[FieldTrip] No mtmconvol on data with partial nans

[Stephen Whitmarsh]

Hi Jim!

Thanks. Ofcourse, that's the problem. However, method = 'wavelet', and
method = 'tfr' give the same problem. I'm afraid I'll end up writing my own
code, cutting up data and using an FFT :-/

Thank again,

Stephen

On 25 May 2016 at 15:34, Herring, J.D. (Jim) <j.herring at donders.ru.nl>
wrote:

> Hi Stephen,
>
> As far as I know this is expected as mtmconvol is actually multiplying the
> fft of the entire trial with the fft of your tapered windows. Perhaps it
> will work of you use one of the methods that actually uses convolution in
> the time domain rather than multiplication in the frequency domain.
>
> Best,
>
> Jim
>
>
>
> > On 25 May 2016, at 15:29, Stephen Whitmarsh <stephen.whitmarsh at gmail.com>
> wrote:
> >
> > Hi FieldTrippers,
> >
> > I hope someone can help me with the following.
> >
> > My problem is that I like to maintain my original rpt/chan/time/freq
> size after artefact rejection based on the time series data, i.e. to have
> the same dimensions of the TFR as if I did not reject data. This is for
> reasons of bookkeeping between different types of channels that are
> processed differently throughout my analysis.
> >
> > What works well is to detect artifacts in the data and replace those
> intervals with nans using ft_rejectartifact, with cfg.reject = 'nan'. So
> far this is perfect for the approach I had in mind.
> >
> > However, ft_freqanalysis (method = 'mtmconvol') outputs whole trials as
> nans whenever a (small) period has nans. What I would need - and in fact
> expect - is that only those time/frequency windows that have (one or more)
> nan values will output nan, while the rest should merrily go round giving
> power values. After all, the data is there.
> >
> > It is unclear to me whether this is expected behaviour or not. I might
> be making a mistake but some simple tests replicated this behaviour.
> >
> > Is there a solution that still allows me to end up with a
> rpt/chan/time/freq representation of the same size as when i would not have
> rejected artifacts?
> >
> > The only other FieldTrip-like option I can think of is to use
> ft_rejectartifact with method = 'partial', do the freqanalysis on trial
> parts, and somehow glue the separate trial parts together again afterwards.
> But I really don't want to go in that direction.
> >
> > In the end I'm afraid I don't understand the core of
> ft_specest_mtmconvol enough to see where I could hack it. I hope some of
> you might be able to help.
> >
> > Best wishes,
> > Stephen
> >
> >
> > _______________________________________________
> > fieldtrip mailing list
> > fieldtrip at donders.ru.nl
> > http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20160525/6964c57b/attachment-0001.html>