Tutorial by Examples: r

To perform actions in Django using commandline or other services (where the user/request is not used), you can use the management commands. Django modules can be imported as needed. For each command a separate file needs to be created: myapp/management/commands/my_command.py (The management and...

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.

If you want to calculate with BigDecimal you have to use the returned value because BigDecimal objects are immutable: BigDecimal a = new BigDecimal("42.23"); BigDecimal b = new BigDecimal("10.001"); a.add(b); // a will still be 42.23 BigDecimal c = a.add(b); // c will be ...

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...

The most simple data structure available in R is a vector. You can make vectors of numeric values, logical values, and character strings using the c() function. For example: c(1, 2, 3) ## [1] 1 2 3 c(TRUE, TRUE, FALSE) ## [1] TRUE TRUE FALSE c("a", "b", "c") ## ...

Under the hood, a matrix is a special kind of vector with two dimensions. Like a vector, a matrix can only have one data class. You can create matrices using the matrix function as shown below. matrix(data = 1:6, nrow = 2, ncol = 3) ## [,1] [,2] [,3] ## [1,] 1 3 5 ## [2,] 2 4...

Data frames are likely the data structure you will used most in your analyses. A data frame is a special kind of list that stores same-length vectors of different classes. You create data frames using the data.frame function. The example below shows this by combining a numeric and a character vector...

Lists allow users to store multiple elements (like vectors and matrices) under a single object. You can use the list function to create a list: l1 <- list(c(1, 2, 3), c("a", "b", "c")) l1 ## [[1]] ## [1] 1 2 3 ## ## [[2]] ## [1] "a" "b" &q...

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(...

stri_dup("abc",3) # [1] "abcabcabc" A base R solution that does the same would look like this: paste0(rep("abc",3),collapse = "") # [1] "abcabcabc"

You can specify different application IDs or package names for each buildType or productFlavor using the applicationIdSuffix configuration attribute: Example of suffixing the applicationId for each buildType: defaultConfig { applicationId "com.package.android" minSdkVersion 17 ...

To compare strings alphabetically, use localeCompare(). This returns a negative value if the reference string is lexicographically (alphabetically) before the compared string (the parameter), a positive value if it comes afterwards, and a value of 0 if they are equal. var a = "hello"; va...

Detailed instructions on getting stripe-payments set up or installed.

This is an example of a function which returns a string. In the example, the function is called in a statement assigning a value to a variable. The value in this case is the return value of the function. function Get-Greeting{ "Hello World" } # Invoking the function $greeting ...

A function can be defined with parameters using the param block: function Write-Greeting { param( [Parameter(Mandatory,Position=0)] [String]$name, [Parameter(Mandatory,Position=1)] [Int]$age ) "Hello $name, you are $age years old." } ...

Parameters to a function can be marked as mandatory function Get-Greeting{ param ( [Parameter(Mandatory=$true)]$name ) "Hello World $name" } If the function is invoked without a value, the command line will prompt for the value: $greeting = Get-Greeting ...

A compound view is a custom ViewGroup that's treated as a single view by the surrounding program code. Such a ViewGroup can be really useful in DDD-like design, because it can correspond to an aggregate, in this example, a Contact. It can be reused everywhere that contact is displayed. This means t...