Udit Vashisht
Author: Udit Vashisht


If __name__ == '__main__' in Python

  • 3 minutes read
  • 244 Views
If __name__ == '__main__' in Python

    Table of Contents

What does if __name__ == ‘__main__‘in python means?

In python, you must have come accross the following code :-

if __name__ == '__main__':
    main()

In this tutorial, we will learn in detail what does the above statement means. As per official documentation:

‘__main__‘ is the name of the scope in which top-level code executes. A module’s __name__ is set equal to ‘__main__‘ when read from standard input, a script, or from an interactive prompt.

It means that if any module/python file is running as the main program, it sets the special__name__ variable to have a value ‘__main__‘

Create a python file ‘module_one.py’ and type the following code:-

# module_one.py

print f'The name of module one is {__name__}' 

If you will run it. You will get the following output:-

The name of module one is __main__

However, if this module is imported in some other file or module, variable __name-- will be set as the name of the first module.

To make it clear, create another python file (module) called ‘module_two.py’ and import first module in it:-

# module_two.py

import module_one

Since, we have imported module_one in module_two.py, when we will run the second module, it will execute the first module and we will get the following output on running module_two.py:-

The name of module one is module_one

Since, now we are directly running module_two.py, Python will set it’s __name__ as ‘__main__‘

# module_two.py

import module_one

print f'The name of module two is {__name__}' 

Output of this module will be:-

The name of module one is module_one
The name of module two is __main__

Hence if __name__ == ‘__main__‘ checks whether the file is being run directly or it has been imported into some other file. The following example will make it more clear:-

# module_one.py

print "This will always be printed"

if __name__ == "__main__": 
    print "Module one has been run directly"
else: 
    print "Module one has been imported"
# Output
This will always be printed
Module one has been run directly

Now if we just import module_one in module_two.py and run it, we will get the following output.

# module_two.py
import module_one
# Output
This will always be printed
Module one has been imported

We use this if we want to make a certain function run, when a module is run directly and some other function to run if it is imported.

If you have any query, please feel free to ask in comment section.



Related Posts

Python Realtime Plotting | Matplotlib Tutorial | Chapter 9
By Udit Vashisht

Python Realtime Plotting in Matplotlib

Python Realtime Plotting | Chapter 9

In this tutorial, we will learn to plot live data in python using matplotlib. In the beginning, we will be plotting realtime data from a local script and later on we will create a python live plot ...

Read More
Matplotlib Tutorial in Python | Chapter 2 | Extracting Data from CSVs and plotting Bar Charts.
By Udit Vashisht

Matplotlib Tutorial in Python

Chapter 2 | Extracting Data from CSVs and plotting Bar Charts

In the last chapter, we learned to draw simple plots in Matplotlib and further customizing it.In this chapter we will be learning to extract data from external sources like CSV and creating ...

Read More
Time Series Analysis with Pandas
By Udit Vashisht

Introduction

Python’s pandas library is frequently used to import, manage, and analyze datasets in a variety of formats. In this article, we’ll use it to analyze Amazon’s stock prices and perform some basic time series operations.
Stock markets play an important role in the economy of ...

Read More
Search
Tags
tech tutorials automate python beautifulsoup web scrapping webscrapping bs4 Strip Python3 programming Pythonanywhere free Online Hosting hindi til github today i learned Windows Installations Installation Learn Python in Hindi Python Tutorials Beginners macos installation guide linux SaralGyaan Saral Gyaan json in python JSON to CSV Convert json to csv python in hindi convert json csv in python remove background python mini projects background removal remove.bg tweepy Django Django tutorials Django for beginners Django Free tutorials Proxy Models User Models AbstractUser UserModel convert json to csv python json to csv python Variables Python cheats Quick tips == and is f string in python f-strings pep-498 formatting in python python f string smtplib python send email with attachment python send email automated emails python python send email gmail automated email sending passwords secrets environment variables if name == main Matplotlib tutorial Matplotlib lists pandas Scatter Plot Time Series Data Live plots Matplotlib Subplots Matplotlib Candlesticks plots Tutorial Logging unittest testing python test Object Oriented Programming Python OOP Database Database Migration Python 3.8 Walrus Operator Data Analysis Pandas Dataframe Pandas Series Dataframe index pandas index python pandas tutorial python pandas python pandas dataframe python f-strings padding how to flatten a nested json nested json to csv json to csv python pandas Pandas Tutorial insert rows pandas pandas append list