<div dir="ltr">Dear Martin,<div><br></div><div>Use ft_selectdata instead of ft_redefinetrial.</div><div><br></div><div>"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.</div><div>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.</div><div><br></div><div>Cheers,</div><div>Stephen</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr">On Mon, 14 Jan 2019 at 18:47, Martin Rosenfelder <<a href="mailto:martin.rosenfelder@uni-ulm.de">martin.rosenfelder@uni-ulm.de</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Dear Fieldtrip community,<br>
<br>
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. <br>
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.<br>
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.<br>
<br>
I tried ft_redefinetrial, but do not know how to define the cfg.trials field of this function. <br>
<br>
% trial redefinition<br>
<br>
% containing only trials in the 'swim' condition<br>
cfg.trials = (1, data_ref.cfg.previous.previous.previous{1,1}.previous.previous.trialdef.eventvalue(1,1));<br>
swim = ft_redefinetrial(cfg,data_ref);<br>
<br>
% containing only trials in the 'resting' condition<br>
cfg.trials = (1, data_ref.cfg.previous.previous.previous{1,1}.previous.previous.trialdef.eventvalue(1,2));<br>
rest = ft_redefinetrial(cfg,data_ref);<br>
<br>
I hope the description was quite clear. In case, I can provide some more lines of code to clarify the issue.<br>
<br>
Thank you very much in advance for your advice!<br>
<br>
Best regards,<br>
Martin<br>
<br>
-- <br>
M.Sc.-Psych. Martin Rosenfelder<br>
Wissenschaftlicher Mitarbeiter<br>
Klinische und Biologische Psychologie<br>
Universität Ulm<br>
Raum 47.2.259<br>
+49 731-50 26592<br>
<a href="mailto:martin.rosenfelder@uni-ulm.de" target="_blank">martin.rosenfelder@uni-ulm.de</a><br>
<br>
<br>
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</blockquote></div>