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Error message for simulate evoked. #3372

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Merged
agramfort merged 3 commits into from
Jul 4, 2016
Merged

Error message for simulate evoked. #3372

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26f00d6
Error message for simulate evoked.
jaeilepp Jul 1, 2016
b13be1d
Check channel names.
jaeilepp Jul 4, 2016
0981a0a
Added test.
jaeilepp Jul 4, 2016
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10 changes: 8 additions & 2 deletions mne/simulation/evoked.py
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Original file line number Diff line number Diff line change
Expand Up @@ -69,8 +69,8 @@ def simulate_evoked(fwd, stc, info, cov, snr=3., tmin=None, tmax=None,
evoked = apply_forward(fwd, stc, info)
if snr < np.inf:
noise = simulate_noise_evoked(evoked, cov, iir_filter, random_state)
evoked_noise = add_noise_evoked(evoked, noise, snr,
tmin=tmin, tmax=tmax)
evoked_noise = add_noise_evoked(evoked, noise, snr, tmin=tmin,
tmax=tmax)
else:
evoked_noise = evoked
return evoked_noise
Expand Down Expand Up @@ -111,6 +111,12 @@ def _generate_noise(info, cov, iir_filter, random_state, n_samples, zi=None):
"""Helper to create spatially colored and temporally IIR-filtered noise"""
from scipy.signal import lfilter
noise_cov = pick_channels_cov(cov, include=info['ch_names'], exclude=[])
if set(info['ch_names']) != set(noise_cov.ch_names):
raise ValueError('Evoked and covariance channel names are not '
'identical. Cannot generate the noise matrix. '
'Channels missing in covariance %s.' %
np.setdiff1d(info['ch_names'], noise_cov.ch_names))

rng = check_random_state(random_state)
c = np.diag(noise_cov.data) if noise_cov['diag'] else noise_cov.data
mu_channels = np.zeros(len(c))
Expand Down
9 changes: 7 additions & 2 deletions mne/simulation/tests/test_evoked.py
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Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,7 @@ def test_simulate_evoked():
stc_bad = stc.copy()
mv = np.max(fwd['src'][0]['vertno'][fwd['src'][0]['inuse']])
stc_bad.vertices[0][0] = mv + 1

assert_raises(RuntimeError, simulate_evoked, fwd, stc_bad,
evoked_template.info, cov, snr, tmin=0.0, tmax=0.2)
evoked_1 = simulate_evoked(fwd, stc, evoked_template.info, cov, np.inf,
Expand All @@ -82,9 +83,13 @@ def test_simulate_evoked():
iir_filter=None)
noise = evoked_noise.data - evoked_clean.data

empirical_snr = 10 * np.log10(np.mean((evoked_clean.data**2).ravel()) /
np.mean((noise**2).ravel()))
empirical_snr = 10 * np.log10(np.mean((evoked_clean.data ** 2).ravel()) /
np.mean((noise ** 2).ravel()))

assert_almost_equal(snr, empirical_snr, decimal=5)

cov['names'] = cov.ch_names[:-2] # Error channels are different.
assert_raises(ValueError, simulate_evoked, fwd, stc, evoked_template.info,
cov, snr=3., tmin=None, tmax=None, iir_filter=None)

run_tests_if_main()