If you have issues with installing numpy related packages on Big sur, these steps helped me: 1- Uninstall pyhon installed with homebrew and use python-installer. This resolves numpy issue. And it's better to install 1.18 or just anything bellow 1.19.
brew uninstall python
And install it from: https://www.python.org/downloads/
Then:
pip install numpy==1.18
2- For other packages like matplotlib, scipy and etc, delete command line tools and replace it with xcode.
sudo rm -r /Library/Developer/CommandLineTools
sudo xcode-select -s /Applications/Xcode.app
For scipy I can't find anyway to solve the problems about accellorators and the resolve is to use wheels build for the previous MacOS versions.
pip install --platform macosx_10_9_x86_64 --only-binary=:all: --target=/usr/local/lib/python3.8/site-packages scipy
https://stackoverflow.com/questions/64847996/force-usage-of-10-x-wheel-in-macos-big-sur
Also this is an alternative way that I used to install gensim:
pip install smart-open
pip install six
pip install --platform macosx_10_9_x86_64 --only-binary=:all: --target=/usr/local/lib/python3.6/site-packages --no-deps gensim
pip install --platform macosx_10_9_x86_64 --only-binary=:all: --target=/usr/local/lib/python3.6/site-packages --no-deps scipy
pip install --platform macosx_10_9_x86_64 --only-binary=:all: --target=/usr/local/lib/python3.6/site-packages --no-deps numpy
As you saw it worked only with python3.6