Tutorial by Examples: u

Start using ES6/7 with Babel

Browser support for ES6 is growing, but to be sure your code will work on environments that dont fully support it, you can use Babel, the ES6/7 to ES5 transpiler, try it out! If you would like to use ES6/7 in your projects without having to worry about compatibility, you can use Node and Babel CLI ...

JavaScript • Transpiling

Build and install OpenCV from source

This is a step-by-step guide to installing OpenCV 3 on a Debian-based Linux system from source. The steps should stay the same for other distros, just replace the relevant package manager commands when installing packages for the build. Note: If you don't feel like wasting time building stuff or di...

opencv • Getting started with opencv

D3js with Angular

Using D3js with Angular can open up new fronts of possibilities such as live updation of charts as soon as data is updated. We can encapsulate complete chart functionality within an Angular directive, which makes it easily reusable. index.html >> <!DOCTYPE html> <html ng-app="...

d3.js • Using D3 with other frameworks

Numeric value of a pointer

The result of casting a pointer to an integer using reinterpret_cast is implementation-defined, but "... is intended to be unsurprising to those who know the addressing structure of the underlying machine." int x = 42; int* p = &x; long addr = reinterpret_cast<long>(p); std::...

C++ • Implementation-defined behavior

Using callback closure(block) passing data back

this topic is a classical issue in iOS development, and its solution is various as other example already shown. In this example I'll show another daily common use one: passing data using closure by adapting delegate pattern example on this page into callback closure! one thing this method is superi...

iOS • Passing Data between View Controllers

SEQUENCEFILE

Store data in SEQUENCEFILE if the data needs to be compressed. You can import text files compressed with Gzip or Bzip2 directly into a table stored as TextFile. The compression will be detected automatically and the file will be decompressed on-the-fly during query execution. CREATE TABLE raw_seque...

hive • File formats in HIVE

PARQUET

Parquet columnar storage format in Hive 0.13.0 and later. Parquet is built from the ground up with complex nested data structures in mind, and uses the record shredding and assembly algorithm described in the Dremel paper. We believe this approach is superior to simple flattening of nested name spac...

hive • File formats in HIVE

Toggle line enumerating

To enable - type: :set number or :set nu. To disable - type: :set nonumber or :set nonu. To enable enumerating relative to the cursor location - type: :set relativenumber. To disable enumerating relative to the cursor location - type: :set norelativenumber. Note: To change whether the curren...

vim • Configuring Vim

Scaffolding projects in other languages

By default, dotnet new creates C# projects. You can use the -l or --lang flag to scaffold projects in other languages: dotnet new -l f# dotnet restore dotnet run Currently, dotnet new supports C# and F#.

.net-core • .NET Core command line interface

Creating a NuGet package

To create a NuGet package from a project, run this command from a directory that contains project.json: dotnet pack The resulting .nupkg file will be named and versioned according to the properties in project.json. If there are multiple frameworks targeted in the project file, the package will s...

.net-core • .NET Core command line interface

Running automated tests

Running dotnet test from inside a folder that contains a test project will launch the test runner. The test runner will discover and run the tests in the project. To be compatible with dotnet test, the project.json file must contain a testRunner property and a dependency on a compatible test runner...

.net-core • .NET Core command line interface

Adding command line scripts to your python package

Command line scripts inside python packages are common. You can organise your package in such a way that when a user installs the package, the script will be available on their path. If you had the greetings package which had the command line script hello_world.py. greetings/ greetings/ ...

Python Language • setup.py

Delete "unaligned" apk automatically

If you don't need automatically generated apk files with unaligned suffix (which you probably don't), you may add the following code to build.gradle file: // delete unaligned files android.applicationVariants.all { variant -> variant.assemble.doLast { variant.outputs.each { output ->...

Android • Gradle for Android

Rounding (ROUND, FLOOR, CEIL)

Round a decimal number to an integer value For exact numeric values (e.g. DECIMAL): If the first decimal place of a number is 5 or higher, this function will round a number to the next integer away from zero. If that decimal place is 4 or lower, this function will round to the next integer value cl...

MySQL • Arithmetic

Raise a number to a power (POW)

To raise a number x to a power y, use either the POW() or POWER() functions SELECT POW(2,2); => 4 SELECT POW(4,2); => 16

MySQL • Arithmetic

Square Root (SQRT)

Use the SQRT() function. If the number is negative, NULL will be returned SELECT SQRT(16); -> 4 SELECT SQRT(-3); -> NULL

MySQL • Arithmetic

Random Numbers (RAND)

Generate a random number To generate a pseudorandom floating point number between 0 and 1, use the RAND() function Suppose you have the following query SELECT i, RAND() FROM t; This will return something like this iRAND()10.619143887068220.9384516830914230.83482678498591 Random Number in a r...

MySQL • Arithmetic

Absolute Value and Sign (ABS, SIGN)

Return the absolute value of a number SELECT ABS(2); -> 2 SELECT ABS(-46); -> 46 The sign of a number compares it to 0. SignResultExample-1n < 0SELECT SIGN(42); -> 10n = 0SELECT SIGN(0); -> 01n > 0SELECT SIGN(-3); -> -1 SELECT SIGN(-423421); -> -1

MySQL • Arithmetic

How to install and run ggplot2

To install and load the current stable version of ggplot2 for your R installation use: # install from CRAN install.packages("ggplot2") To install the development version from github use # install.packages("devtools") devtools::install_github("hadley/ggplot2") ...

ggplot2 • Getting started with ggplot2

Create unconnected socket, try connect to it and check if connection is established

public class ConnectSocketExample { private int HTTP_PORT = 80; /** * example method to create unconnected socket * then connect to it * at end return connected socket * * @param httpHostName - endpoint host name fot socket connection * @throws IOEx...

sockets • Getting started with sockets