“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.