Contains of HashSet in Python

Question

In Java we have HashSet, I need similar structure in Python to use contains like below:

A = [1, 2, 3]
S = set()
S.add(2)
for x in         


        

Answer 1

In Python, there is a built-in type, set. The major difference from the hashmap in Java is that the Python set is not typed, i.e., it is legal to have a set {'2', 2} in Python.

Out of the box, the class set does not have a contains() method implemented. We typically use the Python keyword in to do what you want, i.e.,

A = [1, 2, 3]
S = set()
S.add(2)
for x in A:
  if x in S:
    print("Example")

If that does not work for you, you can invoke the special method __contains__(), which is NOT encouraged.

A = [1, 2, 3]
S = set()
S.add(2)
for x in A:
  if S.__contains__(x):
    print("Example")