"UserWarning: Matplotlib is currently using agg, which is a non-GUI backend, so cannot show the figure." when plotting figure with pyplot on Pycharm

Solution 1: is to install the GUI backend tk

I found a solution to my problem (thanks to the help of ImportanceOfBeingErnest).

All I had to do was to install tkinter through the Linux bash terminal using the following command:

sudo apt-get install python3-tk

instead of installing it with pip or directly in the virtual environment in Pycharm.

Solution 2: install any of the matplotlib supported GUI backends

• solution 1 works fine because you get a GUI backend... in this case the TkAgg
• however you can also fix the issue by installing any of the matplolib GUI backends like Qt5Agg, GTKAgg, Qt4Agg, etc
  • for example pip install pyqt5 will fix the issue also

NOTE:

• usually this error appears when you pip install matplotlib and you are trying to display a plot in a GUI window and you do not have a python module for GUI display.
• The authors of matplotlib made the pypi software deps not depend on any GUI backend because some people need matplotlib without any GUI backend.

In my case, the error message was implying that I was working in a headless console. So plt.show() could not work. What worked was calling plt.savefig:

import matplotlib.pyplot as pltplt.plot([1,2,3], [5,7,4])plt.savefig("mygraph.png")

I found the answer on a github repository.

If you use Arch Linux (distributions like Manjaro or Antegros) simply type:

sudo pacman -S tk

And all will work perfectly!