迭代时从集合中删除项目 [英] delete items from a set while iterating over it

问题描述

我有一个集合 myset，我有一个函数可以迭代它以对其项目执行一些操作，这个操作最终会从集合中删除项目.

显然，我无法在迭代原始集合的同时做到这一点.但是，我可以这样做:

mylist = list(myset)对于 mylist 中的项目:#做某事

有没有更好的方法?

解决方案

首先，使用集合，正如零比雷埃夫斯告诉我们的，你可以

myset = set([3,4,5,6,2])而我的:myset.pop()打印(我的)

我添加了一个 print 方法来提供这些输出

<预><代码>>>>设置([3, 4, 5, 6])设置([4, 5, 6])设置([5, 6])设置([6])放([])

如果你想坚持你对列表的选择，我建议你使用列表理解深度复制列表，并循环复制，同时从原始列表中删除项目.在我的示例中，我在每个循环中减少原始列表的长度.

l = list(myset)l_copy = [x for x in l]对于 l_copy 中的 k:l = l[1:]打印(升)

给予

<预><代码>>>>[3, 4, 5, 6][4, 5, 6][5, 6][6][]

I have a set myset, and I have a function which iterates over it to perform some operation on its items and this operation ultimately deletes the item from the set.

Obviously, I cannot do it while still iterating over the original set. I can, however, do this:

mylist = list(myset)
for item in mylist:
    # do sth

Is there any better way?

解决方案

First, using a set, as Zero Piraeus told us, you can

myset = set([3,4,5,6,2])
while myset:
    myset.pop()
    print(myset)

I added a print method giving these outputs

>>> 
set([3, 4, 5, 6])
set([4, 5, 6])
set([5, 6])
set([6])
set([])

If you want to stick to your choice for a list, I suggest you deep copy the list using a list comprehension, and loop over the copy, while removing items from original list. In my example, I make length of original list decrease at each loop.

l = list(myset)
l_copy = [x for x in l]
for k in l_copy:
    l = l[1:]
    print(l)

gives

>>> 
[3, 4, 5, 6]
[4, 5, 6]
[5, 6]
[6]
[]

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