Gymnasium/gym/spaces/discrete.py

import numpy as np
import gym
from .space import Space


class Discrete(Space):
    """
    {0,1,...,n-1}

    Example usage:
    self.observation_space = spaces.Discrete(2)
    """
    def __init__(self, n):
        self.n = n
        super().__init__((), np.int64)
        self.np_random = np.random.RandomState()

    def seed(self, seed):
        self.np_random.seed(seed)

    def sample(self):
        return self.np_random.randint(self.n)

    def contains(self, x):
        if isinstance(x, int):
            as_int = x
        elif isinstance(x, (np.generic, np.ndarray)) and (x.dtype.kind in np.typecodes['AllInteger'] and x.shape == ()):
            as_int = int(x)
        else:
            return False
        return as_int >= 0 and as_int < self.n

    def __repr__(self):
        return "Discrete(%d)" % self.n

    def __eq__(self, other):
        return self.n == other.n