simple_corridor.py

"""
Reference: https://github.com/ray-project/ray/blob/f8a91c7fad248b1c7f81fd6d30191ac930a92bc4/rllib/examples/env/simple_corridor.py

Fixes:
ValueError: ('Observation ({}) outside given space ({})!', array([0.]), Box([0.], [999.], (1,), float32))
"""

import gym
from gym.spaces import Box, Discrete
import numpy as np


class SimpleCorridor(gym.Env):
    """Example of a custom env in which you have to walk down a corridor.

    You can configure the length of the corridor via the env config."""

    def __init__(self, config=None):
        config = config or {}
        self.end_pos = config.get("corridor_length", 10)
        self.start_pos = config.get("corridor_start", 0)
        self.cur_pos = self.start_pos
        self.action_space = Discrete(2)
        self.observation_space = Box(self.start_pos, self.end_pos, shape=(1, ), dtype=np.float32)

    def set_corridor_length(self, length):
        self.end_pos = length
        self.observation_space = Box(self.start_pos, self.end_pos, shape=(1, ), dtype=np.float32)
        print("Updated corridor length to {}".format(length))

    def reset(self):
        self.cur_pos = self.start_pos
        return np.full(self.observation_space.shape, self.cur_pos, dtype=np.float32)

    def step(self, action):
        assert action in [0, 1], action
        if action == 0 and self.cur_pos > 0:
            self.cur_pos -= 1.0
            self.cur_pos = max(self.cur_pos, self.start_pos)
        elif action == 1:
            self.cur_pos += 1.0
            self.cur_pos = min(self.cur_pos, self.end_pos)
        done = self.cur_pos >= self.end_pos
        obs = np.full(self.observation_space.shape, self.cur_pos, dtype=np.float32)
        return obs, 1 if done else 0, done, {}