pip freeze creates some weird path instead of the package version

I am working on developing a python package. I use pip freeze > requirements.txt to add the required package into the requirement.txt file. However, I realized that some of the packages, instead of the package version, have some path in front of them.

numpy==1.19.0
packaging==20.4
pandas @ file:///opt/concourse/worker/volumes/live/38d1301c-8fa9-4d2f-662e-34dddf33b183/volume/pandas_1592841668171/work
pandocfilters==1.4.2

Whereas, inside the environment, I get:

>>> pandas.__version__
'1.0.5'

Do you have any idea how to address this problem?

It looks like this is an open issue with pip freeze in version 20.1, the current workaround is to use:

pip list --format=freeze > requirements.txt

In a nutshell, this is caused by changing the behavior of pip freeze to include direct references for distributions installed from direct URL references.

You can read more about the issue on GitHub:

pip freeze does not show version for in-place installs

Output of "pip freeze" and "pip list --format=freeze" differ for packages installed via Direct URLs

Better freeze of distributions installed from direct URL references

Also, you can create txt file with another name and it won't include direct references then you can change the file name to requirements.txt

pip freeze > req.txt