How to append data into an Excel File when writing data in a loop.?

I am writing an complex double 10X1 variable X into an excel file inside a loop. The value of X updates for every iteration of the loop. But the data keeps getting over written. The values inside the complex double X are being to every row in a particular column of the excel sheet. See below for the code.

for i = 1:44
    % code to calculate the value of X
    R(1,1:length(X))=X; 
    xlswrite(write_file,R');
end

So for column A of the excel sheet, in the row 1 to 10 (A1 to A10) the data within X gets written in the first loop. Then during the 2nd time it gets re-written on top of the old data and so on.

Answer 1

[Madheswaran]

Hi

The 'xlswrite' function is not recommended starting from MATLAB R2019a. To write a column vector into an Excel file, you can use the 'writematrix' function.

If you want to append all the values in a single column, you can use the 'WriteMode' parameter set to 'append':

for i = 1:44
    % existing code to calculate the value of X
    writematrix(X, filename, 'WriteMode', 'append');
end

However, if you would like to append each of the column vectors in separate columns, you can modify your loop as follows:

function colName = getColumnName(colNumber)
    colName = "";
    while colNumber > 0
        modulo = mod(colNumber - 1, 26);
        colName = char('A' + modulo) + colName;
        colNumber = floor((colNumber - modulo) / 26);
    end
end

for i = 1:44
    % existing code to calculate the value of X
    colName = getColumnName(i);
    writematrix(X, filename,  'Range', sprintf('%s1', colName));
end

The above function 'getColumnName' converts integer to Excel Column name. For more information on 'writetable', refer to the following documentation: https://mathworks.com/help/matlab/ref/writetable.html

Hope this helps!