Preallocation for a cell help needed

Hello,

I could not find out how to properly do the preallocation for the following situation. Could you please give me a hand?

Regards

Size of tracks' changes every loop, so I want to do preallocation for it but could not figure out how. (Size of tracks(1,i).nPoints remains same. Only tracks(1,i).matrix changes, 1≤i≤max_n_trks)

%% Interpolation

interp=1;

for param=1:interp

    for k=1:max_n_trks % maximum number of tracks

        vector = tracks(1,k).matrix;
        len = tracks(1,k).nPoints;

        for i=len:-1:1

            vector(2*i-1,:,:)=vector(i,:,:);

        end

        tracks(1,k).nPoints = (tracks(1,k).nPoints*2)-1;
        len = tracks(1,k).nPoints;

        for i=1:2:len-1

            vector(i+1,:,:) = (vector(i,:,:) + vector(i+2,:,:))/2;

        end

        tracks(1,k).matrix = vector;

    end

end

note: Now, I found a way:

B = struct('nPoints',repmat({zeros(1)},1,110470),'matrix2',repmat({zeros([n 3])},1,110470))

I can assign the maximum value that n can take, however I want to make it more efficient. How can I do it? For example tracks(1,1).matrix has 3 elements and tracks(1,133).matrix has 170 elements. I do not want to assign 170 to each, I want to separately do to assignment.

Answer 1

[Sean de Wolski]

It sounds like you should assign an empty cell to each value:

S = struct('field1',cell(10,1));

You can then fill in the values as necessary:

for ii = 1:10;
    S(ii).field1 = magic(randperm(10,1));
end