"Scaling" a matrix of matrices into a supermatrix

Question

Carl Emil Mørch Nielsen 2019-11-4

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/489109-scaling-a-matrix-of-matrices-into-a-supermatrix

评论： Carl Emil Mørch Nielsen 2019-11-5

Is there a simple command for repeating matrix-like elements within a matrix without using a loop? For example, say I have a matrix such as

>> A = [1,2,5,6;3,4,7,8;9,10,13,14;11,12,15,16]
A =
     1     2     5     6
     3     4     7     8
     9    10    13    14
    11    12    15    16

I want to scale this matrix, such that it becomes

>> B = [1,2,1,2,5,6,5,6;3,4,3,4,7,8,7,8;1,2,1,2,5,6,5,6;3,4,3,4,7,8,7,8;9,10,9,10,13,14,13,14;11,12,11,12,15,16,15,16;9,10,9,10,13,14,13,14;11,12,11,12,15,16,15,16]
B =
   2     1     2     5     6     5     6
   4     3     4     7     8     7     8
   2     1     2     5     6     5     6
   4     3     4     7     8     7     8
  10     9    10    13    14    13    14
  12    11    12    15    16    15    16
  10     9    10    13    14    13    14
  12    11    12    15    16    15    16

I'm simply looking for a command or a combination of such to create this matrix.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

JESUS DAVID ARIZA ROYETH 2019-11-4

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/489109-scaling-a-matrix-of-matrices-into-a-supermatrix#answer_399722

easy solution:

A=[1,2,5,6;3,4,7,8;9,10,13,14;11,12,15,16]
B=cell2mat(repelem( mat2cell(A,[2 2],[2 2]),2,2))

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Carl Emil Mørch Nielsen 2019-11-4

编辑：Carl Emil Mørch Nielsen 2019-11-4

This is useful, but in the current case, the cells should all be 3x3 and A is a 1728 x 1728 matrix. Would it be possible to use a similar approach without having to do a loop?

Edit: I have found a solution to this myself. Thank you.

请先登录，再进行评论。

Answer 2

Guillaume 2019-11-4

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/489109-scaling-a-matrix-of-matrices-into-a-supermatrix#answer_399721

One way:

blocksize = [2, 2];  %size of blocks along rows/columns
numrepeat = [2, 2];  %number of repeat of each block along rows/columns
assert(all(mod(size(A), blocksize) == 0), 'Matrix size is not a multiple of block size');
B = mat2cell(A, repelem(blocksize(1), size(A, 1)/blocksize(1)), repelem(blocksize(2), size(A, 2)/blocksize(2)));
B = cell2mat(repelem(B, numrepeat(1), numrepeat(2)))

3 个评论
显示 1更早的评论隐藏 1更早的评论

Guillaume 2019-11-4

Well, I'd say a lot more helpful than the answer you accepted which only applied to the example.

This works for any size of matrix, block and number of repeats.

Carl Emil Mørch Nielsen 2019-11-5

This is probably true. I must however admit, that I found it easier to understand the accepted answer and then generalise it to my case - or any case for that matter.

cellsize_x = 3
cellsize_y = 3
cellrep_x = 3
cellrep_y = 3
cellx = cellsize_x*ones(1,size(A,1)/cellsize_x);
celly = cellsize_y*ones(1,size(A,2)/cellsize_y);
M = cell2mat(repelem(mat2cell(Iv,cellx,celly),cellsrep_x,cellrep_y));