Tutorial by Examples: r

The Math.random() function should give random numbers that have a standard deviation approaching 0. When picking from a deck of card, or simulating a dice roll this is what we want. But in most situations this is unrealistic. In the real world the randomness tends to gather around an common normal...

Future<Results> costlyQuery() { var completer = new Completer(); database.query("SELECT * FROM giant_table", (results) { // when complete completer.complete(results); }, (error) { completer.completeException(error); }); // this returns essentially im...

Common Lisp REPL is an interactive environment. Every form written after the prompt is evaluated, and its value is afterwards printed as result of the evaluation. So the simplest possible “Hello, World!” program in Common Lisp is: CL-USER> "Hello, World!" "Hello, World!" CL...

Flash Player 10 introduced the Vector.<*> generic list type that was faster than the Array. However, this is not entirely true. Only the following Vector types are faster than the Array counterparts, due to the way they are implemented in Flash Player. Vector.<int> - Vector of 32-bit ...

Creating and configuring Sprite and TextField objects at runtime can be costly if you are creating hundreds of thousands of these on a single frame. Therefore a common trick is "pooling" these objects for later reuse. Remember we are not just trying to optimize the creation time (new Sprit...

You can create your own events and dispatch them, by extending the Event class. import flash.events.Event; class MyEvent extends Event { var data: String; static public var MY_EVENT_TYPE = "my_event_my_event_code"; public function MyEvent(type: String, data: Str...

class Person(models.Model): name = models.CharField(max_length=50) description = models.TextField() class Club(models.Model): name = models.CharField(max_length=50) members = models.ManyToManyField(Person) Here we define a relationship where a club has many Persons and memb...

Codename One is a set of tools for mobile application development that derive a great deal of its architecture from Java. Codename One's mission statement is: Unify the complex and fragmented task of mobile device programming into a single set of tools, APIs & services. As a result create a...

UITextView has built in support to auto detect a variety of data. The data that is able to be auto-detected currently includes: enum { UIDataDetectorTypePhoneNumber = 1 << 0, UIDataDetectorTypeLink = 1 << 1, UIDataDetectorTypeAddress = 1 << 2, UID...

Single JAR Sometimes you have a local JAR file you need to add as a dependency to your Gradle build. Here's how you can do this: dependencies { compile files('path/local_dependency.jar') } Where path is a directory path on your filesystem and local_dependency.jar is the name of your local...

In F#, all functions take exactly one parameter. This seems an odd statement, since it's trivially easy to declare more than one parameter in a function declaration: let add x y = x + y But if you type that function declaration into the F# interactive interpreter, you'll see that its type signat...

It is possible to find the first element of a Stream that matches a condition. For this example, we will find the first Integer whose square is over 50000. IntStream.iterate(1, i -> i + 1) // Generate an infinite stream 1,2,3,4... .filter(i -> (i*i) > 50000) // Filter to find element...

Variables can be incremented or decremented by 1 with ++ or --, respectively. They can either precede or succeed variables and slightly vary semantically, as shown below. $i = 1; echo $i; // Prints 1 // Pre-increment operator increments $i by one, then returns $i echo ++$i; // Prints 2 // P...

Concept Use an Event to synchronize the scheduling of multiple coroutines. Put simply, an event is like the gun shot at a running race: it lets the runners off the starting blocks. Example import asyncio # event trigger function def trigger(event): print('EVENT SET') event.set() #...

Electron ports HTML web applications to native applications for a range of devices, including creating native desktop applications. It's also very easy to get started! To begin, we must have electron, nodejs, npm, git and meteor installed. Familiarity with these tools is vital for working with Mete...

Let's download a Meteor Todos example project, using a Linux shell (command line) script, to test out Electrifying a project for the first time: Requirements for this section: Git apt-get install git-all There are many ways to install Git. Check them out here. git is a version control sys...

Defining our terms By array here we mean a Lua table used as a sequence. For example: -- Create a table to store the types of pets we like. local pets = {"dogs", "cats", "birds"} We're using this table as a sequence: a group of items keyed by integers. Many langua...

Installing Angular Material npm npm install angular-material --save bower bower install angular-material --save jspm jspm install angular-material From Cloud cdnjs | jsdelivr | googlecdn Getting Started (blank shell) <html lang="en"> <head> <meta name...

Files: - example.rs (root of our modules tree, generally named lib.rs or main.rs when using Cargo) - first.rs - second/ - mod.rs - sub.rs Modules: - example -> example - first -> example::first - second -> example::second - sub -> exampl...

Given that the function has a proper prototype, integers are widened for calls to functions according to the rules of integer conversion, C11 6.3.1.3. 6.3.1.3 Signed and unsigned integers When a value with integer type is converted to another integer type other than _Bool, if the value can be r...