self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk,sync, use)
TclError: no display name and no $DISPLAY environment variable

import matplotlib
import matplotlib.pyplot

# force headless backend, or set 'backend' to 'Agg'
# in your ~/.matplotlib/matplotlibrc
matplotlib.use('Agg')

# force non-interactive mode, or set 'interactive' to False
# in your ~/.matplotlib/matplotlibrc
matplotlib.pyplot.ioff()

import matplotlib
# force headless backend, or set 'backend' to 'Agg'
# in your ~/.matplotlib/matplotlibrc
matplotlib.use('Agg')

import matplotlib.pyplot
# force non-interactive mode, or set 'interactive' to False
# in your ~/.matplotlib/matplotlibrc
matplotlib.pyplot.ioff()