Set in Python
Characteristics:
- Unordered: Sets do not maintain any particular order of elements. The order in which elements are added does not necessarily match the order in which they are stored.
- Mutable: Sets can be modified after their creation. You can add or remove elements from a set.
- Unique Elements: Sets automatically remove duplicate elements. Each element in a set must be unique.
- Unindexed: Sets do not support indexing. You cannot access set elements by their position.
- Heterogeneous: Sets can contain elements of different data types, including other sets (but not mutable types like lists or dictionaries).
Syntax:
Sets are defined by placing a comma-separated sequence of values inside curly braces {} or by using the set() function.
my_set = {1, 2, 3}
another_set = set(['a', 'b', 'c'])
You can create sets using curly braces {} or the set() constructor.
Using Curly Braces:
my_set = {1, 2, 3, 4} print(my_set) # Output: {1, 2, 3, 4}Using the
set()Constructor:another_set = set([1, 2, 3, 4]) print(another_set) # Output: {1, 2, 3, 4}
You can add elements to a set using the add() and update() methods.
add(): Adds a single element to the set.
my_set = {1, 2, 3} my_set.add(4) print(my_set) # Output: {1, 2, 3, 4}update(): Adds multiple elements to the set. Accepts any iterable.
my_set = {1, 2, 3} my_set.update([4, 5]) print(my_set) # Output: {1, 2, 3, 4, 5}
You can remove elements using the remove(), discard(), and pop() methods.
remove(): Removes a specified element. Raises a
KeyErrorif the element is not found.my_set = {1, 2, 3, 4} my_set.remove(3) print(my_set) # Output: {1, 2, 4}discard(): Removes a specified element. Does not raise an error if the element is not found.
my_set = {1, 2, 3, 4} my_set.discard(3) print(my_set) # Output: {1, 2, 4}pop(): Removes and returns an arbitrary element from the set. Raises a
KeyErrorif the set is empty.my_set = {1, 2, 3, 4} element = my_set.pop() print(element) # Output: (One of the elements from the set) print(my_set) # Output: (Remaining elements in the set)clear(): Removes all elements from the set.
my_set = {1, 2, 3, 4} my_set.clear() print(my_set) # Output: set()
Set Operations
Sets support various mathematical operations like union, intersection, difference, and symmetric difference.
union(): Returns a set containing all elements from both sets.
set1 = {1, 2, 3} set2 = {3, 4, 5} union_set = set1.union(set2) # or a | b print(union_set) # Output: {1, 2, 3, 4, 5}intersection(): Returns a set containing only the common elements between sets.
set1 = {1, 2, 3} set2 = {2, 3, 4} intersection_set = set1.intersection(set2) # (or) a & b print(intersection_set) # Output: {2, 3}difference(): Returns a set containing elements that are in the first set but not in the second set.
set1 = {1, 2, 3} set2 = {2, 3, 4} difference_set = set1.difference(set2) # or a-b print(difference_set) # Output: {1}symmetric_difference(): Returns a set containing elements that are in either set, but not in both.
set1 = {1, 2, 3} set2 = {2, 3, 4} sym_diff_set = set1.symmetric_difference(set2) # (or) a ^ b print(sym_diff_set) # Output: {1, 4}
# Creating setss1 = {1, 2, 3, 4}s2 = {3, 4, 5, 6}print(s1) # Output: {1, 2, 3, 4}print(s2) # Output: {3, 4, 5, 6}# Adding elementss1.add(5)print(s1) # Output: {1, 2, 3, 4, 5}# Removing elementss1.remove(5)print(s1) # Output: {1, 2, 3, 4}# Unionprint(s1.union(s2)) # Output: {1, 2, 3, 4, 5, 6}# Intersectionprint(s1.intersection(s2)) # Output: {3, 4}# Differenceprint(s1.difference(s2)) # Output: {1, 2}# Symmetric Differenceprint(s1.symmetric_difference(s2)) # Output: {1, 2, 5, 6}# Membership testprint(2 in s1) # Output: Trueprint(7 in s1) # Output: False# Subset, Superset, and Disjoints3 = {1, 2}print(s3.issubset(s1)) # Output: Trueprint(s1.issuperset(s3)) # Output: Trueprint(s1.isdisjoint({6, 7})) # Output: True
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