Matplotlib not working for LInux. Cannot load backend 'TkAgg'

Question

Trying to use Matplotlib on Linux, but I keep getting this error:

ImportError: Cannot load backend 'TkAgg' which requires the 'tk' interactive framework, as 'headless' is currently running

I am using a virtual environment on OS: Linux 18.04 LTS. Python version: 3.6

I have tried many solutions other posts have suggested:

sudo apt-get install tk-dev libpng-dev libffi-dev dvipng texlive-latex-base
pip uninstall matplotlib
pip --no-cache-dir install matplotlib

I have tried fiddling with the python script where matplotlib is used:

#TOP OF FILE
import matplotlib
matplotlib.use('Agg') # or 'TkAgg', or removing the line altogether
import matplotlib.pyplot as plt
...

Running python to see what backend is being used:

import matplotlib
matplotlib.get_backend()   # -> 'agg'

Any ideas? Thank you

Answer 1

I had a similar issue using iPython on macOS getting the error message

matplotlib.use('TkAgg') 

ImportError: Cannot load backend 'TkAgg' which requires the 'tk' interactive framework, as 'macosx' is currently running

I was able to show my plots using

matplotlib.use('WebAgg') # shows in the browser

or

matplotlib.use('MacOSX') # shows on the desktop

To get list of all available backends I typed:

matplotlib.use('?')
...

ValueError: Unrecognized backend string '?': valid strings are ['GTK3Agg', 'GTK3Cairo', 'MacOSX', 'nbAgg', 'Qt4Agg', 'Qt4Cairo', 'Qt5Agg', 'Qt5Cairo', 'TkAgg', 'TkCairo', 'WebAgg', 'WX', 'WXAgg', 'WXCairo', 'agg', 'cairo', 'pdf', 'pgf', 'ps', 'svg', 'template']

See also What is a backend?