Anyone an idea? Variable in nested for loop does not update...

Dear Community,

I made the following script to automatize my data analysis:

clear, clc
myDir = uigetdir; %gets directory
myFiles = dir(fullfile(myDir,'*_DistX.xlsx'));
for k = 1:length(myFiles)
  baseFileName = myFiles(k).name;
  fname = strcat(myFiles(k).name);
  fullFileName = fullfile(myDir, baseFileName);
  fprintf(1, 'Now reading %s\n', baseFileName);
  opts = detectImportOptions(fname ,'NumHeaderLines',0);
  T = readtable(fname, opts)
  A = table2array(T)
  NumberOfParticles = length(A(:,1))
    for i = 1:NumberOfParticles
        NumberOfZero(i) = sum(A(i,:)==0);
        NumberOfRetrograde(i) = sum(A(i,:)<0);
        NumberOfAnterograde(i) = sum(A(i,:)>0);
        TotalNumber(i) = numel(rmmissing(A(i,:)));
    end
   B = [(NumberOfRetrograde)', (NumberOfZero)', (NumberOfAnterograde)', (TotalNumber)']
   C = array2table (B,'VariableNames',{'NumberOfRetrograde', 'NumberOfZero', 'NumberOfAnterograde','TotalNumber'})
   D(k,:) = [sum(NumberOfRetrograde), sum(NumberOfZero), sum(NumberOfAnterograde), sum(TotalNumber)]
   E = array2table (D, 'RowNames',{fname},'VariableNames',{'NumberOfRetrograde', 'NumberOfZero', 'NumberOfAnterograde','TotalNumber'})
   writetable(E,fname,'Sheet',1,'Range','A1')
end

It works fine, except for the variable B, which does not update through iterations of k, which messes up C,D and E consequentially.

Anybody an idea where the problem could be? Is it possible that the first "end" closes both for loops?

Thanks a lot in advance for any idea...

Answer 1

[Uttiya Ghosh]

Hi Mara,

I have checked your code assuming the data in your file as a table of size 3*3 containing integers. I am also assuming that you want to store the data for each file as a row in variable D. Since you are using the variable fname as rownames for the variable E, you should consider creating it as a vector of strings and not just a single string. You should also try to compute E outside the outer for loop. I believe these steps will solve your error. I have made the following changes to your code and placed variable E outside the loop which solved the issue.

fname(k) = string(myFiles(k).name);
...
opts = detectImportOptions(baseFileName ,'NumHeaderLines',0);
T = readtable(baseFileName, opts);
...
E = array2table (D, 'RowNames',fname,'VariableNames',{'NumberOfRetrograde', 'NumberOfZero', 'NumberOfAnterograde','TotalNumber'});

You can then write the variable E in a file as required.

For more information, refer to the links given below:

https://www.mathworks.com/help/matlab/ref/array2table.html