[Eeglablist] Possible bug or hidden feature in pop_reref

[Arnaud Delorme]

Dear Alexandre,

I think it has been addressed but would you mind to check if it works with the latest version of EEGLAB 11 with your configuration, that would be very useful to us and other users.
Thanks,

Arno

On Jun 2, 2012, at 11:11 PM, Alexandre Lehmann wrote:

>  Hello, 
> 
> Sorry if this has been fixed already but I came across a tricky index issue in eeglab 09.0.4.4b using pop_reref.
> 
> Say that I have 4 channels :
> 
> 1 VEOG (bipolar)
> 2 M1
> 3 Fz
> 4 Cz
> 
> If I want to re_reference my data to M1, but not modify my EOG channel and remove my new reference (M2) from the channels.
> 
> I type
>  EEG = pop_reref( EEG, 2 ,'exclude',1,'keepref','off');
> 
> What happens in that case, is that data gets re_referenced to Fz (which is channel 3, but the second non-excluded channel).
> But then the channel that is actually removed is M2 (channel 2).
> 
> I kept wondering why I was left with an empty Fz after re-ref, which made the kurstosis rejection crash.
> 
> So as I said in the title, I am not sure this is really a bug an tricky index gymnastics
> 
> Most people don't have to face this this EOG channels are usually at the end. It just so happened that I made some recordings with a custom mapping of single electrodes.
> 
> If you are in a similar situation you can just reference by hand, or use a similiar workaround :
> 
>         EEG = pop_reref( EEG, ref_chans-1 ,'exclude',1,'keepref','on'); 
>         EEG = pop_select( EEG,'nochannel',ref_chans); 
> 
> Best Regards
> 
> Alex
> 
> -- 
> Alexandre Lehmann, Phd
> Postdoctoral research fellow
> Laboratory for Brain, Music & Sound Research
> BRAMS - Université de Montréal
> Pavillon 1420 boul. Mont Royal
> Case Postale 6128, Station Centre-Ville
> Montreal (QC)  H3C 3J7
> Tel. (514) 343-6111 poste 28306
> 
> 
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