Tutorial by Examples: d

One might want to group their data by the runs of a variable and perform some sort of analysis. Consider the following simple dataset: (dat <- data.frame(x = c(1, 1, 2, 2, 2, 1), y = 1:6)) # x y # 1 1 1 # 2 1 2 # 3 2 3 # 4 2 4 # 5 2 5 # 6 1 6 The variable x has three runs: a run of l...

Given this setup code: var dict = new Dictionary<int, string>() { { 1, "First" }, { 2, "Second" }, { 3, "Third" } }; You may want to read the value for the entry with key 1. If key doesn't exist getting a value will throw KeyNotFoundException,...

The following code is for iOS 8 and lower for creating a login alert. // Create the UIAlertView var loginAlertView = new UIAlertView(title, message, null, cancelTitle, okTitle); // Setting the AlertViewStyle to UIAlertViewStyle.LoginAndPasswordInput loginAlertView.AlertViewStyle = UIAlertViewS...

The module cmath includes additional functions to use complex numbers. import cmath This module can calculate the phase of a complex number, in radians: z = 2+3j # A complex number cmath.phase(z) # 0.982793723247329 It allows the conversion between the cartesian (rectangular) and polar repr...

To install Eclipse, go to the Eclipse Downloads Web page where there is usually a direct link to download the latest version of Eclipse. Starting Eclipse Mars (version 4.5), an installer can be downloaded which guides you through the installation procedure, as opposed to downloading the whole instal...

This a basic example aimed at new users. It does not focus on explaining the difference between char and cellstring. It might happen that you want to get rid of the ' in your strings, although you never added them. In fact, those are artifacts that the command window uses to distinguish between ...

function Invoke-MyCmdlet { [CmdletBinding(SupportsShouldProcess = $true)] param() # ... }

if ($PSCmdlet.ShouldProcess("Target of action")) { # Do the thing } When using -WhatIf: What if: Performing the action "Invoke-MyCmdlet" on target "Target of action" When using -Confirm: Are you sure you want to perform this action? Performing operation &qu...

class Person { [string] $FirstName [string] $LastName [string] Greeting() { return "Greetings, {0} {1}!" -f $this.FirstName, $this.LastName } } $x = [Person]::new() $x.FirstName = "Jane" $x.LastName = "Doe" $greeting = $x.Greeting() #...

class Person { [string] $Name [int] $Age Person([string] $Name) { $this.Name = $Name } Person([string] $Name, [int]$Age) { $this.Name = $Name $this.Age = $Age } }

Vector size is simply the number of elements in the vector: Current vector size is queried by size() member function. Convenience empty() function returns true if size is 0: vector<int> v = { 1, 2, 3 }; // size is 3 const vector<int>::size_type size = v.size(); cout << size...

Declaration-site variance can be thought of as declaration of use-site variance once and for all the use-sites. class Consumer<in T> { fun consume(t: T) { ... } } fun charSequencesConsumer() : Consumer<CharSequence>() = ... val stringConsumer : Consumer<String> = cha...

MATLAB code can be saved in m-files to be reused. m-files have the .m extension which is automatically associated with MATLAB. An m-file can contain either a script or functions. Scripts Scripts are simply program files that execute a series of MATLAB commands in a predefined order. Scripts do no...

--- trim: a string-trimming module for Lua -- Author, date, perhaps a nice license too -- -- The code here is taken or adapted from material in -- Programming in Lua, 3rd ed., Roberto Ierusalimschy -- trim_all(string) => return string with white space trimmed on both sides local trim_al...

-- The following assumes that trim module is installed or in the caller's package.path, -- which is a built-in variable that Lua uses to determine where to look for modules. local trim = require "trim" local msg = " Hello, world! " local cleaned = trim.trim_all(msg)...

Microsoft Windows applications are usually written as either a console application or a windowed application (there are other types such as services and plug-ins). The difference for the programmer is the difference in the interface for the main entry point for the application source provided by the...

Reading a file line by line public class Main { public static void main(String[] args) { try { Scanner scanner = new Scanner(new File("example.txt")); while(scanner.hasNextLine()) { String line = scanner.nextLine(); ...

The data.table package provides a convenient way to group by runs in data. Consider the following example data: library(data.table) (DT <- data.table(x = c(1, 1, 2, 2, 2, 1), y = 1:6)) # x y # 1: 1 1 # 2: 1 2 # 3: 2 3 # 4: 2 4 # 5: 2 5 # 6: 1 6 The variable x has three runs: a run ...

DT[where, select|update|do, by] syntax is used to work with columns of a data.table. The "where" part is the i argument The "select|update|do" part is the j argument These two arguments are usually passed by position instead of by name. Our example data below is mtcars =...

<PROJECT_ROOT>\app\build.gradle is specific for app module. <PROJECT_ROOT>\build.gradle is a "Top-level build file" where you can add configuration options common to all sub-projects/modules. If you use another module in your project, as a local library you would have another...