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

Silfverberg Sebastian sebastian.silfverberg at aalto.fi
Thu Jul 31 06:37:39 EDT 2014
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This next snippet is from the offline version I've been testing:


for ii, data in enumerate(epochs.get_data()):

    # make the 2D epoch to 3D

    data = data[newaxis, ...]

    ep = EpochsArray(data=data, info=raw.info, events=events, tmin=0,event_id=event_id, reject=reject)

    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)

and the error comes in the last command.

What is the best way to iterate over rt_epochs? rt.epochs.next()? I'm now doing just

for ii, data in enumerate(rt_epochs):


Sebastian

________________________________
Lähettäjä: mne_analysis-bounces at nmr.mgh.harvard.edu [mne_analysis-bounces at nmr.mgh.harvard.edu] käyttäjän Mainak Jas [mainakjas at gmail.com] puolesta
Lähetetty: 31. heinäkuuta 2014 12:22
Vastaanottaja: Discussion and support forum for the users of MNE Software
Aihe: Re: [Mne_analysis] Strange errors with calculating source estimates in a frequency band

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<mailto: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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