[FieldTrip] Can the warning "Warning: could not determine dimord of "comp" in:" influence the results?

[Helena Pereira]

Dear Eelk,

Yes, 'ica_cleaned' is produced directly from ft_componentanalysis:

cfg = [];
cfg.dataset=subject;
cfg.trialfun = 'ft_trialfun_general'; % this is the default
cfg.trialdef.eventtype  = 'Stimulus';
cfg.trialdef.eventvalue ={Stimulus}';
cfg.trialdef.prestim    = 2; %latency in seconds
cfg.trialdef.poststim   = 2; %latency in seconds
cfg=ft_definetrial(cfg);

cfg.channel = [1:69]; %discard channels not used
cfg.preproc.reref = 'yes';
cfg.preproc.refchannel = {'M1' 'M2'}; %avg mastoids
cfg.continuous = 'yes';
cfg.preproc.detrend = 'no';
%Baseline correction
%cfg.preproc.demean = 'yes';
cfg.prepoc.baselinewindow  = [-0.2 0];
%Filtering
cfg.preproc.lpfilter = 'yes';
cfg.preproc.hpfilter = 'yes';
cfg.preproc.lpfreq = 100;
cfg.preproc.hpfreq = 1;
data=ft_preprocessing(cfg);

cfg = [];
cfg.method = 'runica';
cfg.demean = 'yes';
ica_cleaned = ft_componentanalysis(cfg,data);

% %Save ICA data
% outfile=strcat(save_dir,'/',infile,'_', sti,'.mat')
% save(outfile, 'ica_cleaned', '-v7.3')

cfg = [];
cfg.component = 1:20;

cfg.layout = 'biosemi64.lay';
cfg.comment   = 'no';
figure();
ft_topoplotIC(cfg,ica_cleaned)

The data is in the BrainVision Format ( .vhdr, .vmrk and .seg), obtained as
suggested by Fieldtrip website:
http://www.fieldtriptoolbox.org/getting_started/brainvision/

Can I ignore the Warning?

Best,
Helena Pereira

Eelke Spaak <e.spaak at donders.ru.nl> escreveu no dia terça, 9/06/2020 à(s)
08:15:

> Dear Helena,
>
> In general, you can probably safely ignore the warning. It just means
> that FieldTrip is unsure of the dimensionality of the 'comp' field,
> because there is no 'compdimord' and also the dimensionality does not
> match the data in any straightforward way.
>
> However, the structure of your componentanalysis output is somewhat
> strange. From .topo and .unmixing, it appears there is only one
> component. However, .label has 69 elements, and there is no .topolabel
> (which usually is there). Is the output you posted directly produced
> by ft_componentanalysis (i.e. it is the 'ica_cleaned' variable
> immediately after the step you showed)?
>
> Best,
> Eelke
>
> On Mon, 8 Jun 2020 at 21:42, Helena Pereira
> <hri.pereira at campus.fct.unl.pt> wrote:
> >
> > Dear FieldTrip users,
> >
> > I'm running the ft_componentanalysis function after applying ICA to my
> data. Although I'm not getting any error, the following warning came out:
> >
> > Warning: could not determine dimord of "comp" in:
> >
> >              label: {69×1 cell}
> >                cfg: [1×1 struct]
> >               topo: [69×1 double]
> >         topodimord: 'chan_comp'
> >               comp: 7
> >           unmixing: [1×69 double]
> >     unmixingdimord: 'chan_topochan'
> >
> > Can this influence the way the components are displayed and consequently
> my results? Is this associated with the layout that I used or with the
> "demean" option?
> >
> > My code is as follows:
> > cfg = [];
> > %cfg.channel = 1:64;
> > cfg.method = 'runica';
> > cfg.demean = 'yes';
> > ica_cleaned = ft_componentanalysis(cfg, data);
> >
> > cfg = [];
> > cfg.component = 1:20;
> > cfg.layout = 'biosemi64.lay';
> > cfg.comment   = 'no';
> > ft_topoplotIC(cfg, ica_cleaned )
> >
> > Thanks in advance,
> > Keep safe,
> > Helena Pereira
> >
> >
> >
> >
> >
> >
> > _______________________________________________
> > fieldtrip mailing list
> > https://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> > https://doi.org/10.1371/journal.pcbi.1002202
>
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> https://doi.org/10.1371/journal.pcbi.1002202
>
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