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In Python, a set is a built-in data structure that represents an unordered collection of unique elements. Sets are mutable, meaning they can be modified after creation.

Python sets are useful for tasks that involve storing and manipulating distinct elements, such as removing duplicates from a list, checking for membership, and performing set operations like union, intersection, and difference.

Creation:

Sets in Python are created using curly braces or the set() constructor. Duplicate elements are automatically removed.

# Creating a set
my_set = {1, 2, 3}
another_set = set([4, 5, 6])

print("my_set =", my_set)
print("another_set =", another_set)

Output:

my_set = {1, 2, 3}
another_set = {4, 5, 6}

Adding and Removing Elements:

Elements can be added to a set using the add() method, and removed using the remove() or discard() methods.

my_set = {1, 2, 3}

my_set.add(4)
my_set.remove(3)

print("Updated my_set after adding 4 and removing 3:", my_set)

Output:

Updated my_set after adding 4 and removing 3: {1, 2, 4}

Operations on Sets:

Sets support various operations, including union ( | ), intersection (&), difference (-), and symmetric difference (^).

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

# Union
print(set1 | set2)  # Output: {1, 2, 3, 4, 5}

# Intersection
print(set1 & set2)  # Output: {3}

# Difference
print(set1 - set2)  # Output: {1, 2}

Output:

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

Membership:

You can check if an element is present in a set using the in operator.

print(3 in my_set)

Output:

True

Length of Sets:

The len() function returns the number of elements in a set.

print(len(my_set))

Output:

3

Iteration:

You can iterate over the elements of a set using a for loop.

for element in my_set:
      print(element)

Output:

1
2
3

Set Comprehensions:

Similar to list comprehensions, you can use set comprehensions to create sets based on existing iterables.

squares = {x**2 for x in range(10)}

The output for the given expression squares = {x**2 for x in range(10)} would be a set containing the squares of numbers from 0 to 9.

Output:

{0, 1, 4, 9, 16, 25, 36, 49, 64, 81}

Explanation:

• The expression {x**2 for x in range(10)} is a set comprehension that generates a set by iterating over the numbers from 0 to 9 (inclusive) using range(10).
• For each number x, it calculates the square x**2.
• As a result, it produces a set containing the squares of numbers from 0 to 9.