Sometime after installation
pip install some_module
Python can't find this module and shows error ModuleNotFoundError
import some_module ModuleNotFoundError: No module named 'some_module'
Not so often problem is that module uses different name for installation and different for import. It can be totally different name - like install python-some_module and import some_module - or only upper/lower chars - like install some_module and import SomeModule.
But often problem is because you may have installed many versions of Python (which is popular on Linux) and pip installs module in different version then you run with command python
Every version of Python has own folder for modules because it may need module compiled specially for this version.
First you can check versions (upper V)
pip -V python -V
You may also check if you don't have also similar commands
pip3 -V pip3.7 -V pip3.8 -V pip3.9 -V python3 -V python3.7 -V python3.8 -V python3.9 -V
All these names with numbers let you simply run code with specific version.
You can use pip3.9 to make sure you install it for commands python3.9
But sometimes the simplest method is to use directly python to run module pip and install module with correct python.
python -m pip install some_module
it is always pip, not pip3, pip3.7 etc
python3 -m pip install some_module python3.7 -m pip install some_module python3.8 -m pip install some_module python3.9 -m pip install some_module
Later you can try to clean this mess and put correct pip3.x in place of pip.
On Linux (and probably on MacOS too) you can find folder with pip using
which pip which pip3
whereis pip whereis pip3
All versions should be in the same folder (ie. /usr/local/bin) You can go to folder with pip and pip3.x, remove pip and create symbolic link to other version using
ln -s pip3.9 pip # or ln -s pip3.9 pip3
instead of copying file.
The same you can do with python3.9 and python3 If you still use Python 2 (or system uses it) and command python runs Python 2 then better don't put python3 in places of python
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