My second snap ;-)

[Robert Park]

And, if you're *so crazy* that you decide you want a snap that doesn't
contain tkinter, you can do this in your snapcraft.yaml:

parts:
    myapp:
        plugin: dump
        source: .
        stage-packages:
            - python3-matplotlib
            - python3-numpy
        organize:
            files/matplotlibrc: usr/share/matplotlib/mpl-data/matplotlibrc


"files/matplotlibrc" contains just "backend: Agg"

and then the same wrapper:

#!/bin/sh
export MATPLOTLIBRC="$SNAP/usr/share/matplotlib/mpl-data"
export MATPLOTLIBDATA="$MATPLOTLIBRC"
exec "$SNAP/run.py" "$@"