[Eeglablist] Automated way of placing events

[Arnaud Delorme]

Dear Marco,

yes, I thought you had continuous data. It is not conventional to extract data segments from multiple trials. This is the code below you should use

EEG = pop_epoch( EEG, { }, [10  EEG.xmax-10]); % re-epoch the data (remove first 10 and last 10 seconds)

% convert the data trials to continuous data and add boundary events
EEG.data = EEG.data(:,:);
for index = EEG.pnts:EEG.pnts:EEG.trials*EEG.pnts
	EEG.event(end+1).type = 'boundary';
	EEG.event(end).latency = index;
end;
EEG.pnts = EEG.trials*EEG.pnts;
EEG.trials = 1;
EEG.xmin = 0;
EEG = eeg_checkset(EEG);

% extract 2-second epochs
EEG = eeg_regepoch(EEG, 'recurrence', 2); % divide into 2 seconds non-overlaping blocks

Alternatively, as Tarik mentioned you could write a script to extract the 2 second epochs yourself.
Best,

Arno

On May 14, 2012, at 2:33 PM, Marco Montalto wrote:

> Dear Arno,
> 
> I have tried the script you supplied me with but found a problem with it. The first part of the script (EEG=pop_select….) treats the data file as one continuous dataset; it ignores the events that mark the beginning and end of a trial. I would like to remove the first and last ten seconds within the boundaries of a trial delimited by the events marking the beginning and end of a trial. As it is the script merely removes the first 10 seconds of the continuous data and last ten seconds of the same continuous data. Let's say A marks beginning of trial 1 and B marks the end of the same trial - I would like to remove the first and last 10 seconds within the block marked by events A and B. And so on for the rest of trails within the same data file. Is this possible? Is there a way of doing this by using some script? Any help you could provide me with would be greatly appreciated.
> 
> Thanks and regards,
> Marco
> 
> On 11 May 2012, at 05:54, Arnaud Delorme wrote:
> 
>> Hi Marco,
>> 
>> to do what you want to do, you should type in
>> 
>> EEG = pop_select(EEG, 'time', [10 EEG.xmax-10]); % remove the first and last 10 seconds
>> EEG = eeg_regepoch(EEG, 'recurrence', 2); % divide into 2 seconds non-overlaping blocks
>> 
>> Best,
>> 
>> Arno
>> 
>> On May 5, 2012, at 6:38 PM, Stephen Politzer-Ahles wrote:
>> 
>>> Hi Marco,
>>> 
>>> I haven't tried this myself, but you should be able to get any of these epochs from the same event using pop_epoch. Assuming that you have an event marking the beginning of the block, then the first epoch you want (i.e. 10-12 seconds after the event) would be
>>> 
>>> OUTEEG = pop_epoch( EEG, {events}, [10 12]);
>>> 
>>> the second would be
>>> 
>>> OUTEEG = pop_epoch( EEG, {events}, [12 14]);
>>> 
>>> etc.
>>> 
>>> Best,
>>> Steve
>>> 
>>> On Sat, May 5, 2012 at 4:33 PM, Marco Montalto <montaltomarco at onvol.net> wrote:
>>> Dear List,
>>> 
>>> In my experiment I have three conditions and each trial is 30 seconds long. I ignore the first and last 10 seconds of each block and the middle 10-second block I divide into epochs of 2-second duration. Currently I am doing this manually through the EEGLAB GUI by placing an event (with the same 'type' for blocks from the same condition) at every two seconds (in the middle 10-second block) and then extracting epochs around those events. Would anyone know whether there is a more automated and a faster way of doing this? Thanks in advance.
>>> 
>>> Regards,
>>> Marco Montalto
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>>> 
>>> 
>>> -- 
>>> Stephen Politzer-Ahles
>>> University of Kansas
>>> Linguistics Department
>>> http://www.linguistics.ku.edu/
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>> 
> 

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