[Python] numpy.sum

import numpy as np

#Syntax:
numpy.sum(a, axis=None, dtype=None, out=None, keepdims=<class numpy._globals._NoValue at 0x40b6a26c>)

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]