@rflamary Given these changes, we might be able to roll-back the numpy requirement bump made in #326. If POT doesn't use anything special (at build time) from numpy==1.20.0, we could allow oldest-numpy-version to compile against even older versions (by decreasing the minimum Python version requirement in python_requires of setup.py, which, in turn, would allow older numpy versions).

The reason I introduced the minimum Python version / python_requires>=3.7 in the first place, is to respect the already merged precedent that Python 3.6 support is dropped.

But it looks like it might have been dropped pre-maturely due to the nature of the numpy>=1.20 build-time constraint that is now improved in this PR. I realize that a Python 3.6 runtime can still use POT by compiling it from source, but the proper way to specify what versions of Python you support is by using python_requires. I'd be happy to bump python_requires down to >=3.6 and re-enable wheel building for cp36, now that wheels will be properly built against the proper numpy version. Let me know what you think.

If you change numpy>=1.20 -> numpy>=1.16 in install_requires, you should also change python_requires=">=3.7" -> python_requires=">=3.6", because numpy<1.20 is not compatible with Python 3.7+ anyways.

That is if you want to re-add Python 3.6 support.

Hello @davidghiurco and thank you for the PR. I'm not sure why but the github actions for building the wheels are not triggered so I will probably ope a new PR wfrom this one on a branc of POT to ensure that the wheels are building OK before merging

@rflamary is there a difference between build all wheels in your first commit and build wheels in your second commit?

well build all wheels is longer because it build on ARM for linux but both should run, i really believe i need to have the pr on a branch of POT to make it work (but i don't see why it does not run in PR only from the github action conditions...)

I'm closing this PR since #349 have now been merged, thanks again @davidghiurco we will have a smooth release next time ;)