[Mne_analysis] Strange errors with calculating source estimates in a frequency band

Mainak Jas mainakjas at gmail.com
Thu Jul 31 05:22:58 EDT 2014
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Hi Sebastian,

It seems to me that you are somehow iterating over the epochs and stc
objects incorrectly. You do not need to use EpochsArray because you can
iterate over the Epochs object directly (same with RtEpochs I think). For
stc, if you have a single epoch, can you check if your iterations are
correct?

A small code snippet / gist that reproduces this issue would be great.

Mainak


On Thu, Jul 31, 2014 at 9:14 AM, Silfverberg Sebastian <
sebastian.silfverberg at aalto.fi> wrote:

>  Hi everyone!
>
> I have been trying to code a program that would enable to plot user
> selectable time windows of averaged source estimates in a certain frequency
> band in real time with FieldTrip Buffer. I'm now trying to simulate that in
> offline mode with looping through the epochs.get_data() and then building
> an Epoch from a single epoch with EpochsArray (because that's the way the
> real time sytem works). I  end up with a couple of odd errors using
> *compute_source_psd_epochs* depending on how long my time window is. If
> my time window is shorter than 10 seconds, my error is this:
>
> /usr/lib/python2.7/dist-packages/IPython/utils/py3compat.pyc in
> execfile(fname, *where)
>     173             else:
>     174                 filename = fname
> --> 175             __builtin__.execfile(filename, *where)
>
> /home/silfves1/mne-python/examples/omatfunktiot/jatk_off.py in <module>()
>     380
>     381
> --> 382         stc = compute_source_psd_epochs(epochs=ep,
> inverse_operator=inverse_operator, lambda2=lambda2, method=method,
> fmin=15.0, fmax=25.0, pick_ori=None, pca=True, bandwidth=bandwidth,
> n_jobs=10, return_generator=False)
>     383
>     384
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/minimum_norm/time_frequency.pyc
> in compute_source_psd_epochs(epochs, inverse_operator, lambda2, method,
> fmin, fmax, pick_ori, label, nave, pca, inv_split, bandwidth, adaptive,
> low_bias, return_generator, n_jobs, verbose, pick_normal)
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/utils.pyc
> in verbose(function, *args, **kwargs)
>     549         return ret
>     550     else:
> --> 551         ret = function(*args, **kwargs)
>     552         return ret
>     553
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/minimum_norm/time_frequency.pyc
> in compute_source_psd_epochs(epochs, inverse_operator, lambda2, method,
> fmin, fmax, pick_ori, label, nave, pca, inv_split, bandwidth, adaptive,
> low_bias, return_generator, n_jobs, verbose, pick_normal)
>     669         # return a list
>
>     670         stcs = list()
> --> 671         for stc in stcs_gen:
>     672             stcs.append(stc)
>     673
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/minimum_norm/time_frequency.pyc
> in _compute_source_psd_epochs(epochs, inverse_operator, lambda2, method,
> fmin, fmax, pick_ori, label, nave, pca, inv_split, bandwidth, adaptive,
> low_bias, n_jobs, verbose)
>     519
>     520     dpss, eigvals = dpss_windows(n_times, half_nbw, n_tapers_max,
> --> 521                                  low_bias=low_bias)
>     522     n_tapers = len(dpss)
>     523
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/time_frequency/multitaper.pyc
> in dpss_windows(N, half_nbw, Kmax, low_bias, interp_from, interp_kind)
>     202         # only calculate the highest Kmax eigenvalues
>
>     203         w = linalg.eigvals_banded(ab, select='i',
> --> 204                                   select_range=(N - Kmax, N - 1))
>     205         w = w[::-1]
>     206
>
> /usr/lib/python2.7/dist-packages/scipy/linalg/decomp.pyc in
> eigvals_banded(a_band, lower, overwrite_a_band, select, select_range)
>     698     return eig_banded(a_band, lower=lower, eigvals_only=1,
>     699                       overwrite_a_band=overwrite_a_band,
> select=select,
> --> 700                       select_range=select_range)
>     701
>     702 _double_precision = ['i','l','d']
>
> /usr/lib/python2.7/dist-packages/scipy/linalg/decomp.pyc in
> eig_banded(a_band, lower, eigvals_only, overwrite_a_band, select,
> select_range, max_ev)
>     490             vl, vu, il, iu = 0.0, 0.0, min(select_range),
> max(select_range)
>     491             if min(il, iu) < 0 or max(il, iu) >= a1.shape[1]:
> --> 492                 raise ValueError('select_range out of bounds')
>     493             max_ev = iu - il + 1
>     494         else:  # 1, 'v', 'value'
>
> ValueError: select_range out of bounds
>
>
> However, if my time window is 10 seconds, here's the error then:
>
> error                                     Traceback (most recent call last)
> /usr/lib/python2.7/dist-packages/IPython/utils/py3compat.pyc in
> execfile(fname, *where)
>     173             else:
>     174                 filename = fname
> --> 175             __builtin__.execfile(filename, *where)
>
> /home/silfves1/mne-python/examples/omatfunktiot/jatk_off.py in <module>()
>     380
>     381
> --> 382         stc = compute_source_psd_epochs(epochs=ep,
> inverse_operator=inverse_operator, lambda2=lambda2, method=method,
> fmin=15.0, fmax=25.0, pick_ori=None, pca=True, bandwidth=bandwidth,
> n_jobs=10, return_generator=False)
>     383
>     384
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/minimum_norm/time_frequency.pyc
> in compute_source_psd_epochs(epochs, inverse_operator, lambda2, method,
> fmin, fmax, pick_ori, label, nave, pca, inv_split, bandwidth, adaptive,
> low_bias, return_generator, n_jobs, verbose, pick_normal)
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/utils.pyc
> in verbose(function, *args, **kwargs)
>     549         return ret
>     550     else:
> --> 551         ret = function(*args, **kwargs)
>     552         return ret
>     553
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/minimum_norm/time_frequency.pyc
> in compute_source_psd_epochs(epochs, inverse_operator, lambda2, method,
> fmin, fmax, pick_ori, label, nave, pca, inv_split, bandwidth, adaptive,
> low_bias, return_generator, n_jobs, verbose, pick_normal)
>     669         # return a list
>
>     670         stcs = list()
> --> 671         for stc in stcs_gen:
>     672             stcs.append(stc)
>     673
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/minimum_norm/time_frequency.pyc
> in _compute_source_psd_epochs(epochs, inverse_operator, lambda2, method,
> fmin, fmax, pick_ori, label, nave, pca, inv_split, bandwidth, adaptive,
> low_bias, n_jobs, verbose)
>     545
>     546         # compute tapered spectra in sensor space
>
> --> 547         x_mt, freqs = _mt_spectra(data, dpss, sfreq)
>     548
>     549         if k == 0:
>
> /home/silfves1/.local/lib/python2.7/site-packages/mne-0.8.git-py2.7.egg/mne/time_frequency/multitaper.pyc
> in _mt_spectra(x, dpss, sfreq, n_fft)
>     439     # remove mean (do not use in-place subtraction as it may
> modify input x)
>
>     440     x = x - np.mean(x, axis=-1)[:, np.newaxis]
> --> 441     x_mt = fftpack.fft(x[:, np.newaxis, :] * dpss, n=n_fft)
>     442
>     443     # only keep positive frequencies
>
>
> /usr/lib/python2.7/dist-packages/scipy/fftpack/basic.pyc in fft(x, n,
> axis, overwrite_x)
>     213
>     214     if axis == -1 or axis == len(tmp.shape) - 1:
> --> 215         return work_function(tmp,n,1,0,overwrite_x)
>     216
>     217     tmp = swapaxes(tmp, axis, -1)
>
> error: failed in converting 1st argument `x' of _fftpack.zrfft to
> C/Fortran array
>
> I don't know, why these error come up. Do some of you have any ideas to
> help? Thank you so much!
>
> Best regards
>
> Sebastian
>
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