Manage package dependencies in Python project

If we share a python project with others, use a build system or restore an environment, we need to specify the external packages that the project requires.

The recommended approach is to use a requirements.txt file that contains a list of commands for pip that installs the required versions of dependent packages.

Note: My assumption is that you are using a virtual environment to set up your project. Developing python projects in a virtual environment is the recommended method.

There are multiple methods to generate requirements.txt.

1) pip freeze command

pip freeze > requirements.txt

This command records an environment’s current package list into requirements.txt. We can ship this file with our project & later every one can easily install dependent packages.

The drawback of this method is freeze command records all packages in the current environment to requirements.txt. There is a chance for unused packages.

2) Using pipreqs package

pip install pipreqs

If we are in the same path with our file, we can just write ./. Otherwise we need to give path of our file.

pipreqs ./

or

pipreqs /home/project/location

That will create a requirements.txt file for our project. The important advantage is pipreqs package only records packages that are imported in project files.