1. Operations on two sets

Use these sets in the four examples. In the original pictures, Set1 is A and Set2 is B.

A = {4, 5, 6, 8}
B = {1, 2, 5, 8}

Union

At least one of the two sets.

result = A | B
# equivalent: A.union(B)

Result: {1, 2, 4, 5, 6, 8}

Intersection

Both sets.

result = A & B
# equivalent: A.intersection(B)

Result: {5, 8}

Difference / subtraction

In A but not in B.

result = A - B
# equivalent: A.difference(B)

Result: {4, 6}

Symmetric difference

Exactly one set; exclude shared elements.

result = A ^ B
# equivalent: A.symmetric_difference(B)

Result: {1, 2, 4, 6}

Direction matters: A - B gives {4, 6}, while B - A gives {1, 2}. Reversing the operands preserves union, intersection and symmetric difference.

A ^ B is equivalent to (A | B) - (A & B).

2. Compare sets

Compare the elements and containment, rather than sizes alone.

A = {2, 4}
B = {2, 4, 6}
print(A <= B) # True
print(A < B) # True
print(B > A) # True
print(A < A) # False

3. Set laboratory

4. Exercises

8 exercises in total: 3 LearningApps activities and 5 checked tasks. Set answers may use any element order; type set() for an empty set.

Reference: Python documentation: set.