在列表中重复列表X次 [英] Repeat a list within a list X number of times

问题描述

我正在做一个项目，因此我需要在列表中重复列表多次.显然，L.append(L)只是在不创建单独列表的情况下再次添加了元素.我只是对如何使列表在大列表中分开感到困惑.

I'm working on a project and I need to repeat a list within a list a certain number of times. Obviously, L.append(L) just adds the elements again without creating separate lists. I'm just stumped on how to make the lists separate within the big list.

简而言之，这就是我所拥有的:

In short form, this is what I have:

L = [1,2,3,4,5]

如果我想重复一遍，说3次，这样我就可以了:

If I wanted to to repeat it, say, 3 times so I'd have:

L = [[1,2,3,4,5],[1,2,3,4,5],[1,2,3,4,5]]

我该如何实现?我正在寻找大名单中的名单.

How do I achieve this? I'm looking for lists within the big list.

推荐答案

无需任何功能:

>>> L = [1,2,3,4,5]
>>> [L]*3
[[1, 2, 3, 4, 5], [1, 2, 3, 4, 5], [1, 2, 3, 4, 5]]

但是，您应该注意，如果您更改任何一个列表中的一个值，其他所有都将更改，因为它们引用了相同的对象.

However, you should note that if you change one value in any of the lists, all the others will change because they reference the same object.

>>> mylist = [L]*3
>>> mylist[0][0] = 6
>>> print mylist
[[6, 2, 3, 4, 5], [6, 2, 3, 4, 5], [6, 2, 3, 4, 5]]
>>> print L
[6, 2, 3, 4, 5]

为避免这种情况:

>>> L = [1,2,3,4,5]
>>> mylist = [L[:] for _ in range(3)]
>>> mylist[0][0] = 6
>>> print L
[1, 2, 3, 4, 5]
>>> print mylist
[[6, 2, 3, 4, 5], [1, 2, 3, 4, 5], [1, 2, 3, 4, 5]]

请注意L的更改方式，只有mylist中的第一个列表更改了.

Notice how L didn't change, and only the first list in mylist changed.

感谢评论中的每个人都对您有帮助:).

Thanks everyone in the comments for helping :).

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