Python: Check if a set is a subset of another set

Last update on April 21 2025 13:04:45 (UTC/GMT +8 hours)

10. Check if a Set is a Subset of Another Set

Write a Python program to check if a set is a subset of another set.

From Wikipedia,
In mathematics, a set A is a subset of a set B if all elements of A are also elements of B; B is then a superset of A. It is possible for A and B to be equal; if they are unequal, then A is a proper subset of B. The relationship of one set being a subset of another is called inclusion (or sometimes containment). A is a subset of B may also be expressed as B includes (or contains) A or A is included (or contained) in B.

Visual Presentation:

Sample Solution:

Python Code:

# Print a message to describe the purpose of the code.
print("Check if a set is a subset of another set, using comparison operators and issubset():\n")

# Create sets 'setx', 'sety', and 'setz' with different elements.
setx = set(["apple", "mango"])
sety = set(["mango", "orange"])
setz = set(["mango"])

# Print the contents of sets 'setx', 'sety', and 'setz'.
print("x: ", setx)
print("y: ", sety)
print("z: ", setz, "\n")

# Check if 'setx' is a subset of 'sety' and print the result using both comparison operators and 'issubset()'.
print("If x is a subset of y")
print(setx <= sety)
print(setx.issubset(sety))

# Check if 'sety' is a subset of 'setx' and print the result using both comparison operators and 'issubset()'.
print("If y is a subset of x")
print(sety <= setx)
print(sety.issubset(setx))

# Check if 'sety' is a subset of 'setz' and print the result using both comparison operators and 'issubset()'.
print("\nIf y is a subset of z")
print(sety <= setz)
print(sety.issubset(setz))

# Check if 'setz' is a subset of 'sety' and print the result using both comparison operators and 'issubset()'.
print("If z is a subset of y")
print(setz <= sety)
print(setz.issubset(sety)) 

Sample Output:

Check if a set is a subset of another set, using comparison operators and issubset():

x:  {'mango', 'apple'}
y:  {'mango', 'orange'}
z:  {'mango'} 

If x is subset of y
False
False
If y is subset of x
False
False

If y is subset of z
False
False
If z is subset of y
True
True

For more Practice: Solve these Related Problems:

• Write a Python program to check if one set is a subset of another using the issubset() method.
• Write a Python program to compare two sets using the <= operator to determine subset relation.
• Write a Python program to implement a function that returns True if a given set is entirely contained in another set.
• Write a Python program to use set intersection and comparison to verify the subset relationship between two sets.

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