Why am I getting UserWarning: Matplotlib is currently using ps, which is a non-GUI backend, so cannot show the figure

Question

This is not in a jupyter notebook so this is not a duplicate of this question, but my code is:

from gluoncv import model_zoo, data, utils
from matplotlib import pyplot as plt

...
plt.show()

The error I'm getting is:

/figure.py:445: UserWarning: Matplotlib is currently using ps, which is a non-GUI backend, so cannot show the figure.
  % get_backend())

If it matters, I'm using OS X. What do I need to do to get the image to show?

The `PS` backend is intended for creating PostScript files, not displaying graphs. That warning is `matplotlib` telling you that your call to `plt.show()` won't do what you think it'll do. — yorodm, Jan 22 '19 at 19:45

philshem · Answer 1 · 2019-05-05T15:22:45.197

5

You can use

matplotlib.use("TkAgg")

instead of

matplotlib.use("PS")

when developing on MacOS.

Please note that the import should be before importing plt, like this:

import matplotlib
matplotlib.use('TkAgg')
from matplotlib import pyplot as plt

edited May 05 '19 at 15:22

answered May 05 '19 at 12:03

philshem

ImportanceOfBeingErnest · Accepted Answer · 2019-01-22T20:00:17.337

4

matplotlib.use('PS') and plt.show() are mutually exclusive. You need to decide:

Do you want to show the figure on screen? Solution: Remove the line matplotlib.use('PS').
Do you want to use the PS backend? This seems unlikely, because there is rarely a reason to set the backend to something non-interactive unless working on a server. Anyways, solution: Replace plt.show() by plt.savefig("filname.ps").

edited Jan 22 '19 at 20:00

answered Jan 22 '19 at 19:55

I modified the code and removed `matplotlib.use('PS')`. I'm getting the same error – Shamoon Jan 22 '19 at 19:55
Probably because you didn't restart the kernel after doing that change. – ImportanceOfBeingErnest Jan 22 '19 at 19:56
I'm not running a notebook. This is `Python` running on my mac, so how would I restart the kernel? – Shamoon Jan 22 '19 at 19:58
Ok, how are you running this? Can you create a [mcve]? What is gluoncv? – ImportanceOfBeingErnest Jan 22 '19 at 20:01
I created a repl at https://repl.it/@shamoons/WelloffHarmfulMineral, however I'm running on Mac OS X – Shamoon Jan 22 '19 at 20:02
That repl.it link results in different errors for me. Also, on the repl.it server you may indeed not be able to `show()` a figure. So coming back to your local computer, can you set the backend before importing gluoncv, `import matplotlib; matplotlib.use("TkAgg"); import gluoncv....`? – ImportanceOfBeingErnest Jan 22 '19 at 20:12
@ImportanceOfBeingErnest what if i want to show a live plot ? i mean, i'm updating my plot continously, so `savefig` is not a good idea since i have to close/re-open the images lots of time. do you have any suggestion ? – AcaNg Aug 01 '19 at 08:17
@Tiendung You cannot use the the PS backend for live plots. – ImportanceOfBeingErnest Aug 01 '19 at 11:55

2 Answers2