problem

The method Node.__hash__() is now returning the node.state attribute that is not guaranteed to be a integer.

The method sample of the environment returns a numpy.int64 object, in this way using the following code A TypeError will be raised with the following message: __hash__ method should return an integer.

envname = "SmallMaze-v0"
environment = gym.make(envname)

a_queue_node = NodeQueue()

# creating a list of nodes from the startstate
for action in environment.actions:
    a_queue_node.add(Node(environment.sample(environment.startstate, action)))

# error
node = a_queue_node.remove()
print(node in a_queue_node)

workaround

The stupidest workaround to solve the problem is to cast the sample value to int before the creation of the node

envname = "SmallMaze-v0"
environment = gym.make(envname)

a_queue_node = NodeQueue()

# creating a list of nodes from the startstate
for action in environment.actions:
    a_queue_node.add(Node(int(environment.sample(environment.startstate, action))))

# error
node = a_queue_node.remove()
print(node in a_queue_node)

possible solutions

I propose two possible solutions:

1. Forcing the type of the Node.state attribute to be a integer in the Node.__init__() method:

class Node:
    def __init__(self, state, parent=None, pathcost=0, value=0):
        self.state = int(state)
        self.pathcost = pathcost
        self.value = value
        self.parent = parent
        self.removed = False

    def __hash__(self):
        return self.state

    def __lt__(self, other):
        return self.value < other.value

2. Forcing the type of the Node.state attribute to be convertible to an int when it's needed:

class Node:
    def __init__(self, state, parent=None, pathcost=0, value=0):
        self.state = state
        self.pathcost = pathcost
        self.value = value
        self.parent = parent
        self.removed = False

    def __hash__(self):
        return int(self.state)

    def __lt__(self, other):
        return self.value < other.value