“Is it safe to delete __pycache__?”

Yes. You can even suppress the creation of these files. Ditto with .pyc and .pyo files. It’s Python’s bytecode.

##

python3 -m venv env

. env/bin/activate

deactivate

The dot operator is also called the source

To fix your current installation, you need to find out if your pip installed packages were with –user or sudo:

import site
site.getsitepackages()
site.getusersitepackages()

Run this in py2 and py3 to get their respective pip install locations. So, from now on, either use –user or a virtual environment. Never use sudo! Shame on pip developers for not making –user the default! As a matter of fact:

cd ~/
python3 -m venv env
cd myProject
ls ../env
../env/bin/pip3 install [desired module]

Or an alternative for the last line:

. ../env/bin/activate

To test that you are using the “right” python:

which python

The first time you do this, you should see it in /usr/bin/python or something like that. Now:

source ../env/bin/activate
which python

Now this should work for myProject.

Use diff to compare current and future Python setup:

pip freeze > ~/Desktop/installed.txt
pip -r ~/Desktop/installed.txt

If there is a need to reinstall pip:

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python3 get-pip.py --force-reinstall

For an error like this: “/usr/local/share/doc/ghostscript is not writable.”

sudo chown -R `whoami` /usr/local/share/ghostscript

Wrote this a while back: “Do this for all new Mac install: sudo easy_install pip”

Don’t do this. Instead, for new installs, brew install python and brew install python3. Speaking of which, use virtual environment!

To raise recursion limit:

import sys

sys.setrecursionlimit(n)