为什么on语句创建一个6x6数组，而其他语句创建一个1x6数组

Question

另一个超级noob问题 为什么

a = [["?" for i in range(6)] for i in range(6)]

创建一个6x6阵列，带有单独的“？”s

print(a)

给予

[['?', '?', '?', '?', '?', '?'], ['?', '?', '?', '?', '?', '?'], ['?', '?', '?', '?', '?', '?'], ['?', '?', '?', '?', '?', '?'], ['?', '?', '?', '?', '?', '?'], ['?', '?', '?', '?', '?', '?']]

但是

a = [["?" * 6] *6]

一起创建带有“”的a1x6阵列

print(a)

给予

[['??????', '??????', '??????', '??????', '??????', '??????']]

如何创建6x6而不在声明步骤中使用for循环

Answer 1

如果必须在没有明确的for的情况下执行此操作：

import itertools

>>> s = '?'*6
>>> s
'??????'
>>> q = itertools.repeat(s,6)
>>> list(map(list,q))
[['?', '?', '?', '?', '?', '?'], ['?', '?', '?', '?', '?', '?'],
 ['?', '?', '?', '?', '?', '?'], ['?', '?', '?', '?', '?', '?'],
 ['?', '?', '?', '?', '?', '?'], ['?', '?', '?', '?', '?', '?']]
>>>

或

>>> s
'??????'
>>> z = zip(*itertools.tee(s,6))
>>> list(z)
[('?', '?', '?', '?', '?', '?'), ('?', '?', '?', '?', '?', '?'), ('?', '?', '?', '?', '?', '?'), ('?', '?', '?', '?', '?', '?'), ('?', '?', '?', '?', '?', '?'), ('?', '?', '?', '?', '?', '?')]
>>>