Tutorial by Examples: p

To generate random permutation of 5 numbers: sample(5) # [1] 4 5 3 1 2 To generate random permutation of any vector: sample(10:15) # [1] 11 15 12 10 14 13 One could also use the package pracma randperm(a, k) # Generates one random permutation of k of the elements a, if a is a vector, # ...

In Python 3.x all classes are new-style classes; when defining a new class python implicitly makes it inherit from object. As such, specifying object in a class definition is a completely optional: Python 3.x3.0 class X: pass class Y(object): pass Both of these classes now contain object in ...

A Simple FXML document outlining an AnchorPane containing a button and a label node: <?xml version="1.0" encoding="UTF-8"?> <?import java.lang.*?> <?import java.util.*?> <?import javafx.scene.*?> <?import javafx.scene.control.*?> <?import ...

Returns the changed object, but the original object remains as it was. For example: arr = [1, 2, 3] arr.map { |i| i + 1 } # => [2, 3, 4] arr # => [1, 2, 3] map! changes the original object: arr = [1, 2, 3] arr.map! { |i| i + 1 } # => [2, 3, 4] arr # => [2, 3, 4] Note: you can...

Arrays You can iterate over nested arrays: [[1, 2], [3, 4]].each { |(a, b)| p "a: #{ a }", "b: #{ b }" } The following syntax is allowed too: [[1, 2], [3, 4]].each { |a, b| "a: #{ a }", "b: #{ b }" } Will produce: "a: 1" "b: 2" ...

Equivalently, we can use the $inject property annotation to achieve the same as above: var MyController = function($scope) { // ... } MyController.$inject = ['$scope']; myModule.controller('MyController', MyController);

.' is the correct way to transpose a vector or matrix in MATLAB. ' is the correct way to take the complex conjugate transpose (a.k.a. Hermitian conjugate) of a vector or matrix in MATLAB. Note that for the transpose .', there is a period in front of the apostrophe. This is in keeping with the ...

To duplicate a table, simply do the following: CREATE TABLE newtable LIKE oldtable; INSERT newtable SELECT * FROM oldtable;

// Calculate what day of the week is 36 days from this instant. System.DateTime today = System.DateTime.Now; System.TimeSpan duration = new System.TimeSpan(36, 0, 0, 0); System.DateTime answer = today.Add(duration); System.Console.WriteLine("{0:dddd}", answer);

DateTime date1 = new DateTime(2009, 8, 1, 0, 0, 0); DateTime date2 = new DateTime(2009, 8, 1, 12, 0, 0); int result = DateTime.Compare(date1, date2); string relationship; if (result < 0) relationship = "is earlier than"; else if (result == 0) relationship = "is the...

This allows the BackgroundWorker to be cancelled in between tasks bgWorker.WorkerSupportsCancellation = true; This allows the worker to report progress between completion of tasks... bgWorker.WorkerReportsProgress = true; //this must also be used in conjunction with the ProgressChanged event...

The following example demonstrates the use of a BackgroundWorker to update a WinForms ProgressBar. The backgroundWorker will update the value of the progress bar without blocking the UI thread, thus showing a reactive UI while work is done in the background. namespace BgWorkerExample { public...

application-name Giving the name of the Web application that the page represents. <meta name="application-name" content="OpenStreetMap"> If it’s not a Web application, the application-name meta tag must not be used. author Set the author of the page: <meta name=&...

The foreach package brings the power of parallel processing to R. But before you want to use multi core CPUs you have to assign a multi core cluster. The doSNOW package is one possibility. A simple use of the foreach loop is to calculate the sum of the square root and the square of all numbers from...

Properties can be added with categories using associated objects, a feature of the Objective-C runtime. Note that the property declaration of retain, nonatomic matches the last argument to objc_setAssociatedObject. See Attach object to another existing object for explanations. #import <objc/run...

A namespace is a URI, but to avoid verbosity, prefixes are used as a proxy. In the following example, the prefix my-prefix is bound to the namespace http://www.example.com/my-namespace by using the special attribute xmlns:my-prefix (my-prefix can be replaced with any other prefix): <?xml versio...

In XML, element and attribute names live in namespaces. By default, they are in no namespace: <?xml version="1.0"?> <foo attr="value"> <!-- the foo element is in no namespace, neither is the attr attribute --> </foo>

These two documents are semantically equivalement, as namespaces matter, not prefixes. <?xml version="1.0"?> <myns:foo xmlns:myns="http://www.example.com/my-namespace"> </myns:foo> <?xml version="1.0"?> <ns:foo xmlns:ns="http://www...

Installing linq-to-sql: Right-click the App_Code folder and then click Add New Item. The Add New Item dialog box is displayed. Under Visual Studio installed templates, select the LINQ to SQL Classes template and rename the file Tasks.dbml. Click Add. OR: Under VS2102, in your solution explorer, r...

import pandas as pd Create a DataFrame from a dictionary, containing two columns: numbers and colors. Each key represent a column name and the value is a series of data, the content of the column: df = pd.DataFrame({'numbers': [1, 2, 3], 'colors': ['red', 'white', 'blue']}) Show contents of d...