Python Program To Check Two Set Are Equal

Python sets are unordered collections of unique elements that are useful for mathematical operations. Checking if two sets are equal is a common task that can be accomplished using several methods.

What Is A Set?

A set is an unordered collection data type that is iterable, mutable and has no duplicate elements. Sets are represented by curly brackets {} and are highly optimized for checking whether a specific element is present.

Sets are created by placing elements inside curly brackets, separated by commas, or by using the built-in set() function.

Example

# Simple set
names = {"ahana", "jacob", "yana", "ankush", "umang"}
print(names)

# Mixed data types
mixed_set = {1, "ahana", 2, "jacob", 3.5, "yana"}
print(mixed_set)

{'yana', 'ahana', 'jacob', 'ankush', 'umang'}
{1, 2, 3.5, 'yana', 'ahana', 'jacob'}

Methods to Check Set Equality

There are four main methods to check if two sets are equal in Python:

• Using "==" operator Direct comparison

• Using "issubset()" Check if sets are subsets of each other

• Using "symmetric_difference()" Check if difference is empty

• Using set operations Compare using union and intersection

Method 1: Using "==" Operator

The == operator compares two sets directly. It returns True if both sets contain exactly the same elements, regardless of order.

Example

set1 = {1, 2, 3, 4, 5}
set2 = {1, 2, 3, 4, 5}
set3 = {5, 4, 3, 2, 1}  # Same elements, different order

print("set1 == set2:", set1 == set2)
print("set1 == set3:", set1 == set3)  # Order doesn't matter

# Different sets
set4 = {1, 2, 3}
print("set1 == set4:", set1 == set4)

set1 == set2: True
set1 == set3: True
set1 == set4: False

Method 2: Using issubset()

Two sets are equal if each is a subset of the other. The issubset() method returns True if all elements of one set are present in another.

Example

set_a = {1, 2, 3}
set_b = {1, 2, 3, 4, 5}
set_c = {1, 2, 3}

# Check if sets are equal using mutual subset relationship
def are_sets_equal(s1, s2):
    return s1.issubset(s2) and s2.issubset(s1)

print("set_a and set_b equal:", are_sets_equal(set_a, set_b))
print("set_a and set_c equal:", are_sets_equal(set_a, set_c))
print("set_a.issubset(set_b):", set_a.issubset(set_b))
print("set_b.issubset(set_a):", set_b.issubset(set_a))

set_a and set_b equal: False
set_a and set_c equal: True
set_a.issubset(set_b): True
set_b.issubset(set_a): False

Method 3: Using symmetric_difference()

The symmetric_difference() method returns elements that are in either set but not in both. If two sets are equal, their symmetric difference will be empty.

Example

set1 = {1, 2, 3, 4, 5}
set2 = {1, 2, 3, 4, 5}
set3 = {1, 2, 3}

def check_equality_symmetric_diff(s1, s2):
    return len(s1.symmetric_difference(s2)) == 0

print("set1 and set2 equal:", check_equality_symmetric_diff(set1, set2))
print("set1 and set3 equal:", check_equality_symmetric_diff(set1, set3))

# Show the actual difference
print("Difference between set1 and set3:", set1.symmetric_difference(set3))

set1 and set2 equal: True
set1 and set3 equal: False
Difference between set1 and set3: {4, 5}

Method 4: Using Set Operations

Two sets are equal if their union equals their intersection in terms of elements.

Example

set1 = {1, 2, 3, 4}
set2 = {4, 3, 2, 1}
set3 = {1, 2, 5}

def check_equality_operations(s1, s2):
    return s1.union(s2) == s1.intersection(s2).union(s1).union(s2)

# Simpler approach: union should equal both original sets
def sets_equal_simple(s1, s2):
    return s1.union(s2) == s1 and s1.union(s2) == s2

print("set1 and set2 equal:", sets_equal_simple(set1, set2))
print("set1 and set3 equal:", sets_equal_simple(set1, set3))

set1 and set2 equal: True
set1 and set3 equal: False

Comparison of Methods

Conclusion

The == operator is the most efficient and readable method for checking set equality. Use issubset() when you need to understand the relationship between sets, and symmetric_difference() when you want to see the actual differences between sets.