YourFunctionName, Milliseconds);


setTimeout( () => { /*Your Code*/ }, Milliseconds );

However with every major browser supporting async/await it less useful.

Update: TypeScript 2.1 is here with async/await.

Just do not forget that you need Promise implementation when you compile to ES5, where Promise is not natively available.


You have to export the function if you want to use it outside of the original file.

How do I find which transaction is causing a "Waiting for table metadata lock" state?


Look for the Section -



Useful Queries

To check about all the locks transactions are waiting for:


A list of blocking transactions:




A List of locks on particular table:

WHERE LOCK_TABLE = db_name.table_name;

A list of transactions waiting for locks:


Reference - MySQL Troubleshooting: What To Do When Queries Don't Work, Chapter 6 - Page 96.

Histogram with Logarithmic Scale and custom breaks

It's not entirely clear from your question whether you want a logged x-axis or a logged y-axis. A logged y-axis is not a good idea when using bars because they are anchored at zero, which becomes negative infinity when logged. You can work around this problem by using a frequency polygon or density plot.

Copy folder recursively in Node.js

The easiest approach for this problem is to use only the 'fs' and 'Path' module and some logic...

All files in the root folder copy with the new name if you want to just set the version number, i.e., " var v = 'Your Directory Name'"

In the file name prefix with content added with the file name.

var fs = require('fs-extra');
var path = require('path');

var c = 0;
var i = 0;
var v = "1.0.2";
var copyCounter = 0;
var directoryCounter = 0;
var directoryMakerCounter = 0;
var recursionCounter = -1;
var Flag = false;
var directoryPath = [];
var directoryName = [];
var directoryFileName = [];
var fileName;
var directoryNameStorer;
var dc = 0;
var route;

if (!fs.existsSync(v)) {

var basePath = path.join(__dirname, v);

function walk(dir) {

    fs.readdir(dir, function(err, items) {

        items.forEach(function(file) {

            file = path.resolve(dir, file);

            fs.stat(file, function(err, stat) {

                if(stat && stat.isDirectory()) {
                    directoryNameStorer = path.basename(file);
                    route = file;
                    route = route.replace("gd", v);

                    directoryFileName[directoryCounter] = route;
                    directoryPath[directoryCounter] = file;
                    directoryName[directoryCounter] = directoryNameStorer;


                    if (!fs.existsSync(basePath + "/" + directoryName[directoryMakerCounter])) {
                else {
                    fileName = path.basename(file);
                    if(recursionCounter >= 0) {
                        fs.copyFileSync(file, directoryFileName[recursionCounter] + "/" + v + "_" + fileName, err => {
                            if(err) return console.error(err);
                    else {
                        fs.copyFileSync(file, v + "/" + v + "_" + fileName, err => {
                            if(err) return console.error(err);
                if(copyCounter + dc == items.length && directoryCounter > 0 && recursionCounter < directoryMakerCounter-1) {
                    console.log("COPY COUNTER:             " + copyCounter);
                    console.log("DC COUNTER:               " + dc);
                    dc = 0;
                    copyCounter = 0;
                    console.log("ITEM DOT LENGTH:          " + items.length);
                    console.log("RECURSION COUNTER:        " + recursionCounter);
                    console.log("DIRECOTRY MAKER COUNTER:  " + directoryMakerCounter);
                    console.log(": START RECURSION:        " + directoryPath[recursionCounter]);
                    walk(directoryPath[recursionCounter]); //recursive call to copy sub-folder

walk('./gd', function(err, data) { // Just pass the root directory which you want to copy
        throw err;

Why are C++ inline functions in the header?

There are two ways to look at it:

  1. Inline functions are defined in the header because, in order to inline a function call, the compiler must be able to see the function body. For a naive compiler to do that, the function body must be in the same translation unit as the call. (A modern compiler can optimize across translation units, and so a function call may be inlined even though the function definition is in a separate translation unit, but these optimizations are expensive, aren't always enabled, and weren't always supported by the compiler)

  2. functions defined in the header must be marked inline because otherwise, every translation unit which includes the header will contain a definition of the function, and the linker will complain about multiple definitions (a violation of the One Definition Rule). The inline keyword suppresses this, allowing multiple translation units to contain (identical) definitions.

The two explanations really boil down to the fact that the inline keyword doesn't exactly do what you'd expect.

A C++ compiler is free to apply the inlining optimization (replace a function call with the body of the called function, saving the call overhead) any time it likes, as long as it doesn't alter the observable behavior of the program.

The inline keyword makes it easier for the compiler to apply this optimization, by allowing the function definition to be visible in multiple translation units, but using the keyword doesn't mean the compiler has to inline the function, and not using the keyword doesn't forbid the compiler from inlining the function.

pass post data with window.location.href

Use this file : "jquery.redirect.js"

            user_name: "khan",
            city : "Meerut",
            country : "country"


Check if an array contains any element of another array in JavaScript

I came up with a solution in node using underscore js like this:

var checkRole = _.intersection(['A','B'], ['A','B','C']);
if(!_.isEmpty(checkRole)) { 

How come I can't remove the blue textarea border in Twitter Bootstrap?


If you do not want to kill a fly with bazooka by use -webkit-appearance:none; which also kills nice sliderinputs btw and presuming you are working with the bootstrap form css selector "form-control" for your input.

This is the solution:

.form-control:focus {
    box-shadow: none!important;
    border-color: #ced4da!important;

If you want to keep a tiny small blue outline the leave border-color out.

Cannot access wamp server on local network

I had the same problem but mine worked fine. Turn off your firewall, antivirus. Make sure your port 80 is enabled and both pcs are set to be remotely accessed. In each pc under users, add new user using the host ip address of the other pc. Restart all services. Put your wampserver online. It should connect

How to purge tomcat's cache when deploying a new .war file? Is there a config setting?

A little late for the party, here's how I do it

  1. Undeploy application from manager
  2. Shutdown tomcat using ./
  3. Delete browser cache
  4. Delete the application from webapps, and from /work/Catalina/...
  5. Startup tomcat using ./
  6. Copy the new version of the application into /webapps and start it.

What is the difference between a candidate key and a primary key?

John Woo's answer is correct, as far as it goes. Here are a few additional points.

A primary key is always one of the candidate keys. Fairly often, it's the only candidate.

A table with no candidate keys does not represent a relation. If you're using the relational model to help you build a good database, then every table you design will have at least one candidate key.

The relational model would be complete without the concept of primary key. It wasn't in the original presentation of the relational model. As a practical matter, the use of foreign key references without a declared primary key leads to a mess. It could be a logically correct mess, but it's a mess nonetheless. Declaring a primary key lets the DBMS help you enforce the data rules. Most of the time, having the DBMS help you enforce the data rules is a good thing, and well worth the cost.

Some database designers and some users have some mental confusion about whether the primary key identifies a row (record) in a table or an instance of an entity in the subject matter that the table represents. In an ideal world, it's supposed to do both, and there should be a one-for-one correspondence between rows in an entity table and instances of the corresponding entity.

In the real world, things get screwed up. Somebody enters the same new employee twice, and the employee ends up with two ids. Somebody gets hired, but the data entry slips through the cracks in some manual process, and the employee doesn't get an id, until the omission is corrected. A database that does not collapse the first time things get screwed up is more robust than one that does.

Ruby, Difference between exec, system and %x() or Backticks


The system method calls a system program. You have to provide the command as a string argument to this method. For example:

>> system("date")
Wed Sep 4 22:03:44 CEST 2013
=> true

The invoked program will use the current STDIN, STDOUT and STDERR objects of your Ruby program. In fact, the actual return value is either true, false or nil. In the example the date was printed through the IO object of STDIN. The method will return true if the process exited with a zero status, false if the process exited with a non-zero status and nil if the execution failed.

As of Ruby 2.6, passing exception: true will raise an exception instead of returning false or nil:

>> system('invalid')
=> nil

>> system('invalid', exception: true)
Traceback (most recent call last):
Errno::ENOENT (No such file or directory - invalid)

Another side effect is that the global variable $? is set to a Process::Status object. This object will contain information about the call itself, including the process identifier (PID) of the invoked process and the exit status.

>> system("date")
Wed Sep 4 22:11:02 CEST 2013
=> true
>> $?
=> #<Process::Status: pid 15470 exit 0>


Backticks (``) call a system program and return its output. As opposed to the first approach, the command is not provided through a string, but by putting it inside a backticks pair.

>> `date`
=> Wed Sep 4 22:22:51 CEST 2013   

The global variable $? is set through the backticks, too. With backticks you can also make use string interpolation.


Using %x is an alternative to the backticks style. It will return the output, too. Like its relatives %w and %q (among others), any delimiter will suffice as long as bracket-style delimiters match. This means %x(date), %x{date} and %x-date- are all synonyms. Like backticks %x can make use of string interpolation.


By using Kernel#exec the current process (your Ruby script) is replaced with the process invoked through exec. The method can take a string as argument. In this case the string will be subject to shell expansion. When using more than one argument, then the first one is used to execute a program and the following are provided as arguments to the program to be invoked.


Sometimes the required information is written to standard input or standard error and you need to get control over those as well. Here Open3.popen3 comes in handy:

require 'open3'

Open3.popen3("curl") do |stdin, stdout, stderr, thread|
   pid =

PySpark 2.0 The size or shape of a DataFrame

Use df.count() to get the number of rows.

Setting default value in select drop-down using Angularjs

we should use name value pair binding values into dropdown.see the code for more details

function myCtrl($scope) {_x000D_
     $scope.statusTaskList = [_x000D_
        { name: 'Open', value: '1' },_x000D_
        { name: 'In Progress', value: '2' },_x000D_
        { name: 'Complete', value: '3' },_x000D_
        { name: 'Deleted', value: '4' },_x000D_
    $scope.atcStatusTasks = $scope.statusTaskList[0]; // 0 -> Open _x000D_
<select ng-model="atcStatusTasks" ng-options=" for s in statusTaskList"></select>

How to start an Android application from the command line?

Example here.

Pasted below:

This is about how to launch android application from the adb shell.

Command: am

Look for invoking path in AndroidManifest.xml

Browser app::

# am start -a android.intent.action.MAIN -n
Starting: Intent { action=android.intent.action.MAIN comp={} }
Warning: Activity not started, its current task has been brought to the front

Settings app::

# am start -a android.intent.action.MAIN -n
Starting: Intent { action=android.intent.action.MAIN comp={} }

How to get the current URL within a Django template?

I suppose send to template full request is little bit redundant. I do it this way

from django.shortcuts import render

def home(request):
    app_url = request.path
    return render(request, 'home.html', {'app_url': app_url})

{{ app_url }}

Android and Facebook share intent

Here is what I did (for text). In the code, I copy whatever text is needed to clipboard. The first time an individual tries to use the share intent button, I pop up a notification that explains if they wish to share to facebook, they need to click 'Facebook' and then long press to paste (this is to make them aware that Facebook has BROKEN the android intent system). Then the relevant information is in the field. I might also include a link to this post so users can complain too...

private void setClipboardText(String text) { // TODO
    int sdk = android.os.Build.VERSION.SDK_INT;
    if(sdk < android.os.Build.VERSION_CODES.HONEYCOMB) {
        android.text.ClipboardManager clipboard = (android.text.ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE);
    } else {
        android.content.ClipboardManager clipboard = (android.content.ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE); 
        android.content.ClipData clip = android.content.ClipData.newPlainText("text label",text);

Below is a method for dealing w/prior versions

public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        Intent shareIntent = new Intent(Intent.ACTION_SEND);
        shareIntent.putExtra(Intent.EXTRA_TEXT, "text here");

        ClipboardManager clipboard = (ClipboardManager) getSystemService(CLIPBOARD_SERVICE); //TODO
         ClipData clip = ClipData.newPlainText("label", "text here");


        return super.onOptionsItemSelected(item);

Is it possible to specify condition in Count()?

I think you can use a simple WHERE clause to select only the count some record.

Node.js spawn child process and get terminal output live

Adding an answer related to child_process.exec as I too had needed live feedback and wasn't getting any until after the script finished. This also supplements my comment to the accepted answer, but as it's formatted it will a bit more understandable and easier to read.

Basically, I have a npm script that calls Gulp, invoking a task which subsequently uses child_process.exec to execute a bash or batch script depending on the OS. Either script runs a build process via Gulp and then makes some calls to some binaries that work with the Gulp output.

It's exactly like the others (spawn, etc.), but for the sake of completion, here's exactly how to do it:

import * as childProcess from 'child_process'; // ES6 Syntax

let exec = childProcess.exec; // Or use 'var' for more proper 
                              // semantics, though 'let' is 
                              // true-to-scope

// Assign exec to a variable, or chain stdout at the end of the call
// to exec - the choice, yours (i.e. exec( ... ).stdout.on( ... ); )
let childProcess = exec
    './binary command -- --argument argumentValue',
    ( error, stdout, stderr ) =>
        if( error )
            // This won't show up until the process completes:
            console.log( '[ERROR]: "' + + '" - ' + error.message );
            console.log( '[STACK]: ' + error.stack );

            console.log( stdout );
            console.log( stderr );
            callback();            // Gulp stuff

        // Neither will this:
        console.log( stdout );
        console.log( stderr );
        callback();                // Gulp stuff

Now its as simple as adding an event listener. For stdout:

    ( data ) =>
        // This will render 'live':
        console.log( '[STDOUT]: ' + data );

And for stderr:

    ( data ) =>
        // This will render 'live' too:
        console.log( '[STDERR]: ' + data );

Not too bad at all - HTH

Make a link in the Android browser start up my app?

Just want to open the app through browser? You can achieve it using below code:


<a href="intent:#Intent;action=packageName;category=android.intent.category.DEFAULT;category=android.intent.category.BROWSABLE;end">Click here</a>


      <action android:name="packageName" />
      <category android:name="android.intent.category.DEFAULT" />
      <category android:name="android.intent.category.BROWSABLE" />

This intent filter should be in Launcher Activity.

If you want to pass the data on click of browser link, just refer this link.

How to style a JSON block in Github Wiki?

You can use some online websites to beautify JSON, such as: JSON Formatter, and then paste the beautified result to WIKI

Script parameters in Bash

In bash $1 is the first argument passed to the script, $2 second and so on

/usr/local/bin/abbyyocr9 -rl Swedish -if "$1" -of "$2" 2>&1

So you can use:

./ some_source_file.png destination_file.txt

Explanation on double quotes;

consider three scripts:

bash $1

# cat
bash "$1"

echo "1-$1" "2-$2"

Now invoke:

$ bash "a b"
1-a 2-b

$ bash "a b"
1-a b 2-

When you invoke "a b" then it invokes a b (two arguments), and with "a b" it invokes "a b" (1 argument). Always have in mind how parameters are passed and expaned in bash, it will save you a lot of headache.

Python - Count elements in list

To find count of unique elements of list use the combination of len() and set().

>>> ls = [1, 2, 3, 4, 1, 1, 2]
>>> len(ls)
>>> len(set(ls))

How do you run a Python script as a service in Windows?

A complete pywin32 example using loop or subthread

After working on this on and off for a few days, here is the answer I would have wished to find, using pywin32 to keep it nice and self contained.

This is complete working code for one loop-based and one thread-based solution. It may work on both python 2 and 3, although I've only tested the latest version on 2.7 and Win7. The loop should be good for polling code, and the tread should work with more server-like code. It seems to work nicely with the waitress wsgi server that does not have a standard way to shut down gracefully.

I would also like to note that there seems to be loads of examples out there, like this that are almost useful, but in reality misleading, because they have cut and pasted other examples blindly. I could be wrong. but why create an event if you never wait for it?

That said I still feel I'm on somewhat shaky ground here, especially with regards to how clean the exit from the thread version is, but at least I believe there are nothing misleading here.

To run simply copy the code to a file and follow the instructions.


Use a simple flag to terminate thread. The important bit is that "thread done" prints.
For a more elaborate example exiting from an uncooperative server thread see my post about the waitress wsgi server.

# uncomment mainthread() or mainloop() call below
# run without parameters to see HandleCommandLine options
# install service with "install" and remove with "remove"
# run with "debug" to see print statements
# with "start" and "stop" watch for files to appear
# check Windows EventViever for log messages

import socket
import sys
import threading
import time
from random import randint
from os import path

import servicemanager
import win32event
import win32service
import win32serviceutil
# see for details

def dummytask_once(msg='once'):
    fn = path.join(path.dirname(__file__),
                '%s_%s.txt' % (msg, randint(1, 10000)))
    with open(fn, 'w') as fh:

def dummytask_loop():
    global do_run
    while do_run:

class MyThread(threading.Thread):
    def __init__(self):

    def run(self):
        global do_run
        do_run = True
        print('thread start\n')
        print('thread done\n')

    def exit(self):
        global do_run
        do_run = False

class SMWinservice(win32serviceutil.ServiceFramework):
    _svc_name_ = 'PyWinSvc'
    _svc_display_name_ = 'Python Windows Service'
    _svc_description_ = 'An example of a windows service in Python'

    def parse_command_line(cls):

    def __init__(self, args):
        win32serviceutil.ServiceFramework.__init__(self, args)
        self.stopEvt = win32event.CreateEvent(None, 0, 0, None)  # create generic event

    def SvcStop(self):
                            (self._svc_name_, ''))
        win32event.SetEvent(self.stopEvt)  # raise event

    def SvcDoRun(self):
                            (self._svc_name_, ''))
        # self.mainthread()
        # self.mainloop()

    # Wait for stopEvt indefinitely after starting thread.
    def mainthread(self):
        print('main start')
        self.server = MyThread()
        print('wait for win32event')
        win32event.WaitForSingleObject(self.stopEvt, win32event.INFINITE)
        print('wait for thread')
        print('main done')

    # Wait for stopEvt event in loop.
    def mainloop(self):
        print('loop start')
        rc = None
        while rc != win32event.WAIT_OBJECT_0:
            rc = win32event.WaitForSingleObject(self.stopEvt, 3000)
        print('loop done')

if __name__ == '__main__':

How can I let a table's body scroll but keep its head fixed in place?

Have you tried using thead and tbody, and setting a fixed height on tbody with overflow:scroll?

What are your target browsers?

EDIT: It worked well (almost) in firefox - the addition of the vertical scrollbar caused the need for a horizontal scrollbar as well - yuck. IE just set the height of each td to what I had specifed the height of tbody to be. Here's the best I could come up with:

    <style type="text/css">
    table { width:300px; }
    tbody { height:10em;  overflow:scroll;}
    td { height:auto; }

Change background of LinearLayout in Android

1- Select LinearLayout findViewById

LinearLayout llayout =(LinearLayout) findViewById(; 

2- Set color from R.color.colorId


How to load images dynamically (or lazily) when users scrolls them into view

Some of the answers here are for infinite page. What Salman is asking is lazy loading of images.



EDIT: How do these plugins work?

This is a simplified explanation:

  1. Find window size and find the position of all images and their sizes
  2. If the image is not within the window size, replace it with a placeholder of same size
  3. When user scrolls down, and position of image < scroll + window height, the image is loaded

How to get single value of List<object>

Define a class like this :

public class myclass {
       string id ;
       string title ;
       string content;

 public class program {
        public void Main () {
               List<myclass> objlist = new List<myclass> () ;
               foreach (var value in objlist)  {
                       TextBox1.Text = ;
                       TextBox2.Text= value.title;
                       TextBox3.Text= value.content ;

I tried to draw a sketch and you can improve it in many ways. Instead of defining class "myclass", you can define struct.

Selecting a Record With MAX Value

The query answered by sandip giri was the correct answer, here a similar example getting the maximum id (PresupuestoEtapaActividadHistoricoId), after calculate the maximum value(Base)

select * 
from (
    select PEAA.PresupuestoEtapaActividadId,
        sum(PEAA.ValorTotalDesperdicioBase) as Base,
        sum(PEAA.ValorTotalDesperdicioEjecucion) as Ejecucion
    from hgc.PresupuestoActividadAnalisis as PEAA
    inner join hgc.PresupuestoEtapaActividad as PEA
        on PEAA.PresupuestoEtapaActividadId = PEA.PresupuestoEtapaActividadId
    inner join hgc.PresupuestoEtapaActividadHistorico as PEAH
        on PEA.PresupuestoEtapaActividadId = PEAH.PresupuestoEtapaActividadId                                                         
    group by PEAH.PresupuestoEtapaActividadHistoricoId, PEAA.PresupuestoEtapaActividadId    
) as t
where exists (
    select 1 
    from (
        select MAX(PEAH.PresupuestoEtapaActividadHistoricoId) as PresupuestoEtapaActividadHistoricoId                                                                     
        from hgc.PresupuestoEtapaActividadHistorico as PEAH                       
        group by PEAH.PresupuestoEtapaActividadId  
    ) as ti
    where t.PresupuestoEtapaActividadHistoricoId = ti.PresupuestoEtapaActividadHistoricoId 

Package php5 have no installation candidate (Ubuntu 16.04)

You must use prefix "php5.6-" instead of "php5-" as in ubuntu 14.04 and olders:

sudo apt-get install php5.6 php5.6-mcrypt

Getting a browser's name client-side

It's all about what you really want to do, but in times to come and right now, the best way is avoid browser detection and check for features. like Canvas, Audio, WebSockets, etc through simple javascript calls or in your CSS, for me your best approach is use a tool like ModernizR:

Unlike with the traditional—but highly unreliable—method of doing “UA sniffing,” which is detecting a browser by its (user-configurable) navigator.userAgent property, Modernizr does actual feature detection to reliably discern what the various browsers can and cannot do.

If using CSS, you can do this:

.no-js .glossy,
.no-cssgradients .glossy {
    background: url("images/glossybutton.png");

.cssgradients .glossy {
    background-image: linear-gradient(top, #555, #333);

as it will load and append all features as a class name in the <html> element and you will be able to do as you wish in terms of CSS.

And you can even load files upon features, for example, load a polyfill js and css if the browser does not have native support

  // Presentational polyfills
    // Logical list of things we would normally need
    test : Modernizr.fontface && Modernizr.canvas && Modernizr.cssgradients,
    // Modernizr.load loads css and javascript by default
    nope : ['presentational-polyfill.js', 'presentational.css']
  // Functional polyfills
    // This just has to be truthy
    test : Modernizr.websockets && window.JSON,
    // socket-io.js and json2.js
    nope : 'functional-polyfills.js',
    // You can also give arrays of resources to load.
    both : [ 'app.js', 'extra.js' ],
    complete : function () {
      // Run this after everything in this group has downloaded
      // and executed, as well everything in all previous groups
  // Run your analytics after you've already kicked off all the rest
  // of your app.

a simple example of requesting features from javascript:

CSS transition fade in

I believe you could addClass to the element. But either way you'd have to use Jquery or reg JS

div {
  transition:opacity 1s linear;*
div.SomeClass {

How to run mysql command on bash?

This one worked, double quotes when $user and $password are outside single quotes. Single quotes when inside a single quote statement.

mysql --user="$user" --password="$password" --database="$user" --execute='DROP DATABASE '$user'; CREATE DATABASE '$user';'

How to close the current fragment by using Button like the back button?

getActivity().onBackPressed does the all you need. It automatically calls the onBackPressed method in parent activity.

How to access route, post, get etc. parameters in Zend Framework 2

The easiest way to do that would be to use the Params plugin, introduced in beta5. It has utility methods to make it easy to access different types of parameters. As always, reading the tests can prove valuable to understand how something is supposed to be used.

Get a single value

To get the value of a named parameter in a controller, you will need to select the appropriate method for the type of parameter you are looking for and pass in the name.


$this->params()->fromPost('paramname');   // From POST
$this->params()->fromQuery('paramname');  // From GET
$this->params()->fromRoute('paramname');  // From RouteMatch
$this->params()->fromHeader('paramname'); // From header
$this->params()->fromFiles('paramname');  // From file being uploaded


Default values

All of these methods also support default values that will be returned if no parameter with the given name is found.


$orderBy = $this->params()->fromQuery('orderby', 'name');

When visiting, $orderBy will have the value birthdate.
When visiting, $orderBy will have the default value name.

Get all parameters

To get all parameters of one type, just don't pass in anything and the Params plugin will return an array of values with their names as keys.


$allGetValues = $this->params()->fromQuery(); // empty method call

When visiting $allGetValues will be an array like

    'orderby' => 'birthdate',
    'filter'  => 'hasphone',


Not using Params plugin

If you check the source code for the Params plugin, you will see that it's just a thin wrapper around other controllers to allow for more consistent parameter retrieval. If you for some reason want/need to access them directly, you can see in the source code how it's done.


$this->getRequest()->getRequest('name', 'default');
$this->getEvent()->getRouteMatch()->getParam('name', 'default');

NOTE: You could have used the superglobals $_GET, $_POST etc., but that is discouraged.

Pandas column of lists, create a row for each list element

import pandas as pd
df = pd.DataFrame([{'Product': 'Coke', 'Prices': [100,123,101,105,99,94,98]},{'Product': 'Pepsi', 'Prices': [101,104,104,101,99,99,99]}])
df = df.assign(Prices=df.Prices.str.split(',')).explode('Prices')

Try this in pandas >=0.25 version

SQL left join vs multiple tables on FROM line?

When you need an outer join the second syntax is not always required:


  FROM a, b
 WHERE a.x = b.x(+)

MSSQLServer (although it's been deprecated in 2000 version)/Sybase:

  FROM a, b
 WHERE a.x *= b.x

But returning to your question. I don't know the answer, but it is probably related to the fact that a join is more natural (syntactically, at least) than adding an expression to a where clause when you are doing exactly that: joining.

MacOSX homebrew mysql root password

Try with sudo to avoid the "Access denied" error:

sudo $(brew --prefix mariadb)/bin/mysqladmin -u root password NEWPASS

Creating a custom JButton in Java

When I was first learning Java we had to make Yahtzee and I thought it would be cool to create custom Swing components and containers instead of just drawing everything on one JPanel. The benefit of extending Swing components, of course, is to have the ability to add support for keyboard shortcuts and other accessibility features that you can't do just by having a paint() method print a pretty picture. It may not be done the best way however, but it may be a good starting point for you.

Edit 8/6 - If it wasn't apparent from the images, each Die is a button you can click. This will move it to the DiceContainer below. Looking at the source code you can see that each Die button is drawn dynamically, based on its value.

alt text
alt text
alt text

Here are the basic steps:

  1. Create a class that extends JComponent
  2. Call parent constructor super() in your constructors
  3. Make sure you class implements MouseListener
  4. Put this in the constructor:

  5. Override these methods:

    public Dimension getPreferredSize()  
    public Dimension getMinimumSize()  
    public Dimension getMaximumSize()
  6. Override this method:

    public void paintComponent(Graphics g)

The amount of space you have to work with when drawing your button is defined by getPreferredSize(), assuming getMinimumSize() and getMaximumSize() return the same value. I haven't experimented too much with this but, depending on the layout you use for your GUI your button could look completely different.

And finally, the source code. In case I missed anything.


Use a seperate column to indicate the join condition

SELECT  t.importid, 
            when t.importid = g.home 
            then 'home' 
            else 'away' 
        end as join_condition,, 
FROM    game g
INNER JOIN team t ON (t.importid = g.home OR t.importid = g.away)
ORDER BY date_start DESC 

How do I get a python program to do nothing?

You can use continue

if condition:
    #do something

How do I configure the proxy settings so that Eclipse can download new plugins?

I installed HandyCache, in them install link on my general proxy.

In IE set proxy

In Eclipse, Window > Preferences > General > Network Connections, set Active Provider = Native.

Get Environment Variable from Docker Container

If by any chance you use VSCode and has installed the docker extension, just right+click on the docker you want to check (within the docker extension), click on Inspect, and there search for env, you will find all your env variables values

Magento: Set LIMIT on collection

Order Collection Limit :

$orderCollection = Mage::getResourceModel('sales/order_collection'); 

foreach ($orderCollection->getItems() as $order) :
   $orderModel = Mage::getModel('sales/order');
   $order =   $orderModel->load($order['entity_id']);
   echo $order->getId().'<br>'; 

No 'Access-Control-Allow-Origin' header is present on the requested resource error

Try this - set Ajax call by setting up the header as follows:

var uri = "http://localhost:50869/odata/mydatafeeds"
    url: uri,
    beforeSend: function (request) {
        request.setRequestHeader("Authorization", "Negotiate");
    async: true,
    success: function (data) {
    error: function (xhr, textStatus, errorMessage) {

Then run your code by opening Chrome with the following command line:

chrome.exe --user-data-dir="C:/Chrome dev session" --disable-web-security

'cout' was not declared in this scope

Use std::cout, since cout is defined within the std namespace. Alternatively, add a using std::cout; directive.

Can we rely on String.isEmpty for checking null condition on a String in Java?

Use StringUtils.isEmpty instead, it will also check for null.

Examples are:

 StringUtils.isEmpty(null)      = true
 StringUtils.isEmpty("")        = true
 StringUtils.isEmpty(" ")       = false
 StringUtils.isEmpty("bob")     = false
 StringUtils.isEmpty("  bob  ") = false

See more on official Documentation on String Utils.

Save current directory in variable using Bash?

You can use shell in-build variable PWD, like this:

export PATH=$PATH:$PWD+somethingelse

What are queues in jQuery?

The uses of jQuery .queue() and .dequeue()

Queues in jQuery are used for animations. You can use them for any purpose you like. They are an array of functions stored on a per element basis, using They are First-In-First-Out (FIFO). You can add a function to the queue by calling .queue(), and you remove (by calling) the functions using .dequeue().

To understand the internal jQuery queue functions, reading the source and looking at examples helps me out tremendously. One of the best examples of a queue function I've seen is .delay():

$.fn.delay = function( time, type ) {
  time = jQuery.fx ? jQuery.fx.speeds[time] || time : time;
  type = type || "fx";

  return this.queue( type, function() {
    var elem = this;
    setTimeout(function() {
      jQuery.dequeue( elem, type );
    }, time );

The default queue - fx

The default queue in jQuery is fx. The default queue has some special properties that are not shared with other queues.

  1. Auto Start: When calling $(elem).queue(function(){}); the fx queue will automatically dequeue the next function and run it if the queue hasn't started.
  2. 'inprogress' sentinel: Whenever you dequeue() a function from the fx queue, it will unshift() (push into the first location of the array) the string "inprogress" - which flags that the queue is currently being run.
  3. It's the default! The fx queue is used by .animate() and all functions that call it by default.

NOTE: If you are using a custom queue, you must manually .dequeue() the functions, they will not auto start!

Retrieving/Setting the queue

You can retrieve a reference to a jQuery queue by calling .queue() without a function argument. You can use the method if you want to see how many items are in the queue. You can use push, pop, unshift, shift to manipulate the queue in place. You can replace the entire queue by passing an array to the .queue() function.

Quick Examples:

// lets assume $elem is a jQuery object that points to some element we are animating.
var queue = $elem.queue();
// remove the last function from the animation queue.
var lastFunc = queue.pop(); 
// insert it at the beginning:    
// replace queue with the first three items in the queue

An animation (fx) queue example:

Run example on jsFiddle

$(function() {
    // lets do something with google maps:
    var $map = $("#map_canvas");
    var myLatlng = new google.maps.LatLng(-34.397, 150.644);
    var myOptions = {zoom: 8, center: myLatlng, mapTypeId: google.maps.MapTypeId.ROADMAP};
    var geocoder = new google.maps.Geocoder();
    var map = new google.maps.Map($map[0], myOptions);
    var resized = function() {
        // simple animation callback - let maps know we resized
        google.maps.event.trigger(map, 'resize');

    // wait 2 seconds
    // resize the div:
        width: 250,
        height: 250,
        marginLeft: 250,
    }, resized);
    // geocode something
    $map.queue(function(next) {
        // find stackoverflow's whois address:
      geocoder.geocode({'address': '55 Broadway New York NY 10006'},handleResponse);

      function handleResponse(results, status) {
          if (status == google.maps.GeocoderStatus.OK) {
              var location = results[0].geometry.location;
              new google.maps.Marker({ map: map, position: location });
          // geocoder result returned, continue with animations:
    // after we find stack overflow, wait 3 more seconds
    // and resize the map again
        width: 500,
        height: 500,
        marginTop: 0
    }, resized);

Another custom queue example

Run example on jsFiddle

var theQueue = $({}); // jQuery on an empty object - a perfect queue holder

$.each([1,2,3],function(i, num) {
  // lets add some really simple functions to a queue:
  theQueue.queue('alerts', function(next) { 
    // show something, and if they hit "yes", run the next function.
    if (confirm('index:'+i+' = '+num+'\nRun the next function?')) {

// create a button to run the queue:
$("<button>", {
  text: 'Run Queue', 
  click: function() { 

// create a button to show the length:
$("<button>", {
  text: 'Show Length', 
  click: function() { 

Queueing Ajax Calls:

I developed an $.ajaxQueue() plugin that uses the $.Deferred, .queue(), and $.ajax() to also pass back a promise that is resolved when the request completes. Another version of $.ajaxQueue that still works in 1.4 is posted on my answer to Sequencing Ajax Requests

* jQuery.ajaxQueue - A queue for ajax requests
* (c) 2011 Corey Frang
* Dual licensed under the MIT and GPL licenses.
* Requires jQuery 1.5+
(function($) {

// jQuery on an empty object, we are going to use this as our Queue
var ajaxQueue = $({});

$.ajaxQueue = function( ajaxOpts ) {
    var jqXHR,
        dfd = $.Deferred(),
        promise = dfd.promise();

    // queue our ajax request
    ajaxQueue.queue( doRequest );

    // add the abort method
    promise.abort = function( statusText ) {

        // proxy abort to the jqXHR if it is active
        if ( jqXHR ) {
            return jqXHR.abort( statusText );

        // if there wasn't already a jqXHR we need to remove from queue
        var queue = ajaxQueue.queue(),
            index = $.inArray( doRequest, queue );

        if ( index > -1 ) {
            queue.splice( index, 1 );

        // and then reject the deferred
        dfd.rejectWith( ajaxOpts.context || ajaxOpts,
            [ promise, statusText, "" ] );

        return promise;

    // run the actual query
    function doRequest( next ) {
        jqXHR = $.ajax( ajaxOpts )
            .done( dfd.resolve )
            .fail( dfd.reject )
            .then( next, next );

    return promise;


I have now added this as an article on, there are other great articles on that site about queues, go look.

Add objects to an array of objects in Powershell

To append to an array, just use the += operator.

$Target += $TargetObject

Also, you need to declare $Target = @() before your loop because otherwise, it will empty the array every loop.

Rollback to last git commit

If you want to remove newly added contents and files which are already staged (so added to the index) then you use:

git reset --hard

If you want to remove also your latest commit (is the one with the message "blah") then better to use:

git reset --hard HEAD^

To remove the untracked files (so new files not yet added to the index) and folders use:

git clean --force -d

How do I find my host and username on mysql?

Default user for MySQL is "root", and server "localhost".

Creating stored procedure and SQLite?

SQLite has had to sacrifice other characteristics that some people find useful, such as high concurrency, fine-grained access control, a rich set of built-in functions, stored procedures, esoteric SQL language features, XML and/or Java extensions, tera- or peta-byte scalability, and so forth

Source : Appropriate Uses For SQLite

pop/remove items out of a python tuple

Yes we can do it. First convert the tuple into an list, then delete the element in the list after that again convert back into tuple.


my_tuple = (10, 20, 30, 40, 50)

# converting the tuple to the list
my_list = list(my_tuple)
print my_list  # output: [10, 20, 30, 40, 50]

# Here i wanna delete second element "20"
my_list.pop(1) # output: [10, 30, 40, 50]
# As you aware that pop(1) indicates second position

# Here i wanna remove the element "50"
my_list.remove(50) # output: [10, 30, 40]

# again converting the my_list back to my_tuple
my_tuple = tuple(my_list)

print my_tuple # output: (10, 30, 40)


How do I get a reference to the app delegate in Swift?

Try simply this:

Swift 4

// Call the method
(UIApplication.shared.delegate as? AppDelegate)?.whateverWillOccur()

where in your AppDelegate:

// MARK: - Whatever
func whateverWillOccur() {

    // Your code here.


JQuery Error: cannot call methods on dialog prior to initialization; attempted to call method 'close'

So you use this:

var opt = {
        autoOpen: false,
        modal: true,
        width: 550,
        title: 'Details'

var theDialog = $("#divDialog").dialog(opt);

and if you open a MVC Partial View in Dialog, you can create in index a hidden button and JQUERY click event:


then inside partial view html you call button trigger click like:


see ya.

Change default timeout for mocha

Adding this for completeness. If you (like me) use a script in your package.json file, just add the --timeout option to mocha:

"scripts": {
  "test": "mocha 'test/**/*.js' --timeout 10000",
  "test-debug": "mocha --debug 'test/**/*.js' --timeout 10000"

Then you can run npm run test to run your test suite with the timeout set to 10,000 milliseconds.

The ALTER TABLE statement conflicted with the FOREIGN KEY constraint

Try DELETE the current datas from tblDomare.PersNR . Because the values in tblDomare.PersNR didn't match with any of the values in tblBana.BanNR.

Mark error in form using Bootstrap

(UPDATED with examples for Bootstrap v4, v3 and v3)

Examples of forms with validation classes for the past few major versions of Bootstrap.

Bootstrap v4

See the live version on codepen

bootstrap v4 form validation

<div class="container">
    <div class="form-group row">
      <label for="inputEmail" class="col-sm-2 col-form-label text-success">Email</label>
      <div class="col-sm-7">
        <input type="email" class="form-control is-valid" id="inputEmail" placeholder="Email">

    <div class="form-group row">
      <label for="inputPassword" class="col-sm-2 col-form-label text-danger">Password</label>
      <div class="col-sm-7">
        <input type="password" class="form-control is-invalid" id="inputPassword" placeholder="Password">
      <div class="col-sm-3">
        <small id="passwordHelp" class="text-danger">
          Must be 8-20 characters long.

Bootstrap v3

See the live version on codepen

bootstrap v3 form validation

<form role="form">
  <div class="form-group has-warning">
    <label class="control-label" for="inputWarning">Input with warning</label>
    <input type="text" class="form-control" id="inputWarning">
    <span class="help-block">Something may have gone wrong</span>
  <div class="form-group has-error">
    <label class="control-label" for="inputError">Input with error</label>
    <input type="text" class="form-control" id="inputError">
    <span class="help-block">Please correct the error</span>
  <div class="form-group has-info">
    <label class="control-label" for="inputError">Input with info</label>
    <input type="text" class="form-control" id="inputError">
    <span class="help-block">Username is taken</span>
  <div class="form-group has-success">
    <label class="control-label" for="inputSuccess">Input with success</label>
    <input type="text" class="form-control" id="inputSuccess" />
    <span class="help-block">Woohoo!</span>

Bootstrap v2

See the live version on jsfiddle

bootstrap v2 form validation

The .error, .success, .warning and .info classes are appended to the .control-group. This is standard Bootstrap markup and styling in v2. Just follow that and you're in good shape. Of course you can go beyond with your own styles to add a popup or "inline flash" if you prefer, but if you follow Bootstrap convention and hang those validation classes on the .control-group it will stay consistent and easy to manage (at least since you'll continue to have the benefit of Bootstrap docs and examples)

  <form class="form-horizontal">
    <div class="control-group warning">
      <label class="control-label" for="inputWarning">Input with warning</label>
      <div class="controls">
        <input type="text" id="inputWarning">
        <span class="help-inline">Something may have gone wrong</span>
    <div class="control-group error">
      <label class="control-label" for="inputError">Input with error</label>
      <div class="controls">
        <input type="text" id="inputError">
        <span class="help-inline">Please correct the error</span>
    <div class="control-group info">
      <label class="control-label" for="inputInfo">Input with info</label>
      <div class="controls">
        <input type="text" id="inputInfo">
        <span class="help-inline">Username is taken</span>
    <div class="control-group success">
      <label class="control-label" for="inputSuccess">Input with success</label>
      <div class="controls">
        <input type="text" id="inputSuccess">
        <span class="help-inline">Woohoo!</span>

Return positions of a regex match() in Javascript?

Here is a cool feature I discovered recently, I tried this on the console and it seems to work:

var text = "border-bottom-left-radius";

var newText = text.replace(/-/g,function(match, index){
    return " " + index + " ";

Which returned: "border 6 bottom 13 left 18 radius"

So this seems to be what you are looking for.

jQuery jump or scroll to certain position, div or target on the page from button onclick

$("html, body").scrollTop($(element).offset().top); // <-- Also integer can be used

How to re-enable right click so that I can inspect HTML elements in Chrome?

Open inspect mode before navigating to the page. It worked.hehe

How to post query parameters with Axios?

As of 2021 insted of null i had to add {} in order to make it work!
          params: {
      .then(response => {
        return success(response);
      .catch(error => {
        return fail(error);

docker error - 'name is already in use by container'

I was running into this issue that when I run docker rm (which usually works) I would get:

Error: No such image

The easiest solution to this is removing all stopped containers by running:

docker container prune

Stripping non printable characters from a string in python

This function uses list comprehensions and str.join, so it runs in linear time instead of O(n^2):

from curses.ascii import isprint

def printable(input):
    return ''.join(char for char in input if isprint(char))

How to check if a table is locked in sql server

Better yet, consider sp_getapplock which is designed for this. Or use SET LOCK_TIMEOUT

Otherwise, you'd have to do something with sys.dm_tran_locks which I'd use only for DBA stuff: not for user defined concurrency.

Logical Operators, || or OR?

I don't think one is inherently better than another one, but I would suggest sticking with || because it is the default in most languages.

EDIT: As others have pointed out there is indeed a difference between the two.

Get only the date in timestamp in mysql

$date= new DateTime($row['your_date']) ;  
echo $date->format('Y-m-d');

What's the difference between a Python module and a Python package?

First, keep in mind that, in its precise definition, a module is an object in the memory of a Python interpreter, often created by reading one or more files from disk. While we may informally call a disk file such as a/b/ a "module," it doesn't actually become one until it's combined with information from several other sources (such as sys.path) to create the module object.

(Note, for example, that two modules with different names can be loaded from the same file, depending on sys.path and other settings. This is exactly what happens with python -m my.module followed by an import my.module in the interpreter; there will be two module objects, __main__ and my.module, both created from the same file on disk, my/

A package is a module that may have submodules (including subpackages). Not all modules can do this. As an example, create a small module hierarchy:

$ mkdir -p a/b
$ touch a/b/

Ensure that there are no other files under a. Start a Python 3.4 or later interpreter (e.g., with python3 -i) and examine the results of the following statements:

import a
a                ? <module 'a' (namespace)>
a.b              ? AttributeError: module 'a' has no attribute 'b'
import a.b.c
a.b              ? <module 'a.b' (namespace)>
a.b.c            ? <module 'a.b.c' from '/home/cjs/a/b/'>

Modules a and a.b are packages (in fact, a certain kind of package called a "namespace package," though we wont' worry about that here). However, module a.b.c is not a package. We can demonstrate this by adding another file, a/ to the directory structure above and starting a fresh interpreter:

import a.b.c
? ImportError: No module named 'a.b.c'; 'a.b' is not a package
import a.b
a                ? <module 'a' (namespace)>
a.__path__       ? _NamespacePath(['/.../a'])
a.b              ? <module 'a.b' from '/home/cjs/tmp/a/'>
a.b.__path__     ? AttributeError: 'module' object has no attribute '__path__'

Python ensures that all parent modules are loaded before a child module is loaded. Above it finds that a/ is a directory, and so creates a namespace package a, and that a/ is a Python source file which it loads and uses to create a (non-package) module a.b. At this point you cannot have a module a.b.c because a.b is not a package, and thus cannot have submodules.

You can also see here that the package module a has a __path__ attribute (packages must have this) but the non-package module a.b does not.

Bootstrap Accordion button toggle "data-parent" not working

Bootstrap 3

Try this. Simple solution with no dependencies.

$('[data-toggle="collapse"]').click(function() {

How to get UTC timestamp in Ruby?

time =

It will work as

=> 2017-12-02 12:06:41 UTC

How to convert Moment.js date to users local timezone?

You do not need to use moment-timezone for this. The main moment.js library has full functionality for working with UTC and the local time zone.

var testDateUtc = moment.utc("2015-01-30 10:00:00");
var localDate = moment(testDateUtc).local();

From there you can use any of the functions you might expect:

var s = localDate.format("YYYY-MM-DD HH:mm:ss");
var d = localDate.toDate();
// etc...

Note that by passing testDateUtc, which is a moment object, back into the moment() constructor, it creates a clone. Otherwise, when you called .local(), it would also change the testDateUtc value, instead of just the localDate value. Moments are mutable.

Also note that if your original input contains a time zone offset such as +00:00 or Z, then you can just parse it directly with moment. You don't need to use .utc or .local. For example:

var localDate = moment("2015-01-30T10:00:00Z");

How to properly make a http web GET request

var request = (HttpWebRequest)WebRequest.Create("sendrequesturl");
var response = (HttpWebResponse)request.GetResponse();
string responseString;
using (var stream = response.GetResponseStream())
    using (var reader = new StreamReader(stream))
        responseString = reader.ReadToEnd();

How do you make an element "flash" in jQuery

Working with jQuery 1.10.2, this pulses a dropdown twice and changes the text to an error. It also stores the values for the changed attributes to reinstate them.

// shows the user an error has occurred
$("#myDropdown").fadeOut(700, function(){
    var text = $(this).find("option:selected").text();
    var background = $(this).css( "background" );

    $(this).css('background', 'red');
    $(this).find("option:selected").text("Error Occurred");

        $(this).fadeIn(700, function(){
            $(this).fadeOut(700, function(){
                $(this).fadeIn(700, function(){
                    $(this).fadeOut(700, function(){

                        $(this).css("background", background);

Done via callbacks - to ensure no animations are missed.

How to fix error "ERROR: Command errored out with exit status 1: python." when trying to install django-heroku using pip

You need to add the package containing the executable pg_config.

A prior answer should have details you need: pg_config executable not found

How to workaround 'FB is not defined'?

    window.fbAsyncInit = function() {    
            appId      :'your-app-id',      
            xfbml      :true,      
            version    :'v2.1'
    (function(d, s, id) {
        var js, fjs = d.getElementsByTagName(s)[0];
        if(d.getElementById(id)) {
        js = d.createElement(s); = id;     
        js.src ="// /sdk.js";     
        fjs.parentNode.insertBefore(js, fjs);

From the documentation: The Facebook SDK for JavaScript doesn't have any standalone files that need to be downloaded or installed, instead you simply need to include a short piece of regular JavaScript in your HTML tha

The application may be doing too much work on its main thread

this usually happens when you are executing huge processes in main thread. it's OK to skip frames less than 200. but if you have more than 200 skipped frames, it can slow down your application UI thread. what you can do is to do these processes in a new thread called worker thread and after that, when you want to access and do something with UI thread(ex: do something with views, findView etc...) you can use handler or runOnUiThread(I like this more) in order to display the processing results. this absolutely solves the problem. using worker threads are very useful or even must be used when it comes to this cases.

Python: SyntaxError: non-keyword after keyword arg

To really get this clear, here's my for-beginners answer: You inputed the arguments in the wrong order.
A keyword argument has this style:

nullable=True, unique=False

A fixed parameter should be defined: True, False, etc. A non-keyword argument is different:

name="Ricardo", fruit="chontaduro" 

This syntax error asks you to first put name="Ricardo" and all of its kind (non-keyword) before those like nullable=True.

What is the difference between H.264 video and MPEG-4 video?

They are names for the same standard from two different industries with different naming methods, the guys who make & sell movies and the guys who transfer the movies over the internet. Since 2003: "MPEG 4 Part 10" = "H.264" = "AVC". Before that the relationship was a little looser in that they are not equal but an "MPEG 4 Part 2" decoder can render a stream that's "H.263". The Next standard is "MPEG H Part 2" = "H.265" = "HEVC"

PHP: How to generate a random, unique, alphanumeric string for use in a secret link?

Simplifying Scotts code above by removing unnecessary loops which is slowing down badly and does not make it any more secure than calling openssl_random_pseudo_bytes just once

function crypto_rand_secure($min, $max)
 $range = $max - $min;
 if ($range < 1) return $min; // not so random...
 $log = ceil(log($range, 2));
 $bytes = (int) ($log / 8) + 1; // length in bytes
 $rnd = hexdec(bin2hex(openssl_random_pseudo_bytes($bytes)));
 return $min + $rnd%$range;

function getToken($length)
 return bin2hex(openssl_random_pseudo_bytes($length)

How to get rid of `deprecated conversion from string constant to ‘char*’` warnings in GCC?


char *str = "hello";


char *str = (char*)"hello";

or if you are calling in function:


replace this with

foo((char*) "hello");

Using a custom typeface in Android

Hey i also need 2 different fonts in my app for different widgeds! I use this way:

In my Application class i create an static method:

public static Typeface getTypeface(Context context, String typeface) {
    if (mFont == null) {
        mFont = Typeface.createFromAsset(context.getAssets(), typeface);
    return mFont;

The String typeface represents the xyz.ttf in the asset folder. (i created an Constants Class) Now you can use this everywhere in your app:

mTextView = (TextView) findViewById(;
mTextView.setTypeface(MyApplication.getTypeface(this, Constants.TYPEFACE_XY));

The only problem is, you need this for every widget where you want to use the Font! But i think this is the best way.

Vertical (rotated) text in HTML table

Have a look at this, i found this while looking for a solution for IE 7.

totally a cool solution for css only vibes

Thanks aiboy for the soultion

heres the link

and here is the stack-overflow link where i came across this link meow


                /* this is for shity "non IE" browsers
                   that dosn't support writing-mode */
                -webkit-transform: translate(1.1em,0) rotate(90deg);
                   -moz-transform: translate(1.1em,0) rotate(90deg);
                     -o-transform: translate(1.1em,0) rotate(90deg);
                        transform: translate(1.1em,0) rotate(90deg);
                -webkit-transform-origin: 0 0;
                   -moz-transform-origin: 0 0;
                     -o-transform-origin: 0 0;
                        transform-origin: 0 0;  
             /* IE9+ */    ms-transform: none;    
                   -ms-transform-origin: none;    
        /* IE8+ */    -ms-writing-mode: tb-rl;    
   /* IE7 and below */    *writing-mode: tb-rl;


Proper way to exit command line program?

if you do ctrl-z and then type exit it will close background applications.

Ctrl+Q is another good way to kill the application.

Prevent double submission of forms in jQuery

I solved a very similar issue using:


How to color the Git console?

For example see

The interesting part is

Colorized output:

git config --global color.branch auto
git config --global color.diff auto
git config --global color.interactive auto
git config --global color.status auto

switch case statement error: case expressions must be constant expression*, since ADT 14 are not more declared as final static int so you can not use in switch case construct. You could use if else clause instead.

Html.EditorFor Set Default Value

This worked for me

In Controlle

 ViewBag.AAA = default_Value ;

In View

@Html.EditorFor(model => model.AAA, new { htmlAttributes = new { @Value = ViewBag.AAA } }

How to create PDFs in an Android app?

If you are developing for devices with API level 19 or higher you can use the built in PrintedPdfDocument:

// open a new document
PrintedPdfDocument document = new PrintedPdfDocument(context,

// start a page
Page page = document.startPage(0);

// draw something on the page
View content = getContentView();

// finish the page
. . .
// add more pages
. . .
// write the document content

//close the document

Bridged networking not working in Virtualbox under Windows 10

i had same problem. i updated to new version of VirtualBox 5.2.26 and checked to make sure Bridge Adapter was enabled in the installation process now is working

number several equations with only one number

First of all, you probably don't want the align environment if you have only one column of equations. In fact, your example is probably best with the cases environment. But to answer your question directly, used the aligned environment within equation - this way the outside environment gives the number:

  w^T x_i + b &\geq 1-\xi_i &\text{ if }& y_i=1,  \\
  w^T x_i + b &\leq -1+\xi_i & \text{ if } &y_i=-1,

The documentation of the amsmath package explains this and more.

Drop all duplicate rows across multiple columns in Python Pandas

Actually, drop rows 0 and 1 only requires (any observations containing matched A and C is kept.):

In [335]:

In [336]:

print df.drop_duplicates('C', take_last=True) #this dataset is a special case, in general, one may need to first drop_duplicates by 'c' and then by 'a'.
     A  B  C    AC
2  foo  1  B  fooB
3  bar  1  A  barA

[2 rows x 4 columns]

But I suspect what you really want is this (one observation containing matched A and C is kept.):

In [337]:

print df.drop_duplicates('AC')
     A  B  C    AC
0  foo  0  A  fooA
2  foo  1  B  fooB
3  bar  1  A  barA

[3 rows x 4 columns]


Now it is much clearer, therefore:

In [352]:
DG=df.groupby(['A', 'C'])   
print pd.concat([DG.get_group(item) for item, value in DG.groups.items() if len(value)==1])
     A  B  C
2  foo  1  B
3  bar  1  A

[2 rows x 3 columns]

Moment.js: Date between dates

Please use the 4th parameter of moment.isBetween function (inclusivity). Example:

var startDate = moment("15/02/2013", "DD/MM/YYYY");
var endDate = moment("20/02/2013", "DD/MM/YYYY");

var testDate = moment("15/02/2013", "DD/MM/YYYY");

testDate.isBetween(startDate, endDate, 'days', true); // will return true
testDate.isBetween(startDate, endDate, 'days', false); // will return false

HTML Mobile -forcing the soft keyboard to hide

Those answers aren't bad, but they are limited in that they don't actually allow you to enter data. We had a similar problem where we were using barcode readers to enter data into a field, but we wanted to suppress the keyboard.

This is what I put together, it works pretty well:

<!-- must be a select box with no children to suppress the keyboard -->
input: <select id="hiddenField" /> 
<span id="fakecursor" />

<input type="text" readonly="readonly" id="visibleField" />
<div id="cursorMeasuringDiv" />

#hiddenField {
  border-width:0px 0px 0px 1px;

#cursorMeasuringDiv {

#hiddenField:focus {
  border:1px solid gray;  
  border-width:0px 0px 0px 1px;
  animation-name: cursor;
  animation-duration: 1s;
  animation-iteration-count: infinite;

@keyframes cursor {
    from {opacity:0;}
    to {opacity:1;}

// whenever the visible field gets focused
$("#visibleField").bind("focus", function(e) {
  // silently shift the focus to the hidden select box
  $("#cursorMeasuringDiv").css("font", $("#visibleField").css("font"));

// whenever the user types on his keyboard in the select box
// which is natively supported for jumping to an <option>
$("#hiddenField").bind("keypress",function(e) {
  // get the current value of the readonly field
  var currentValue = $("#visibleField").val();

  // and append the key the user pressed into that field
  $("#visibleField").val(currentValue + e.key);
  $("#cursorMeasuringDiv").text(currentValue + e.key);

  // measure the width of the cursor offset
  var offset = 3;
  var textWidth = $("#cursorMeasuringDiv").width();


When you click in the <input> box, it simulates a cursor in that box but really puts the focus on an empty <select> box. Select boxes naturally allow for keypresses to support jumping to an element in the list so it was only a matter of rerouting the keypress to the original input and offsetting the simulated cursor.

This won't work for backspace, delete, etc... but we didn't need those. You could probably use jQuery's trigger to send the keyboard event directly to another input box somewhere but we didn't need to bother with that so I didn't do it.

uint8_t vs unsigned char

It documents your intent - you will be storing small numbers, rather than a character.

Also it looks nicer if you're using other typedefs such as uint16_t or int32_t.

What is ANSI format?

Once upon a time Microsoft, like everyone else, used 7-bit character sets, and they invented their own when it suited them, though they kept ASCII as a core subset. Then they realised the world had moved on to 8-bit encodings and that there were international standards around, such as the ISO-8859 family. In those days, if you wanted to get hold of an international standard and you lived in the US, you bought it from the American National Standards Institute, ANSI, who republished international standards with their own branding and numbers (that's because the US government wants conformance to American standards, not international standards). So Microsoft's copy of ISO-8859 said "ANSI" on the cover. And because Microsoft weren't very used to standards in those days, they didn't realise that ANSI published lots of other standards as well. So they referred to the standards in the ISO-8859 family (and the variants that they invented, because they didn't really understand standards in those days) by the name on the cover, "ANSI", and it found its way into Microsoft user documentation and hence into the user community. That was about 30 years ago, but you still sometimes hear the name today.

Neither user 10102 nor current process has android.permission.READ_PHONE_STATE

I was experiencing this problem on Samsung devices (fine on others). like zyamys suggested in his/her comment, I added the manifest.permission line but in addition to rather than instead of the original line, so:

<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.Manifest.permission.READ_PHONE_STATE" />

I'm targeting API 22, so don't need to explicitly ask for permissions.

Computing cross-correlation function?

If you are looking for a rapid, normalized cross correlation in either one or two dimensions I would recommend the openCV library (see The cross-correlation code maintained by this group is the fastest you will find, and it will be normalized (results between -1 and 1).

While this is a C++ library the code is maintained with CMake and has python bindings so that access to the cross correlation functions is convenient. OpenCV also plays nicely with numpy. If I wanted to compute a 2-D cross-correlation starting from numpy arrays I could do it as follows.

import numpy
import cv

#Create a random template and place it in a larger image
templateNp = numpy.random.random( (100,100) )
image = numpy.random.random( (400,400) )
image[:100, :100] = templateNp

#create a numpy array for storing result
resultNp = numpy.zeros( (301, 301) )

#convert from numpy format to openCV format
templateCv = cv.fromarray(numpy.float32(template))
imageCv = cv.fromarray(numpy.float32(image))
resultCv =  cv.fromarray(numpy.float32(resultNp))

#perform cross correlation
cv.MatchTemplate(templateCv, imageCv, resultCv, cv.CV_TM_CCORR_NORMED)

#convert result back to numpy array
resultNp = np.asarray(resultCv)

For just a 1-D cross-correlation create a 2-D array with shape equal to (N, 1 ). Though there is some extra code involved to convert to an openCV format the speed-up over scipy is quite impressive.

How to find the largest file in a directory and its subdirectories?

Quote from this link-

If you want to find and print the top 10 largest files names (not directories) in a particular directory and its sub directories

$ find . -printf '%s %p\n'|sort -nr|head

To restrict the search to the present directory use "-maxdepth 1" with find.

$ find . -maxdepth 1 -printf '%s %p\n'|sort -nr|head

And to print the top 10 largest "files and directories":

$ du -a . | sort -nr | head

** Use "head -n X" instead of the only "head" above to print the top X largest files (in all the above examples)

Check if a variable is of function type

jQuery (deprecated since version 3.3) Reference


AngularJS Reference


Lodash Reference


Underscore Reference


Node.js deprecated since v4.0.0 Reference

var util = require('util');

How to disable sort in DataGridView?

private void dataGridView1_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
      for (int i = 0; i < dataGridView1.Columns.Count; i++)
           dataGridView1.Columns[i].SortMode = DataGridViewColumnSortMode.NotSortable;

Output PowerShell variables to a text file

Use this:

"$computer, $Speed, $Regcheck" | out-file -filepath C:\temp\scripts\pshell\dump.txt -append -width 200

Using Helvetica Neue in a Website

They are taking a 'shotgun' approach to referencing the font. The browser will attempt to match each font name with any installed fonts on the user's machine (in the order they have been listed).

In your example "HelveticaNeue-Light" will be tried first, if this font variant is unavailable the browser will try "Helvetica Neue Light" and finally "Helvetica Neue".

As far as I'm aware "Helvetica Neue" isn't considered a 'web safe font', which means you won't be able to rely on it being installed for your entire user base. It is quite common to define "serif" or "sans-serif" as a final default position.

In order to use fonts which aren't 'web safe' you'll need to use a technique known as font embedding. Embedded fonts do not need to be installed on a user's computer, instead they are downloaded as part of the page. Be aware this increases the overall payload (just like an image does) and can have an impact on page load times.

A great resource for free fonts with open-source licenses is Google Fonts. (You should still check individual licenses before using them.) Each font has a download link with instructions on how to embed them in your website.

not:first-child selector

li + li {
    background-color: red;

Roblox Admin Command Script

for i=1,#target do[i].Character:BreakJoints()

Is incorrect, if "target" contains "FakeNameHereSoNoStalkers" then the run code would be:

Which is completely incorrect.

c = game.Players:GetChildren()

Never use "Players:GetChildren()", it is not guaranteed to return only players.

Instead use:

c = Game.Players:GetPlayers()

if msg:lower()=="me" then
    table.insert(people, source)
    return people

Here you add the player's name in the list "people", where you in the other places adds the player object.

Fixed code:

local Admins = {"FakeNameHereSoNoStalkers"}

function Kill(Players)
    for i,Player in ipairs(Players) do
        if Player.Character then

function IsAdmin(Player)
    for i,AdminName in ipairs(Admins) do
        if Player.Name:lower() == AdminName:lower() then return true end
    return false

function GetPlayers(Player,Msg)
    local Targets = {}
    local Players = Game.Players:GetPlayers()

    if Msg:lower() == "me" then
        Targets = { Player }
    elseif Msg:lower() == "all" then
        Targets = Players
    elseif Msg:lower() == "others" then
        for i,Plr in ipairs(Players) do
            if Plr ~= Player then
        for i,Plr in ipairs(Players) do
            if Plr.Name:lower():sub(1,Msg:len()) == Msg then
    return Targets

    if IsAdmin(Player) then
            if Msg:lower():sub(1,6) == ":kill " then

Oracle SQL Developer spool output?

You can export the query results to a text file (or insert statements, or even pdf) by right-clicking on Query Result row (any row) and choose Export

using Sql Developer 3.0

See SQL Developer downloads for latest versions

Screenshot sizes for publishing android app on Google Play

It has to be any one of the given sizes and a minimum of 2 but up to 8 screenshots are accepted in Google Playstore.

Get counts of all tables in a schema

Get counts of all tables in a schema and order by desc

select 'with tmp(table_name, row_number) as (' from dual 
union all 
select 'select '''||table_name||''',count(*) from '||table_name||' union  ' from USER_TABLES 
union all
select 'select '''',0 from dual) select table_name,row_number from tmp order by row_number desc ;' from dual;

Copy the entire result and execute

Open a new tab in the background?

I did exactly what you're looking for in a very simple way. It is perfectly smooth in Google Chrome and Opera, and almost perfect in Firefox and Safari. Not tested in IE.

function newTab(url)
    tab.document.write("<!DOCTYPE html><html>"+document.getElementsByTagName("html")[0].innerHTML+"</html>");

Fiddle :

Let's say there is windows A1 and B1 and websites A2 and B2.
Instead of opening B2 in B1 and then return to A1, I open B2 in A1 and re-open A2 in B1.
(Another thing that makes it work is that I don't make the user re-download A2, see line 4)

The only thing you may doesn't like is that the new tab opens before the main page.

fill an array in C#

public static void Fill<T>(this IList<T> col, T value, int fromIndex, int toIndex)
    if (fromIndex > toIndex)
        throw new ArgumentOutOfRangeException("fromIndex");

    for (var i = fromIndex; i <= toIndex; i++)
        col[i] = value;

Something that works for all IList<T>s.

How to add and get Header values in WebApi

You need to get the HttpRequestMessage from the current OperationContext. Using OperationContext you can do it like so

OperationContext context = OperationContext.Current;
MessageProperties messageProperties = context.IncomingMessageProperties;

HttpRequestMessageProperty requestProperty = messageProperties[HttpRequestMessageProperty.Name] as HttpRequestMessageProperty;

string customHeaderValue = requestProperty.Headers["Custom"];

Mockito match any class argument

There is another way to do that without cast:


This solution forces the method any() to return Class<A> type and not its default value (Object).

string.split - by multiple character delimiter

To show both string.Split and Regex usage:

string input = "abc][rfd][5][,][.";
string[] parts1 = input.Split(new string[] { "][" }, StringSplitOptions.None);
string[] parts2 = Regex.Split(input, @"\]\[");

ObjectiveC Parse Integer from String

NSArray *_returnedArguments = [serverOutput componentsSeparatedByString:@":"];

_returnedArguments is an array of NSStrings which the UITextField text property is expecting. No need to convert.

Syntax error:

[_appDelegate loggedIn:usernameField.text:passwordField.text:(int)[[_returnedArguments objectAtIndex:2] intValue]];

If your _appDelegate has a passwordField property, then you can set the text using the following

[[_appDelegate passwordField] setText:[_returnedArguments objectAtIndex:2]];

How do I merge changes to a single file, rather than merging commits?

Assuming B is the current branch:

$ git diff A <file-path> > patch.tmp
$ git apply patch.tmp -R

Note that this only applies changes to the local file. You'll need to commit afterwards.

How can I remove all text after a character in bash?

An example might have been useful, but if I understood you correctly, this would work:

echo "Hello: world" | cut -f1 -d":"

This will convert Hello: world into Hello.

Applying an ellipsis to multiline text

If you want to apply ellipsis (...) to a single line of text, CSS makes that somewhat easy with the text-overflow property. It's still a bit tricky (due to all the requirements – see below), but text-overflow makes it possible and reliable.

If, however, you want to use ellipsis on multiline text – as would be the case here – then don't expect to have any fun. CSS has no standard method for doing this, and the workarounds are hit and miss.

Ellipsis for Single Line Text

With text-overflow, ellipsis can be applied to a single line of text. The following CSS requirements must be met:

  • must have a width, max-width or flex-basis
  • must have white-space: nowrap
  • must have overflow with value other than visible
  • must be display: block or inline-block (or the functional equivalent, such as a flex item).

So this will work:

p {_x000D_
  width: 200px;_x000D_
  white-space: nowrap;_x000D_
  overflow: hidden;_x000D_
  display: inline-block;_x000D_
  text-overflow: ellipsis;_x000D_
  border: 1px solid #ddd;_x000D_
  margin: 0;_x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_

jsFiddle version

BUT, try removing the width, or letting the overflow default to visible, or removing white-space: nowrap, or using something other than a block container element, AND, ellipsis fails miserably.

One big takeaway here: text-overflow: ellipsis has no effect on multiline text. (The white-space: nowrap requirement alone eliminates that possibility.)

p {_x000D_
    width: 200px;_x000D_
    /* white-space: nowrap; */_x000D_
    height: 90px; /* new */_x000D_
    overflow: hidden;_x000D_
    display: inline-block;_x000D_
    text-overflow: ellipsis;_x000D_
    border: 1px solid #ddd;_x000D_
    margin: 0;_x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_

jsFiddle version

Ellipsis for Multiline Text

Because CSS has no property for ellipsis on multiline text, various workarounds have been created. Several of these methods can be found here:

The Mobify link above was removed and now references an copy, but appears to be implemented in this codepen.

How to break out or exit a method in Java?

If you are deeply in recursion inside recursive method, throwing and catching exception may be an option.

Unlike Return that returns only one level up, exception would break out of recursive method as well into the code that initially called it, where it can be catched.

How to round down to nearest integer in MySQL?

Both Query is used for round down the nearest integer in MySQL

  1. SELECT FLOOR(445.6) ;
  2. SELECT NULL(222.456);

Kill a postgresql session/connection

Just wanted to point out that Haris's Answer might not work if some other background process is using the database, in my case it was delayed jobs, I did:

script/delayed_job stop

And only then I was able to drop/reset the database.

the MySQL service on local computer started and then stopped

You also might have accidentally added some wrong text in my.ini file. Make sure no invalid character is added at the beginning of the file.

How to squash all git commits into one?

The easiest way is to use the 'plumbing' command update-ref to delete the current branch.

You can't use git branch -D as it has a safety valve to stop you deleting the current branch.

This puts you back into the 'initial commit' state where you can start with a fresh initial commit.

git update-ref -d refs/heads/master
git commit -m "New initial commit"

Make the console wait for a user input to close

I used simple hack, asking windows to use cmd commands , and send it to null.

// Class for Different hacks for better CMD Display
public class CMDWindowEffets
    public static void getch() throws IOException, InterruptedException
        new ProcessBuilder("cmd", "/c", "pause > null").inheritIO().start().waitFor();

Get random item from array

Use PHP Rand function

  $input = array("Neo", "Morpheus", "Trinity", "Cypher", "Tank");
  $rand_keys = array_rand($input, 2);
  echo $input[$rand_keys[0]] . "\n";
  echo $input[$rand_keys[1]] . "\n";

More Help

Codeigniter : calling a method of one controller from other

I posted a somewhat similar question a while back, but regarding a model on CI.

Returning two separate query results within a model function

Although your question is not exactly the same, I believe the solution follows the same principle: if you're proposing to do what you mention in your question, there may be something wrong in the way you're coding and some refactoring could be in order.

The take home message is that what you're asking is not the way to go when working with MVC.

The best practice is to either use a Model to place reusable functions and call them in a controller that outputs the data through a view -- or even better use helpers or libraries (for functions that may be needed repeatedly).

Query Mongodb on month, day, year... of a datetime

how about storing the month in its own property since you need to query for it? less elegant than $where, but likely to perform better since it can be indexed.

Is there something like Codecademy for Java

As of right now, I do not know of any. It appears the code academy folks have set their sites on Ruby on Rails. They do not rule Java out of the picture however.

How to remove a package in sublime text 2

Follow below steps-

Step1 - Ctrl+Shift+P

Step2 - Enter Disable Package

Step3 - enter the package name that you want to disable and press enter

Successfully removed, if not removed then restart Sublime

Using prepared statements with JDBCTemplate

class Main {
    public static void main(String args[]) throws Exception {
        ApplicationContext ac = new
          ClassPathXmlApplicationContext("context.xml", Main.class);
        DataSource dataSource = (DataSource) ac.getBean("dataSource");
// DataSource mysqlDataSource = (DataSource) ac.getBean("mysqlDataSource");

        JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);

        String prasobhName = 
           "select first_name from customer where last_name like ?",
            new PreparedStatementSetter() {
              public void setValues(PreparedStatement preparedStatement) throws
                SQLException {
                  preparedStatement.setString(1, "nair%");
            new ResultSetExtractor<Long>() {
              public Long extractData(ResultSet resultSet) throws SQLException,
                DataAccessException {
                  if ( {
                      return resultSet.getLong(1);
                  return null;

test if event handler is bound to an element in jQuery

For jQuery 1.9+

var eventListeners = $._data($('.classname')[0], "events");

I needed the [0] array literal.

Case Function Equivalent in Excel

I used this solution to convert single letter color codes into their descriptions:


You basically look up the element you're trying to decode in the array, then use CHOOSE() to pick the associated item. It's a little more compact than building a table for VLOOKUP().

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

The answer is to DISABLE "Enable auto-completion on each input". Tested and works perfectly.

Convert XML String to Object

Try this method to Convert Xml to an object. It is made for exactly what you are doing:

protected T FromXml<T>(String xml)
    T returnedXmlClass = default(T);

        using (TextReader reader = new StringReader(xml))
                returnedXmlClass = 
                    (T)new XmlSerializer(typeof(T)).Deserialize(reader);
            catch (InvalidOperationException)
                // String passed is not XML, simply return defaultXmlClass
    catch (Exception ex)

    return returnedXmlClass ;        

Call it using this code:

YourStrongTypedEntity entity = FromXml<YourStrongTypedEntity>(YourMsgString);

Kafka consumer list

High level consumers are registered into Zookeeper, so you can fetch a list from ZK, similarly to the way fetches the list of topics. I don't think there's a way to collect all consumers; any application sending in a few consume requests is actually a "consumer", and you cannot tell whether they are done already.

On the consumer side, there's a JMX metric exposed to monitor the lag. Also, there is Burrow for lag monitoring.

C++ IDE for Linux?

Having been raised on Visual Studio, I've found the relatively young Code::Blocks to be very familiar.

How to reformat JSON in Notepad++?

I use 32-bit Notepad++ version 7.5.6. I have found that 32-bit JSToolNpp 1.20.0 does a great job.
The direct link is:
which is redirected from
VirusTotal link:

JSON-Viewer works fine too, but cannot sort the JSON data.

libxml install error using pip

I am using Ubuntu 14.04 and this solves the issue for me

sudo apt-get build-dep python3-lxml
sudo apt-get install libxml2-dev libxslt-dev python-dev

Having both a Created and Last Updated timestamp columns in MySQL 4.0

This is how can you have automatic & flexible createDate/lastModified fields using triggers:

First define them like this:

CREATE TABLE `entity` (
  `entityid` int(11) NOT NULL AUTO_INCREMENT,
  `createDate` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
  `lastModified` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
  `name` varchar(255) DEFAULT NULL,
  `comment` text,
  PRIMARY KEY (`entityid`),

Then add these triggers:

CREATE trigger entityinsert BEFORE INSERT ON entity FOR EACH ROW BEGIN SET NEW.createDate=IF(ISNULL(NEW.createDate) OR NEW.createDate='0000-00-00 00:00:00', CURRENT_TIMESTAMP, IF(NEW.createDate<CURRENT_TIMESTAMP, NEW.createDate, CURRENT_TIMESTAMP));SET NEW.lastModified=NEW.createDate; END;;
CREATE trigger entityupdate BEFORE UPDATE ON entity FOR EACH ROW SET NEW.lastModified=IF(NEW.lastModified<OLD.lastModified, OLD.lastModified, CURRENT_TIMESTAMP);
  • If you insert without specifying createDate or lastModified, they will be equal and set to the current timestamp.
  • If you update them without specifying createDate or lastModified, the lastModified will be set to the current timestamp.

But here's the nice part:

  • If you insert, you can specify a createDate older than the current timestamp, allowing imports from older times to work well (lastModified will be equal to createDate).
  • If you update, you can specify a lastModified older than the previous value ('0000-00-00 00:00:00' works well), allowing to update an entry if you're doing cosmetic changes (fixing a typo in a comment) and you want to keep the old lastModified date. This will not modify the lastModified date.

How can you create pop up messages in a batch script?

I put together a script based on the good answers here & in other posts

You can set title timeout & even sleep to schedule it for latter & \n for new line

also you get back the key press into a variable (%pop.key%).

Here is my code

Catching KeyboardInterrupt in Python during program shutdown

Checkout this thread, it has some useful information about exiting and tracebacks.

If you are more interested in just killing the program, try something like this (this will take the legs out from under the cleanup code as well):

if __name__ == '__main__':
    except KeyboardInterrupt:
        except SystemExit:

How to replace all double quotes to single quotes using jquery?

Use double quote to enclose the quote or escape it.

newTemp = mystring.replace(/"/g, "'");


newTemp = mystring.replace(/"/g, '\'');

ImportError: No module named xlsxwriter

I have the same issue. It seems that pip is the problem. Try

pip uninstall xlsxwriter
easy_install xlsxwriter

Postgres where clause compare timestamp

Assuming you actually mean timestamp because there is no datetime in Postgres

Cast the timestamp column to a date, that will remove the time part:

select *
from the_table
where the_timestamp_column::date = date '2015-07-15';

This will return all rows from July, 15th.

Note that the above will not use an index on the_timestamp_column. If performance is critical, you need to either create an index on that expression or use a range condition:

select *
from the_table
where the_timestamp_column >= timestamp '2015-07-15 00:00:00'
  and the_timestamp_column < timestamp '2015-07-16 00:00:00';

How to find out what character key is pressed?

**check this out** 
<!DOCTYPE html>
<script src=""></script>

            var keynum;
            { // IE                 
                keynum = e.keyCode;
                else if(e.which)
                    // Netscape/Firefox/Opera                   
                    keynum = e.which;
                    var unicode=e.keyCode? e.keyCode : e.charCode;


<input type="text"></input>

TypeError: 'undefined' is not an object

I'm not sure how you could just check if something isn't undefined and at the same time get an error that it is undefined. What browser are you using?

You could check in the following way (extra = and making length a truthy evaluation)

if (typeof(sub.from) !== 'undefined' && sub.from.length) {


I see that you reset sub and thereby reset sub.from but fail to re check if sub.from exist:

for (var i = 0; i < sub.from.length; i++) {//<== assuming sub.from.exist
            mainid = sub.from[i]['id'];
            var sub = afcHelper_Submissions[mainid]; // <== re setting sub

My guess is that the error is not on the if statement but on the for(i... statement. In Firebug you can break automatically on an error and I guess it'll break on that line (not on the if statement).

How to display an IFRAME inside a jQuery UI dialog

The problems were:

  1. iframe content comes from another domain
  2. iframe dimensions need to be adjusted for each video

The solution based on omerkirk's answer involves:

  • Creating an iframe element
  • Creating a dialog with autoOpen: false, width: "auto", height: "auto"
  • Specifying iframe source, width and height before opening the dialog

Here is a rough outline of code:


<div class="thumb">
    <a href=""   data-title="Std 4:3 ratio video" data-width="512" data-height="384"><img src="" /></a></li>
    <a href="" data-title="HD 16:9 ratio video" data-width="512" data-height="288"><img src="" /></a></li>


$(function () {
    var iframe = $('<iframe frameborder="0" marginwidth="0" marginheight="0" allowfullscreen></iframe>');
    var dialog = $("<div></div>").append(iframe).appendTo("body").dialog({
        autoOpen: false,
        modal: true,
        resizable: false,
        width: "auto",
        height: "auto",
        close: function () {
            iframe.attr("src", "");
    $(".thumb a").on("click", function (e) {
        var src = $(this).attr("href");
        var title = $(this).attr("data-title");
        var width = $(this).attr("data-width");
        var height = $(this).attr("data-height");
            width: +width,
            height: +height,
            src: src
        dialog.dialog("option", "title", title).dialog("open");

Demo here and code here. And another example along similar lines

SQL Server 100% CPU Utilization - One database shows high CPU usage than others

According to this article on sqlserverstudymaterial;

Remember that "%Privileged time" is not based on 100%.It is based on number of processors.If you see 200 for sqlserver.exe and the system has 8 CPU then CPU consumed by sqlserver.exe is 200 out of 800 (only 25%).

If "% Privileged Time" value is more than 30% then it's generally caused by faulty drivers or anti-virus software. In such situations make sure the BIOS and filter drives are up to date and then try disabling the anti-virus software temporarily to see the change.

If "% User Time" is high then there is something consuming of SQL Server. There are several known patterns which can be caused high CPU for processes running in SQL Server including

Execute write on doc: It isn't possible to write into a document from an asynchronously-loaded external script unless it is explicitly opened.

An asynchronously loaded script is likely going to run AFTER the document has been fully parsed and closed. Thus, you can't use document.write() from such a script (well technically you can, but it won't do what you want).

You will need to replace any document.write() statements in that script with explicit DOM manipulations by creating the DOM elements and then inserting them into a particular parent with .appendChild() or .insertBefore() or setting .innerHTML or some mechanism for direct DOM manipulation like that.

For example, instead of this type of code in an inline script:

<div id="container">
document.write('<span style="color:red;">Hello</span>');

You would use this to replace the inline script above in a dynamically loaded script:

var container = document.getElementById("container");
var content = document.createElement("span"); = "red";
content.innerHTML = "Hello";

Or, if there was no other content in the container that you needed to just append to, you could simply do this:

var container = document.getElementById("container");
container.innerHTML = '<span style="color:red;">Hello</span>';

How to find the highest value of a column in a data frame in R?

Assuming that your data in data.frame called maxinozone, you can do this

max(maxinozone[1, ], na.rm = TRUE)

ClassCastException, casting Integer to Double

We can cast an int to a double but we can't do the same with the wrapper classes Integer and Double:

 int     a = 1;
 Integer b = 1;   // inboxing, requires Java 1.5+

 double  c = (double) a;   // OK
 Double  d = (Double) b;   // No way.

This shows the compile time error that corresponds to your runtime exception.

Internet Explorer cache location

If it's been moved you can also (in IE 11, and I'm pretty sure this translates back to at least 10):

  • Tools - Internet Options
  • Under Browsing history click Settings
  • Under Current location it shows the directory name

Note: The View files button will open a Windows Explorer window there.

For example, mine shows C:\BrowserCache\IE\Temporary Internet Files

MySQL "Group By" and "Order By"

I struggled with both these approaches for more complex queries than those shown, because the subquery approach was horribly ineficient no matter what indexes I put on, and because I couldn't get the outer self-join through Hibernate

The best (and easiest) way to do this is to group by something which is constructed to contain a concatenation of the fields you require and then to pull them out using expressions in the SELECT clause. If you need to do a MAX() make sure that the field you want to MAX() over is always at the most significant end of the concatenated entity.

The key to understanding this is that the query can only make sense if these other fields are invariant for any entity which satisfies the Max(), so in terms of the sort the other pieces of the concatenation can be ignored. It explains how to do this at the very bottom of this link.

If you can get am insert/update event (like a trigger) to pre-compute the concatenation of the fields you can index it and the query will be as fast as if the group by was over just the field you actually wanted to MAX(). You can even use it to get the maximum of multiple fields. I use it to do queries against multi-dimensional trees expresssed as nested sets.

How to connect PHP with Microsoft Access database

If you are just getting started with a new project then I would suggest that you use PDO instead of the old odbc_exec() approach. Here is a simple example:

$bits = 8 * PHP_INT_SIZE;
echo "(Info: This script is running as $bits-bit.)\r\n\r\n";

$connStr = 
        'odbc:Driver={Microsoft Access Driver (*.mdb, *.accdb)};' .

$dbh = new PDO($connStr);

$sql = 
        "SELECT AgentName FROM Agents " .
        "WHERE ID < ? AND AgentName <> ?";
$sth = $dbh->prepare($sql);

// query parameter value(s)
$params = array(


while ($row = $sth->fetch()) {
    echo $row['AgentName'] . "\r\n";

NOTE: The above approach is sufficient if you do not need to support Unicode characters above U+00FF. If you do need to support such characters then neither PDO_ODBC nor the old odbc_ functions will work; you'll need to use the solution described in this answer.

cannot download, $GOPATH not set

Run 'go env' and see where your GOPATH is currently pointing towards. If you change to that directory, your 'go get..etc' command should work.

Why does Eclipse automatically add appcompat v7 library support whenever I create a new project?

According to

The ActionBar APIs were first added in Android 3.0 (API level 11) but they are also available in the Support Library for compatibility with Android 2.1 (API level 7) and above.

In short, that auto-generated project you're seeing modularizes the process of adding the ActionBar to APIs 7-10.

Example of ActionBar on Froyo

See for a simplified explanation and tutorial on the topic.

Fastest way to get the first n elements of a List into an Array

Option 1 Faster Than Option 2

Because Option 2 creates a new List reference, and then creates an n element array from the List (option 1 perfectly sizes the output array). However, first you need to fix the off by one bug. Use < (not <=). Like,

String[] out = new String[n];
for(int i = 0; i < n; i++) {
    out[i] = in.get(i);

jQuery .search() to any string

Ah, that would be because RegExp is not jQuery. :)

Try this page. jQuery.attr doesn't return a String so that would certainly cause in this regard. Fortunately I believe you can just use .text() to return the String representation.

Something like:


POST request with JSON body

You need to use the cURL library to send this request.

// Your ID and token
$blogID = '8070105920543249955';
$authToken = 'OAuth 2.0 token here';

// The data to send to the API
$postData = array(
    'kind' => 'blogger#post',
    'blog' => array('id' => $blogID),
    'title' => 'A new post',
    'content' => 'With <b>exciting</b> content...'

// Setup cURL
$ch = curl_init(''.$blogID.'/posts/');
curl_setopt_array($ch, array(
        'Authorization: '.$authToken,
        'Content-Type: application/json'
    CURLOPT_POSTFIELDS => json_encode($postData)

// Send the request
$response = curl_exec($ch);

// Check for errors
if($response === FALSE){

// Decode the response
$responseData = json_decode($response, TRUE);

// Close the cURL handler

// Print the date from the response
echo $responseData['published'];

If, for some reason, you can't/don't want to use cURL, you can do this:

// Your ID and token
$blogID = '8070105920543249955';
$authToken = 'OAuth 2.0 token here';

// The data to send to the API
$postData = array(
    'kind' => 'blogger#post',
    'blog' => array('id' => $blogID),
    'title' => 'A new post',
    'content' => 'With <b>exciting</b> content...'

// Create the context for the request
$context = stream_context_create(array(
    'http' => array(
        'method' => 'POST',
        'header' => "Authorization: {$authToken}\r\n".
            "Content-Type: application/json\r\n",
        'content' => json_encode($postData)

// Send the request
$response = file_get_contents(''.$blogID.'/posts/', FALSE, $context);

// Check for errors
if($response === FALSE){

// Decode the response
$responseData = json_decode($response, TRUE);

// Print the date from the response
echo $responseData['published'];

How do I test if a string is empty in Objective-C?

One of the best solution I ever seen (better than Matt G's one) is this improved inline function I picked up on some Git Hub repo (Wil Shipley's one, but I can't find the link) :

// Check if the "thing" passed is empty
static inline BOOL isEmpty(id thing) {
    return thing == nil
    || [thing isKindOfClass:[NSNull class]]
    || ([thing respondsToSelector:@selector(length)]
        && [(NSData *)thing length] == 0)
    || ([thing respondsToSelector:@selector(count)]
        && [(NSArray *)thing count] == 0);

Ajax Success and Error function failure

One also may use the following to catch the errors:

    url: url, 
    success: function (data) {
        // Handle success here
    cache: false
}).fail(function (jqXHR, textStatus, error) {
    // Handle error here

Bluetooth pairing without user confirmation

Well, this should really be broken into 2 parts:

  1. Can you pair 2 Bluetooth devices without going through a Bluetooth pairing handshake? No, you can't. That's baked into the protocol so there is no way around this.
  2. Can you perform the handshake without a user interface? Yes, you can: that's just code.

I'm not sure how you do it in Windows land, but in *nix land there are functions buried in the Bluez stack that let you receive notifications about when a new device appears, and send it the pairing code (clearly there have to be these functions: those are what the user interface use). Given sufficient time and experience I'm sure you could figure out how to write your own version of the Bluetooth Settings app that somehow:

  • Detected a new device had arrived
  • Looked at the name/bluetooth mac address and checked some internal database for the pairing code to use.
  • Sent the pairing code and completed the operation

All without having to pop up a user interface.

If you go ahead and write the code I'd LOVE to get my hands on it.

How to check programmatically if an application is installed or not in Android?

So nicer with Kotlin suger:

  private fun isSomePackageInstalled(context: Context, packageName: String): Boolean {

    val packageManager = context.packageManager

    return runCatching { packageManager.getPackageInfo(packageName, 0) }.isSuccess

In MS DOS copying several files to one file

filenames must sort correctly to combine correctly!

file1.bin file2.bin ... file10.bin wont work properly

file01.bin file02.bin ... file10.bin will work properly

c:>for %i in (file*.bin) do type %i >> onebinary.bin

Works for ascii or binary files.

HTML5 best practices; section/header/aside/article elements

[explanations in my “main answer”]

line 7. section around the whole website? Or only a div?

Neither. For styling: use the <body>, it’s already there. For sectioning/semantics: as detailed in my example HTML its effect is contrary to usefulness. Extra wrappers to already wrapped content is no improvement, but noise.

line 8. Each section start with a header?

No, it is the author’s choice where to put content typically summarized as “header”. And if that header-content is clearly recognizable without extra marking, it may perfectly stay without <header>. This is also the author’s choice.

line 23. Is this div right? or must this be a section?

The <div> is probably wrong. It depends on the intentions: is it for styling only it could be right. If it’s for semantic purposes it is wrong: it should be an <article> instead as shown in my other answer. <article> is also right if it is for both styling and sectioning combined.

<section> looks wrong here, as there are no similar sections before or after this one, like chapters in a book. (This is the purpose of <section>).

line 24. Split left/right column with a div.

No. Why?

line 25. Right place for the article tag?

Yes, makes sense.

line 26. Is it required to put your h1-tag in the header-tag?

No. A lone <h*> element probably never needs to go in a <header> (but it can if you want to) as it is already clear that it’s the heading of what is about to come. – It would make sense if that <header> also encompassed a tagline (marked with <p>), for example.

line 43. The content is not related to the main article, so I decided this is a section and not an aside.

It is a misunderstanding that an <aside> has to be “tangentially related” to the content around. The point is: use an <aside> if the content is only “tangentially related” or not at all!

Nevertheless, apart from <aside> being a decent choice, <article> might still be better than a <section> as “hot items” and “new items” are not to be read like two chapters in a book. You can perfectly go for one of them and not the other like an alternative sorting of something, not like two parts of a whole.

line 44. H2 without header

Is great.

line 53. section without header

Well, there is no <header>, but the <h2>-heading leaves pretty clear which part in this section is the header.

line 63. Div with all (non-related) news items

<article> or <aside> might be better.

line 64. header with h2

Discussed already.

line 65. Hmm, div or section? Or remove this div and only use the article-tag

Exactly! Remove the <div>.

line 105. Footer :-)

Very reasonable.

How do I find all the files that were created today in Unix/Linux?

Use ls or find to have all the files that were created today.

Using ls : ls -ltr | grep "$(date '+%b %e')"

Using find : cd $YOUR_DIRECTORY; find . -ls 2>/dev/null| grep "$(date '+%b %e')"

Setting Inheritance and Propagation flags with set-acl and powershell

I think your answer can be found on this page. From the page:

This Folder, Subfolders and Files:

InheritanceFlags.ContainerInherit | InheritanceFlags.ObjectInherit 

Convert web page to image

Not sure if this is what you want but this is what I do sometimes in a pinch when certain websites are not saving right.

I just print them to PDF and I get a PDF file of the 'print output'. There's an Microsoft XPS Document writer under my list of printers as well, but I don't use it.

Hope this helps! =)

How to get a microtime in Node.js?

now('milli'); //  120335360.999686
now('micro') ; // 120335360966.583
now('nano') ; //  120335360904333

Known that now is :

const now = (unit) => {
  const hrTime = process.hrtime();
  switch (unit) {
    case 'milli':
      return hrTime[0] * 1000 + hrTime[1] / 1000000;
    case 'micro':
      return hrTime[0] * 1000000 + hrTime[1] / 1000;
    case 'nano':
      return hrTime[0] * 1000000000 + hrTime[1];

Click event on select option element in chrome

Since $(this) isn't correct anymore with ES6 arrow function which don't have have the same this than function() {}, you shouldn't use $( this ) if you use ES6 syntax.
Besides according to the official jQuery's anwser, there's a simpler way to do that what the top answer says.
The best way to get the html of a selected option is to use

$('#yourSelect option:selected').html();

You can replace html() by text() or anything else you want (but html() was in the original question).
Just add the event listener change, with the jQuery's shorthand method change(), to trigger your code when the selected option change.

 $ ('#yourSelect' ).change(() => {
    process($('#yourSelect option:selected').html());

If you just want to know the value of the option:selected (the option that the user has chosen) you can just use $('#yourSelect').val()

GridLayout (not GridView) how to stretch all children evenly

I wanted to have a centered table with the labels right aligned and the values left aligned. The extra space should be around the table. After much experimenting and not following what the documentation said I should do, I came up with something that works. Here's what I did:

<LinearLayout xmlns:android=""
android:orientation="vertical" >

    android:useDefaultMargins="true" >

        android:text="Short label:" />

        android:text="Long extended value" />

        android:text="A very long extended label:" />

        android:text="Short value" />

This seems to work but the GridLayout shows the message:

"This GridLayout layout or its LinearLayout parent is useless"

Not sure why it is "useless" when it works for me.

I'm not sure why this works or if this is a good idea, but if you try it and can provide a better idea, small improvement or explain why it works (or won't work) I'd appreciate the feedback.


Remove empty array elements

I had to do this in order to keep an array value of (string) 0

$url = array_filter($data, function ($value) {
  return (!empty($value) || $value === 0 || $value==='0');

HTTP get with headers using RestTemplate

Take a look at the JavaDoc for RestTemplate.

There is the corresponding getForObject methods that are the HTTP GET equivalents of postForObject, but they doesn't appear to fulfil your requirements of "GET with headers", as there is no way to specify headers on any of the calls.

Looking at the JavaDoc, no method that is HTTP GET specific allows you to also provide header information. There are alternatives though, one of which you have found and are using. The exchange methods allow you to provide an HttpEntity object representing the details of the request (including headers). The execute methods allow you to specify a RequestCallback from which you can add the headers upon its invocation.

What's a good hex editor/viewer for the Mac?

The one that I like is HexEdit Quick and easy to use

How to get back to the latest commit after checking out a previous commit?

If you have a branch different than master, one easy way is to check out that branch, then check out master. Voila, you are back at the tip of master. There's probably smarter ways...