python sum the columns in 2D list

Python 二维数组按列求和

1.不使用 numpy

col_totals = [ sum(x) for x in zip(*my_list) ]

[stackoverflow] How do I sum the columns in 2D list?

2.使用 numpy

import numpy as np
a = [1, 2, 3]
b = np.array(a)

c = np.ndarray.tolist(b)

numpy数组与python的list类型的互换

>>> x = np.array([[1, 1], [2, 2]])
>>> x
    array([[1, 1],
           [2, 2]])
>>> x.sum(axis=0) 
    array([3, 3])

对Numpy数组按axis运算的理解