[FieldTrip] Importing large edf data

Fri Dec 18 14:13:16 CET 2015

 Thanks for your reply Anja.I need to have all the channel information at a segment of time to decide if it there is seizure occurring.  Down sampling will loose the information and I am not sure if I want to go that way, as I need to do some feature extractions/classification etc on the data.
Not sure how I could cut the data in fieldtrip. Do you know?ThanksBest regards
___________________________________________________ Leila Ayoubian 

      From: Anja Pflug <anja.pflug at musterkind.eu>
 To: fieldtrip at science.ru.nl 
 Sent: Friday, December 18, 2015 1:06 PM
 Subject: [FieldTrip] Importing large edf data

 Hello Leila,
have you tried to import only one of your 51 channels?
If this works you  could cut the data or downsample it and then combine all channels in a later step.
Best,
Anja

fieldtrip-request at science.ru.nl hat am 18. Dezember 2015 um 12:00 geschrieben:

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Today's Topics:

 1. importing large edf data (Leila Ayoubian)

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Message: 1
Date: Fri, 18 Dec 2015 09:43:43 +0000 (UTC)
From: Leila Ayoubian <leilayou_54 at yahoo.com>
To: "fieldtrip at science.ru.nl" <fieldtrip at science.ru.nl>
Subject: [FieldTrip] importing large edf data
Message-ID:
 <807603762.476165.1450431823359.JavaMail.yahoo at mail.yahoo.com>
Content-Type: text/plain; charset="utf-8"

Hi:Thanks for providing us with this amazing toolbox.
I am new to fieldtrip. I am trying to import EEG data in the format of *.edf for the purpose of seizure detection for epileptic patients. I can't break up the data as you understand the detection has to have continuous data. However I could load section of the data at a time and clear what is already used and reload again.?
So trying to load the data like this:
cfg.dataset= ('mydata.edf');
rawdata=ft_preprocessing(cfg);
This is the error message I get :
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error using zeros
Requested 51x51927040 (19.7GB) array exceeds maximum array size preference. Creation of arrays greater than this limit may take a long time
and cause MATLAB to become unresponsive. See array size limit or preference panel for more information.

Error in read_edf (line 403)
? dat = zeros(length(chanindx),nepochs*epochlength);

Error in ft_read_data (line 622)
??? dat = read_edf(filename, hdr, begsample, endsample, chanindx);

Error in ft_preprocessing (line 566)
????? dat = ft_read_data(cfg.datafile, 'header', hdr, 'begsample', begsample, 'endsample', endsample, 'chanindx', rawindx, 'checkboundary',
????? strcmp(cfg.continuous, 'no'), 'dataformat', cfg.dataformat);

Error in ReadFedfiles (line 8)
rawdata=ft_preprocessing(cfg);%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
I tried the ft_redefinetrial, but since the input to this file is the output from ft-PREPROCESSING it gives me the same error. 

I also tried to use ft_read_data to choose the samples I want to load :?filename???? = 'mydata.edf'
?hdr?? = ft_read_header(filename);
?sample.start=1
?sample.end=100
dat = ft_read_data(filename,'sample.start','1','sample.end','100') 
and here is again the error message:
Error using zeros
Requested 51x51927040 (19.7GB) array exceeds maximum array size preference. Creation of arrays greater than this limit may take a
long time and cause MATLAB to become unresponsive. See array size limit or preference panel for more information.

Error in read_edf (line 403)
? dat = zeros(length(chanindx),nepochs*epochlength);

Error in ft_read_data (line 622)
??? dat = read_edf(filename, hdr, begsample, endsample, chanindx);

Error in ReadFedfiles (line 31)
dat = ft_read_data(filename,'sample.start','1','sample.end','100')
?
>> 

Could you please direct me as to which functions and in which order I should be using the functions to load data in smaller samples.Some examples would be useful.
Thanks again for your support and assistance. 
We appreciate your effort.
Kind regards

___________________________________________________ Dr. Leila Ayoubian 
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