Creation of double columns whose max size is 2 x 2 from a matrix whose size is n>2 x n>2 ( e.g. with n max = 800)
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I need your help. Here is an example of what I want to do:
B = [1 2 3; 4 5 6; 7 8 9]
[m,n] = size(B);
B(m-2:m-1, n-2:n-1)
B(m-1:m , n-2:n-1)
B(m-2:m-1, n-1:n)
B(m-1:m , n-1:n)
Input:
B =
1 2 3
4 5 6
7 8 9
Output:
ans =
1 2
4 5
ans =
4 5
7 8
ans =
2 3
5 6
ans =
5 6
8 9
Can you please show me how I can do this or give me an example to do it automatically, for example for a larger matrix such as B = magic(10) or more?
Thank you!
2 Comments
James Tursa
on 19 Dec 2017
These can easily be created, but what do you intend to do with these sub-matrices downstream in your code? There may be a way to do this downstream processing without physically creating all of these sub-matrices.
Accepted Answer
Harish Ramachandran
on 20 Dec 2017
Edited: Harish Ramachandran
on 20 Dec 2017
B = rand(2,4);
count = 1;
[xdim ydim] = size(B);
for i=1:xdim-1
for j=1:ydim-1
C{count} = B(i:i+1,j:j+1);
count = count+1;
end
end
In this case, the resultant output will be a cell array with each cell block (C{1}, C{2}...) a distinct 2x2 sub component of the input matrix.
4 Comments
Harish Ramachandran
on 20 Dec 2017
Also, I have edited the code above to make sure it works for non square matrix.
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