demonstration (test) of channel picking in fwd['sol'] vs. fwd['info']

test_pick_forward_channels_gist.py

from os import path as op
from os import rmdir
import mne
from mne.datasets import testing
from mne.utils import _TempDir

sample_path = op.join(testing.data_path(download=False), 'MEG', 'sample')
raw_fname = op.join(sample_path, 'sample_audvis_trunc_raw.fif')
trans_fname = op.join(sample_path, 'sample_audvis_trunc-trans.fif')

sample_bem_path = op.join(testing.data_path(download=False), 'subjects',
                          'sample', 'bem')
bem_fname = op.join(sample_bem_path, 'sample-320-320-320-bem-sol.fif')
src_fname = op.join(sample_bem_path, 'sample-oct-2-src.fif')

raw = mne.io.Raw(raw_fname, preload=True, proj=True)

# reorder info-struct, don't worry about the data as it won't be used!
# new order: EOG, EEG, MEG, STI
new_order = [375] + range(315, 375) + range(0,306) + range(306, 315)

# Are these the only two that need reordering?
raw.info['ch_names'] = [raw.info['ch_names'][n] for n in new_order]
raw.info['chs'] = [raw.info['chs'][n] for n in new_order]

fwd = mne.make_forward_solution(raw.info, trans_fname, src_fname,
                                bem_fname, eeg=True, mindist=5.0)
fwd = mne.convert_forward_solution(fwd, surf_ori=True)

print "Now sol and info keys will contain different channel orderings"
print ''''fwd['sol']['row_names'][:5]'''
print fwd['sol']['row_names'][:5]
print ''''fwd['info']['ch_names'][:5]'''
print fwd['info']['ch_names'][:5]

print 'Note that picking EEG type will now return a fwd with MEG channels'
print 'fwd_picked = mne.pick_types_forward(fwd, meg=False, eeg=True)'
fwd_picked = mne.pick_types_forward(fwd, meg=False, eeg=True)
print fwd_picked

print 'And sensititivy map calculation (average ref-part) will fail:'
try:
    eeg_map = mne.sensitivity_map(fwd, ch_type='eeg', mode='fixed')
except ValueError, e:
    print '\nValueError:', e