How can I index these matrix blocks into numbers?

Question

Yuxing Zhang 2018-11-6

评论： Yuxing Zhang 2018-11-6

I have a 80×80 matrix A and divide it into 16 blocks of size 20x20, by

A=rand(80,80);
C= mat2cell(A,[20 20 20 20 ],[20 20 20 20]);

And I want to index these blocks in order from 1 to 16 like the figure shows, how can I do this?

Any help will be excellent!

Answer 1

Stephen23 2018-11-6

编辑：Stephen23 2018-11-6

Actually you can already access it like you want, using linear indexing. Try it:

C{1}
C{2}
...
C{16}

Here is a demonstration using the second-to-last cell, C{15}:

>> A = rand(80,80);
>> C = mat2cell(A,[20,20,20,20],[20,20,20,20]);
>> isequal(C{15},A(41:60,61:80))
ans = 1

Stephen23 2018-11-6

If this is related to your earlier question:

Then all you need is this:

C = mat2cell(...)
C(:) = C(V);
new = cell2mat(C)

Yuxing Zhang 2018-11-6

yeah, I do get, thank you.