Report which custom reference was applied

Currently, after calling set_eeg_reference() with a custom channel name, or invoking add_reference_channels() (which calls the former after adding all-zeros channels), to my knowledge it’s impossible to retrieve which reference channels are being used in the current referencing scheme. The only thing that gets set in info is 'custom_ref_applied'.

import os.path as op
import mne

data_path = mne.datasets.testing.data_path()
examples_dir = op.join(data_path, 'Brainvision')
vhdr_file = op.join(examples_dir, 'Analyzer_nV_Export.vhdr')

raw = mne.io.read_raw(vhdr_file, preload=True)
raw.set_eeg_reference(['F8'])

# do fancy stuff here
# ...
# Wait … WHICH reference did I apply again? Guess I'll have to find the channel
# with all-zero data :(

Isn’t there a way to keep track of which references were set?

[cbrnr]

I don’t like the pickle format either, but two files are also asking for trouble. Maybe we should just store as .mat (I’m only half-joking here)…

[agramfort]

ok fair enough It seems that storing both names and locations is necessary…