[Eeglablist] Version 2026 bug? Unable to rereference to the average reference and add back online ref

[Andrew Corcoran]

I recently experienced a similar problem to Kelsey when trying to adapt some old code for new BioSemi data using EEGLAB 2026 in MATLAB 2025a.

With some playing around via the gui I managed to get things working as follows :

% import chanlocs & define chantype
EEG = pop_chanedit(EEG, {'lookup','standard_1005.elc'});

% assign ref
EEG = pop_reref( EEG, [ contains({EEG.chanlocs.labels}, {'Cz'} ) ] );

% reintroduce Cz & reref to common average
EEG = pop_chanedit(EEG, 'append', EEG.nbchan, 'changefield', {EEG.nbchan+1,'labels','Cz'}, ...
        'lookup', 'standard_1005.elc');

EEG = pop_reref( EEG, [], 'refloc', struct('labels',{'Cz'}, 'type',{'eeg'}, ...
        'theta',177.4959, 'radius',0.029055, 'X',-9.167, 'Y',-0.4009, 'Z',100.244, ...
        'sph_theta',-177.4959, 'sph_phi',84.77, 'sph_radius',100.6631, 'urchan',EEG.nbchan+1, ...
        'ref',{''}, 'datachan',0) );

While this code appears to function as intended, running it produces the following warning :
Warning: some channels have the same label

I cannot see any evidence of incorrect labelling despite the warning. Whatever the source of the issue, it appears to be the same problem as previously raised on this list by Raquel London https://sccn.ucsd.edu/pipermail/eeglablist/2016/011065.html  (I’m not sure if anyone got to the bottom of it).

Venlig hilsen
Andrew

Dr. Andrew W. Corcoran
Postdoctoral Researcher

Københavns Universitet
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