对序列使用+和*

1、nparray显然更适合数据分析与科学计算

import numpy as np
a=np.array([[[1,2,3],[4,5,6]],[[7,8,9],[10,11,12]]])
b=[[[1,2,3],[4,5,6]],[[7,8,9],[10,11,12]]]
a*5
Out[53]: 
array([[[ 5, 10, 15],
        [20, 25, 30]],

       [[35, 40, 45],
        [50, 55, 60]]])
b*5
Out[55]: 
[[[1, 2, 3], [4, 5, 6]],
 [[7, 8, 9], [10, 11, 12]],
 [[1, 2, 3], [4, 5, 6]],
 [[7, 8, 9], [10, 11, 12]],
 [[1, 2, 3], [4, 5, 6]],
 [[7, 8, 9], [10, 11, 12]],
 [[1, 2, 3], [4, 5, 6]],
 [[7, 8, 9], [10, 11, 12]],
 [[1, 2, 3], [4, 5, 6]],
 [[7, 8, 9], [10, 11, 12]]]

2、nparray可以使用元组作为index，内置的list方法不可以。

a[1,1]
Out[60]: array([10, 11, 12])
b[1,1]
Traceback (most recent call last):

  File "<ipython-input-61-346be69afb77>", line 1, in <module>
    b[1,1]

TypeError: list indices must be integers or slices, not tuple

3、如果使用第一种方法实际三个列表是同一个指针指向的位置

board=[['_']*3]*3

board
Out[67]: [['_', '_', '_'], ['_', '_', '_'], ['_', '_', '_']]

board[1][2]='o'

board
Out[69]: [['_', '_', 'o'], ['_', '_', 'o'], ['_', '_', 'o']]

board=[['_']*3 for i in range(3)] 

board
Out[71]: [['_', '_', '_'], ['_', '_', '_'], ['_', '_', '_']]

board[1][2]='x'

board
Out[73]: [['_', '_', '_'], ['_', '_', 'x'], ['_', '_', '_']]