[FieldTrip] Problems with ft_appendata - merging datasets

["Jörn M. Horschig"]

Hi Sascha,

I just got reminded (thx Yuka-san) that you could use a ctf command to 
combine CTF datasets (of course, only if you got data from a CTF system):

newCombinedDs [options] <dataset> <dataset>

This program takes two or more datasets that have exactly the same 
collection
parameters and combines them to make one dataset.


Best,
Jörn

On 7/9/2012 3:56 PM, styll at med.ovgu.de wrote:
> Hello,
>
> I probably have a problem with the use of ft_appendata. I want to merge 4
> MEG datasets (i.e. 4 runs, all the same number of channels, sampling rate,
> etc.) of the same subject after I defined my trials of interest and
> preprocessed the 4 datasets individually. If I use ft_databrowser for a
> look into every single dataset, all trials (10 in each run/dataset) seems
> to be OK with the correct sequence: defined prestim time range, trigger
> and poststim time range. If I check the merged dataset I can go through
> all of the 40 trials, but there is no sequence like: prestim time range,
> trigger and poststim-time.  Here is my pipeline for the first steps:
>
> %%%% run1
> cfg.dataset='…\train01_64\run1\c,rfDC';
> cfg.trialdef.prestim=1;      %%% in sec
> cfg.trialdef.poststim=5;     %%% in sec
> cfg.trialfun = 'traildef_train01_all_pics_run1';
> data_run1 = ft_definetrial(cfg)
>
> cfg.channel    = {'MEG'};
> cfg.dftfilter='yes';
> prepro_run_1 = ft_preprocessing(cfg)
>
> %%%% run2
> cfg.dataset='…\train01_64\run2\c,rfDC';
> cfg.trialdef.prestim=1;      %%% in sec
> cfg.trialdef.poststim=5;     %%% in sec
> cfg.trialfun = 'traildef_train01_all_pics_run2';
> data_run1 = ft_definetrial(cfg)
>
> cfg.channel    = {'MEG'};
> cfg.dftfilter='yes';
> prepro_run_2 = ft_preprocessing(cfg)
>
> the same for run3 and run4
>
> %%%% merging the data
>
> cfg=[];
> merged_data = ft_appenddata(cfg, prepro_run_1, prepro_run_2, prepro_run_3,
> prepro_run_4)
>
> Do I miss something or is there in error in my pipeline or in my strategy…
>
> Best regards
>
> Sascha
>
>
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-- 
Jörn M. Horschig
PhD Student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen
Neuronal Oscillations Group

P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands

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E-Mail: jm.horschig at donders.ru.nl
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