Direct way to generate sum of all parallel diagonals in Numpy / Pandas?

Question

I have a rectangular (can\'t be assumed to be square) Pandas DataFrame of numbers. Say I pick a diagonal direction (either \"upperleft to lowerright\" or \"upperright to lowerl

Answer 1

For a 2D numpy array A this might be (?) the shortest code to sum diagonals:

np.bincount(sum(np.indices(A.shape)).flat, A.flat)

To sum the opposite diagonals, you can np.fliplr the array.