Python中的frozenset()

freezeset()是Python中的一个内置函数，它接受一个可迭代对象作为输入并使它们不可变。简单地说，它冻结了可迭代对象并使它们不可更改。

在Python中，frozenset 与 set 相同，只是 freezeset 是不可变的，这意味着 freezeset 中的元素一旦创建就不能添加或删除。此函数将输入作为任何可迭代对象并将它们转换为不可变对象。不保证保留元素的顺序。

Syntax : frozenset(iterable_object_name)
Parameter : This function accepts iterable object as input parameter.
Return Type: This function return an equivalent frozenset object.

下面的例子清楚地解释了它。

示例 #1：
如果没有参数传递给 freezeset()函数，则它返回一个空的 freezeset 类型对象。

Python3

# Python program to understand frozenset() function
 
# tuple of numbers
nu = (1, 2, 3, 4, 5, 6, 7, 8, 9)
 
# converting tuple to frozenset
fnum = frozenset(nu)
 
# printing details
print("frozenset Object is : ", fnum)

输出：

frozenset Object is :  frozenset({1, 2, 3, 4, 5, 6, 7, 8, 9})

示例 #2：frozenset() 的使用。
由于frozenset 对象是不可变的，它们主要用作字典中的键或其他集合的元素。下面的例子清楚地解释了它。

Python3

# Python program to understand use
# of frozenset function
 
# creating a dictionary
Student = {"name": "Ankit", "age": 21, "sex": "Male",
           "college": "MNNIT Allahabad", "address": "Allahabad"}
 
# making keys of dictionary as frozenset
key = frozenset(Student)
 
# printing keys details
print('The frozen set is:', key)

输出：

The frozen set is: frozenset({'sex', 'age', 'address', 'name', 'college'})

示例 #3：警告
如果我们错误地想要更改freezeset对象，则会引发错误“ 'frozenset' object does not support item assignment ”。

Python3

# Python program to understand
# use of frozenset function
 
# creating a list
favourite_subject = ["OS", "DBMS", "Algo"]
 
# making it frozenset type
f_subject = frozenset(favourite_subject)
 
# below line will generate error
 
f_subject[1] = "Networking"

输出：

Traceback (most recent call last):
  File "/home/0fbd773df8aa631590ed0f3f865c1437.py", line 12, in 
    f_subject[1] = "Networking"
TypeError: 'frozenset' object does not support item assignment