37 lines
1.6 KiB
Markdown
37 lines
1.6 KiB
Markdown
---
|
||
title: Python Frozenset
|
||
localeTitle: Python Frozenset
|
||
---
|
||
**`frozenset`基本信息** `frozenset`类型是一个内置的集合类型,它是不可变的和可散列的 - 它的内容在创建后不能被改变;但是,它可以用作字典键或另一组的元素。 Frozensets就像套装一样,只是它们不能改变,即它们是不变的。
|
||
```
|
||
>>> cities = frozenset(["Frankfurt", "Basel", "Freiburg"])
|
||
>>> cities.add("Strasbourg")
|
||
Traceback (most recent call last):
|
||
File "<stdin>", line 1, in <module>
|
||
AttributeError: 'frozenset' object has no attribute 'add'
|
||
>>>
|
||
```
|
||
|
||
`frozenset`构造函数: `frozenset([iterable])` iterable包含用于初始化frozenset的元素。可以设置iterable,dictionary,tuple等。如果没有传递参数, `frozenset()`方法返回一个空的冻结集。
|
||
|
||
**例子**
|
||
```
|
||
>>> vowels = ('a', 'e', 'i', 'o', 'u')
|
||
>>> fSet = frozenset(vowels)
|
||
>>> print("The frozen set is: ", fSet)
|
||
The frozen set is: frozenset({'i', 'e', 'a', 'u', 'o'})
|
||
>>> print("The empty frozen set is: ", frozenset())
|
||
The empty frozen set is: frozenset()
|
||
>>>
|
||
```
|
||
|
||
**另一个例子**
|
||
```
|
||
>>> person = {"name": "John", "age": 23, "sex": "male"}
|
||
>>> fSet = frozenset(person)
|
||
>>> print("The frozen set is: ", fSet)
|
||
The frozen set is: frozenset({'sex', 'name', 'age'})
|
||
>>>
|
||
```
|
||
|
||
**附加信息** [Python Frozenset()](https://www.programiz.com/python-programming/methods/built-in/frozenset) [设置类型 - 设置,冷冻设置](https://docs.python.org/2.4/lib/types-set.html) [Python教程:集合和冻结集](https://www.python-course.eu/sets_frozensets.php) |