[FieldTrip] Removing channels from processed data

Matt Mollison matt.mollison at gmail.com
Fri Apr 6 20:05:56 CEST 2012


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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