When displaying ERP/ERF image in Epochs plot, a superfluous empty matplotlib figure opens in the background

[hoechenberger]

MWE:

# %%
from pathlib import Path
import mne


sample_dir = Path(mne.datasets.sample.data_path())
sample_fname = sample_dir / 'MEG' / 'sample' / 'sample_audvis_raw.fif'

raw = mne.io.read_raw_fif(sample_fname)
raw.crop(tmax=60)

events = mne.find_events(raw, stim_channel='STI 014')
event_id = {'auditory/left': 1, 'auditory/right': 2, 'visual/left': 3,
            'visual/right': 4, 'face': 5, 'buttonpress': 32}

epochs = mne.Epochs(raw, events=events, event_id=event_id,
                    tmin=-0.2, tmax=0.5, baseline=(None, 0),
                    preload=True)

epochs.plot()

Screen.Recording.2022-04-05.at.11.31.14.mov

This problem does not occur with Raw data when opening the channel location window via a right-click on the channel name.

[hoechenberger]

I've tracked this down to happen in the following line that creates the colorbar in the upstream plotting code:

https://github.com/mne-tools/mne-python/blob/93dc7dc9022ed861ddb2afda73143efbbaf6bf4a/mne/viz/epochs.py#L552

The matplotlib code internally calls gcf(), which opens an empty figure.

[agramfort]

you see how to fix?

…

Message ID: ***@***.***>

[hoechenberger]

you see how to fix?

Not yet.
I think we'd need to fix this in MNE. I need to check whether the same is present with the MPL backend too.