Frozen set is just an immutable version of a Python set object. While elements of a set can be modified at any time, elements of the frozen set remain the same after creation.
Due to this, frozen sets can be used as keys in Dictionary or as elements of another set. But like sets, it is not ordered (the elements can be set at any index).
The syntax of frozenset() function is:
frozenset([iterable])
frozenset() Parameters
The frozenset() function takes a single parameter:
- iterable (Optional) - the iterable which contains elements to initialize the frozenset with.
Iterable can be set, dictionary, tuple, etc.
Return value from frozenset()
The frozenset() function returns an immutable frozenset initialized with elements from the given iterable.
If no parameters are passed, it returns an empty frozenset.
Example 1: Working of Python frozenset()
# tuple of vowels vowels = ('a', 'e', 'i', 'o', 'u') fSet = frozenset(vowels) print('The frozen set is:', fSet) print('The empty frozen set is:', frozenset()) # frozensets are immutable fSet.add('v') Output
The frozen set is: frozenset({'a', 'o', 'u', 'i', 'e'}) The empty frozen set is: frozenset() Traceback (most recent call last): File "<string>, line 8, in <module> fSet.add('v') AttributeError: 'frozenset' object has no attribute 'add' Example 2: frozenset() for Dictionary
When you use a dictionary as an iterable for a frozen set, it only takes keys of the dictionary to create the set.
# random dictionary person = {"name": "John", "age": 23, "sex": "male"} fSet = frozenset(person) print('The frozen set is:', fSet) Output
The frozen set is: frozenset({'name', 'sex', 'age'}) Frozenset operations
Like normal sets, frozenset can also perform different operations like copy(), difference(), intersection(), symmetric_difference(), and union().
# Frozensets # initialize A and B A = frozenset([1, 2, 3, 4]) B = frozenset([3, 4, 5, 6]) # copying a frozenset C = A.copy() # Output: frozenset({1, 2, 3, 4}) print(C) # union print(A.union(B)) # Output: frozenset({1, 2, 3, 4, 5, 6}) # intersection print(A.intersection(B)) # Output: frozenset({3, 4}) # difference print(A.difference(B)) # Output: frozenset({1, 2}) # symmetric_difference print(A.symmetric_difference(B)) # Output: frozenset({1, 2, 5, 6}) Output
frozenset({1, 2, 3, 4}) frozenset({1, 2, 3, 4, 5, 6}) frozenset({3, 4}) frozenset({1, 2}) frozenset({1, 2, 5, 6}) Similarly, other set methods like isdisjoint(), issubset(), and issuperset() are also available.
# Frozensets # initialize A, B and C A = frozenset([1, 2, 3, 4]) B = frozenset([3, 4, 5, 6]) C = frozenset([5, 6]) # isdisjoint() method print(A.isdisjoint(C)) # Output: True # issubset() method print(C.issubset(B)) # Output: True # issuperset() method print(B.issuperset(C)) # Output: True Output
True True True