Problems with importing self-defined module in Jupyter notebook using PyCharm

Question

I'm trying to import a self-defined module in a Jupyter notebook using PyCharm (2016.1). However, I always get "ImportError: No module named xxx". Importing packages like NumPy or Matplotlib works fine. The self-defined module and the notebook are in the same directory and I've tried to set the directory as sources root. How can I fix this? Thanks a lot!

Answer 1

If you run the following in your notebook...

import sys
sys.path

...and you don't see the path to the directory containing the packages/modules, there are a couple ways around it. I can't speculate why this might happen in this example. I have seen some discrepancies in the results of sys.path when running Jupyter locally from PyCharm on OS X vs. on a managed Linux service.

An easy if hacky workaround is to set the sys path in your notebook to reflect where the packages/modules are rooted. For example, if your notebook was in a subdirectory from where the packages or modules are and sys.path only reflects that subdirectory:

import sys
sys.path.append("../")

The point is that sys.path must include the the directory the packages and modules are rooted in so the path you append will depend on the circumstances.

Perhaps a more proper solution, if you are using a virtualenv as your project interpreter, is to create a setup.py for your project and install the project as an editable package with pip. E.g. pip install -e . Then as long as Jupyter is running from that virtualenv there shouldn't be any issues with imports.

One ugly gotcha I ran into on OS X was Jupyter referencing the wrong virtualenv when started. This should also be apparent by inspecting the results of sys.path. I don't really know how I unintentionally managed set this but presume it was due to futzing around my first time getting Jupyter working in PyCharm. Instead of starting Jupyter with the local virtual env it would run with the one defined in ~/Library/Jupyter/kernels/.python/kernel.json. I was able to clear it by cleaning out that directory, e.g. rm -r ~/Library/Jupyter/kernels/.python.