Tutorial by Examples: r

The underscore _ may be used as a digit separator. Being able to group digits in large numeric literals has a significant impact on readability. The underscore may occur anywhere in a numeric literal except as noted below. Different groupings may make sense in different scenarios or with different ...

Basics A tuple is an ordered, finite list of elements. Tuples are commonly used in programming as a means to work with one single entity collectively instead of individually working with each of the tuple's elements, and to represent individual rows (ie. "records") in a relational databa...

Define AccumulatorParam import org.apache.spark.AccumulatorParam object StringAccumulator extends AccumulatorParam[String] { def zero(s: String): String = s def addInPlace(s1: String, s2: String)= s1 + s2 } Use: val accumulator = sc.accumulator("")(StringAccumulator) sc.pa...

Define AccumulatorParam: from pyspark import AccumulatorParam class StringAccumulator(AccumulatorParam): def zero(self, s): return s def addInPlace(self, s1, s2): return s1 + s2 accumulator = sc.accumulator("", StringAccumulator()) def add(x): gl...

Preconditions allows methods to provide minimum required values for input parameters Example... void DoWork(string input) { Contract.Requires(!string.IsNullOrEmpty(input)); //do work } Static Analysis Result...

AlertDialog.Builder builder = new AlertDialog.Builder(context); //Set Title builder.setTitle("Reset...") //Set Message .setMessage("Are you sure?") //Set the icon of the dialog .setIcon(drawable) //Set...

Let there be Activity B that can be opened, and can further start more Activities. But, user should not encounter it when navigating back in task activities. The simplest solution is to set the attribute noHistory to true for that <activity> tag in AndroidManifest.xml: <activity a...

Imagine you have the following HTML: <div> <label>Name:</label> John Smith </div> And you need to locate the text "John Smith" after the label element. In this case, you can locate the label element by text and then use .next_sibling property: from ...

BeautifulSoup has a limited support for CSS selectors, but covers most commonly used ones. Use select() method to find multiple elements and select_one() to find a single element. Basic example: from bs4 import BeautifulSoup data = """ <ul> <li class="item&quo...

When the destructor for std::thread is invoked, a call to either join() or detach() must have been made. If a thread has not been joined or detached, then by default std::terminate will be called. Using RAII, this is generally simple enough to accomplish: class thread_joiner { public: thre...

Leading Zeros let number: Int = 7 let str1 = String(format: "%03d", number) // 007 let str2 = String(format: "%05d", number) // 00007 Numbers after Decimal let number: Float = 3.14159 let str1 = String(format: "%.2f", number) // 3.14 let str2 = String(format: &...

This example was done in order to demonstrate how you can perform a deep filter in a child array without the necessity of a custom filter. Controller: (function() { "use strict"; angular .module('app', []) .controller('mainCtrl', mainCtrl); function mainCtrl() { ...

Download a distributed archive from Binaries section of JMeter from Download Apache JMeter page. Depending on the version you downloaded, check minimal Java version requirements and install Java if needed. Ensure the JAVA_HOME environment variable is set and points to a correct version. ...

demoApp.directive('demoDirective', function () { var directiveDefinitionObject = { multiElement: priority: terminal: scope: {}, bindToController: {}, controller: controllerAs: require: restrict: templateNamespace: template: templateU...

SyncAdapter /** * Define a sync adapter for the app. * <p/> * <p>This class is instantiated in {@link SyncService}, which also binds SyncAdapter to the system. * SyncAdapter should only be initialized in SyncService, never anywhere else. * <p/> * <p>The system ca...

Validating array form input fields is very simple. Suppose you have to validate each name, email and father name in a given array. You could do the following: $validator = \Validator::make($request->all(), [ 'name.*' => 'required', 'email.*' => 'email|unique:users'...

In Julia, the @show macro is often useful for debugging purposes. It displays both the expression to be evaluated and its result, finally returning the value of the result: julia> @show 1 + 1 1 + 1 = 2 2 It is straightforward to create our own version of @show: julia> macro myshow(exp...

A pure function is a function that, given the same input, will always return the same output and are side-effect free. // This is a pure function function add($a, $b) { return $a + $b; } Some side-effects are changing the filesystem, interacting with databases, printing to the screen. //...

Sometimes you want to add an element to the beginning of an array without modifying any of the current elements (order) within the array. Whenever this is the case, you can use array_unshift(). array_unshift() prepends passed elements to the front of the array. Note that the list of elements is ...

When running from the CLI, PHP exhibits some different behaviours than when run from a web server. These differences should be kept in mind, especially in the case where the same script might be run from both environments. No directory change When running a script from a web server, the current w...