在矩阵中查找指数的某些值

Question

I have two vectors which are of same length M and N. The values of the vectors represent the indices of another matrix A so that the corresponding indices in vector M and N make index pairs of A.

For example I have matrices

M=[1 2 3 4] and N=[5 6 7 8]

I would like to find the values of specific indices in matrix A and store them to another vector I, like this:

I = [A(1,5) A(2,6) A(3,7) A(4,8)]

How could this be done?

Answer 1

You can convert them to linear indices using sub2ind and then use those linear indices to index A :

ind = sub2ind(size(A), M(:), N(:));
I = A(ind);

Note I've gone M(:) as this guarantees that M will be a column vector