Tutorial by Examples: io

If you have a vector in polar form (direction & distance) you will want to convert it to a cartesian vector with a x and y component. For referance the screen coordinate system has directions as 0 deg points from left to right, 90 (PI/2) point down the screen, and so on in a clock wise direction...

Math.sin and Math.cos are cyclic with a period of 2*PI radians (360 deg) they output a wave with an amplitude of 2 in the range -1 to 1. Graph of sine and cosine function: (courtesy Wikipedia) They are both very handy for many types of periodic calculations, from creating sound waves, to animati...

This is a script saved as .Rmd, on the contrary of r scripts saved as .R. To knit the script, either use the render function or use the shortcut button in Rstudio. --- title: "Rstudio exemple of a rmd file" author: 'stack user' date: "22 July 2016" output: html_document -...

CommandDescriptionzRedraw current line at the top of the window and put the cursor on the first non-blank character on the line.ztLike z but leave the cursor in the same column.z.Redraw current line at the center of the window and put the cursor on the first non-blank character on the line.zzLike z....

Whenever AFNetworking is used the call is dispatched on a custom thread provided by AFNetworking. When the call returns to the completion block, it gets executed on the main thread. This example sets a custom thread that dispatch to the completion block: AFNetworking 2.xx: // Create dispatch_queu...

One can clear the user data of a specific app using adb: adb shell pm clear <package> This is the same as to browse the settings on the phone, select the app and press on the clear data button. pm invokes the package manager on the device clear deletes all data associated with a packag...

Gradle has the ability to add a wrapper to projects. This wrapper alleviates the need for all users or continuous integration systems to have Gradle installed. It also prevents version issues where there is some incompatibility between the version the project uses and that which users have installed...

RoboGuice is a framework that brings the simplicity and ease of Dependency Injection to Android, using Google's own Guice library. RoboGuice 3 slims down your application code. Less code means fewer opportunities for bugs. It also makes your code easier to follow -- no longer is your code littered ...

By default class annotations do not apply to types extending them. This can be changed by adding the @Inherited annotation to the annotation definition Example Consider the following 2 Annotations: @Inherited @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) public @interface Inher...

Self-referential association is used to associate a model with itself. The most frequent example would be, to manage association between a friend and his follower. ex. rails g model friendship user_id:references friend_id:integer now you can associate models like; class User < ActiveRecord:...

Because in .NET 3.5 and older you don't have Lazy<T> class you use the following pattern: public class Singleton { private Singleton() // prevents public instantiation { } public static Singleton Instance { get { return Nested.instanc...

All collection objects contain a map method that takes a Function as an argument, which must take a single argument. This returns an Iterable backed by the collection. When the Iterable is iterated, each step calls the function with a new element of the collection, and the result of the call becomes...

mount is used to mount another application (basically rack application) or rails engines to be used within the current application syntax: mount SomeRackApp, at: "some_route" Now you can access above mounted application using route helper some_rack_app_path or some_rack_app_url. But ...

In this example we want to create a class that will generate and output to console, a random number between a range of two integers which are passed as arguments during the initialization. public class SimpleRangeRandom implements Runnable { private int min; private int max; pr...

When you implement java.io.Serializable interface to make a class serializable, the compiler looks for a static final field named serialVersionUID of type long. If the class doesn't have this field declared explicitly then the compiler will create one such field and assign it with a value which come...

Converting an integer type to the corresponding promoted type is better than converting it to some other integer type. void f(int x); void f(short x); signed char c = 42; f(c); // calls f(int); promotion to int is better than conversion to short short s = 42; f(s); // calls f(short); exact mat...

Download the Atlassian conversion utility here. This utility requires Java, so please ensure that you have the Java Runtime Environment JRE installed on the machine you plan to do the conversion. Use the command java -jar svn-migration-scripts.jar verify to check if your machine is missing any of t...

Installing Tcl 8.6.4 on Windows : The easiest way to get Tcl on a windows machine is to install the ActiveTcl distribution from ActiveState. Navigate to www.activestate.com and follow the links to download the Free Community Edition of ActiveTcl for Windows (choose 32/64 bit version app...

There are three kinds of options: boolean options, string options, number options. To check the value of an option, use :set option? to check the value of an option, use :verbose set option? to also see where it was last set. Setting boolean options set booloption " Set boo...

Don't forget the bang to allow Vim to overwrite that function next time you reload the script where the function is defined. Custom functions must start either with an uppercase character (global functions), or with s: (script local functions), or they must be prefixed with the name associated to...