使用{}从列表创建集合 [英] Create a set from a list using {}

问题描述

有时候我有一个列表，我想用它做一些设定的动作.我要做的是写这样的东西:

Sometimes I have a list and I want to do some set actions with it. What I do is to write things like:

>>> mylist = [1,2,3]
>>> myset = set(mylist)
{1, 2, 3}

今天我发现从Python 2.7中，您还可以通过直接说{1,2,3}来定义集合，这似乎是定义它的等效方法.

Today I discovered that from Python 2.7 you can also define a set by directly saying {1,2,3}, and it appears to be an equivalent way to define it.

然后，我想知道是否可以使用此语法从给定列表中创建一个集合.

Then, I wondered if I can use this syntax to create a set from a given list.

{list}失败，因为它试图创建仅包含一个元素(列表)的集合.而且列表是不可散列的.

{list} fails because it tries to create a set with just one element, the list. And lists are unhashable.

>>> mylist = [1,2,3]
>>> {mylist}
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'

所以，我想知道:是否可以使用{}语法而不是set()从列表中创建集合?

So, I wonder: is there any way to create a set out of a list using the {} syntax instead of set()?

推荐答案

我最近问了一个相关问题:

I asked a related question recently: Python Set: why is my_set = {*my_list} invalid?. My question contains your answer if you are using Python 3.5

>>> my_list = [1,2,3,4,5]
>>> my_set = {*my_list}
>>> my_set
   {1, 2, 3, 4, 5}

它在Python 2上不起作用(这是我的问题)

It won't work on Python 2 (that was my question)

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