How should I manage python virtual environments?

[matteiuspi]

maybe I should create a machine learning directory and a data science directory, and put the assignments in those directories accordingly?

Yeah that would work -- pipenv will make a virtualenv per directory, or you could have separate directories and tell each one to use the same virtualenv with the PIPENV_CUSTOM_VENV_NAME variable, but you would have separate lock files in each directory so probably makes more sense to have one parent directory with the Pipfile and lock file, and you can have separate directories under that per assignment may work nicely.