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I have an struct, for example...

A = struct();

where we have a 4x4 matrix

A.G = rand(4,4);

I want to build on values within the (4x4) matrix but stack new values in a n'th dimension.

How do I build on the maxtrix in the n'th dimesnion if I don't know how many non-zero values exist in respective field A.G(1,1,n), A.G(1,2,n), A.G(2,2.n) and A.G(4,4,n). the n't value can stack randomly. I wan't to know how many non-zero values lies behind for example A.G.(1,2,n) where n is a unkown value depending how many values i already put into A.G(1,2,n), which i don't keep track on.

Mrutyunjaya Hiremath
on 28 Apr 2020

Hello Happy PhD,

Try this one...

clc;

clear all;

A.G(:,:,1) = [1 2 1 1 ; 4 9 5 6 ];

A.G(:,:,2) = [0 1 0 0; 0 6 0 0];

A.G(:,:,3) = [0 5 0 0; 0 0 0 0];

N = 10; % random number

idx = find(A.G == 0);

if ~isempty(idx)

A.G(idx(1)) = N;

else

n = size(A.G,3);

A.G(1,1,n+1) = N;

end

disp(A.G);

Rik
on 28 Apr 2020

It sounds like you can just assign that value. Matlab will expand the array and fill empty positions with 0.

A.G=cat(3,[ 1 2 0 1 ; 4 9 5 6 ], [ 0 1 0 0; 0 6 0 0],[0 5 0 0; 0 0 0 0 ]);

A.G(1,2,4)=8;%Matlab fills the 4th page with zeros

disp(A.G)

Rik
on 28 Apr 2020

You can find the first empty page like this:

[r,c,val]=deal(1,2,8);

A.G=cat(3,[ 1 2 0 1 ; 4 9 5 6 ], [ 0 1 0 0; 0 6 0 0],[0 5 0 0; 0 0 0 0 ]);

N_by_rc=sum(logical(A.G),3)+1;

n=N_by_rc(r,c);

A.G(r,c,n)=val;

clc,disp(A.G)

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