[FieldTrip] Fwd: ft_freqdescriptives and cfg.trial

Jasper Poort poortjasper at gmail.com
Thu Aug 23 12:34:48 CEST 2012


Dear Fieldtrip users,


I have a problem with using a trial selection to do freqdescriptives on a
subset of trials:


I first do ft_freqanalysis with these setttings, which results in freq:


cfg.output      = 'fourier';

cfg.method      = 'mtmconvol';

cfg.keeptrials  = 'yes';



freq =



            label: {1x64 cell}

           dimord: 'rpttap_chan_freq_time'

             freq: [30 35 40 45 50 55 60 65 70 75 80 85 90 95 100]

             time: [1x36 double]

    fourierspctrm: [4-D double]

        cumtapcnt: [857x15 double]

              cfg: [1x1 struct]



size(freq.fourierspctrm)

ans =

        2571          64          15          36



then i try running ft_freqdescriptives with these settings

tmpcfg = [];

        tmpcfg.jackknife = 'no';

        tmpcfg.keeptrials = 'no';

        tmpcfg.channel    = freq.label([chnix1,chnix2])

        tmpcfg.trials     = [1:10:100];

        tmp = ft_freqdescriptives(tmpcfg,freq);



Error using  +

Array dimensions must match for binary array op.



Error in ft_checkdata>fixcsd (line 740)

      powspctrm = powspctrm +
abs(data.fourierspctrm(p:ntap:end,:,:,:,:)).^2;



Error in ft_checkdata (line 646)

    data = fixcsd(data, cmbrepresentation, channelcmb);



Error in ft_freqdescriptives (line 131)

freq = ft_checkdata(freq, 'cmbrepresentation', 'sparsewithpow',
'channelcmb', {});


the error seems to happen because the cumtapcnt seems to be updated after
calling ft_selectdata in ft_freqdescriptives such that it no longer
contains a row for every trial which causes nrpt = size(data.cumtapcnt,1);
in ft_checkdata to return 1 instead of the number of trials.


            label: {2x1 cell}
           dimord: 'rpttap_chan_freq_time'
             freq: [30 35 40 45 50 55 60 65 70 75 80 85 90 95 100]
             time: [1x36 double]
    fourierspctrm: [4-D double]
        cumtapcnt: [3 3 3 3 3 3 3 3 3 3]
              cfg: [1x1 struct]


I was wondering if this is a bug or am I somehow specifying the input
incorrectly?


Thanks! best, Jasper
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