Customizing Matplotlib

If you're using Matplotlib (or an application that uses it, like QIIME) on a server, you'll likely need to change its display backend. A quick way to do so for your own environment:

$ mkdir -p $HOME/.config/matplotlib/
$ echo "backend: Agg" >> $HOME/.config/matplotlib/matplotlibrc

Choosing the "Agg" backend prevents "RuntimeError: Invalid DISPLAY variable".