[Eeglablist] load EGI files

Alois Schloegl alois.schloegl at ist.ac.at
Sat Sep 13 12:45:41 PDT 2014


On 2014-09-12 19:15, Iman M.Rezazadeh wrote:
>  
> 
> I run the EP toolbox on Windows 64bit.
> 
> From: eeglablist-bounces at sccn.ucsd.edu
> [mailto:eeglablist-bounces at sccn.ucsd.edu] On Behalf Of Govindan,
> Rathinaswamy
> Sent: Friday, September 12, 2014 4:04 AM
> To: Ramón Martinez; EEGLAB List
> Subject: Re: [Eeglablist] load EGI files
> 
>  
> 
> Dear all:
> 
> Thanks every one for all the suggestions. Here I address your questions;
> also post my questions related to your suggestions.
> 
>  
> 
> Srini: Our sampling rate is 1KHz. I can down sample the data to 250Hz or
> even lower however I am worried that it might affect the gamma band activity
> that we are interested in.
> 
>  
> 
> Andrew: I am using IMAC to import the data. I am running 32bit MATLAB in it.
> It has 16GB of RAM. I was suggested by EGI techs to insert event in the file
> and use segmentation option to segment the data based on the events. After I
> segmented the data, I used the convert to mat format function that came with
> EGI software.  I could not able to import these mat files in MATLAB.  
> 
>  
> 
> Simon: I will also try your suggestion. How would I check if it has exported
> the right set of electrode layout?
> 
>  
> 
> Iman: Are you running EP Toolbox on Windows PC or on Linux/Unix/MAC. I am
> trying to understand if I need to install this in a computer running on
> 64bit processor.
> 
>  
> 
> Ramon and Alois: Does the biosig4matlab tool have to be installed on a Linux
> system? Can it work on IMAC in which a 32 bit MATLAB is installed? 
> 


Biosig will work on 32 bit and 64 bit systems. That's not the issue.

But if you want to load files larger than 2 GByte, you will run into
limitations of 32bit platform (Matlab, operating system), because with
32bit you can only address up to 4GB.

You should also be aware that if your data is stored in int16 format,
loading it into Matlab will usually convert them into double precision
format, increasing its size by a factor of 4 (from 2 to 8 bytes per
sample). Biosig can avoid that (e.g. set UCAL=1 in SOPEN/SLOAD), but you
have to take special care, and a number of matlab operators will only
work with double precision numbers. If you just need to load parts of
the data, and you will never exceed the RAM limit, Biosig will support
you loading only those segments from the file into memory that you are
interested in (help SREAD).

In general, if you have large data sets, its usually easiest to handle
them on a 64 bit platform.


Regards,
  Alois




>  
> 
> I am going to try out the following:
> 
>  
> 
> Install EP Toolbox and check if it helps.
> 
>  
> 
> Install Biosig4matlab tool and check if it helps.
> 
>  
> 
> I will keep you posted on the status.
> 
>  
> 
> Thanks, again.
> 
>  
> 
> Best regards,
> 
>  
> 
> RB
> 
>  
> 
>  
> 
> R. B. Govindan, PhD  
> 
> Staff Scientist III
> 
> Director of Advanced Physiologic Signals Processing Lab
> 
> Fetal Medicine Institute
> 
> Division of Fetal and Transitional Medicine
> 
> Children's National Health System
> 
> 111 Michigan Ave, NW, M3118C
> 
> Washington, DC
> 
> 202-476-5309
> 
> We stand for children.
> 
>   _____  
> 
> From: Ramón Martinez [nucleuscub at gmail.com]
> Sent: Thursday, September 11, 2014 3:28 PM
> To: Govindan, Rathinaswamy; EEGLAB List
> Subject: Re: [Eeglablist] load EGI files
> 
> Hi Govindan, 
> 
> 1- From the EEGLAB side,  yes, you can import EGI files using pop_readegi.m,
> but for a big file, should be better to use the Biosig plugin for EEGLAB
> (you can try both)
> 
> You'll find the Biosig plugin in the EEGLAB extension manger:
> 
>  
> 
>  File -> Manage EEGLAB extesions -> Data import extensions
> 
>  
> 
> After checking out the plugin,  you can try pop_biosig.m,  or from the GUI
> 
>  
> 
> File -> Using the Biosig interface
> 
>  
> 
> 2- Other memory issues can arise from the PC-MATLAB side. Check this link to
> have an idea.
> 
> http://www.mathworks.com/matlabcentral/answers/91711-what-is-the-maximum-mat
> rix-size-for-each-platform
> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mathworks.com_matla
> bcentral_answers_91711-2Dwhat-2Dis-2Dthe-2Dmaximum-2Dmatrix-2Dsize-2Dfor-2De
> ach-2Dplatform&d=AAMFaQ&c=Zoipt4Nmcnjorr_6TBHi1A&r=4JR34R10jj9uXt37C2EM4uXHW
> YJdQA42rymb5F0yfJY&m=GsEjw4m_8nx3fkAo7zDVR3Ol0zIb_5r_viVtSqbdjfU&s=CLVXtTG8n
> c_AkBkZXfMXanIdrUgDQWrFccevCjNUTzA&e=> 
> 
>  
> 
> Hope this helps,
> 
>  Ramon
> 
>  
> 
> On Thu, Sep 11, 2014 at 11:44 AM, Govindan, Rathinaswamy
> <rgovinda at childrensnational.org <mailto:rgovinda at childrensnational.org> >
> wrote:
> 
> Dear List: 
> 
> This RB Govindan from Children's Hospital, Washington, DC. We have EEG
> recorded from premature infants using HD EEG system. Some of our recordings
> last for more than 2 hours. We would like to export the data to MATLAB and
> process them in MATLAB. The software that came with the HD EEG system is not
> allowing us to convert our huge files (>2GB) into mat format. Would like to
> know if there are tools available in EEGLAB or some similar to export the
> data to MATLAB environment?
> 
>  
> 
> Thank you very much in anticipation.
> 
>  
> 
> Best regards,
> 
>  
> 
> RB Govindan
> 
>  
> 
> 
>   _____  
> 
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