MATLAB: Concatenate multi dimensional matrix

3dmatrix

I have a matrix which has these 3rd dimensions or pages. A(:,:,1), A(:,:,2), A(:,:,3)
Now, I wanted these three to be vertically concatenated. But i'm looking for an algorithm like in a for sentence for do it in large scale.
I know this: b = cat(1,a(:,:,i)) but i don't have the entire matrix in b because its override. Thank you.

Best Answer

Your b = cat(1, a(:, :, i)) is incorrect and is just equivalent to b = a(:, :, i). If you were to use a loop you could do it like this:
b = [];
for i = 1:size(a, 3)
  b = [b; a(:, :, 1)];   %which is cat(1, b, a(:, :, i))
end
This would be extremely innefficient and matlab's editor will warn you that you're resizing b on every iteration. The proper way to do it in matlab is:
b = reshape(permute(a, [1 3 2]), [], size(a, 2))
without a loop.
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