为什么我不能分配给特定的元素列表

Question

的名单，我不明白为什么我在下面每个列表分配给第一个元素：

➜ ~ python 
Python 2.7.3 (default, Sep 26 2012, 21:53:58) 
[GCC 4.7.2] on linux2 
Type "help", "copyright", "credits" or "license" for more information. 
>>> board = [[None]*5]*5 
>>> print board 
[[None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None]] 
>>> board[0][0] = 1 
>>> print board 
[[1, None, None, None, None], [1, None, None, None, None], [1, None, None, None, None], [1, None, None, None, None], [1, None, None, None, None]] 

我希望最终输出到是这样的：

[[1, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None], [None, None, None, None, None]] 

Answer 1

你的代码是等效于此：

x = [None]*5 
board = [x for i in range(5)] 

如果你想5个不同的列表，这样做：

board = [[None]*5 for i in range(5)]