1. Creating a Set

Sets are created using curly braces {} or the set() constructor.

Syntax:

my_set = {item1, item2, item3, ...}
# or
my_set = set([item1, item2, item3, ...])

Example:

fruits = {"apple", "banana", "cherry"}
print(fruits)

Output:

{'apple', 'banana', 'cherry'}

Real-world Example:

Dodagatta Nihar creates a set of his favorite hobbies:

hobbies = {"reading", "cycling", "painting"}
print(hobbies)

Output:

{'painting', 'reading', 'cycling'}

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2. Accessing Set Items

Sets do not support indexing or slicing, so you cannot access items by position. However, you can check for membership using the in keyword and iterate through a set.

Syntax:

item in my_set

Example:

fruits = {"apple", "banana", "cherry"}
print("banana" in fruits)

Output:

True

Real-world Example:

Harsha checks if a specific color is in his set of favorite colors:

favorite_colors = {"blue", "green", "red"}
print("blue" in favorite_colors)

Output:

True

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3. Adding and Removing Items

You can add items to a set using the add() method and remove items using the remove() or discard() methods. The remove() method raises an error if the item is not found, while discard() does not.

Adding Items:

fruits = {"apple", "banana"}
fruits.add("cherry")
print(fruits)

Output:

{'apple', 'banana', 'cherry'}

Removing Items:

fruits = {"apple", "banana", "cherry"}
fruits.remove("banana")
print(fruits)

Output:

{'apple', 'cherry'}

Using discard():

fruits = {"apple", "banana", "cherry"}
fruits.discard("orange")  # No error even if "orange" is not in the set
print(fruits)

Output:

{'apple', 'banana', 'cherry'}

Real-world Example:

Vasanta Kumar adds and removes items from a set of his favorite movies:

movies = {"Inception", "Interstellar", "The Matrix"}
movies.add("Tenet")
movies.remove("The Matrix")
print(movies)

Output:

{'Inception', 'Tenet', 'Interstellar'}

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4. Set Operations

Sets support several mathematical operations, such as union, intersection, difference, and symmetric difference.

Union:

Combines all unique elements from both sets.

set1 = {1, 2, 3}
set2 = {3, 4, 5}
union_set = set1 | set2
print(union_set)

Output:

{1, 2, 3, 4, 5}

Intersection:

Returns elements that are present in both sets.

set1 = {1, 2, 3}
set2 = {3, 4, 5}
intersection_set = set1 & set2
print(intersection_set)

Output:

{3}

Difference:

Returns elements that are in the first set but not in the second set.

set1 = {1, 2, 3}
set2 = {3, 4, 5}
difference_set = set1 - set2
print(difference_set)

Output:

{1, 2}

Symmetric Difference:

Returns elements that are in either of the sets, but not in both.

set1 = {1, 2, 3}
set2 = {3, 4, 5}
symmetric_difference_set = set1 ^ set2
print(symmetric_difference_set)

Output:

{1, 2, 4, 5}

Real-world Example:

Praveen performs set operations with his collection of books:

collection1 = {"Book A", "Book B", "Book C"}
collection2 = {"Book C", "Book D", "Book E"}

# Union
all_books = collection1 | collection2
print("All Books:", all_books)

# Intersection
common_books = collection1 & collection2
print("Common Books:", common_books)

# Difference
unique_books = collection1 - collection2
print("Unique to Collection 1:", unique_books)

# Symmetric Difference
exclusive_books = collection1 ^ collection2
print("Exclusive Books:", exclusive_books)

Output:

All Books: {'Book A', 'Book B', 'Book D', 'Book E', 'Book C'}
Common Books: {'Book C'}
Unique to Collection 1: {'Book A', 'Book B'}
Exclusive Books: {'Book A', 'Book B', 'Book D', 'Book E'}

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5. Set Methods

Sets have several useful methods for modifying and querying their contents, such as copy(), clear(), and pop().

Using copy():

Returns a shallow copy of the set.

fruits = {"apple", "banana", "cherry"}
fruits_copy = fruits.copy()
print(fruits_copy)

Output:

{'apple', 'banana', 'cherry'}

Using clear():

Removes all elements from the set.

fruits = {"apple", "banana", "cherry"}
fruits.clear()
print(fruits)

Output:

set()

Using pop():

Removes and returns a random element from the set. Raises a KeyError if the set is empty.

fruits = {"apple", "banana", "cherry"}
popped_item = fruits.pop()
print(f"Removed item: {popped_item}")
print(fruits)

Output:

Removed item: apple
{'banana', 'cherry'}

Real-world Example:

Harsha uses set methods to manage his collection of tech gadgets:

gadgets = {"Smartphone", "Laptop", "Tablet"}
gadgets_copy = gadgets.copy()
gadgets.clear()
print("Original Gadgets:", gadgets_copy)
print("Cleared Gadgets:", gadgets)

Output:

Original Gadgets: {'Smartphone', 'Laptop', 'Tablet'}
Cleared Gadgets: set()

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Few more examples

Example 1: Creating and Accessing a Set

numbers = {1, 2, 3, 4, 5}
print(numbers)
print(3 in numbers)

Output:

{1, 2, 3, 4, 5}
True

Example 2: Adding and Removing Items

numbers = {1, 2, 3}
numbers.add(4)
numbers.remove(2)
print(numbers)

Output:

{1, 3, 4}

Example 3: Set Operations

a = {1, 2, 3}
b = {3, 4, 5}
print("Union:", a | b)
print("Intersection:", a & b)
print("Difference:", a - b)
print("Symmetric Difference:", a ^ b)

Output:

Union: {1, 2, 3, 4, 5}
Intersection: {3}
Difference: {1, 2}
Symmetric Difference: {1, 2, 4, 5}

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