Export to excel from matlab

Hello, I have a script that runs all the text filles, that containes a signal, in one folder and calculates the amplitude for all.

I want so save those amplitudes in excel, but when I tried it only saves the amplitude of the last signal, like in the image, instead of all the amplitudes for all the signals.

I hope you can help me, thank you very much!

%%
paste = '/Users/sofiasantos/Desktop/sinais'; %directory
data=dir(fullfile(paste,'*.txt'));
for k=1:numel(data)
  signal=data(k).name
  data_org = importdata(signal,'\t',7); %text file with 7 columms
  EDA=data_org.data; 
  EDA= EDA(:,6); %I only want the 6 collum of the text file 
  EDAuS=((EDA/2^10)*3)/0.12; %convert to uS
  N= length(EDAuS); 
  fs = 1000; 
  T=N/fs;
  t = (0:N-1)/fs; %time 
  f = (0:N-1)/T;
  %%
  [b,a] = butter(6,0.0035,'low');
  EDAuS_filter = filtfilt(b,a,EDAuS);  %filtering signal EDA
  minimo= min(EDAuS_filter);
  maximo= max(EDAuS_filter);
  amp=abs(maximo-minimo);
  disp('amplitude='); disp(amp); %amplitude da SCR
  %% Export to excel
    T = table(amp,'RowNames',{signals});
    fileName='signals_EDA.xlsx';
    writetable(T,fileName);
end 

Answer 1

[Guillaume]

Indeed, you will end with just the data for the last file in the excel file since for each file, you overwrite what you wrote in the excel file for the previous text file.

Probably, the best solution is to store the amp you calculate in an array that you fill one row at a time. Then once the loop has finished, convert that to a table and save it all at once in the excel file:

%your pre-loop code unchanged:
paste = '/Users/sofiasantos/Desktop/sinais'; %directory
data=dir(fullfile(paste,'*.txt'));
%create array to store all the amp:
amp_all = zeros(numel(data), 1);
for k=1:numel(data)
    %.. your loop code unchanged except for the last 3 lines that are removed and the addition of
    amp_all(k) = amp;
end
T = table(amp_all, 'RowNames', {data.name}, 'VariableNames', {'amp'});
writetable(T, 'signals_EDA.xlsx', 'WriteRowNames', true);  %not much point in giving names to the rows if you don't write them to the excel file

The alternative is writing to the excel file after you've processed each file, you then have to tell writetable to write on different rows each time and make sure it only writes the header for the first file:

%most of the code unchanged
paste = '/Users/sofiasantos/Desktop/sinais'; %directory
data=dir(fullfile(paste,'*.txt'));
for k=1:numel(data)
    %... until it comes to write/create the table:
    T = table(amp,'RowNames',{signals});   %note that signals is undefined in your code. Did you mean signal (without an s)
    dowriteheader = k == 1;  %only write header for the first file
    destination = sprintf('A%d', k+1);  %row 1 is header, therefore data goes into row k+1.
    writetable(T, 'signals_EDA.xlsx', 'WriteVariableNames', dowriteheader, 'WriteRowNames', true, 'Range', destination);    
end

As you can see it's more complicated and is going to be slower (matlab load and saves the excel file at each iteration). The only benefit of this option is that if your code errors before the loop is finished, you have what's been processed so far written in the excel file.

[Sofia Santos]

Solved my problem :)

Thank you so much for your help and for such a detailed explanation!!