[FieldTrip] Removing channels from processed data

[Matt Mollison]

Thanks, JM. That seems to solve it. Bug submitted:
http://bugzilla.fcdonders.nl/show_bug.cgi?id=1409

Matt

--
Univ. of Colorado at Boulder
Dept. of Psychology and Neuroscience
matthew.mollison at colorado.edu
http://psych.colorado.edu/~mollison/

On Fri, Apr 6, 2012 at 12:50 PM, jan-mathijs schoffelen <
jan.schoffelen at donders.ru.nl> wrote:

> Dear Matt,
>
> It seems you have stumbled on some code that is still a bit under
> development, and apparently not really stable.
>
> ft_selectdata should be able to do the trick for you, but I suspect a bug
> in ft_selectdata_new, so I'd try ft_selectdata_old instead.
>
> To achieve this, you need to do something like this:
>
> selchan = ft_channelselection({'all' '-E59'}, data.label);
> data = ft_selectdata(data, 'channel', selchan); % notice the function's
> input now with key-value pairs, rather than a cfg.
>
> We hope to find some time to improve the ft_selectdata_new soon. For the
> time being, could you file a bug on this issue on our bugzilla website? (
> www.bugzilla.fcdonders.nl)
>
> Cheers,
>
> JM
>
>
> On Apr 6, 2012, at 8:05 PM, Matt Mollison wrote:
>
> Dear FieldTrippers,
>
> I'm using fieldtrip-20120405. I'm trying to remove a "bad" channel from a
> subject's processed data (output of ft_timelockanalysis and
> ft_freqanalysis). I've found the function ft_selectdata (which runs
> ft_selectdata_new), but when I define my cfg to remove the bad channel
> (cfg.channels={'all','-E59'}) and use the function, it also removes the
> dimord field which subsequent ft_* functions need (e.g., ft_multiplotER,
> ft_timelockgrandaverage).
>
> I could manually remove the channel, but I was hoping for a ft_* function
> that would modify the label field automatically. Manually replacing the
> channel with NaNs does not seem to be a solution because when I use
> ft_singleplotER to plot data from a ROI (i.e., multiple channels in a
> region) that includes this now-all-NaNs channel, nothing gets plotted
> (meaning a mean, and not a nanmean, function gets used to average over the
> ROI), so I fear the same thing will happen with other functions (e.g.,
> ft_timelockstatistics). I also know I can use ft_rejectvisual early on in
> my processing, but I don't want to re-process my data (and I'm not
> currently using FT for artifact detection).
>
> So my question is: what's the best FieldTrip function-based way to remove
> a channel?
>
> Thanks,
> Matt
>
> --
> Univ. of Colorado at Boulder
> Dept. of Psychology and Neuroscience
> matthew.mollison at colorado.edu
> http://psych.colorado.edu/~mollison/
>  _______________________________________________
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> fieldtrip at donders.ru.nl
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>
>
>    Jan-Mathijs Schoffelen, MD PhD
>
> Donders Institute for Brain, Cognition and Behaviour,
> Centre for Cognitive Neuroimaging,
> Radboud University Nijmegen, The Netherlands
>
> Max Planck Institute for Psycholinguistics,
> Nijmegen, The Netherlands
>
> J.Schoffelen at donders.ru.nl
> Telephone: +31-24-3614793
>
>
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