How to Check if a Python package is installed

# Table of Contents

# Check if a Python package is installed

To check if a Python package is installed:

Import the package in a try block.
Use an except block to handle the potential ModuleNotFoundError.
If the try block runs successfully, the module is installed.

main.py

Copied!
try:
    import requests
    print('The requests module is installed.')
except ModuleNotFoundError:
    print('The requests module is NOT installed.')

check if python package is installed

Make sure to replace requests with the name of your specific module.

We used a try/except block to check if a module is installed.

If the try block doesn't raise an exception, the module is installed.

If the module isn't installed, a ModuleNotFoundError error is raised and the except block runs.

# Installing the module if it isn't already installed

You can also extend the try/except statement to install the module if it isn't installed.

main.py

Copied!
import sys
import subprocess

try:
    import requests
    print('The requests module is installed')
except ModuleNotFoundError:
    print('The requests module is NOT installed')

    # 👇️ Optionally install module
    python = sys.executable
    subprocess.check_call(
        [python, '-m', 'pip', 'install', 'requests'],
        stdout=subprocess.DEVNULL
    )
finally:
    import requests

installing the module if it is not already installed

If you need to check if a package is installed using pip, use the pip show command.

shell

Copied!
pip show requests

check if module installed using pip

The pip show module_name command will either state that the package is not installed or will show a bunch of information about the package, including the location where the package is installed.

You can also use the following one-liner command.

shell

Copied!
python -c 'import pkgutil; print(1 if pkgutil.find_loader("module_name") else 0)'

Make sure to replace module_name with the actual name of the module you are checking for.

The command returns 1 if the module is installed and 0 if it isn't but this can be easily adjusted.

# Check if a Python package is installed using find_spec

An alternative approach is to use the importlib.util.find_spec method.

The find_spec() method will return a spec object if the module is installed, otherwise, None is returned.

main.py

Copied!
import importlib.util

module_name = 'requests'

spec = importlib.util.find_spec(module_name)

if spec:
    print(f'The {module_name} module is installed')
else:
    print(f'The {module_name} module is NOT installed')

check if python package is installed using find spec

The importlib.util.find_spec method finds the spec for a module.

The spec for a module is a namespace containing the import-related information used to load the module.

If no spec is found, the method returns None.

# Installing the package if it isn't already installed

You can optionally install the package if it isn't already installed.

main.py

Copied!
import importlib.util

import sys
import subprocess

module_name = 'requests'

spec = importlib.util.find_spec(module_name)

if spec:
    print(f'The {module_name} module is installed')
else:
    print(f'The {module_name} module is NOT installed')

    # 👇️ Optionally install the module if it's not installed
    python = sys.executable
    subprocess.check_call(
        [python, '-m', 'pip', 'install', 'requests'],
        stdout=subprocess.DEVNULL
    )

# Checking if the module isn't installed

If you need to check if the module isn't installed, check if the spec variable stores a None value.

main.py

Copied!
import importlib.util

import sys
import subprocess

module_name = 'requests'

spec = importlib.util.find_spec(module_name)

if spec is None:
    print(f'The {module_name} module is NOT installed')

    # 👇️ Optionally install the module if it's not installed
    python = sys.executable
    subprocess.check_call(
        [python, '-m', 'pip', 'install', 'requests'],
        stdout=subprocess.DEVNULL
    )

    print(f'The {module_name} module is now installed')

Which approach you pick is a matter of personal preference. I'd use the try/except statement because I find it quite direct and easy to read.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

I wrote a book in which I share everything I know about how to become a better, more efficient programmer.

You can use the search field on my Home Page to filter through all of my articles.

How to Check if a Python package is installed

# Table of Contents

# Check if a Python package is installed

# Installing the module if it isn't already installed

# Check if a Python package is installed using find_spec

# Installing the package if it isn't already installed

# Checking if the module isn't installed

# Additional Resources

Borislav Hadzhiev