[Eeglablist] Pop_biosig channels import issue

[Makoto Miyakoshi]

Dear Adrien,

size(EEG.data,1) should absolutely match with the number of channels to
import (if you have fiducials, plus 3). You can discard channel info in GUI
right after importing it so that it matches size(EEG.data,1).

Also, do not confuse channel edit with channel selection! pop_select() will
reject channels with time-series, so it's a channel rejection and your
size(EEG.data,1) will be smaller after rejection.

Makoto

On Wed, Sep 23, 2015 at 4:13 AM, Adrien Martel <amartel at tcd.ie> wrote:

> Hello,
>
> I’m trying to import raw biosemi data with the function ‘pop_biosig’ but
> I’d like to only import 64 channels and the 4 EOGs with P9 and P10 as
> linked mastoid references. Due to a bad config file for the biosemi system
> 234 channels were saved while only 64+6 channels were actually recording.
>
> When I import using the line:
>
>   EEG = pop_biosig(file, 'channels',[1:64 227:230] ,'ref',[24 61] ,
> 'refoptions',{'keepref' 'on'});
> and later edit the channel locations with:
>
> EEG=pop_chanedit(EEG, 'load',{'cap64_new.loc' 'filetype' 'loc'},'setref',{'24
> 61' 'P9  P10'});
>
> The last line produces the warning:
> Warning: channel labels should not be empty, creating unique labels
> Warning: the size of the channel location structure does not match with
>          number of channels. Channel information have been removed.
>
> and the EEG.chanlocs structure is changed to a default template ( .labels:
> Ch1 , Ch2 …)
>
> I tried first importing all the channels and then use pop_select but
> unfortunately many of the 234 channels have the same name which either
> selects empty channels or deletes actually recording ones.
>
> Is there a way to import only certain channels without discrepancies
> between the .data and .chanlocs?
> Or can channels be targeted by pop_select in a different way than with the
> name of the channels, or possibly rename the channels according to a 10-20
> channel template?
>
> Any help would be much appreciated!
> Adrien Martel
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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