英文:
Iteratively remove one item at a time from a Python list
问题
我觉得我不明白Python中的.remove()方法如何工作。
我有这个片段。b 变量的目的是在每次迭代中拥有一个不受影响的 a 列表的副本，但它并没有按照我期望的方式工作：
a = [0, 1, 2, 3, 4, 5]
for i in a:
b = a.copy()
a_i = b.remove(i)
print(a_i)
我期望以下结果：
[1, 2, 3, 4, 5]
[0, 2, 3, 4, 5]
[0, 1, 3, 4, 5]
[0, 1, 2, 4, 5]
[0, 1, 2, 3, 5]
[0, 1, 2, 3, 4]
但实际上我得到了：
None
None
None
None
None
我的误解在哪里？
注意：我需要一个for循环格式的答案，因为这是我的代码的一部分的简化。
编辑：原始版本的代码片段中有一行 b = a，而不是 b = a.copy()。我已经纠正了它（谢谢），但我仍然得到一组 None 的数组。
英文:
I think I do not understand how the .remove() method works in Python.
I have this snippet. The point of the b variable is to have an untouched copy of the a list in every iteration, but it is not working as I expected:
a = [0, 1, 2, 3, 4, 5]
for i in a:
b = a.copy()
a_i = b.remove(i)
print(a_i)
I would expect the following outcome:
[1, 2, 3, 4, 5]
[0, 2, 3, 4, 5]
[0, 1, 3, 4, 5]
[0, 1, 2, 4, 5]
[0, 1, 2, 3, 5]
[0, 1, 2, 3, 4]
And instead I get:
None
None
None
None
None
Where is my misconception?
NOTE: I need an answer in a for loop format because this is a simplification of a bigger part of my code.
EDIT: The original version of the snippet had a b = a line instead of b = a.copy(). I corrected that (thanks) but I am still getting an array of None's.
答案1
得分: 1
考虑这个答案：
https://stackoverflow.com/a/10665602/21445669
似乎问题是因为你在迭代过程中移除了元素。可能由于引用语义，将a赋值给b并不会创建一个独立的对象，这与你预期的不同。
尝试使用这个：
b = a.copy() 而不是 b = a。
此外，.remove() 方法的返回值是 None！实际上，你希望在b.remove(i)之后的行中 print(b)。
英文:
Consider this answer:
https://stackoverflow.com/a/10665602/21445669
Seems like the issue comes from removing elements of something you are iterating over. Probably assigning a to b doesn't create an independent object like you would expect due to reference semantics.
Try including this:
b = a.copy() instead of b = a.
Furthermore - the return value of the .remove() method is None! You actually want to print(b) in the line after b.remove(i)
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论