How to save data from multiple matlab file in a single excel sheet?

I have multiple patient files, each with multiple outputs. I managed to export each output in a different excel file, and I created a for loop to go through all the files. The code looks like this (SEF90 is one of the outputs):

for k = 3 : 31
    matFileName = sprintf('mat%d.mat', k);
    if isfile(matFileName)
        matData = load(matFileName);
    else 
        fprintf('File %s does not exist.\n', matFileName);
    end
    
%% SEF90
P = SEF90
V1 = reshape(P,1,20);
writematrix(V1, 'SEF90.xlsx', 'WriteMode','append');

end 

The data is saved in the right format in excel and it goes to a new row every time, the problem is that it only writes data from the first file (see screenshot). How can I solve this so that each row is a different file (possibly in order of file number)?

[Antoni Garcia-Herreros]

Hello Alice,

You could try to create the 2D array/table with the lines for the different files and then finish the loop and save it as an Excel file

FinalMat=zeros(28,20); % Create the array to store the values of each file
for k = 3 : 31
    i=1
    matFileName = sprintf('mat%d.mat', k);
    if isfile(matFileName)
        matData = load(matFileName);
    else 
        fprintf('File %s does not exist.\n', matFileName);
    end
    
    %% SEF90
    P = SEF90
    V1 = reshape(P,1,20);
    FinalMat(i,:)=V1;
end 
xlswrite('SEF90.xlsx',FinalMat);

Hope this helps!

Answer 1

[Gyan Vaibhav]

Hi Alice,

I understand that your goal is to export the data from various “MAT” files to a single excel file in order of the files.

The code you've shared appears to be mostly correct, however you are trying to append every time in the excel sheet. You need to use the “matData” for every iteration. Further even when the else condition is valid, the loop is trying to append it to the file, which could lead to wrong output.

This can be done easily by creating an array, by including the data from all the “MAT” files, and then writing this to an excel file.

The above code can be modified as follows:

% Initialize an empty matrix to store all the data 
allData = []; 

for k = 3 : 31 
    matFileName = sprintf('mat%d.mat', k); 
    if isfile(matFileName) 
        matData = load(matFileName);      
        %‘SEF90’ 
        P = SEF90; 
        V1 = reshape(P, 1, 20);     
     
        % Append the data to the allData matrix 
        allData = [allData; V1]; 
    else  
        fprintf('File %s does not exist.\n', matFileName); 
    end 
end 

% Write all the data to the 'SEF90.xlsx' file 
writematrix(allData, 'SEF90.xlsx'); 

Hope this helps and resolves your issue.

Thanks

Gyan