Sets have their own operations that other collections do not have. These are all methods of creating a new set out of two other sets.

Union - The set of items that are present in either set.

Intersection - The set of items that are present in both sets.

Complement - The set where all items in one set are removed from the other.

Java

these example assume the existance of two sets a and b

Union

public Set complement(Set a, Set b){
    a.addAll(b);
    return a;
}

Intersection

public Set Intersection(Set a, Set b){
    a.retainAll(b);
    return a;
}

Complement

public Set complement(Set a, Set b){
    a.removeAll(b);
    return a;
}

Python

• len(s) - cardinality of set s
• x in s - test x for membership in s
• x not in s - test x for non-membership in s
• s.issubset(t) - test whether every element in s is in t
• s.issuperset(t) - test whether every element in t is in s
• s.union(t) - new set with elements from both s and t
• s.intersection(t) - new set with elements common to s and t
• s.difference(t) - new set with elements in s but not in t
• s.symmetric_difference(t) - new set with elements in either s or t but not both

python sets