Add structs in a saved array of structures

Hello,

I have a function (fun1) which generates several results (r1,r2,r3...). I organise them in a struct.

results=struct('results1',{r1},'results2',{r2},'results3',{r3},...);

This struct is the output of the funtion.

I have to run this same function for several variables and I want to keep all the results in the same array of structs. Therefore could I do:

results(1)=fun1(variable1,otherinputs);
results(2)=fun1(variable2,otherinputs);
results(3)=fun1(variable3,otherinputs);
...

However, the function deals with huge sets of data so it can take on the order of 45 minutes to run, and I have to run it more than 20 times. Is there any way to save the output struct so that each time that I run the function it adds the output to the previous ones? I mean to do something similar to what I do in the workspace but directly in a .mat file.

Thanks!

Answer 1

[Mohammad Sami]

You can use the matfile function to write directly to a mat file

a = matfile('newfile.mat','Writable',true);
n = 10;
for i = 1:n
    % your code
    a.mystruct(i,1) = struct('abc',123,'def',456);
end
clear a;

[Miquel]

Thanks!

So, to check that I understood: In my example the loop should be the following, right?

n = numberofvariables;
for i = 1:n
    a.results(i,1)=fun1(variable(i),otherinputs(i));
end

[Mohammad Sami]

Yes. that should work, as long as the output is always a struct with same fieldnames.

[Miquel]

Cool, yes. Thanks :)

[Miquel]

BTW, is it advisable to start the loop in the end for allocation issues (as Jan always remarks in the forum)? Or is this not the case with structs?

n = numberofvariables;
for i = n:-1:1
    a.results(i,1)=fun1(variable(i),otherinputs(i));
end

[Stephen23]

Unless the structure itself** is huge, iterating in reverse is unlikely to make much difference. But you can experiment and tell us the results.

** not the data it contains!

[Miquel]

Ok, thanks. No, I generate 2 stucts that are only 7 fields and around 20... rows? So I guess it should make almost no difference. And I will be using the computer most of the time while Matlab is running. Thanks both!