Tutorial by Examples: re

In Python 3.x all classes are new-style classes; when defining a new class python implicitly makes it inherit from object. As such, specifying object in a class definition is a completely optional: Python 3.x3.0 class X: pass class Y(object): pass Both of these classes now contain object in ...

Here is an example of a method that would live inside a SQLiteOpenHelper subclass. It uses the searchTerm String to filter the results, iterates through the Cursor's contents, and returns those contents in a List of Product Objects. First, define the Product POJO class that will be the container f...

Ansible can be installed on CentOS or other Red Hat based systems. Firstly you should install the prerequisites: sudo yum -y update sudo yum -y install gcc libffi-devel openssl-devel python-pip python-devel then install Ansible with pip: sudo pip install ansible I can recommend for you to u...

CREATE SEQUENCE orders_seq START WITH 1000 INCREMENT BY 1; Creates a sequence with a starting value of 1000 which is incremented by 1.

DateTime date1 = new DateTime(2009, 8, 1, 0, 0, 0); DateTime date2 = new DateTime(2009, 8, 1, 12, 0, 0); int result = DateTime.Compare(date1, date2); string relationship; if (result < 0) relationship = "is earlier than"; else if (result == 0) relationship = "is the...

A BackgroundWorker is commonly used to perform tasks, sometimes time consuming, without blocking the UI thread. // BackgroundWorker is part of the ComponentModel namespace. using System.ComponentModel; namespace BGWorkerExample { public partial class ExampleForm : Form { ...

The foreach package brings the power of parallel processing to R. But before you want to use multi core CPUs you have to assign a multi core cluster. The doSNOW package is one possibility. A simple use of the foreach loop is to calculate the sum of the square root and the square of all numbers from...

Extension methods are useful to extend the behaviour of libraries we don't own. They are used similar to instance methods thanks to the compiler's syntactic sugar: Sub Main() Dim stringBuilder = new StringBuilder() 'Extension called directly on the object. stringBuilder.AppendIf(t...

A good use of extension method is to make the language more functional Sub Main() Dim strings = { "One", "Two", "Three" } strings.Join(Environment.NewLine).Print() End Sub <Extension> Public Function Join(strings As IEnumerable(Of String), separa...

A namespace is a URI, but to avoid verbosity, prefixes are used as a proxy. In the following example, the prefix my-prefix is bound to the namespace http://www.example.com/my-namespace by using the special attribute xmlns:my-prefix (my-prefix can be replaced with any other prefix): <?xml versio...

These two documents are semantically equivalement, as namespaces matter, not prefixes. <?xml version="1.0"?> <myns:foo xmlns:myns="http://www.example.com/my-namespace"> </myns:foo> <?xml version="1.0"?> <ns:foo xmlns:ns="http://www...

First, add relevant dependencies into the build.gradle file. dependencies { .... compile 'com.squareup.retrofit2:retrofit:2.3.0' compile 'com.squareup.retrofit2:converter-gson:2.3.0' compile 'com.squareup.retrofit2:adapter-rxjava:2.3.0' .... } Then create the model you ...

import pandas as pd Create a DataFrame from a dictionary, containing two columns: numbers and colors. Each key represent a column name and the value is a series of data, the content of the column: df = pd.DataFrame({'numbers': [1, 2, 3], 'colors': ['red', 'white', 'blue']}) Show contents of d...

Create a DataFrame of random numbers: import numpy as np import pandas as pd # Set the seed for a reproducible sample np.random.seed(0) df = pd.DataFrame(np.random.randn(5, 3), columns=list('ABC')) print(df) # Output: # A B C # 0 1.764052 0.400157 0.9787...

Imports System.Reflection Public Class PropertyExample Public Function GetMyProperties() As PropertyInfo() Dim objProperties As PropertyInfo() objProperties = Me.GetType.GetProperties(BindingFlags.Public Or BindingFlags.Instance) Return objProperties End Fun...

As Handlers are used to send Messages and Runnables to a Thread's message queue it's easy to implement event based communication between multiple Threads. Every Thread that has a Looper is able to receive and process messages. A HandlerThread is a Thread that implements such a Looper, for example th...

Swift 2.3 //Remove observer for single notification NSNotificationCenter.defaultCenter().removeObserver(self, name: "TestNotification", object: nil) //Remove observer for all notifications NotificationCenter.defaultCenter().removeObserver(self) Swift 3 //Remove observer for s...

Syntax: REPLACE( String to search , String to search for and replace , String to place into the original string ) Example: SELECT REPLACE( 'Peter Steve Tom', 'Steve', 'Billy' ) --Return Values: Peter Billy Tom

my $filename = '/path/to/file'; open my $fh, '<', $filename or die "Failed to open file: $filename"; # You can then either read the file one line at a time... while(chomp(my $line = <$fh>)) { print $line . "\n"; } # ...or read whole file into an arra...

The following example finds cities (from the cities example) whose population is below the average temperature (obtained via a sub-qquery): SELECT name, pop2000 FROM cities WHERE pop2000 < (SELECT avg(pop2000) FROM cities); Here: the subquery (SELECT avg(pop2000) FROM cities) is used to s...