What is a set in Python?

A set is a mutable, unordered collection of unique elements. Elements must be hashable.

Main characteristics:

• Unordered: Elements are not stored in a specific order.
• Unique: Duplicates are automatically removed.
• Mutable: Elements can be added and removed.
• Hashable: Elements must be immutable types (numbers, strings, tuples).

Examples of creation:

# Creating from a list
my_set = set([1, 2, 3, 1, 4]) # {1, 2, 3, 4}

# Creating using curly braces
another_set = {5, 6, 7, 7} # {5, 6, 7}

# Empty set
empty_set = set() # {}

Main operations:

Operation	Description	Example	Result
add()	Add an element	s.add(10)	{1, 2, 3, 4, 10}
remove()	Remove an element (with error)	s.remove(2)	{1, 3, 4}
discard()	Remove an element (without error)	s.discard(5)	{1, 2, 3, 4}
clear()	Clear the set	s.clear()	{}
`union(	)`	Union	`s1
intersection(&)	Intersection	s1 & s2	{3, 4}
difference(-)	Difference	s1 - s2	{1, 2}
symmetric_difference(^)	Symmetric difference	s1 ^ s2	{1, 2, 5, 6}
issubset(<=)	Subset	s1 <= s2	False
issuperset(>=)	Superset	s1 >= s2	True

Immutable set (frozenset):

Similar to set, but cannot be modified after creation. Elements of a frozenset can be used as elements of other sets or as dictionary keys.

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