Matrix position stored in a variable!

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Mohsen Davarynejad
Mohsen Davarynejad 2011-12-11
Suppose A=rand(10,10) and I need to access the following elements in A: A(2,3), A(4,5), A(6,7). If the positions are stored in a variable, d=[2 3; 4 5; 6 7], how the matrix elements can be retrieved?
Well, a simple solution is the following for loop.
for i = 1 : size(b, 1)
A(b(i,1), b(i,2))
end
Any better suggestion?

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Fangjun Jiang
Fangjun Jiang 2011-12-11
A=magic(10);
d=[2 3; 4 5; 6 7];
B=A(sub2ind(size(A),d(:,1),d(:,2)))
Update for any size of d
A=rand(2,3,4);
d=[1 2 3;2,3,4;1,2,4];
[m,n]=size(d);
if ndims(A)~=n
error('Dimension mis-match');
end
ind=mat2cell(d,m,ones(1,n));
B=A(sub2ind(size(A),ind{:}))
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