bipedalwalker_env.py

import copy
import os
from datetime import datetime
from typing import List, Dict

import gymnasium as gym
import numpy as np
from ding.envs import BaseEnvTimestep
from ding.envs.common import affine_transform
from ding.torch_utils import to_ndarray
from ding.utils import ENV_REGISTRY
from easydict import EasyDict

from zoo.classic_control.cartpole.envs.cartpole_lightzero_env import CartPoleEnv


@ENV_REGISTRY.register('bipedalwalker')
class BipedalWalkerEnv(CartPoleEnv):
    """
    Overview:
        The BipedalWalker Environment class for LightZero algo.. This class is a wrapper of the gym BipedalWalker environment, with additional
        functionalities like replay saving and seed setting. The class is registered in ENV_REGISTRY with the key 'bipedalwalker'.
    """

    config = dict(
        # (str) The gym environment name.
        env_id="BipedalWalker-v3",
        # (str) The type of the environment. Options: {'normal', 'hardcore'}
        env_type='normal',
        # (bool) If True, save the replay as a gif file.
        save_replay_gif=False,
        # (str or None) The path to save the replay gif. If None, the replay gif will not be saved.
        replay_path_gif=None,
        # replay_path (str or None): The path to save the replay video. If None, the replay will not be saved.
        # Only effective when env_manager.type is 'base'.
        replay_path=None,
        # (bool) If True, the action will be scaled.
        act_scale=True,
        # (bool) If True, the reward will be clipped to [-10, +inf].
        rew_clip=True,
        # (int) The maximum number of steps for each episode during collection.
        collect_max_episode_steps=int(1.08e5),
        # (int) The maximum number of steps for each episode during evaluation.
        eval_max_episode_steps=int(1.08e5),
    )

    @classmethod
    def default_config(cls: type) -> EasyDict:
        """
        Overview:
            Return the default configuration of the class.
        Returns:
            - cfg (:obj:`EasyDict`): Default configuration dict.
        """
        cfg = EasyDict(copy.deepcopy(cls.config))
        cfg.cfg_type = cls.__name__ + 'Dict'
        return cfg

    def __init__(self, cfg: dict) -> None:
        """
        Overview:
            Initialize the BipedalWalker environment.
        Arguments:
            - cfg (:obj:`dict`): Configuration dict. The dict should include keys like 'env_id', 'replay_path', etc.
        """
        self._cfg = cfg
        self._init_flag = False
        self._env_id = cfg.env_id
        self._act_scale = cfg.act_scale
        self._rew_clip = cfg.rew_clip
        self._replay_path = cfg.replay_path
        self._replay_path_gif = cfg.replay_path_gif
        self._save_replay_gif = cfg.save_replay_gif
        self._save_replay_count = 0

    def reset(self) -> Dict[str, np.ndarray]:
        """
        Overview:
            Reset the environment and return the initial observation.
        Returns:
            - obs (:obj:`np.ndarray`): The initial observation after resetting.
        """
        if not self._init_flag:
            assert self._cfg.env_type in ['normal', 'hardcore'], "env_type must be in ['normal', 'hardcore']"
            if self._cfg.env_type == 'normal':
                self._env = gym.make('BipedalWalker-v3', render_mode="rgb_array")
            elif self._cfg.env_type == 'hardcore':
                self._env = gym.make('BipedalWalker-v3', hardcore=True, render_mode="rgb_array")
            self._observation_space = self._env.observation_space
            self._action_space = self._env.action_space
            self._reward_space = gym.spaces.Box(
                low=self._env.reward_range[0], high=self._env.reward_range[1], shape=(1,), dtype=np.float32
            )
            self._init_flag = True
        if self._replay_path is not None:
            timestamp = datetime.now().strftime("%Y%m%d%H%M%S")
            video_name = f'{self._env.spec.id}-video-{timestamp}'
            self._env = gym.wrappers.RecordVideo(
                self._env,
                video_folder=self._replay_path,
                episode_trigger=lambda episode_id: True,
                name_prefix=video_name
            )
        if hasattr(self, '_seed') and hasattr(self, '_dynamic_seed') and self._dynamic_seed:
            np_seed = 100 * np.random.randint(1, 1000)
            self._seed = self._seed + np_seed
            obs, _ = self._env.reset(seed=self._seed)  # using the reset method of Gymnasium env
        elif hasattr(self, '_seed'):
            obs, _ = self._env.reset(seed=self._seed)
        else:
            obs, _ = self._env.reset()
        obs = to_ndarray(obs).astype(np.float32)
        self._eval_episode_return = 0
        if self._save_replay_gif:
            self._frames = []

        action_mask = None
        obs = {'observation': obs, 'action_mask': action_mask, 'to_play': -1}

        return obs

    def step(self, action: np.ndarray) -> BaseEnvTimestep:
        """
        Overview:
            Take a step in the environment with the given action.
        Arguments:
            - action (:obj:`np.ndarray`): The action to be taken.
        Returns:
            - timestep (:obj:`BaseEnvTimestep`): The timestep information including observation, reward, done flag, and info.
        """
        assert isinstance(action, np.ndarray), type(action)
        if action.shape == (1,):
            action = action.squeeze()  # 0-dim array
        if self._act_scale:
            action = affine_transform(action, min_val=self.action_space.low, max_val=self.action_space.high)
        if self._save_replay_gif:
            self._frames.append(self._env.render())

        obs, rew, terminated, truncated, info = self._env.step(action)
        done = terminated or truncated

        action_mask = None
        obs = {'observation': obs, 'action_mask': action_mask, 'to_play': -1}

        self._eval_episode_return += rew
        if self._rew_clip:
            rew = max(-10, rew)
        rew = np.float32(rew)

        if done:
            info['eval_episode_return'] = self._eval_episode_return
            if self._save_replay_gif:
                if not os.path.exists(self._replay_path_gif):
                    os.makedirs(self._replay_path_gif)
                timestamp = datetime.now().strftime("%Y%m%d%H%M%S")
                path = os.path.join(
                    self._replay_path_gif,
                    '{}_episode_{}_seed{}_{}.gif'.format(self._env_id, self._save_replay_count, self._seed, timestamp)
                )
                self.display_frames_as_gif(self._frames, path)
                print(f'save episode {self._save_replay_count} in {self._replay_path_gif}!')
                self._save_replay_count += 1
        obs = to_ndarray(obs)
        rew = to_ndarray([rew])  # wrapped to be transferred to a array with shape (1,)
        return BaseEnvTimestep(obs, rew, done, info)

    @property
    def legal_actions(self) -> np.ndarray:
        """
        Overview:
            Get the legal actions in the environment.
        Returns:
            - legal_actions (:obj:`np.ndarray`): An array of legal actions.
        """
        return np.arange(self._action_space.n)

    @staticmethod
    def display_frames_as_gif(frames: list, path: str) -> None:
        import imageio
        imageio.mimsave(path, frames, fps=20)

    def random_action(self) -> np.ndarray:
        random_action = self.action_space.sample()
        if isinstance(random_action, np.ndarray):
            pass
        elif isinstance(random_action, int):
            random_action = to_ndarray([random_action], dtype=np.int64)
        return random_action

    def __repr__(self) -> str:
        return "LightZero BipedalWalker Env"

    @staticmethod
    def create_collector_env_cfg(cfg: dict) -> List[dict]:
        """
        Overview:
            Create a list of environment configurations for the collector.
        Arguments:
            - cfg (:obj:`dict`): The base configuration dict.
        Returns:
            - cfgs (:obj:`List[dict]`): The list of environment configurations.
        """
        collector_env_num = cfg.pop('collector_env_num')
        cfg = copy.deepcopy(cfg)
        cfg.max_episode_steps = cfg.collect_max_episode_steps
        return [cfg for _ in range(collector_env_num)]

    @staticmethod
    def create_evaluator_env_cfg(cfg: dict) -> List[dict]:
        """
        Overview:
            Create a list of environment configurations for the evaluator.
        Arguments:
            - cfg (:obj:`dict`): The base configuration dict.
        Returns:
            - cfgs (:obj:`List[dict]`): The list of environment configurations.
        """
        evaluator_env_num = cfg.pop('evaluator_env_num')
        cfg = copy.deepcopy(cfg)
        cfg.max_episode_steps = cfg.eval_max_episode_steps
        return [cfg for _ in range(evaluator_env_num)]