Writing tables within a for loop

Hi all,

I'm trying to make a for loop to process some EEG data. The final output is (1x96) for each participant which is finally working great, however, now I'm having issues writing the data/ looping through the participants. I've attached what the output looks like for one particpant as that is how far I can get. Below is what I'm trying to use unnsuccessfully. Any help is greatly appreciated!

SubjectNum = { '01-02' '01-03' }; 

resultsFileName = [fullfile(baseDir, 'MATLAB_Output', 'DIVINE.75results.xlsx')];

for k = 1:length(SubjectNum)

.... (whole bunch of steps)

RelativePowerResults = table(ID,channelsLabel,relativeDelta2,relativeTheta2,relativeAlpha2,relativeBeta2,relativeGamma2)

% unstack resulting in (1 row with 96 columns)
RelativePowerResults_Wide = unstack(RelativePowerResults,"relative"+["Alpha2","Delta2","Theta2","Beta2","Gamma2"],'channelsLabel');

if k == 1
    % First subject, with variable names
    writetable(RelativePowerResults_Wide, resultsFileName, 'Sheet', 1, 'Range', RANGE{k});
        
 else
    % For subsequent subjects, write without variable names
    writetable(RelativePowerResults_Wide, resultsFileName, 'Sheet', 1, 'Range',RANGE{k}, 'WriteVariableNames', false);

end

Answer 1

[Walter Roberson]

Instead of worrying about the Range arguement, consider the possibility of using 'WriteMode', 'append' which will automatically put the new data at the bottom of all previous data.

[Carly]

Hi Walter,

Thanks! I changed it to this based on your advice and it works now!

if nSubject == 1
    % First subject, with variable names
    writetable(RelativePowerResults_Wide,'Sheet',1,resultsFileName);
        
    else
    % For subsequent subjects, write without variable names
    writetable(RelativePowerResults_Wide, resultsFileName, 'Sheet', 1,'WriteMode','append', 'WriteVariableNames',false);

[dpb]

Could cut down code a little by

writetable(RelativePowerResults_Wide,resultsFileName,'Sheet',1,'WriteMode','append', ...
                                                     'WriteVariableNames',nSubject==1)

to generate the logic value on the fly instead.

But, the 'WriteMode','append' flag automagically writes the variable names to an empty sheet and then doesn't write the variable names if there are existing data on the sheet so it's superfluous to add it, anyway, and the single form suffices for both first and subsequent writes.

writetable(RelativePowerResults_Wide,resultsFileName,'Sheet',1,'WriteMode','append')