[FieldTrip] missing sample after using ft_componentanalysis with method bsscca

Drijvers, L. (Linda) l.drijvers at donders.ru.nl
Wed May 6 09:58:33 CEST 2020

Dear all,

I'm analysing an EEG dataset using MATLAB 2016a + FieldTrip version 20200409.

I am trying to use ft_componentanalysis with cfg.method = 'bsscca' (see code):

cfg             = [];
cfg.channel     = 1:length(data_Aclean.label)-2;
cfg.method      = 'bsscca';
cfg.cellmode    = 'yes';
comp_output      = ft_componentanalysis(cfg, data_Aclean);

When I then try to use ft_databrowser with the following code:

    cfg = [];
    cfg.channel = [1:10];
    cfg.viewmode = 'component';
    cfg.layout = 'customlayout.mat';
    ft_databrowser(cfg, comp_output);

I get the following error:

Index exceeds matrix dimensions.

Error in ft_fetch_data (line 199)
    dat(:,ok) = data.trial{utrl}(chanindx,smps);

Error in ft_databrowser>redraw_cb (line 1630)
  dat = ft_fetch_data(opt.orgdata, 'header', opt.hdr, 'begsample', begsample, 'endsample', endsample, 'chanindx', chanindx,
  'allowoverlap', istrue(cfg.allowoverlap));

Error in ft_databrowser (line 729)

A closer look at the data shows that while fsample for my data is 500, smps is 499 after running ft_componentanalysis with method bsscca. However, I can solve the error above by running ft_databrowser with comp_output = rmfield(comp_output, 'sampleinfo').

My question is: what causes this discrepancy in smps (why does this one sample go missing)? Any help would be appreciated.

Best wishes,
Linda Drijvers

dr. Linda Drijvers | postdoctoral researcher | https://cosilab.org
Donders Institute for Brain, Cognition and Behaviour, Radboud University, NL
www.ru.nl/english/people/drijvers-l/ | https://www.mpi.nl/people/drijvers-linda

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