What are the magic commands?

Magic commands are special commands that can help you with running and analyzing data in your notebook. They add a special functionality that is not straight forward to achieve with python code or jupyter notebook interface.

Magic commands are easy to spot within the code. They are either proceeded by % if they are on one line of code or by %% if they are written on several lines.

In this article, I am going to list magic commands that are used most often and show practical examples of how to take an advantage of the functionality they provide.

• List all magic commands
• Run a file
• Get an execution time
• List all variables
• Get detailed information about the variable
• Get and set environmental variables
• Displaying matlpotlib graphs in jupyter notebook
• Load an external file

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1. List all magic commands.

Let’s start by listing all possible magic commands that you can use in the notebook.

%lsmagic

If you run the line above in your notebook you should get a list similar to the screenshot below. These are all the commands available to you. We will go through just a fraction of them in this article.

2. Run a file.

You can run a python file from your jupyter notebook using the following code.

%run <file name>

Imagine that you have a file hello.py with the following content:

def hello_world():
    print('Hello, world')

hello_world()

You can run the following command in the notebook to run the file.

%run hello.py

3. Get an execution time.

You can time the execution of the code using the time command.

%%time

<your code>

Let’s generate 1 000 000 random numbers and see how long it takes.

%%time
import random
for i in range(0, 1000000):
    random.random()

4. List all variables.

There is a magic command that allows you to list all variables that are defined within the current notebook.

%who

You can pass it a data type after command name to list only variables of the specific data type.

To illustrate this let’s define a string variable and two int variables.

var_1 = 1
var_2 = 'hello'
var_3 = 100

Now we can list all strings with:

%who str

Or all integers with:

%who int

#data-science #programming #machine-learning #artificial-intelligence #jupyter-notebook