Create a separate log file for each iteration in a for loop

Question

I just want to make a script which runs multiple files and stores their outputs in separate log files.

So I wrote the code by using diary to generate the output, but the diary function is only 1 log file and the output is updating in the same log file for remaining iterations. In my testconfig_1 file, I have at present only print as the content.

Then I tried to use the fopen method, with this I am getting multiple log files but I don't understand how I can put that data into the log file which I have created through fopen after each run.

% with diary method
clear all;
diary on;
instring ='testconfig_';
for x = 1:3 
fprintf ('Simulation on testconfig_%d \n' , x);
test = [instring num2str(x)];
run(test);
diary testconfig_(x).log;
end

% without diary method
clear all;
diary on;
instring ='testconfig_';
for x = 1:3
fprintf ('Simulation on testconfig_%d \n', x);
test = [instring num2str(x)];
run(test);
fid = fopen(sprintf('testconfig_%d.log',x),'w');
end

I wanted to get testconfig_1.log , testconfig_2.log , testconfig_3.log and I wanted to print in_testconfig_1 , in_testconfig_2 , in_testconfig_3 respectively

Answer 1

You are using command syntax to call the diary function.

% Command syntax
diary filename.log
% Equivalent function syntax
diary( 'filename.log' );

Notice that, when using command syntax, all arguments are treated as strings, despite not having any quote marks!

So when you do diary testconfig_(x).log , the equivalent is

diary( 'diary testconfig_(x).log' );

All of your logs have the same filename, because x is never evaluated as the loop variable, it's always just part of a string!

You are trying to create the strings with the loop variable in the name, for this you cannot use command syntax.

Instead, use function syntax like this:

filename = sprintf( 'diary testconfig_%d.log', x );
diary( filename ); % treat the filename variable as a variable, not a string

You don't have to declare the intermediate filename variable, and there are other ways to create the filename string, but I hope this demonstrates the issue.