import numpy as np
#Syntax:
numpy.sum(a, axis=None, dtype=None, out=None, keepdims=)
计算中所有元素的值
Example:
a = [1,2]
print np.sum(a)
#3
a = np.matrix('1,2;3,4')
print np.sum(a)
#10
print np.sum(a, axis=0)
#[4, 6]
print np.sum(a, axis = 1)
#[3, 7]