[Eeglablist] Loading and Reading Channel by Channel rather thanAll Channels at once using loadcnt.

[Michiel Spape]

Hi Arnaud & List,
I was wondering, is this style of data-reading also available for reading the EGI raw data format? We've recently been running into trouble when reading in data of +- 600 MB even though the largest contiguous blocks of data in MATLAB suggests there's a block of about 1000 MB free, with the function specifically complaining about lack of memory. Currently, the only way around I found was by importing the data into Brain Vision Analyzer, then exporting again and using the bvaio plugin to read it back into EEGLAB. Although that works, it does take a couple of hours, and not everyone here has a BVA dongle.
Thanks,
Mich


Michiel Spapé
Research Fellow
Perception & Action group
University of Nottingham
School of Psychology


-----Original Message-----
From: eeglablist-bounces at sccn.ucsd.edu [mailto:eeglablist-bounces at sccn.ucsd.edu] On Behalf Of Arnaud Delorme
Sent: 06 August 2009 19:16
To: S N
Cc: eeglablist at sccn.ucsd.edu
Subject: Re: [Eeglablist] Loading and Reading Channel by Channel rather thanAll Channels at once using loadcnt.

Dear Sahrmin,

the function that reads CNT files in the latest reversion of EEGLAB  
allows to read the data in a memory mapped format (the data is not  
read in memory).
Select memory mapping in the EEGLAB options. Then in the reading  
interface, there is an option to load the file memory mapped. This was  
recently implemented by Craig Rypstat.
You may then downsample.

Arno

On Aug 2, 2009, at 2:50 PM, S N wrote:

> Hi,
>
> We are manually loading the .CNT on a larger server and are unable  
> to do so on a regular desktop machine because the 64 channel .CNTs  
> are huge ~ 1.5GB. They are 10kHz worth of data for 8-10mins.
>
> Instead of needing any further server involvement, I am trying to  
> modify the loadcnt function to only load one channel at a time.  
> Ideally, I would like to be able to specify the channel and retrieve  
> ONLY the EEG.data for that one specified channel and run our code on  
> it, then get the EEG.data for another specified channel. What we  
> want to avoid is having to load the entire .CNT into RAM to get the  
> data out. We can only afford to retrieve the data for one channel.
>
> In addition, is there a function to get only the EEG.event data out  
> of the .CNT without also having to load the entire, huge .CNT file?
>
> Thanks,
> Sharmin <ATT00001.txt>

_______________________________________________
Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
To unsubscribe, send an empty email to eeglablist-unsubscribe at sccn.ucsd.edu
For digest mode, send an email with the subject "set digest mime" to eeglablist-request at sccn.ucsd.edu

This message has been checked for viruses but the contents of an attachment
may still contain software viruses, which could damage your computer system:
you are advised to perform your own checks. Email communications with the
University of Nottingham may be monitored as permitted by UK legislation.