Extracting index from cell array

I'm currently trying to extract the indexes from a cell array of an EEG experiment and I used the ismember function to line up with the labels and extract the index number of the bad channels, but it didn't give me the results instead of just the order of the channels. Is there any solution to find the index to the corresponding channels?

{EEG.chanlocs.labels}

ans =

1×64 cell array

Columns 1 through 9

{'0Z'} {'1Z'} {'2Z'} {'3Z'} {'4Z'} {'1L'} {'1R'} {'1LB'} {'1RB'}

...

bad = split(string(dataQC(1,5))).'

1×6 string array

"1RC" "2RB" "3LD" "10L" "9L" "4LD"

[~, numchan] = ismember({EEG.chanlocs.labels}, bad)

Answer 1

[Khalif]

bad = split(string({'1RC', '2RB', '3LD', '10L', '9L', '4LD'}).';

bad = convertStringsToChars(bad);

[badchan, numchan] = ismember({EEG.chanlocs.labels}, bad);

badchan = find(badchan);

Answer 2

[Umar]

Hi @Khalif Shirad,

To address your query regarding, “I'm currently trying to extract the indexes from a cell array of an EEG experiment and I used the ismember function to line up with the labels and extract the index number of the bad channels, but it didn't give me the results instead of just the order of the channels. Is there any solution to find the index to the corresponding channels?”

Please see my response to your comments below.

The core of the solution lies in your ismember function, which is employed to find the indexes of the bad channels within the EEG channel labels. The syntax [~, numchan] = ismember(bad, EEG.chanlocs.labels); effectively checks each element of the bad array against the EEG.chanlocs.labels array. The tilde (~) is used to ignore the first output of ismember, which indicates whether each element of bad is found in EEG.chanlocs.labels. Finally, the resulting indexes of the bad channels are displayed using the disp function. This output provides a clear view of which channels are deemed problematic based on their corresponding indexes in the original EEG channel labels array. Here is the updated code,

% Sample EEG channel labels
EEG.chanlocs.labels = {'0Z', '1Z', '2Z', '3Z', '4Z', '1L', '1R', '1LB', '1RB',
...'1RC', '2RB', '3LD', '10L', '9L', '4LD', '5Z', ...'6Z', '7Z', '8Z', '9Z',   '10Z', '11Z', '12Z', ...'13Z', '14Z', '15Z', '16Z', '17Z', '18Z', ...
                      '19Z', '20Z', '21Z', '22Z', '23Z', '24Z', ...
                      '25Z', '26Z', '27Z', '28Z', '29Z', '30Z', ...
                      '31Z', '32Z', '33Z', '34Z', '35Z', '36Z', ...
                      '37Z', '38Z', '39Z', '40Z', '41Z', '42Z', ...
                      '43Z', '44Z', '45Z', '46Z', '47Z', '48Z', ...
                      '49Z', '50Z', '51Z', '52Z', '53Z', '54Z', ...
                      '55Z', '56Z', '57Z', '58Z', '59Z', '60Z', ...
                      '61Z', '62Z', '63Z'};

% Bad channels to be identified
bad = split(string({'1RC', '2RB', '3LD', '10L', '9L', '4LD'})).';

% Find the indexes of bad channels
[~, numchan] = ismember(bad, EEG.chanlocs.labels);

% Display the results
disp('Indexes of bad channels:');
disp(numchan);

Please see attached.

Hope this helps resolve your problem. Please let me know if you have any further questions.

[Khalif]

Thank you for the help. I've found the solution by replacing the tilde (~) with a variable output and using the find function.

bad = split(string({'1RC', '2RB', '3LD', '10L', '9L', '4LD'}).';
bad = convertStringsToChars(bad);
[badchan, numchan] = ismember({EEG.chanlocs.labels}, bad);
badchan = find(badchan);

[Umar]

Hi @Khalif Shirad,

Thank you for sharing your solution with me. I appreciate your initiative in replacing the tilde (~) with a variable output and utilizing the find function. It’s always gratifying to see effective problem-solving in action. If you have any further questions or if there’s anything else I can assist you with, please don’t hesitate to reach out.