cannot import python modules despite having installed them

问题

I have installed both plotly.express and pandas using:

pip install plotly-express

and

pip install pandas

I have tried to import these modules into my program using

import pandas as pd
import plotly.express as px

however, I get a ModuleNotFoundError for both these packages on run.

---

I have tried using alternate installs like:

py -3 -m pip install plotly-express
python -m pip install plotly-express
py -m pip install plotly-express

When I try install these packages again, they say that the requirement is already satisfied in c:\python38\lib\site-packages. All my other packages are installed at C:\Users\Oli\AppData\Local\Programs\Python\Python38-32\Lib\site-packages (I am Oli !).

I think this might be the issue. I've read that it is a bad idea to just stick in these files directly.

How can I get these imports to work?

回答1:

The first thing to do is to check that the directory C:\python38\lib\site-packages is in your PYTHONPATH environment variable. If not, add it or create PYTHONPATH as environment variable if it doesn't exist and add the directory (for Windows, Start -> type "Edit Environment Variables for your Account").

Alternatively, try the following:

import sys
sys.path.insert(0, 'C:\python38\lib\site-packages')
import pandas as pd

回答2:

This seems to be a path problem. Have you updated py recently in your machine? I once had a problem like this after updating, I could only solve it by completely uninstalling all versions first then reinstalling all from scratch. A bit of work, sure, but at least for me solved like a charm!

来源：https://stackoverflow.com/questions/65384294/cannot-import-python-modules-despite-having-installed-them