MATLAB: Use values of array as indices for different array

arrayindexingmatrix arraymatrix manipulation

I have two matrices, A, B, and C, shown below:
A = [16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1];
B = [1 3
2 3
1 4];
C = [1 3 4];
I want to use the elements of B and C as indices of A to create a new matrix, D, such that each element in C corresponds to a row index in A, and the values in each row of B correspond to column indices given the row index from C. e.g. C(1) = 1 and B(1,:) = [1 3] gives me D(1,:) = A(1,[1 3]). The resulting matrix D would look as follows:
D = [16 3
7 6
4 1];
This is relatively straightforward with a for-loop, but I was hoping for a one-line solution along the lines of A(C,B) = D, which doesn't do what I'm describing in MATLAB. Does anything like what I'm describing exist?

Best Answer

  • D = A(sub2ind(size(A),repmat(C(:),1,size(B,2)),B))