Tell about the set data type.

The set data type in Python represents an unordered collection of unique elements.

Main properties:

• Unordered: Elements in a set do not have a fixed order.
• Uniqueness: Each value can appear in the set only once.
• Mutable: Sets can add and remove elements (except frozenset).
• Elements must be hashable: Immutable data types (numbers, strings, tuples) are supported. Mutable types (lists, dictionaries) cannot be used.

Creation:

# Creating an empty set
empty_set = set()

# Creating a set from a list
my_list = [1, 2, 3, 2, 4]
set_from_list = set(my_list) # set_from_list will be {1, 2, 3, 4}

# Creating a set using curly braces
direct_set = {5, 6, 7}

Main operations:

Operation	Method	Description
Add element	add(element)	Adds element to the set.
Remove element	remove(element)	Removes element. Raises an error if not present.
Discard element	discard(element)	Removes element. Does nothing if not present.
Union	union(), `	`
Intersection	intersection(), &	Returns a new set with common elements.
Difference	difference(), -	Returns elements in the first set not in the second.
Symmetric difference	symmetric_difference(), ^	Returns elements in only one of the sets.
Check presence	in	Boolean indicating if an element is in the set.

Usage examples:

set1 = {1, 2, 3, 4}
set2 = {3, 4, 5, 6}

# Union
union_set = set1.union(set2) # union_set = {1, 2, 3, 4, 5, 6}

# Intersection
intersection_set = set1 & set2 # intersection_set = {3, 4}

# Difference
difference_set = set1 - set2 # difference_set = {1, 2}

# Check presence
is_present = 3 in set1 # is_present = True

Application in QA:

• Finding duplicates in data lists.
• Comparing two result sets (e.g., expected vs. actual).
• Filtering unique elements from a sequence.
• Checking for the presence of an element in a large data collection (fast search).

frozenset: Immutable version of a set. Used when an unchangeable set is needed (e.g., as a dictionary key).