how to make a requirements.txt for python code example

Example 1: command to make requirements.txt

pip freeze > requirements.txt

Example 2: python requirements.txt

pip freeze #view requirements to be created (best done in virtual env)
pip freeze > requirements.txt #create requirements.txt (best done in virtual env)
pip install -r requirements.txt #install requirements.txt (best done in virtual env)

Example 3: python generate requirements.txt

# First:
pip install pipreqs

# Then:
pipreqs path/to/project

# There is now a requirements.txt file in the project folder.