hi all, i am trying to write a simple product of 3 arrays (as vectorized code) but am having some difficulty. i have three arrays, one is a list containing several lists: p = array([[ 0.2, 0.8], [ 0.5, 0.5], [ 0.3, 0.7]]) each list in the array 'p' is of size N -- in this case N = 2. i have a second array containing a set of numbers, each between 0 and N-1: l = array([0, 0, 1]) and finally an array of the same size as l: s = array([10, 20, 30]) what i want to do is pick the columns l of p, and multiply each one by the numbers in s. the first step, picking columns l of p, is simply: cols = p[arange(3), l] then i want to multiply each one by the numbers in s, and i do it like this: cols * s.reshape(3,1) this seems to work, but i am concerned that it might be inefficient. is there a cleaner way of doing this? is 'arange' operation necessary to reference all the 'l' columns of p? also, is the reshape operation expensive? thanks very much.