如何创建只有一个元素的 Python 集？
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How do I create a Python set with only one element?
提问by Thalecress
If I have a string, and want to create a set that initially contains onlythat string, is there a more Pythonic approach than the following?
如果我有一个字符串，并且想创建一个最初只包含该字符串的集合，是否有比以下更 Pythonic 的方法？
mySet = set()
mySet.add(myString)
The following gives me a set of the letters in myString:
下面给了我一组 中的字母myString：
mySet = set(myString)
采纳答案by dstromberg
In 2.7 as well as 3.x, you can use:
在 2.7 和 3.x 中，您可以使用：
mySet = {'abc'}
回答by Anatoly Scherbakov
For example, this easy way:
例如，这个简单的方法：
mySet = set([myString])
回答by Ashwini Chaudhary
set_display ::= "{" (expression_list | comprehension) "}"
Example:
例子：
>>> myString = 'foobar'
>>> s = {myString}
>>> s
set(['foobar'])
>>> s = {'spam'}
>>> s
set(['spam'])
Note that an empty {}is not a set, its a dict.
请注意，空{}不是 a set，而是a dict。
Help on set:
帮助set：
class set(object)
| set() -> new empty set object
| set(iterable) -> new set object
As you can see set()expects an iterable and strings are iterable too, so it converts the string characters to a set.
正如您所看到的，set()期望一个可迭代的，而字符串也是可迭代的，因此它将字符串字符转换为一个集合。
Put the string in some iterable and pass it to set():
将字符串放入一些可迭代对象并将其传递给set()：
>>> set(('foo',)) #tuple
set(['foo'])
>>> set(['foo']) #list
set(['foo'])
回答by Simeon Visser
If the set also isn't likely to change, consider using a frozenset:
如果集合也不太可能改变，请考虑使用frozenset：
mySet = frozenset([myString])
回答by SzieberthAdam
set(obj)is going to iterate trough objand add all unique elements to the set. Since strings are also iterable, if you pass a string to set()then you get the unique letters in your set. You can put your obj to a list first:
set(obj)将迭代槽obj并将所有唯一元素添加到集合中。由于字符串也是可迭代的，如果您将字符串传递给，set()那么您将获得集合中的唯一字母。您可以先将 obj 放入列表：
set(["mystring"])
However that is not elegant IMO. You know, even for the creation of an empty dictionary we prefer {}over dict(). Same here. I wolud use the following syntax:
然而，这不是优雅的 IMO。要知道，即使是创造我们更喜欢一个空的字典{}了dict()。同样在这里。我会使用以下语法：
myset = {"mystring"}
Note that for tuples, you need a comma after it:
请注意，对于元组，后面需要一个逗号：
mytuple = ("mystring",)
回答by matt2000
use mySet = {mystring}
用 mySet = {mystring}
Python 3.6.9 (default, Sep 24 2019, 14:35:19)
Type 'copyright', 'credits' or 'license' for more information
IPython 7.8.0 -- An enhanced Interactive Python. Type '?' for help.
In [1]: def s(i):
...: r = set()
...: r.add(i)
...: return r
...:
In [2]: %timeit s(1234)
218 ns ± 5.99 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
In [3]: %timeit set([1234])
201 ns ± 3 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)
In [4]: %timeit {1234}
51.7 ns ± 1.7 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)
