SLURM job - Problem with plot-function / save plot als png

Hello guys,

I am running a python script on a HPC via SLURM.
I want to save a plot without displaying it.
That seems to be a huge problem.
My script looks like this:

import matplotlib.pyplot as plt
import numpy as np

a = np.array([1,2,2,2,2,3,3,3,4,4,5])


I thought that plt.ioff() would prevent the plt.hist(a) from creating a figure that wants to be displayed.
Unfortunately I get the following error.

Traceback (most recent call last):
File “”, line 7, in
File “/fibus/fs1/16/cql7772/.local/lib/python3.7/site-packages/matplotlib/”, line 2631, in hist
return gca().hist(
File “/fibus/fs1/16/cql7772/.local/lib/python3.7/site-packages/matplotlib/”, line 920, in gca
return gcf().gca(**kwargs)
File “/fibus/fs1/16/cql7772/.local/lib/python3.7/site-packages/matplotlib/”, line 597, in gcf
return figure()
File “/fibus/fs1/16/cql7772/.local/lib/python3.7/site-packages/matplotlib/”, line 539, in figure
File “/fibus/fs1/16/cql7772/.local/lib/python3.7/site-packages/matplotlib/”, line 3252, in new_figure_manager
return cls.new_figure_manager_given_figure(num, fig)
File “/fibus/fs1/16/cql7772/.local/lib/python3.7/site-packages/matplotlib/backends/”, line 946, in new_figure_manager_given_figure
window = tk.Tk(className=“matplotlib”)
File “/fibus/fs1/16/cql7772/.conda/envs/ganomaly/lib/python3.7/tkinter/”, line 2023, in init = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: couldn’t connect to display “localhost:11.0”

Does anyone knows how to prevent this error? I just want to get the plot as a .png file

Many thanks in advance!

This issue doesn’t seem to be PyTorch-related, so you might get a better and faster answer in their support board or e.g. StackOverflow.
With that being said, you could try to switch to the Agg backend in matplotlib at the beginning of the script so avoid such issues.

1 Like

Many thanks! Switching to the Agg backend solved my issue!