CODEWITHSUNDEEP
matlabmatrixcell-array
SemtexB
SemtexB

Reputation: 660

Matlab merge matrices to cell

In Matlab I got three matrices (consisting of vectors) x, y, z of size 3xn each.

I want to merge them to a cell with n entries, each a 3x3 matrix:

for i=1:n
    C{i} = [x(:,i), y(:,i), z(:,i)];
end

Is there a faster way than using this for loop, because that takes ages?

I already found functions like mat2cell and cellfun, but they all don't really do what I need, do they?

Upvotes: 0

Views: 104

Answers (3)

Lincoln Cheng
Lincoln Cheng

Reputation: 2303

Try this:

t = reshape([x; y; z], [3 3*n]); %//reshape your vectors into a matrix that could be use nicely with mat2cell
C = mat2cell(t, 3, 3*ones(1,n));

Upvotes: 2

Peter
Peter

Reputation: 14927

Unless the code you are calling demands it, use a 3D array instead. It comes with much less overhead.

C = zeros(3, 3, n);
for ii = 1:n
    C(:, :, ii) = [x(:,ii) y(:,ii) z(:,ii)];
end

In this form, you can vectorize it instead, using reshape:

C = reshape([x; y; z], [3 3 n]);

Upvotes: 4

Puck
Puck

Reputation: 2114

You can pre-allocate the memory the improve performance:

C = cell(n, 1);

Upvotes: 0

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