Tutorial by Examples: r

Tuples can be used to return multiple values from a method without using out parameters. In the following example AddMultiply is used to return two values (sum, product). void Write() { var result = AddMultiply(25, 28); Console.WriteLine(result.Item1); Console.WriteLine(result.Item2...

Feather is an implementation of Apache Arrow designed to store data frames in a language agnostic manner while maintaining metadata (e.g. date classes), increasing interoperability between Python and R. Reading a feather file will produce a tibble, not a standard data.frame. library(feather) pat...

If you want to parse more complex command-line arguments, e.g. with optional parameters, than the best is to use google's GWT approach. All classes are public available at: https://gwt.googlesource.com/gwt/+/2.8.0-beta1/dev/core/src/com/google/gwt/util/tools/ToolBase.java An example for handling ...

The power of AppleScript lies in being able to automate many Mac applications. To find out what you can automate, you need to read an app's scripting dictionary. To do so, launch Script Editor, and select File > Open Dictionary… Once you choose an app, its dictionary will open up in a new win...

C++14 It is often useful to define classes or structures that have a variable number and type of data members which are defined at compile time. The canonical example is std::tuple, but sometimes is it is necessary to define your own custom structures. Here is an example that defines the structure ...

The methods object.wait(), object.notify() and object.notifyAll() are meant to be used in a very specific way. (see http://stackoverflow.com/documentation/java/5409/wait-notify#t=20160811161648303307 ) The "Lost Notification" problem One common beginner mistake is to unconditionally cal...

// 1. Base example not using language support for covariance, dynamic type checking. class Top { public: virtual Top* clone() const = 0; virtual ~Top() = default; // Necessary for `delete` via Top*. }; class D : public Top { public: Top* clone() const override ...

// 2. Covariant result version of the base example, static type checking. class Top { public: virtual Top* clone() const = 0; virtual ~Top() = default; // Necessary for `delete` via Top*. }; class D : public Top { public: D* /* ← Covariant return */ clone() const over...

// 3. Covariant smart pointer result (automated cleanup). #include <memory> using std::unique_ptr; template< class Type > auto up( Type* p ) { return unique_ptr<Type>( p ); } class Top { private: virtual Top* virtual_clone() const = 0; public: unique_ptr&l...

Worse ViewController: // ... myMethod: function () { this.getView().lookup('myhappyfield').setValue(100); } //... View: //... items: [ { xtype: 'textfield', reference: 'myhappyfield' } ] //... Better ViewController: // ... myMethod: function () { ...

Overrides: Override file: Ext.define('MyApp.override.CornField', override: 'Ext.form.field.Text', initComponent: function () { this.callParent(arguments); this.setValue('Corn!'); } ); Use in app: { xtype: 'textfield' } Extensions: Override file: Ext...

Converts the specified string representation of a date and time to its DateTime equivalent using the specified format, culture-specific format information, and style. The format of the string representation must match the specified format exactly. The method returns a value that indicates whether th...

Return the number of characters in the string Syntax: CHAR_LENGTH(str) CHAR_LENGTH('foobar') -- 6 CHAR_LENGTH('fööbar') -- 6 -- contrast with LENGTH(...) = 8

Convert the argument to hexadecimal. This is used for strings. HEX('fööbar') -- 66F6F6626172 -- in "CHARACTER SET latin1" because "F6" is hex for ö HEX('fööbar') -- 66C3B6C3B6626172 -- in "CHARACTER SET utf8 or utf8mb4" because "C3B6" is hex for ö

Resource with same path and name may exist in more than one JAR file on the classpath. Common cases are resources following a convention or that are part of a packaging specification. Examples for such resources are META-INF/MANIFEST.MF META-INF/beans.xml (CDI Spec) ServiceLoader properties con...

Detailed instructions on getting instagram set up or installed.

const source = Rx.Observable.range(1, 3) .map(x => x * x); const subscription = source.subscribe( x => console.log(`Next: ${x}`), err => console.log(`Error: ${err}`), () => console.log(`Completed`) ); // => Next: 1 // => Next: 4 // => Next: 9 // => Compl...

const source = Rx.Observable.range(1, 3) .map((x, idx, obs) => `Element ${x} was at position ${idx}`); const subscription = source.subscribe( x => console.log(`Next: ${x}`), err => console.log(`Error: ${err}`), () => console.log(`Completed`) ); // => Next: Element 1...

In order to get the official I18N Plugin into your CLI Project we need to install it by following the next steps. First you want to install the plugin via npm: npm install aurelia-i18n Since Aurelia-I18N is backed by i18next, you should install it and a backend plugin of your choice. As an exampl...

Often when building a Docker image, the Dockerfile contains instructions that runs programs to fetch resources from the Internet (wget for example to pull a program binary build on GitHub for example). It is possible to instruct Docker to pass set set environment variables so that such programs per...