Tutorial by Examples: en

If you want two or more arguments to be mutually exclusive. You can use the function argparse.ArgumentParser.add_mutually_exclusive_group(). In the example below, either foo or bar can exist but not both at the same time. import argparse parser = argparse.ArgumentParser() group = parser.add_mut...

If a class extends another class and would use the same metadata, providing it @inheritDoc is a simple way for use the same documentation. If multiple classes inherit from a base, only the base would need to be changed for the children to be affected. abstract class FooBase { /** * @par...

# load the library library(ggplot2) # create a blank canvas g <- ggplot(data = diamonds) g + geom_bar(aes(x = cut, fill = cut)) + scale_fill_discrete(guide = guide_legend(title = "CUT", keywidth = 2, ...

In order to enable a multidex configuration you need: to change your Gradle build configuration to use a MultiDexApplication or enable the MultiDex in your Application class Gradle configuration In app/build.gradle add these parts: android { compileSdkVersion 24 buildToolsVersion ...

The dexcount plugin counts methods and class resource count after a successful build. Add the plugin in the app/build.gradle: apply plugin: 'com.android.application' buildscript { repositories { mavenCentral() // or jcenter() } dependencies { classpath 'com.ge...

A reference is a scalar variable (one prefixed by $ ) which “refers to” some other data. my $value = "Hello"; my $reference = \$value; print $value; # => Hello print $reference; # => SCALAR(0x2683310) To get the referred-to data, you de-reference it. say ${$reference}...

Array References are scalars ($) which refer to Arrays. my @array = ("Hello"); # Creating array, assigning value from a list my $array_reference = \@array; These can be created more short-hand as follows: my $other_array_reference = ["Hello"]; Modifying / Using array ref...

Html5-Canvas ... Is an Html5 element. Is supported in most modern browsers (Internet Explorer 9+). Is a visible element that is transparent by default Has a default width of 300px and a default height of 150px. Requires JavaScript because all content must be programmatically added to the Canv...

If you need to roll for a true or false in an "x% chance" situation, use: function roll(chance:Number):Boolean { return Math.random() >= chance; } Used like: var success:Boolean = roll(0.5); // True 50% of the time. var again:Boolean = roll(0.25); // True 25% of the time. ...

The first step in optimizing for speed is finding the slowest sections of code. The Timer VBA function returns the number of seconds elapsed since midnight with a precision of 1/256th of a second (3.90625 milliseconds) on Windows based PCs. The VBA functions Now and Time are only accurate to a secon...

std::sort, found in the standard library header algorithm, is a standard library algorithm for sorting a range of values, defined by a pair of iterators. std::sort takes as the last parameter a functor used to compare two values; this is how it determines the order. Note that std::sort is not stable...

function isEven(n:Number):Boolean { return ((n & 1) == 0); } Examples: isEven(1); // false isEven(2); // true isEven(1.1); // false isEven(1.2); // false isEven(2.1); // true isEven(2.2); // true

Imagine the following XML: <root> <element>hello</element> <another> hello </another> <example>Hello, <nested> I am an example </nested>.</example> </root> The following XPath expression: //*[text() = 'hel...

The static method Date.now returns the number of milliseconds that have elapsed since 1 January 1970 00:00:00 UTC. To get the number of milliseconds that have elapsed since that time using an instance of a Date object, use its getTime method. // get milliseconds using static method now of Date co...

In a Service Provider register method we can bind an interface to an implementation: public function register() { App::bind( UserRepositoryInterface::class, EloquentUserRepository::class ); } From now on, everytime the app will need an instance of UserRepositoryInterface, Larave...

Solution 1: $('#parent').prepend($('#child')); Solution 2: $('#child').prependTo($('#parent')); Both solutions are prepending the element #child (adding at the beginning) to the element #parent. Before: <div id="parent"> <span>other content</span> </di...

Solution 1: $('#parent').append($('#child')); Solution 2: $('#child').appendTo($('#parent')); Both solutions are appending the element #child (adding at the end) to the element #parent. Before: <div id="parent"> <span>other content</span> </div> <d...

chrome.runtime.getManifest() returns the extension's manifest in a form of a parsed object. This method works both on content scripts and all extension pages, it requires no permissions, Example, obtaining the extension's version string: var version = chrome.runtime.getManifest().version;

Elements and attributes behave differently with respect to default namespaces. This is often the source of confusion. An attribute whose name has no prefix lives in no namespace, also when a default namespace is in scope. <?xml version="1.0"?> <foo attr="value" xmlns=...

When you use or, it will either return the first value in the expression if it's true, else it will blindly return the second value. I.e. or is equivalent to: def or_(a, b): if a: return a else: return b For and, it will return its first value if it's false, else it r...