[Eeglablist] Need help converting common reference (Pz) to average reference using pop_reref()

[Hamza Imtiaz]

Hello,

I am currently working on preprocessing EEG data, and I have encountered a challenge while trying to re-referencing data from common Pz reference to average reference. I would be grateful if you could assist me with this issue.

Following the EEGLAB tutorial (5b), I have tried to retain the reference channel "Pz" using the code provided below:

% Add layout information
EEG = pop_chanedit(EEG, 'lookup', lookup_filepath, 'load', {channelloc_filepath, 'filetype', 'autodetect'});
EEG = eeg_checkset(EEG);

% Change reference to Pz
[EEG.chanlocs.ref] = deal('Pz');

% Append Pz
EEG = pop_chanedit(EEG, 'append', 18, 'changefield',{19 'labels' 'Pz'},...
    'changefield',{19 'type' 'REF'}, 'changefield',{19 'theta' '180'}, 'changefield',{19 'radius' '.256'},...
    'changefield',{19 'X' '-0.719'}, 'changefield',{19 'Y' '0'}, 'changefield',{19 'Z' '.695'},...
    'changefield',{19 'sph_theta' '-180'}, 'changefield',{19 'sph_phi' '44'}, 'changefield',{19 'sph_radius' '1'},...
    'changefield',{19 'urchan' '1'});

% Rereference to Pz
EEG = pop_reref(EEG, [],'refloc',struct('labels',{'Pz'},'type',{'REF'},...
        'theta',{180},'radius',{.256},'X',{-0.719},'Y',{0},...
        'Z',{.695},'sph_theta',{-180},'sph_phi',{44},'sph_radius',...
        {1},'urchan',{1},'ref',{''},'datachan',{0}));


Unfortunately, running this code generates an error message:
Error using pop_reref
Missing reference channel information. Edit channels and add reference first.

Thank you all in advance for your time and support.

Best regards,
Hamza Imtiaz