Sequentially save .txt outputs from multiple participants in loop in Matlab

Question

Apologies for the basic question, but if anyone can offer assistance with the following it would be greatly appreciated:

I have a script that calculates the mean reaction time from selected trials in a large matrix, and saves this result to a .txt file for each participant, however it overwrites the txt file each time. I need to save each subject's results individually.

This is what I have so far:

PN = data(:,1);
RT = data(:,9);

for i = 1:20;
    index = PN == i & Variable == 1;
    VariableRT = mean(RT(index));
    dlmwrite('VariableRT.txt', VariableRT)

end

Thank you.

Answer 1

You can change the string you are using to save the file during each iteration of the for loop like so:

for i = 1:20
  ...
  ...
  dlmwrite(['VariableRT',num2str(i),'.txt'], VariableRT);
end

['VariableRT',num2str(i),'.txt'] creates a concatenation of the three strings 'VariableRT', 'iterationNumberAsString' and '.txt'.

Answer 2

you can add a num2str which will number your VariableRT.txt so that you have VariableRT1.txt, VariableRT2.txt ... VariableRT(i).txt. The i is updated each time in your loop, thus naming each txt file with the iteration number.

VariableRTFile = ['VariableRT' num2str(i) '.txt'];
dlmwrite(VariableRTFile, VariableRT)