I’d like to add comments for a few packages in a pip requirements file. (Just to explain why that package is on the list.) Can I do this?

I’m imagining something like

Babel==0.9.5 # translation
CherryPy==3.2.0 # web server
Creoleparser==0.7.1 # wiki formatting
Genshi==0.5.1 # templating

Sure, you can, just use #

pip docs:

A line that begins with # is treated as a comment and ignored. Whitespace followed by a # causes the # and the remainder of the line to be treated as a comment.

You can add comments (lines beginning with #)