3d Matrix to 2d Matrix matlab

Question

I am using Matlab R2014a.

I have a 3-dimensional M x N x M matrix A. I would like a vectorized way to extract a 2 dimensional matrix B from it, such that for each i,j I

Answer 1

Try using sub2ind. This assumes g is defined as an MxN matrix with possible values 1, ..., M:

[ii, jj] = ndgrid(1:M, 1:N);
B = A(sub2ind([M N M], ii, jj, g));