Can I define a structure iteratively?

I am hoping to redefine a structure within each for-loop. Say, given a 1000-by-4 real vector Xs and a 1000-by-4 logical B,

value_i={[]};
fields_global={[]};
values_global={[]};

for i=1:30
    for j=1:4
        A = Xs(:,j);
        C = A.*(B(:,j)*1);           
        E=C(find(C));
        value_i={value_i,E};
    end
    Structure_i=struct('field_i',value);
    Structure_global=struct(fields_global,values_global,'field_i',value_i)
    fields_global={fields_global,'field_i'}
    values_global={values_global,value_i}
    value={[]}
end

MATLAB doesn't seem to appreciate my approach. Is this at all feasable? Is there another way to store

[Ricardo Gomez Uribe]

Is there another way to store, within each iteration, vectors of varying magnitude, and reference them in the output of a function as a structure?

Answer 1

[Guillaume]

It's not very clear what you're trying to achieve. As it is you're always creating the same field always called 'field_i'. You can't have multiple fields with the same name.

The simplest way to store several vectors of different length (if that's what you mean by magnitude) is to use a cell array.

results = cell(1, 30);
for i = 1:30
   values = ...
   results{i} = values;
end

You could use a structure with numbered fields instead but that would be more complicated for no benefit at all.

[Ricardo Gomez Uribe]

That should do it. Cheers!

[Ricardo Gomez Uribe]

One more question: can one code nested cells? That is, in your example,

    results = cell(1, 30);
    for i = 1:30
       values = ...
       results{i} = values;
    end

could "value" be a cell array?