将列表转换为集合会改变元素的顺序吗? [英] Does converting a list to a set change the order of elements?

问题描述

当我做类似的事情时:

U = [(1.0, 0.0), (0.0, 1.0)]
set(U)

它给了我:

{(0.0, 1.0), (1.0, 0.0)}

我只想将列表转换为一组.有帮助吗?

I just want to convert the list into a set. Any help?

谢谢

推荐答案

不对集合进行排序.也不对字典进行排序.如果要保留特定顺序，请使用列表.

Sets are not ordered. Dictionaries are not ordered either. If you want to preserve a specific order, then use a list.

>>> ''.join(set("abcdefg"))
'acbedgf'
>>> ''.join(set("gfedcba"))
'acbedgf'
>>> ''.join(set("1234567"))
'1325476'
>>> ''.join(set("7654321"))
'1325476'

很显然，当您遍历一组 some 时，必须发出某种命令.但是该顺序是您无法指定的任意顺序.

Obviously, when you iterate over a set some kind of order has to come out. But the order is an arbitrary order which you cannot specify.

这是我的最爱:

>>> {'apple', 'banana'}
{'banana', 'apple'}
>>> {'banana', 'apple'}
{'apple', 'banana'}

该顺序受哈希冲突的影响，因此它不仅取决于集合的内容，而且还取决于插入的顺序.但是您无法真正控制订单.

The order is affected by hash collisions, so it's not only dependent on the contents of the set but the order of insertion too. But you have no real control over the order.

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