Tutorial by Examples: me

Create a simple DataFrame. import numpy as np import pandas as pd # Set the seed so that the numbers can be reproduced. np.random.seed(0) df = pd.DataFrame(np.random.randn(5, 3), columns=list('ABC')) # Another way to set column names is "columns=['column_1_name','column_2_name','c...

foo() { while [[ "$#" -gt 0 ]] do case $1 in -f|--follow) local FOLLOW="following" ;; -t|--tail) local TAIL="tail=$2" ;; esac shift done echo "FOLLOW: $FOLLOW" echo "TAIL: $...

You can improve the security for data transit or storing by implementing encrypting techniques. Basically there are two approaches when using System.Security.Cryptography: symmetric and asymmetric. Symmetric Encryption This method uses a private key in order to perform the data transformation. ...

Code class Program { static void Main(string[] args) { int a = 20; Console.WriteLine("Inside Main - Before Callee: a = {0}", a); Callee(a); Console.WriteLine("Inside Main - After Callee: a = {0}", a); Console.WriteLine(); ...

This very simple snippet of XQuery can be executed in QueryConsole using the built-in "Documents" database as a sandbox. Each piece of the snippet has a comment to explain what the following line of code means. xquery version "1.0-ml"; (: Let's first insert a simple document to...

If we know the desired URI of the document we are looking for: fn:doc("/stuff/mysimpledocument.xml") Returns the full document from the database, using the URI to locate it. Since this is XQuery, we can use XPath to find the document when we know about the structure, but not the URI: ...

We will now add some additional XML nodes to the "my-document" element and update the document. The snippet again contains comments to explain what is happening. xquery version "1.0-ml"; (: We are preserving the same URI as we used originally :) let $uri := "/stuff/mysimp...

Traditionally Prolog performed arithmetic using the is and =:= operators. However, several current Prologs offer CLP(FD) (Constraint Logic Programming over Finite Domains) as a cleaner alternative for integer arithmetic. CLP(FD) is based on storing the constraints that apply to an integer value and ...

Let's say we have a table team_person as below: +======+===========+ | team | person | +======+===========+ | A | John | +------+-----------+ | B | Smith | +------+-----------+ | A | Walter | +------+-----------+ | A | Louis | +------+-----------+ | C | ...

RENAME TABLE t TO t_old, t_copy TO t; No other sessions can access the tables involved while RENAME TABLE executes, so the rename operation is not subject to concurrency problems. Atomic Rename is especially for completely reloading a table without waiting for DELETE and load to finish: CREATE ...

Let's say you're working on an app called MyTasks, and you want to allow inbound URLs to create a new task with a title and a body. The URL you're designing might look something like this: mytasks://create?title=hello&body=world (Of course, the text and body parameters are used to populate our...

First Initialize FirebaseDatabase: FirebaseDatabase database = FirebaseDatabase.getInstance(); Write to your database: // Write a message to the database FirebaseDatabase database = FirebaseDatabase.getInstance(); DatabaseReference myRef = database.getReference("message"); myRef....

ACCEPT variable. ACCEPT variable FROM CONSOLE. ACCEPT variable FROM ENVIRONMENT "path". ACCEPT variable FROM COMMAND-LINE. ACCEPT variable FROM ARGUMENT-NUMBER ACCEPT variable FROM ARGUMENT-VALUE ACCEPT variable AT 0101. ACCEPT screen-variable. ACCEPT today FROM DATE. ACCE...

You can pass a pointer variable to a method as parameter. The following example illustrates this: using System; namespace UnsafeCodeApplication { class TestPointer { public unsafe void swap(int* p, int *q) { int temp = *p; *p = *q; *q = temp; ...

In C#, an array name and a pointer to a data type same as the array data, are not the same variable type. For example, int *p and int[] p, are not same type. You can increment the pointer variable p because it is not fixed in memory but an array address is fixed in memory, and you can't increment th...

The PATH environment variable is generally defined in ~/.bashrc or ~/.bash_profile or /etc/profile or ~/.profile or /etc/bash.bashrc (distro specific Bash configuration file) $ echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/usr/lib/jv...

There are frequent behavior patterns that can result in a lot of boilerplate code. By declaring a method that takes a Closure as a parameter, you can simplify your program. As an example, it is a common pattern to retrieve a database connection, start a transaction, do work, and then either commit ...

To remove a PATH from a PATH environment variable, you need to edit ~/.bashrc or ~/.bash_profile or /etc/profile or ~/.profile or /etc/bash.bashrc (distro specific) file and remove the assignment for that particular path. Instead of finding the exact assignment, you could just do a replacement in t...

The following commands can be used to swap the names of two MySQL databases (<db1> and <db2>): mysqladmin -uroot -p<password> create swaptemp mysqldump -uroot -p<password> --routines <db1> | mysql -uroot -p<password> swaptemp mysqladmin -uroot -p<password&gt...

MERGE INTO targetTable t USING sourceTable s ON t.PKID = s.PKID WHEN MATCHED AND NOT EXISTS ( SELECT s.ColumnA, s.ColumnB, s.ColumnC INTERSECT SELECT t.ColumnA, t.ColumnB, s.ColumnC ) THEN UPDATE SET t.Colum...