Tutorial by Examples: reat

Create Subtree Add a new remote called plugin pointing to the plugin's repository: git remote add plugin https://path.to/remotes/plugin.git Then Create a subtree specifying the new folder prefix plugins/demo. plugin is the remote name, and master refers to the master branch on the subtree's rep...

0.18.0 Prior to 0.18.0 you can create ranges like this: > range = [1..5] [1,2,3,4,5] : List number > > negative = [-5..3] [-5,-4,-3,-2,-1,0,1,2,3] : List number 0.18.0 In 0.18.0 The [1..5] syntax has been removed. > range = List.range 1 5 [1,2,3,4,5] : List number > &g...

> listOfNumbers = [1,4,99] [1,4,99] : List number > > listOfStrings = ["Hello","World"] ["Hello","World"] : List String > > emptyList = [] -- can be anything, we don't know yet [] : List a > Under the hood, List (linked list) is ...

To create a collection of n copies of some object x, use the fill method. This example creates a List, but this can work with other collections for which fill makes sense: // List.fill(n)(x) scala > List.fill(3)("Hello World") res0: List[String] = List(Hello World, Hello World, Hello...

A Map is a basic mapping of keys to values. Maps are different from objects in that their keys can be anything (primitive values as well as objects), not just strings and symbols. Iteration over Maps is also always done in the order the items were inserted into the Map, whereas the order is undefine...

To perform actions in Django using commandline or other services (where the user/request is not used), you can use the management commands. Django modules can be imported as needed. For each command a separate file needs to be created: myapp/management/commands/my_command.py (The management and...

Under the hood, a matrix is a special kind of vector with two dimensions. Like a vector, a matrix can only have one data class. You can create matrices using the matrix function as shown below. matrix(data = 1:6, nrow = 2, ncol = 3) ## [,1] [,2] [,3] ## [1,] 1 3 5 ## [2,] 2 4...

A compound view is a custom ViewGroup that's treated as a single view by the surrounding program code. Such a ViewGroup can be really useful in DDD-like design, because it can correspond to an aggregate, in this example, a Contact. It can be reused everywhere that contact is displayed. This means t...

db.people.insert({name: 'Tom', age: 28}); Or db.people.save({name: 'Tom', age: 28}); The difference with save is that if the passed document contains an _id field, if a document already exists with that _id it will be updated instead of being added as new. Two new methods to insert documents...

To be able to use JDBC you need to have the JDBC driver of your database on the class path of your application. There are multiple ways to connect to a database, but the common ways are to either use the java.sql.DriverManager, or to configure and use a database specific implementation of javax.sql...

Stored procedures can be created through a database management GUI (SQL Server example), or through a SQL statement as follows: -- Define a name and parameters CREATE PROCEDURE Northwind.getEmployee @LastName nvarchar(50), @FirstName nvarchar(50) AS -- Define the query to be...

You are allowed to implement custom exceptions that can be thrown just like any other exception. This makes sense when you want to make your exceptions distinguishable from other errors during runtime. In this example we will create a custom exception for clear handling of problems the application ...

You can create one table from another by adding a SELECT statement at the end of the CREATE TABLE statement: CREATE TABLE stack ( id_user INT, username VARCHAR(30), password VARCHAR(30) ); Create a table in the same database: -- create a table from another table in the same data...

import pandas as pd import numpy as np np.random.seed(123) x = np.random.standard_normal(4) y = range(4) df = pd.DataFrame({'X':x, 'Y':y}) >>> df X Y 0 -1.085631 0 1 0.997345 1 2 0.282978 2 3 -1.506295 3

You can create a DataFrame from a list of simple tuples, and can even choose the specific elements of the tuples you want to use. Here we will create a DataFrame using all of the data in each tuple except for the last element. import pandas as pd data = [ ('p1', 't1', 1, 2), ('p1', 't2', 3, 4)...

Due to Node's asynchronous nature, creating or using a directory by first: checking for its existence with fs.stat(), then creating or using it depending of the results of the existence check, can lead to a race condition if the folder is created between the time of the check and the time of ...

If you don't want to use the default Toast view, you can provide your own using the setView(View) method on a Toast object. First, create the XML layout you would like to use in your Toast. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="...

-- Create an index for column 'name' in table 'my_table' CREATE INDEX idx_name ON my_table(name);

A unique index prevents the insertion of duplicated data in a table. NULL values can be inserted in the columns that form part of the unique index (since, by definition, a NULL value is different from any other value, including another NULL value) -- Creates a unique index for column 'name' in tabl...

To share files or to host simple websites(http and javascript) in your local network, you can use Python's builtin SimpleHTTPServer module. Python should be in your Path variable. Go to the folder where your files are and type: For python 2: $ python -m SimpleHTTPServer <portnumber> For p...