Einsum Basics
import numpy as np
a = np.array([1, 2, 3, 4])
a
array([1, 2, 3, 4])
b = np.array([5, 6, 7, 8])
b
array([5, 6, 7, 8])
# Sum of array a
np.einsum('i->', a)
10
More
http://ajcr.net/Basic-guide-to-einsum/
https://stackoverflow.com/questions/26089893/understanding-numpys-einsum
http://numpy-discussion.10968.n7.nabble.com/einsum-td11810.html