def test_resolution_matrix_lcmv():
"""Test computation of resolution matrix for LCMV beamformers."""
# read forward solution
forward = mne.read_forward_solution(fname_fwd)
# remove bad channels
forward = mne.pick_channels_forward(forward, exclude='bads')
# forward operator with fixed source orientations
forward_fxd = mne.convert_forward_solution(forward, surf_ori=True,
force_fixed=True)
# evoked info
info = mne.io.read_info(fname_evoked)
mne.pick_info(info, mne.pick_types(info), copy=False) # good MEG channels
# noise covariance matrix
# ad-hoc to avoid discrepancies due to regularisation of real noise
# covariance matrix
noise_cov = mne.make_ad_hoc_cov(info)
# Resolution matrix for Beamformer
data_cov = noise_cov.copy() # to test a property of LCMV
# compute beamformer filters
# reg=0. to make sure noise_cov and data_cov are as similar as possible
filters = make_lcmv(info, forward_fxd, data_cov, reg=0.,
noise_cov=noise_cov,
pick_ori=None, rank=None,
weight_norm=None,
reduce_rank=False,
verbose=False)
# Compute resolution matrix for beamformer
resmat_lcmv = make_lcmv_resolution_matrix(filters, forward_fxd, info)
# for noise_cov==data_cov and whitening, the filter weights should be the
# transpose of leadfield
# create filters with transposed whitened leadfield as weights
forward_fxd = mne.pick_channels_forward(forward_fxd, info['ch_names'])
filters_lfd = deepcopy(filters)
filters_lfd['weights'][:] = forward_fxd['sol']['data'].T
# compute resolution matrix for filters with transposed leadfield
resmat_fwd = make_lcmv_resolution_matrix(filters_lfd, forward_fxd, info)
# pairwise correlation for rows (CTFs) of resolution matrices for whitened
# LCMV beamformer and transposed leadfield should be 1
# Some rows are off by about 0.1 - not yet clear why
corr = []
for (f, l) in zip(resmat_fwd, resmat_lcmv):
corr.append(np.corrcoef(f, l)[0, 1])
# all row correlations should at least be above ~0.8
assert_allclose(corr, 1., atol=0.2)
# Maximum row correlation should at least be close to 1
assert_allclose(np.max(corr), 1., atol=0.01)
filters_post = make_lcmv(info,
forward,
cov_post,
reg=0.05,
noise_cov=noise_cov,
pick_ori=None,
rank=None,
weight_norm=None,
reduce_rank=False,
verbose=False)
##############################################################################
# Compute resolution matrices for the two LCMV beamformers
# --------------------------------------------------------
rm_pre = make_lcmv_resolution_matrix(filters_pre, forward, info)
rm_post = make_lcmv_resolution_matrix(filters_post, forward, info)
# compute cross-talk functions (CTFs) for one target vertex
sources = [3000]
stc_pre = get_cross_talk(rm_pre, forward['src'], sources, norm=True)
stc_post = get_cross_talk(rm_post, forward['src'], sources, norm=True)
##############################################################################
# Visualise
# ---------
vertno_lh = forward['src'][0]['vertno'] # vertex of selected source
verttrue = [vertno_lh[sources[0]]] # pick one vertex
bf_filts = make_lcmv(info,
fwd_use,
data_cov_use,
reg=0.05,
noise_cov=noise_cov_lcmv,
pick_ori=None,
rank='info',
weight_norm='unit-noise-gain',
reduce_rank=False,
verbose=False)
# bf_filts = _get_matrix_from_lcmv_identity(fwd_use, info, noise_cov_use, data_cov_use)
# resmat = bf_filts.dot(fwd_use['sol']['data'])
resmat = make_lcmv_resolution_matrix(
bf_filts, fwd_use, info)
# resmat = make_resolution_matrix_lcmv(fwd_use, lcmv_filters)
cov_lat_str = C._lat_str(cov_dat[0], cov_dat[1])
meth_str = '%s_%s' % ('LCMV', cov_lat_str)
functions_and_metrics(resmat, fwd_use['src'], functions,
metrics, subject, meth_str)
# Save some PSFs
filetext = meth_str + '_PSFs'
fname = fname_stc = C.fname_STC(C, C.resolution_subdir,
subject, filetext)
