[FieldTrip] using ft_definetrial

[Nikola Valchev]

Hi Pelt, 

Thanks a lot for the help. Somehow I forgot that I can specify my own trl
matrix manually... 

(I’m sorry for the long email but I try to be as clear as possible so that
it takes less time.)

 

 

 

However, there is still something wrong which I don’t understand. What I do
is to use ft_read_event to read all the triggers and events from the cnt
file. What I get is the event structure with the fileds 

type

sample

value

offset

duration

 

I presume that these are read from the trg file (i.e. s14_CI_1.trg which is
associated with the s14_CI_1.cnt). 

 

Inside that file I have: 

  0.000000         0 0

20.568359   2490491 1

23.787109   2879419 9

28.597656   3460687 1

33.056641   3999475 3

45.923828   5554243 1

...

 

 

First column should be the times, second the segment and the third the
trigger. I use your commands to create the matrix: 

u1=find(ismember(triggers(:,2),[1])); 

 

trl= [triggers(u1,2)-.2*1024 triggers(u1,2)+6*1024
repmat(-.2*1024,numel(u1),1)];

 

And at the end I get a matrix:  

 

  1.0e+003 *

 

   -0.2038    6.1450   -0.2048

   -0.2038    6.1450   -0.2048

   -0.2038    6.1450   -0.2048

   -0.2038    6.1450   -0.2048

...

 

Then I attempt to preprocess again: 

cfg=[];

cfg.dataset='C:\eeg_anita\data\S14\s14_CI_1.cnt';

cfg.headerfile='C:\eeg_anita\data\S14\s14_CI_1.cnt';

cfg.trl=trl;

cfg_test=ft_preprocessing(cfg);

 

 

and I get an error: 

??? Error using ==> ft_read_data at 206

cannot read data before the begin of the file

 

Error in ==> ft_preprocessing at 563

      dat = ft_read_data(cfg.datafile, 'header', hdr, 'begsample',
begsample, 'endsample', endsample, 'chanindx', rawindx,

      'checkboundary', strcmp(cfg.continuous, 'no'), 'dataformat',
cfg.dataformat)

 

 

Nikola

 

 

 

From: fieldtrip-bounces at science.ru.nl
[mailto:fieldtrip-bounces at science.ru.nl] On Behalf Of Pelt, S. van (Stan)
Sent: 14 July 2015 09:25
To: FieldTrip discussion list
Subject: Re: [FieldTrip] using ft_definetrial

 

Hi Nikola,

 

You might also try a workaround:

     

% read the events from the data

event = ft_read_event('C:\eeg_anita\data\S14\s14_CI_1.cnt');

    

% search for "trigger" events

triggers=[];

for i=1:size(event,1) 

     a=find(strcmp(event(i).type,'trigger')==1); 

     if a>0

         triggers=[triggers; event(i).value event(i).sample]; 

     end 

end

 

% make cfg.trl: I think this is where things go wrong in your script. You
could check what’s in triggers(:,1). Otherwise, what’s below should work:

u1=find(ismember(triggers(:,1),[1 3 6 9])); % select your eventvalue(s) of
interest

 

trl= [triggers(u1,2)-.2*fs triggers(u1,2)+6*fs repmat(-.2*fs,numel(u1),1)];
% 0.2 prestim, 6s post-stim, with fs being your sampling frequency

 

% next, do preprocessing, with cfg.trl=trl;

 

 

From: fieldtrip-bounces at science.ru.nl
[mailto:fieldtrip-bounces at science.ru.nl] On Behalf Of Jörn M. Horschig
Sent: dinsdag 14 juli 2015 8:38
To: 'FieldTrip discussion list'
Subject: Re: [FieldTrip] using ft_definetrial

 

Hi Nikola,

 

seems to be a nasty problem. I’d start with using event =
ft_read_events(cfg.dataset) and then check up the event-structure on how
they are defined there. ft_trialfun_general is literally checking that
event-structure, so defining them like they are specified in there might
help. 

 

Best,

Jörn

 

--

 

Jörn M. Horschig, PhD, Software Engineer

 <http://www.artinis.com/> Artinis Medical Systems  |  +31 481 350 980 

 

From: fieldtrip-bounces at science.ru.nl
[mailto:fieldtrip-bounces at science.ru.nl] On Behalf Of Nikola Valchev
Sent: Monday, July 13, 2015 9:51 PM
To: 'FieldTrip discussion list'
Subject: Re: [FieldTrip] using ft_definetrial

 

Nope. That’s not it. No matter if I declare it as a double or string when I
call the eventtype ‘trigger’ instead of ‘?’ they are not read. 

 

Nikola

 

 

 

From:  <mailto:fieldtrip-bounces at science.ru.nl>
fieldtrip-bounces at science.ru.nl [ <mailto:fieldtrip-bounces at science.ru.nl>
mailto:fieldtrip-bounces at science.ru.nl] On Behalf Of Pelt, S. van (Stan)
Sent: 13 July 2015 19:30
To: FieldTrip discussion list
Subject: Re: [FieldTrip] using ft_definetrial

 

What about

 

cfg.trialdef.eventvalue     = 1;

 

Op 13 jul. 2015, om 18:36 heeft Eelke Spaak <
<mailto:eelke.spaak at donders.ru.nl> eelke.spaak at donders.ru.nl> het volgende
geschreven:

 

cfg.trialdef.eventvalue     = {'1'};

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20150714/9b2375bd/attachment-0002.html>