[FieldTrip] ?==?utf-8?q? redefining data set

Stephen Whitmarsh stephen.whitmarsh at gmail.com
Tue Jan 15 17:40:46 CET 2019


Hi Martin,

No indeed, your conditions/RT/events should indeed be (re)coded as single
values. This also makes selecting trials etc. much easier with logical
expressions, e.g. you can then simply do cfg.trials = (data.trialinfo(:,1)
== 3 && data.trialinfo(:,2) > 0.5, where the first column e.g. is your
condition, and the second RT, to just give an example.

Cheers,
Stephen

On Tue, 15 Jan 2019 at 17:35, Martin Rosenfelder <
martin.rosenfelder at uni-ulm.de> wrote:

> Dear Stephen,
>
> Thank you very much for the hint on ft_selectdata.
>
> I tried to build the structure for .trialinfo as you described it in your
> reply. I did this creating a structure array with the eventvalues as
> elements.
> Then I concatenated the .trl matrix and the event value matrix. This
> however failed, since .trl is a double array and the event value matrix is
> a struct array.
> I double-checked that the nr. of rows in the two matrices match each other
> (120 elements).
>
> Is there a way to add the event value matrix (120x1 struct) to the .trl
> matrix (120x3 double)?
>
> Best,
> Martin
>
>
> --
> M.Sc.-Psych. Martin Rosenfelder
> Wissenschaftlicher Mitarbeiter
> Klinische und Biologische Psychologie
> Universit├Ąt Ulm
> Raum 47.2.259
> +49 731-50 26592
> martin.rosenfelder at uni-ulm.de
>
> Am Montag, 14. Januar 2019 19:01 CET, Stephen Whitmarsh <
> stephen.whitmarsh at gmail.com> schrieb:
>
> > Dear Martin,
> >
> > Use ft_selectdata instead of ft_redefinetrial.
> >
> >
> "cfg.previous.previous.previous{1,1}.previous.previous.trialdef.eventvalue(1,2)"
> > is scary! And I can imagine very inconvenient, as it will move deeper and
> > deeper in to infinite previousnessness.
> > Instead, one of the best 'easter eggs' (i.e. not so well-documented
> > functionality) of FieldTrip is to create extra columns of info in your
> .trl
> > when using preprocessing to epoch your data. These extra columns will
> then
> > enter into a field .trialinfo of your data. Most if not all functions,
> such
> > as ft_selectdata (selecting trials) will update that field. So I advice
> you
> > to put your eventvalue (as well as RT, response, etc. etc.) as columns in
> > your trialinfo (so same nr. of rows as your nr. of trials). In this way,
> > they will travel with your data, and stay in the same structure and on
> the
> > same level whatever happens.
> >
> > Cheers,
> > Stephen
> >
> >
> > On Mon, 14 Jan 2019 at 18:47, Martin Rosenfelder <
> > martin.rosenfelder at uni-ulm.de> wrote:
> >
> > > Dear Fieldtrip community,
> > >
> > > I have preprocessed a single dataset with two different conditions
> > > ('Swim', 'Rest'). The conditions are stored in the 'eventvalue' field
> of
> > > the cfg as 1x2 cell array. The event values are stored in the
> > >
> 'data_ref.cfg.previous.previous.previous{1,1}.previous.previous.trialdef.eventvalue'
> > > field of the data set.
> > > Having done the preprocessing I now would like to do
> ft_timelockanalysis
> > > and ft_freqanalysis on the data. Afterwards I statistically compare
> the two
> > > conditions using ft_timelockstatistics and ft_freqstatistics.
> > > How can I split the data set according to the event values ('Swim',
> > > 'Rest')? I need the event values to split the data set into the two
> trial
> > > classes in the ft_timelockanalysis / ft_freqanalysis and to compare
> these
> > > two conditions.
> > >
> > > I tried ft_redefinetrial, but do not know how to define the cfg.trials
> > > field of this function.
> > >
> > >          % trial redefinition
> > >
> > >         % containing only trials in the 'swim' condition
> > >          cfg.trials = (1,
> > >
> data_ref.cfg.previous.previous.previous{1,1}.previous.previous.trialdef.eventvalue(1,1));
> > >          swim = ft_redefinetrial(cfg,data_ref);
> > >
> > >         % containing only trials in the 'resting' condition
> > >          cfg.trials = (1,
> > >
> data_ref.cfg.previous.previous.previous{1,1}.previous.previous.trialdef.eventvalue(1,2));
> > >          rest = ft_redefinetrial(cfg,data_ref);
> > >
> > > I hope the description was quite clear. In case, I can provide some
> more
> > > lines of code to clarify the issue.
> > >
> > > Thank you very much in advance for your advice!
> > >
> > > Best regards,
> > > Martin
> > >
> > > --
> > > M.Sc.-Psych. Martin Rosenfelder
> > > Wissenschaftlicher Mitarbeiter
> > > Klinische und Biologische Psychologie
> > > Universit├Ąt Ulm
> > > Raum 47.2.259
> > > +49 731-50 26592
> > > martin.rosenfelder at uni-ulm.de
> > >
> > >
> > > _______________________________________________
> > > fieldtrip mailing list
> > > https://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> > > https://doi.org/10.1371/journal.pcbi.1002202
> > >
>
>
>
>
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