Convert layers of 3D matrix to list of cells

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Stephen
Stephen on 14 Apr 2014
Commented: Stephen on 14 Apr 2014
I'd like to take a 3D matrix and convert it to a list (1D) of cells.
Example:
x(:, :, 1) = magic(3);
x(:, :, 2) = 2*magic(3);
I want c{1} to be x(:, :, 1)
I want c{2} to be x(:, :, 2)
My end goal is to create a block diagonal 2D matrix of the layers of x such that,
z = [x(:,:,1), 0
0, x(:,:,2)]
or for complete...
z = [8, 1, 6, 0, 0, 0;
3, 5, 7, 0, 0, 0;
4, 9, 2, 0, 0, 0;
0, 0, 0, 16, 2, 12;
0, 0, 0, 6, 10, 14;
0, 0, 0, 8, 18, 4]
I know I can do this very easily in a loop, but there has to be a better solution. I like the following solution but it assumes that every matrix along the diagonal is the same:
blk = magic(3);
Arguments = repmat( {blk}, 1, 100 );
A = blkdiag( Arguments{:} );
Thanks in advance

Answers (1)

Azzi Abdelmalek
Azzi Abdelmalek on 14 Apr 2014
Edited: Azzi Abdelmalek on 14 Apr 2014
Edit
x(:, :, 1) = magic(3);
x(:, :, 2) = 2*magic(3);
x(:, :, 3) = 3*magic(3);
x=arrayfun(@(ii) x(:,:,ii),1:size(x,3),'un',0)
A = blkdiag( x{:} )
  3 Comments
Stephen
Stephen on 14 Apr 2014
Wow! That is quite nifty. I'm gonna have to read up on arrayfun. Thanks a lot for your help and if think of any other options, please add them to this page.
Also, is there an easy way to reverse this task? As in take A back into original x? (assign elements of block diagonal back to layers of a 3D matrix)

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