Need to explicitly set the matplotlib backend to TkAgg

[dmalesani]

Hello.

I and two other users using Mac OS X 10.14.6 (and python 2.7.15) had trouble running the NTT pipeline in interactive mode (e.g. PESSTOFASTSPEC -i). The output error message is attached. Looks like an issue with matplotlib, which requires to explicitly set the backend.

There is a user-side easy fix, which is to add the line

backend: TkAgg

to the file ~/.matplotlib/matplotlibrc

Code-wise, I understand one can set explicitly (but I am honestly a newbie here):

matplotlib.use('TkAgg')_

Some extra information here: MTG/sms-tools#36

Maybe worth either updating the source code (if easy/feasible) or the documentation including the easy user-side fix?

Thank you for your consideration,
Daniele
erroroutput_pipeline.txt