Tutorial by Examples: r

A script is a text file with the file extension .ps1 that contains PowerShell commands that will be executed when the script is called. Because scripts are saved files, they are easy to transfer between computers. Scripts are often written to solve a specific problem, ex.: Run a weekly maintenan...

Download the latest stable version from Activiti's website or you can check out the code from github and unzip to a directory of choice and then check out the readme.html that includes pointers to the docs and the release notes. The userguide ( docs/userguide/index.html ) includes instructions on ho...

Temporary tables could be very useful to keep temporary data. Temporary tables option is available in MySQL version 3.23 and above. Temporary table will be automatically destroyed when the session ends or connection is closed. The user can also drop temporary table. Same temporary table name can b...

Drop Temporary Table is used to delete the temporary table which you are created in your current session. DROP TEMPORARY TABLE tempTable1 DROP TEMPORARY TABLE IF EXISTS tempTable1 Use IF EXISTS to prevent an error occurring for tables that may not exist

Although Julia is not a purely functional language, it has full support for many of the cornerstones of functional programming: first-class functions, lexical scope, and closures. The fixed-point combinator is a key combinator in functional programming. Because Julia has eager evaluation semantics ...

The SKI combinator system is sufficient to represent any lambda calculus terms. (In practice, of course, lambda abstractions blow up to exponential size when they are translated into SKI.) Due to the simplicity of the system, implementing the S, K, and I combinators is extraordinarily simple: A Dir...

string is defined as alias string = immutable(char)[];: so need to use dup to make a mutable char array, before it can be reversed: import std.stdio; import std.string; int main() { string x = "Hello world!"; char[] x_rev = x.dup.reverse; writeln(x_rev); // !dlr...

After running your grammar .g4 file with ANTLR.jar you should have a number of files generated such as : 1.yourGrammarNameListener.py 2.yourGrammarNameParser.py 3.yourGrammarName.tokens ... To use these in a python project include the Python runtime in your workspace so any application you ar...

Frequently you may want to filter structures and other complex data types. Searching an array of structs for entries that contain a particular value is a very common task, and easily achieved in Swift using functional programming features. What's more, the code is extremely succinct. struct Painter...

The Autobahn package can be used for Python web socket server factories. Python Autobahn package documentation To install, typically one would simply use the terminal command (For Linux): sudo pip install autobahn (For Windows): python -m pip install autobahn Then, a simple echo server ca...

New Pull Request Whenever you want to create a Pull Request (let's say this is either by a recent change. But, you can also do this with an older change too!), you can go ahead and let GitHub do a lot of the heavy lifting for you and hit the green Compare & Pull Request button (NOT TO BE CONFUS...

To easily select a buffer by filename, you can use: :b [part_of_filename]<Tab><Tab><Tab>...<Enter> The first Tab will expand the word to a full filename, and subsequent Tab presses will cycle through the list of possible matches. When multiple matches are available, you ...

<C-^> will switch to and from the previous edited file. On most keyboards <C-^> is CTRL-6. 3<C-^> will switch to buffer number 3. This is very quick, but only if you know the buffer number. You can see the buffer numbers from :ls or from a plugin such as MiniBufExplorer.

THREE.BoxGeometry builds boxes such as cuboids and cubes. Cubes Cubes created using THREE.BoxGeometry would use the same length for all sides. JavaScript //Creates scene and camera var scene = new THREE.Scene(); var camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHe...

THREE.CylinderGeometry build cylinders. Cylinder Continuing from the previous example, the code to create the box could be replaced with the below. //Makes a new cylinder with // - a circle of radius 5 on top (1st parameter) // - a circle of radius 5 on the bottom (2nd parameter) // - a height...

extension String { func matchesPattern(pattern: String) -> Bool { do { let regex = try NSRegularExpression(pattern: pattern, options: NSRegularExpressionOptions(rawValue: 0)) let range: NSRange = NSMakeRange(...

super keyword performs important role in three places Constructor Level Method Level Variable Level Constructor Level super keyword is used to call parent class constructor. This constructor can be default constructor or parameterized constructor. Default constructor : super(); Pa...

Label Tag Helper can be used to render label for a model property. It replaces method Html.LabelFor in previous versions of MVC. Let's say you have a model: public class FormViewModel { public string Name { get; set; } } In the view you can use label HTML element and asp-for tag helper: ...

You may need to render some content in view, which is specific to some environment only. To achieve this goal you can use Environment tag helper: <environment names="Development"> <h1>This is heading for development environment</h1> </environment> <envi...

Often one want to show the result of a command executed by root to other users. The tee command allows easily to write a file with user perms from a command running as root: su -c ifconfig | tee ~/results-of-ifconfig.txt Only ifconfig runs as root.