Cannot import numpy in Python 3.7 or Python 3.8 - Ubuntu 18.04

Hello! Hope all the devs are staying safe during corona time and thanks for making such a great package.

I manage a group of users so I’m trying to figure out how I can install numpy for all of them to use without having everyone install the package themselves.

I have Python 2.7.17 and Python 3.6.9 (installed by default through Ubuntu 18.04). Additionally, I have installed Python 3.7.5, Python 3.8.0, and numpy using the following.

sudo apt install python3.7
sudo apt install python3.8
sudo apt install python3-numpy

If I run python or python3 or python3.6 which (invokes python 2.7.17 or python 3.6.9), I can run the following command just fine.

import numpy

However, if I try to run the above after running python3.7 or python3.8 I get the following error message:

ImportError: cannot import name 'multiarray' from 'numpy.core' (/usr/lib/python3/dist-packages/numpy/core/__init__.py)

When I install numpy it gets installed to /usr/lib/python3/dist-packages which should be fine since it’s on the sys.path() for all versions of Python.

Could it not be working because the version of numpy being pulled using apt is only for Python 3.6.9? If that’s the case, how should I install numpy for all users for ALL versions of Python?

[rgommers]

When I install numpy it gets installed to /usr/lib/python3/dist-packages which should be fine since it’s on the sys.path() for all versions of Python.

That’s definitely not fine, NumPy contains C code and compiled Python extensions are specific to a minor Python version - you cannot mix 3.6 / 3.7 / 3.8

Could it not be working because the version of numpy being pulled using apt is only for Python 3.6.9?

Correct

If that’s the case, how should I install numpy for all users for ALL versions of Python?

You need to install a Python version per Python version. Probably as simple as:

sudo apt install python3.7
sudo python3.7 -m pip install numpy
sudo apt install python3.8
sudo python3.8 -m pip install numpy

and actually probably better to get rid of your apt-installed python3-numpy and do sudo python3.6 -m pip install numpy for symmetry

[matthew-brett]

For venv vs virtualenv - since a recent comprehensive refactor, virtualenv can now use venv under the. hood - see : https://virtualenv.pypa.io/en/stable/user_guide.html#creators