Cryptic numpy error

Description

The conda environment is quite elaborate and Miniconda tries its best to solve everything. An unresolved issue some MacOS users experience is that the numpy install isn't functional. numpy is required for both postbox and medaka.

The error message you may see is:

File "/miniconda3/envs/realtime-polio/bin/postbox", line 5, in <module>
    from postbox.postbox import main
  File "/miniconda3/envs/realtime-polio/lib/python3.6/site-packages/postbox/postbox.py", line 8, in <module>
    import pandas as pd
  File "/miniconda3/envs/realtime-polio/lib/python3.6/site-packages/pandas/__init__.py", line 17, in <module>
    "Unable to import required dependencies:\n" + "\n".join(missing_dependencies)
ImportError: Unable to import required dependencies:
numpy: 
IMPORTANT: PLEASE READ THIS FOR ADVICE ON HOW TO SOLVE THIS ISSUE!
Importing the multiarray numpy extension module failed.  Most
likely you are trying to import a failed build of numpy.
Here is how to proceed:
- If you're working with a numpy git repository, try `git clean -xdf`
  (removes all files not under version control) and rebuild numpy.
- If you are simply trying to use the numpy version that you have installed:
  your installation is broken - please reinstall numpy.
- If you have already reinstalled and that did not fix the problem, then:
  1. Check that you are using the Python you expect (you're using /miniconda3/envs/realtime-polio/bin/python),
     and that you have no directories in your PATH or PYTHONPATH that can
     interfere with the Python and numpy versions you're trying to use.
  2. If (1) looks fine, you can open a new issue at
     https://github.com/numpy/numpy/issues.  Please include details on:
     - how you installed Python
     - how you installed numpy
     - your operating system
     - whether or not you have multiple versions of Python installed
     - if you built from source, your compiler versions and ideally a build log
     Note: this error has many possible causes, so please don't comment on
     an existing issue about this - open a new one instead.
Original error was: dlopen(/miniconda3/envs/realtime-polio/lib/python3.6/site-packages/numpy/core/_multiarray_umath.cpython-36m-darwin.so, 2): Library not loaded: @rpath/libopenblas.dylib
  Referenced from: /miniconda3/envs/realtime-polio/lib/python3.6/site-packages/numpy/core/_multiarray_umath.cpython-36m-darwin.so
  Reason: image not found

Solution:

The conda version of 'turning it off and on again', pip uninstall and reinstall. The commands you need to run are:

pip uninstall numpy
pip install numpy=1.16.1