Frozenset

What is a Frozenset?

A frozenset in Python is an immutable version of a set. This means once a frozenset is created, its elements cannot be changed, added, or removed. It's created using the frozenset() function.

Creating a Frozenset

Python

my_frozenset = frozenset([1, 2, 3, "apple"])

Key Characteristics

• Immutable: Elements cannot be added, removed, or modified once created.

• Unordered: Like sets, frozensets do not maintain a specific order of elements.

• Unique elements: Duplicate elements are automatically removed.

• Hashable: Frozensets can be used as dictionary keys due to their immutability and hashability.

Use Cases

• Dictionary keys: Since frozensets are immutable and hashable, they can be used as dictionary keys.

• Set operations: Frozensets support set operations like union, intersection, difference, and symmetric difference.

• Constant data: When you have data that should not be modified, frozensets can be used to ensure data integrity.

Example

Python

my_frozenset = frozenset([1, 2, 3])

print(my_frozenset)  # Output: frozenset({1, 2, 3})

# Trying to modify (will raise an error)

# my_frozenset.add(4)  # AttributeError: 'frozenset' object has no attribute 'add'

# Set operations

set1 = {1, 2, 3, 4}

intersection = set1 & my_frozenset

print(intersection)  # Output: frozenset({1, 2, 3})

Comparison with Sets

In essence, frozensets provide a way to create unmodifiable sets, which can be useful in various scenarios where data integrity is crucial.