Tutorial by Examples: r

Eager loading lets you load all your needed entities at once. If you prefer to get all your entities to work on in one database call, then Eager loading is the way to go. It also lets you load multiple levels. You have two options to load related entities, you can choose either strongly typed or st...

Some procedures have optional arguments. Optional arguments always come after required arguments, but the procedure can be called without them. For example, if the function, ProcedureName were to have two required arguments (argument1, argument2), and one optional argument, optArgument3, it could b...

library(gpuR) # gpuMatrix objects X <- gpuMatrix(rnorm(100), 10, 10) Y <- gpuMatrix(rnorm(100), 10, 10) # transfer data to GPU when operation called # automatically copied back to CPU Z <- X %*% Y

library(gpuR) # vclMatrix objects X <- vclMatrix(rnorm(100), 10, 10) Y <- vclMatrix(rnorm(100), 10, 10) # data always on GPU # no data transfer Z <- X %*% Y

From MSDN Use the CInt function to provide conversions from any other data type to an Integer subtype. For example, CInt forces integer arithmetic when currency, single-precision, or double-precision arithmetic would normally occur. Assuming that you have 1 button and 2 textbox. If you type...

TRACE and DEBUG log levels are there to be able to convey high detail about the operation of the given code at runtime. Setting the log level above these is usually recommended, however some care must be taken for these statements to not affect performance even when seemingly "turned off"....

RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_URI} !(.*)/$ RewriteRule ^(.*)$ /$1/ [L,R=301] The first RewriteCond helps exclude the files. The second RewriteCond checks if there is already a trailing slash. If the case is so RewriteRule is not applied. If you have any URL that s...

In most cases, it is illegal to access an object of one type as though it were a different type (disregarding cv-qualifiers). Example: float x = 42; int y = reinterpret_cast<int&>(x); The result is undefined behavior. There are some exceptions to this strict aliasing rule: An obj...

This example will call the windows calculator. It's important to notice that the exit code will vary accordingly to the program/script that is being called. package process.example; import java.io.IOException; public class App { public static void main(String[] args) { try { ...

The ProcessBuilder class makes it easy to send a command through the command line. All it requires is a List of Strings that make up the commands to be entered. You simply call the start() method on your ProcessBuilder instance to execute the command. If you have a program called Add.exe which take...

Launching external processes from Java using the raw java.lang.ProcessBuilder API directly can be a little cumbersome. The Apache Commons Exec library makes it a little easier. The ch.vorburger.exec library further extends upon Commons Exec to make it truly convenient: ManagedProcess proc = new ...

This proxy simply appends the string " went through proxy" to every string property set on the target object. let object = {}; let handler = { set(target, prop, value){ // Note that ES6 object syntax is used if('string' === typeof value){ target[prop] = valu...

Laravel's events allows to implement the Observer pattern. This can be used to send a welcome email to a user whenever they register on your application. New events and listeners can be generated using the artisan command line utility after registering the event and their particular listener in App...

Here's a way to show a GIF preloader while an AJAX call is executing. We need to prepare our add and remove preloader functions: function addPreloader() { // if the preloader doesn't already exist, add one to the page if(!document.querySelector('#preloader')) { var preloaderHTML = '<...

Get current time: Time.now Time.new # is equivalent if used with no parameters Get specific time: Time.new(2010, 3, 10) #10 March 2010 (Midnight) Time.new(2015, 5, 3, 10, 14) #10:14 AM on 3 May 2015 Time.new(2050, "May", 3, 21, 8, 16, "+10:00") #09:08:16 PM on 3 May 2050...

DATA: <TABLE NAME> TYPE <SORTED|STANDARD|HASHED> TABLE OF <TYPE NAME> WITH <UNIQUE|NON-UNIQUE> KEY <FIELDS FOR KEY>. Standard Table This table has all of the entries stored in a linear fashion and records are accessed in a linear way. For large table sizes, ...

Notice, this is only for angular-cli up to 1.0.0-beta.10 version ! Some libraries or plugins may not have typings. Without these, TypeScript can't type check them and therefore causes compilation errors. These libraries can still be used but differently than imported modules. Include a scr...

Though the transaction class method is called on some ActiveRecord class, the objects within the transaction block need not all be instances of that class. This is because transactions are per-database connection, not per-model. In this example a balance record is transactionally saved even though ...

Both #save and #destroy come wrapped in a transaction that ensures that whatever you do in validations or callbacks will happen under its protected cover. So you can use validations to check for values that the transaction depends on or you can raise exceptions in the callbacks to rollback, includin...

ActiveRecord::Base.transaction uses the ActiveRecord::Rollback exception to distinguish a deliberate rollback from other exceptional situations. Normally, raising an exception will cause the .transaction method to rollback the database transaction and pass on the exception. But if you raise an Activ...