Matplotlib, TkAgg backend for interactive plotting under virtualenv, ipython

The easiest way I've found to use matplotlib and Tk for inline plotting under ipython is to actually install it on the base python3 environment with apt-get and use the --system-site-packages flag when creating the new virtualenv. Other techniques require more work.

apt-get is able to build and install these packages while pip install, under a virtualenv, will not see the interactive (Tk) libraries when it builds matplotlib.

So, for the base environment,

deactivate # make sure you're in the base environment
sudo apt-get install python3-tk tk tk-dev
sudo apt-get install python3-matplotlib
python3
import tkinter
import matplotlib
matplotlib.use('agg') # default non interactive shell
matplotlib.use('TkAgg') # interactive plotting backend
quit()

This shows you that you can set an interactive backend. Now create a new virtualenv with,

virtualenv -p /usr/bin/python3.4 --system-site-packages ~/mypy34
source ~/mypy34/bin/activate # enter the new virtualenv
pip install pyzmq # for ipython
pip install ipython

Now in ipython it will pick up your TkAgg backend by default (or else set it directly with %matplotlib TkAgg) and you can plot as expected from within a virtualenv.