CODEWITHSUNDEEP
matlabreshapecell-array
Tobi Hase
Tobi Hase

Reputation: 47

Reshaping cell array in matlab - k*MxN to M x k*N

I have a k * MxN cell array that I want to reshape into a M x k * N array. But I want to do this blockwise so that the row structure is preserved.

A B C         -->        A B C G H I M N O
D E F                    D E F J K L P Q R
G H I   
J K L
M N O
P Q R

Is there a possibility without any loops?

Upvotes: 1

Views: 553

Answers (2)

Luis Mendo
Luis Mendo

Reputation: 112659

This can be done with a combination of reshape and permute. This approach works for numeric arrays or for cell arrays.

Let A denote your array. Then, the desired result is

B = reshape(permute(reshape(A.',N,M,[]),[2 1 3]),M,[]);

Or, as noted by Divakar, you can save the transpose, which will reduce running time:

B = reshape(permute(reshape(A,M,k,[]),[1 3 2]),M,[]);

For example,

A = [ 5     9     2
      5     8     4
      5     0     4
      5     5     7
      7     6     3
      8     5     0
      8     7     5
      3     0     5 ];
M = 2;
N = size(A,2);
k = size(A,1)/M;

gives

B =
     5     9     2     5     0     4     7     6     3     8     7     5
     5     8     4     5     5     7     8     5     0     3     0     5

Upvotes: 2

David
David

Reputation: 8459

If you matrix is small, then this should work,

cell2mat(arrayfun(@(i) A(2*i-1:2*i,:),1:3,'UniformOutput',0))

however performance may be better with a more simple loop, especially for a larger matrix.

Upvotes: 0

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