Python3 创建数组

python3 
Python 3.7.4 (default, Aug 13 2019, 20:35:49) 
[GCC 7.3.0] :: Anaconda, Inc. on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> len =5
>>> matrix = [None]*len
>>> print(matrix)
[None, None, None, None, None]

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
matrix = [None]*2
for i in range(len(matrix)): 
  matrix[i] = [0]*3
print(matrix) 

运行结果：
[[0, 0, 0], [0, 0, 0]]