BUG: Averaging/plotting EpochArray/EvokedArray from ICA.get_sources leads to errors

I’m using ICA.get_sources() to output an EpochArray: epochs_ic. If I tryevoked_ic=epochs_ic.average() I get the following error:

/Users/keithd/mne-python/mne/io/pick.pyc in pick_info(info, sel, copy)
    387         return info
    388     elif len(sel) == 0:
--> 389         raise ValueError('No channels match the selection.')
    390 
    391     info['chs'] = [info['chs'][k] for k in sel]

ValueError: No channels match the selection.

I can deal with this issue by explicitly giving the picks: something like evoked_ic = epochs_ic.average(picks=np.arange(ncomps))

Then if I try to do a butterfly plot of the evoked data I get a different error

/Users/keithd/anaconda2/lib/python2.7/site-packages/matplotlib/gridspec.pyc in __getitem__(self, key)
    152                     k1 += nrows
    153                 if k1 >= nrows or k1 < 0 :
--> 154                     raise IndexError("index out of range")
    155                 row1, row2 = k1, k1+1
    156 

IndexError: index out of range

That error I can’t fix with the previous trick. Below is some code that reproduces both errors with sample data. I think both errors are likely related to the way ICA channels are picked in /mne/io/picks.py. It seems as though the ICA channel type is not listed at all as an option in _PICK_TYPES_DATA_DICT. I think I could fix this myself if others agree it is indeed a bug and I’m not missing something obvious. Let me know what you think!

_Sample Code to reproduce error:_

#import mne and sample data
import sys
import mne
from mne.datasets import sample  # noqa
data_path = sample.data_path()
raw_fname = data_path + '/MEG/sample/sample_audvis_filt-0-40_raw.fif'
raw = mne.io.read_raw_fif(raw_fname, add_eeg_ref=False)

# get the events
events = mne.find_events(raw, stim_channel='STI 014')
event_id = dict(aud_l=1, aud_r=2)  # event trigger and conditions
tmin = -0.5  # start of each epoch (500ms before the trigger)
tmax = 0.5  # end of each epoch (500ms after the trigger)
# pick just the meg channels
picks = mne.pick_types(raw.info, meg=True, eeg=False, eog=False, stim=False,
                       exclude='bads')
# make epochs
epochs = mne.Epochs(raw, events, event_id, tmin, tmax, proj=True, picks=picks,
                    preload=True,add_eeg_ref=False)
# run ICA on the epochs
ncomps = 24
ica=mne.preprocessing.ica.ICA(max_pca_components=ncomps)
ica.fit(epochs)
# put sources into epoch array
src_data=ica.get_sources(epochs)
# try to plot evoked array
evoked_ic = src_data.average(); # get error here, can be avoided by including picks=np.arange(ncomps)
evoked_ic.plot() #then I can get an error here. This is not fixable by the same addition

[kdoelling1919]

I’m happy to do this, if others agree it would be useful.

[agramfort]

+1 to improve docstrings