Permute my center blocks

Question

Yuxing Zhang 2018-11-6

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https://ww2.mathworks.cn/matlabcentral/answers/428201-permute-my-center-blocks

评论： Bruno Luong 2018-11-6

I have a matrix A with center piece (80×80) and I have now divided into 16 blocks of size 20×20. I also have a permutation vector V=[7 11 2 3 ....], which I need to place the 7th block in the location of the first block, place the 11th block in the location of the second block, etc.

Now the issue is I don't know how make make my blocks into numbered blocks and change order, can any one give me some example codes?

below this my code:

A=rand(200,200);
Acenter=A(161:240,161:240);
Ablock= mat2cell(Acenter,[20 20 20 20 ],[20 20 20 20]);

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Bruno Luong 2018-11-6

在 MATLAB Online 中打开

Acenter=A(161:240,161:240)

What is that for, beside just throw out an error because the indexing is wrong?

What is the relation of block permutation?

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Answer 1

per isakson 2018-11-6

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/428201-permute-my-center-blocks#answer_345426

编辑：per isakson 2018-11-6

在 MATLAB Online 中打开

"how make make my blocks into numbered blocks" Matlab does that automatically, e.g.

>> Ablock(11)
ans =
  1×1 cell array
    {20×20 double}

See Array Indexing, and notice "linear indexing"

Check whether this does the trick

A=rand(200,200);
Acenter=A(61:140,61:140);
Ablock= mat2cell(Acenter,[20 20 20 20 ],[20 20 20 20]);
V = randperm(16); % random permutation vector
Bblock = reshape( Ablock(V), size(Ablock) );