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在列表的子集上使用list.reverse()。“NoneType”对象不可迭代。
原标题:Using list.reverse() on a subset of a list. "NoneType" object is not iterable
  • 时间:2010-02-20 03:09:44
  •  标签:
  • python
  • list

因此,我正尝试将另一个列表的子集的反向附加到一个列表中。由于某些原因,解释器似乎不太喜欢它。这就是我正在做的。

list1.extend(list2[someInt:someOtherInt].reverse())

为什么这不是合法的?对我来说,这似乎是合理的。

最佳回答

除了Ignacio的答案,这里有一个解决方案。请尝试:

list1.extend(reversed(list2[someInt:someOtherInt]))

或者,您可以使用具有反向索引的切片,但要注意偏移量误差!

list1.extend(list2[someOtherInt - 1: someInt - 1: -1])

最好还是坚持使用第一种方法,因为第二种方法在0索引的情况下会失败。

reversed 相关,另一个技巧是,你可以使用 sorted(list1) 而不是 list1.sort()

问题回答

list方法在原地操作,意味着它们返回None





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