Tutorial by Examples: d

Hadoop Distributed File System (HDFS) is a Java-based file system that provides scalable and reliable data storage that is designed to span large clusters of commodity servers. HDFS, MapReduce, and YARN form the core of Apache™ Hadoop®. HDFS is designed to be highly fault-tolerant, which is achieve...

STEP 1: CREATE A DIRECTORY IN HDFS, UPLOAD A FILE AND LIST CONTENTS Let’s learn by writing the syntax. You will be able to copy and paste the following example commands into your terminal: hadoop fs -mkdir: Takes the path URI’s as an argument and creates a directory or multiple directories. Usag...

Julia uses similar binary operators for basic arithmetic operations as does mathematics or other programming languages. Most operators can be written in infix notation (that is, placed in between the values being computed). Julia has an order of operations that matches the common convention in mathe...

So you want to deploy your app to multiple sites? and your project has too many dependencies to install them one-by-one? Npm has a solution just issue the following command: npm init In the project's root folder then follow the instructions on screen (type in the desired value then press enter) ...

In many languages, new instances of a class are created using a special new keyword. In Ruby, new is also used to create instances of a class, but it isn't a keyword; instead, it's a static/class method, no different from any other static/class method. The definition is roughly this: class MyClass ...

This example sorts elements in ascending order of a key using a map. You can use any type, including class, instead of std::string, in the example below. #include <iostream> #include <utility> #include <map> int main() { std::map<double, std::string> sorted_map; ...

To detect the endian of the device var isLittleEndian = true; (()=>{ var buf = new ArrayBuffer(4); var buf8 = new Uint8ClampedArray(buf); var data = new Uint32Array(buf); data[0] = 0x0F000000; if(buf8[0] === 0x0f){ isLittleEndian = false; } })(); Lit...

C++11 introduces what are known as scoped enums. These are enumerations whose members must be qualified with enumname::membername. Scoped enums are declared using the enum class syntax. For example, to store the colors in a rainbow: enum class rainbow { RED, ORANGE, YELLOW, GREE...

db.people.createIndex({name: 1}) This creates an ascending single field index on the field name. In this type of indexes the sort order is irrelevant, because mongo can traverse the index in both directions.

db.people.createIndex({name: 1, age: -1}) This creates an index on multiple fields, in this case on the name and age fields. It will be ascending in name and descending in age. In this type of index, the sort order is relevant, because it will determine whether the index can support a sort opera...

To drop an index you could use the index name db.people.dropIndex("nameIndex") Or the index specification document db.people.dropIndex({name: 1})

Show a "Hello World!" in message box. MsgBox, Hello World! Show a "Hello World!" in tooltip. #Persistent Tooltip, Hello World! Show a "Hello World!" message in the traybar edit. #Persistent TrayTip,, Hello World! Prints "Hello, World" to Standard...

A model represents some data object in an application. For example you can have a model such as: Fruit, Car, Building, etc. in your application. Models are normally used by stores. Here is example how you would define a new model class. e.g. Ext.define('MyApp.model.Person', { extend: 'Ext.data...

Create your RecyclerView in your layout xml file: <android.support.v7.widget.RecyclerView android:id="@+id/recycleView" android:layout_width="match_parent" android:layout_height="match_parent" /> Create your Model...

When should I use it When the code inside an inline listener is too big and your method / class becomes ugly and hard to read You want to perform same action in various elements (view) of your app To achieve this you need to create a class implementing one of the listeners in the View API. ...

The NVIDIA installation guide ends with running the sample programs to verify your installation of the CUDA Toolkit, but doesn't explicitly state how. First check all the prerequisites. Check the default CUDA directory for the sample programs. If it is not present, it can be downloaded from the offi...

Some LINQ methods return a query object. This object does not hold the results of the query; instead, it has all the information needed to generate those results: var list = new List<int>() {1, 2, 3, 4, 5}; var query = list.Select(x => { Console.Write($"{x} "); return ...

To show and hide a FloatingActionButton with the default animation, just call the methods show() and hide(). It's good practice to keep a FloatingActionButton in the Activity layout instead of putting it in a Fragment, this allows the default animations to work when showing and hiding. Here is an ...

Suppose we have the following XAML snippet: <ListBox x:Name="MyListBox" /> Then in the code-behind for this XAML file, we write the following in the constructor: MyListBox.ItemsSource = new[] { 1, 2, 3, 4, 5 }; Running the application, we get a list of numbers we enter...

CREATE DATABASE LINK dblink_name CONNECT TO remote_username IDENTIFIED BY remote_password USING 'tns_service_name'; The remote DB will then be accessible in the following way: SELECT * FROM MY_TABLE@dblink_name; To test a database link connection without needing to know any of the objec...