Python Disjoint Sets

Summary: in this tutorial, you’ll learn about disjoint sets and how to use the Python isdisjoint() method to check if two sets are disjoint.

Introduction to Python disjoint sets #

Two sets are disjoint when they have no elements in common. In other words, two disjoint sets are sets whose intersection is an empty set.

For example, the {1,3,5} and {2,4,6} sets are disjoint because they have no common elements.

The following Venn diagram illustrates the disjoint sets:

In Python, you use the Set isdisjoint() method to check if two sets are disjoint or not:

set_a.isdisjoint(set_b)Code language: Python (python)

The isdisjoint() method returns True if the set_a and set_b are disjoint. Otherwise, it returns False.

The isdisjoint() method also accepts any iterable, not just a set.

If you pass a list, a tuple, or a dictionary, the isdisjoint() method will convert it to a set before checking.

The following example uses the isdisjoint() method to check if the set odd_numbers and set even_numbers are disjoint:

odd_numbers = {1, 3, 5}
even_numbers = {2, 4, 6}

result = odd_numbers.isdisjoint(even_numbers)

print(result)Code language: Python (python)

Output:

TrueCode language: Python (python)

Since no elements in the odd_numbers are present in the set even_numbers, the isdisjoint() method returns True.

The following example uses the isdisjoint() method to check if the set letters and the set alphanumerics are disjoint:

letters = {'A', 'B', 'C'}
alphanumerics = {'A', 1, 2}

result = letters.isdisjoint(alphanumerics)

print(result)Code language: Python (python)

Output:

FalseCode language: Python (python)

It returns False because the letter 'A' in the set alphanumerics is present in the set letters.

The following example passes a list to the isdisjoint() method instead of a set:

letters = {'A', 'B', 'C'}
result = letters.isdisjoint([1, 2, 3])

print(result)Code language: Python (python)

Output:

TrueCode language: Python (python)

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