Python Set issubset() Method

Determines whether all items in the set are present in the specified set

Usage

The issubset() method returns True if all items in the set are present in the specified set, otherwise FALSE.

Syntax

set.issubset(set)

Basic Example

# Check if all items in A are present in B
A = {'yellow', 'red'}
B = {'red', 'green', 'blue', 'yellow'}
print(A.issubset(B))
# Prints True

Equivalent Operator <=

You can achieve the same result by using the <= comparison operator.

A = {'yellow', 'red'}
B = {'red', 'green', 'blue', 'yellow'}
print(A <= B)
# Prints True

Find Proper Subset

To test whether the set is a proper subset of other, use < comparison operator.

# Check if A is a proper subset of B
A = {'yellow', 'red'}
B = {'red', 'green', 'blue', 'yellow'}
print(A < B)
# Prints True

# Check if A is a proper subset of B
A = {'yellow', 'red'}
B = {'yellow', 'red'}
print(A < B)
# Prints False