Tutorial by Examples: p

3.0 To run tasks on a dispatch queue, use the sync, async, and after methods. To dispatch a task to a queue asynchronously: let queue = DispatchQueue(label: "myQueueName") queue.async { //do something DispatchQueue.main.async { //this will be called in main t...

Display multiple plots in one image with the different facet functions. An advantage of this method is that all axes share the same scale across charts, making it easy to compare them at a glance. We'll use the mpg dataset included in ggplot2. Wrap charts line by line (attempts to create a square l...

ggplot2 works best with a long data frame. The following sample data which represents the prices for sweets on 20 different days, in a format described as wide, because each category has a column. set.seed(47) sweetsWide <- data.frame(date = 1:20, chocolate = run...

A common question is how to juxtapose (combine) physically separate geographical regions on the same map, such as in the case of a choropleth describing all 50 American states (The mainland with Alaska and Hawaii juxtaposed). Creating an attractive 50 state map is simple when leveraging Google Maps...

Java provides specialized Streams for three types of primitives IntStream (for ints), LongStream (for longs) and DoubleStream (for doubles). Besides being optimized implementations for their respective primitives, they also provide several specific terminal methods, typically for mathematical operat...

The following is a timer that fires at a fixed interval. It's timeout is defined by Period and it invokes a callback defined by Timerfcn upon timeout. t = timer; t.TasksToExecute = Inf; t.Period = 0.01; % timeout value in seconds t.TimerFcn = @(myTimerObj, thisEvent)disp('hello'); % timer callba...

A struct can simply be copied using assignment. type T struct { I int S string } // initialize a struct t := T{1, "one"} // make struct copy u := t // u has its field values equal to t if u == t { // true fmt.Println("u and t are equal") // Prints: &qu...

This pattern is a more strict approach to starting an Activity. Its purpose is to improve code readability, while at the same time decrease code complexity, maintenance costs, and coupling of your components. The following example implements the starter pattern, which is usually implemented as a st...

Suppose you have a simple Customer model: class Customer(models.Model): first_name = models.CharField(max_length=255) last_name = models.CharField(max_length=255) is_premium = models.BooleanField(default=False) You register it in the Django admin and add search field by first_name...

In this example we aim to accomplish one of the most common tasks: I have a small DC motor laying around, how do I use my Arduino to control it? Easy, with PWM and serial communication, using the function analogWrite() and the Serial library. The basics Pulse Width Modulation or PWM for short is a...

With Calendar class it is easy to find AM or PM. Calendar cal = Calendar.getInstance(); cal.setTime(new Date()); if (cal.get(Calendar.AM_PM) == Calendar.PM) System.out.println("It is PM");

Interceptors are used to intercept OkHttp calls. The reason to intercept could be to monitor, rewrite and retry calls. It can be used for outgoing request or incoming response both. class LoggingInterceptor implements Interceptor { @Override public Response intercept(Interceptor.Chain chain) thr...

private static final Interceptor REWRITE_CACHE_CONTROL_INTERCEPTOR = new Interceptor() { @Override public Response intercept(Interceptor.Chain chain) throws IOException { Response originalResponse = chain.proceed(chain.request()); return originalResponse.newBuilder() .header(&q...

class Foo { private string[] cities = new[] { "Paris", "London", "Berlin" }; public string this[int index] { get { return cities[index]; } set { cities[index] = value; } } } Usage...

Delegates can be used as typed function pointers: class FuncAsParameters { public void Run() { DoSomething(ErrorHandler1); DoSomething(ErrorHandler2); } public bool ErrorHandler1(string message) { Console.WriteLine(message); var shouldWeContinue = ... re...

This is an basic example on how to wire up and make an LED turn on/off when the pushbutton is pressed. /* Basic Digital Read * ------------------ * * turns on and off a light emitting diode(LED) connected to digital * pin 13, when pressing a pushbutton attached to pin 7. It illustrates...

Detailed instructions on getting nhibernate set up or installed.

The Singleton pattern is a design pattern that restricts the instantiation of a class to one object. After the first object is created, it will return the reference to the same one whenever called for an object. var Singleton = (function () { // instance stores a reference to the Singlet...

Module Pattern The Module pattern is a creational and structural design pattern which provides a way of encapsulating private members while producing a public API. This is accomplished by creating an IIFE which allows us to define variables only available in its scope (through closure) while return...

With fixed pattern stri_count_fixed("babab", "b") # [1] 3 stri_count_fixed("babab", "ba") # [1] 2 stri_count_fixed("babab", "bab") # [1] 1 Natively: length(gregexpr("b","babab")[[1]]) # [1] 3 length(gregexpr(...