Python's sum vs. NumPy's numpy.sum

Question

What are the differences in performance and behavior between using Python\'s native sum function and NumPy\'s numpy.sum? sum works on

Answer 1

Note that Python sum on multidimensional numpy arrays will only perform a sum along the first axis:

sum(np.array([[[2,3,4],[4,5,6]],[[7,8,9],[10,11,12]]]))
Out[47]: 
array([[ 9, 11, 13],
       [14, 16, 18]])

np.sum(np.array([[[2,3,4],[4,5,6]],[[7,8,9],[10,11,12]]]), axis=0)
Out[48]: 
array([[ 9, 11, 13],
       [14, 16, 18]])

np.sum(np.array([[[2,3,4],[4,5,6]],[[7,8,9],[10,11,12]]]))
Out[49]: 81