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core.py
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core.py
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from __future__ import annotations
from abc import abstractmethod
from typing import TypeVar, Generic, Tuple, Union, Optional, SupportsFloat
import gym
from gym import spaces
from gym.utils import seeding
from gym.logger import deprecation
from gym.utils.seeding import RandomNumberGenerator
ObsType = TypeVar("ObsType")
ActType = TypeVar("ActType")
class Env(Generic[ObsType, ActType]):
"""The main OpenAI Gym class. It encapsulates an environment with
arbitrary behind-the-scenes dynamics. An environment can be
partially or fully observed.
The main API methods that users of this class need to know are:
step
reset
render
close
seed
And set the following attributes:
action_space: The Space object corresponding to valid actions
observation_space: The Space object corresponding to valid observations
reward_range: A tuple corresponding to the min and max possible rewards
Note: a default reward range set to [-inf,+inf] already exists. Set it if you want a narrower range.
The methods are accessed publicly as "step", "reset", etc...
"""
# Set this in SOME subclasses
metadata = {"render_modes": []}
reward_range = (-float("inf"), float("inf"))
spec = None
# Set these in ALL subclasses
action_space: spaces.Space[ActType]
observation_space: spaces.Space[ObsType]
# Created
_np_random: RandomNumberGenerator | None = None
@property
def np_random(self) -> RandomNumberGenerator:
"""Initializes the np_random field if not done already."""
if self._np_random is None:
self._np_random, seed = seeding.np_random()
return self._np_random
@np_random.setter
def np_random(self, value: RandomNumberGenerator):
self._np_random = value
@abstractmethod
def step(self, action: ActType) -> Tuple[ObsType, float, bool, dict]:
"""Run one timestep of the environment's dynamics. When end of
episode is reached, you are responsible for calling `reset()`
to reset this environment's state.
Accepts an action and returns a tuple (observation, reward, done, info).
Args:
action (object): an action provided by the agent
Returns:
observation (object): agent's observation of the current environment
reward (float) : amount of reward returned after previous action
done (bool): whether the episode has ended, in which case further step() calls will return undefined results
info (dict): contains auxiliary diagnostic information (helpful for debugging, logging, and sometimes learning)
"""
raise NotImplementedError
@abstractmethod
def reset(
self,
*,
seed: Optional[int] = None,
return_info: bool = False,
options: Optional[dict] = None,
) -> Union[ObsType, tuple[ObsType, dict]]:
"""Resets the environment to an initial state and returns an initial
observation.
This method should also reset the environment's random number
generator(s) if `seed` is an integer or if the environment has not
yet initialized a random number generator. If the environment already
has a random number generator and `reset` is called with `seed=None`,
the RNG should not be reset.
Moreover, `reset` should (in the typical use case) be called with an
integer seed right after initialization and then never again.
Returns:
observation (object): the initial observation.
info (optional dictionary): a dictionary containing extra information, this is only returned if return_info is set to true
"""
# Initialize the RNG if the seed is manually passed
if seed is not None:
self._np_random, seed = seeding.np_random(seed)
@abstractmethod
def render(self, mode="human"):
"""Renders the environment.
The set of supported modes varies per environment. (And some
third-party environments may not support rendering at all.)
By convention, if mode is:
- human: render to the current display or terminal and
return nothing. Usually for human consumption.
- rgb_array: Return an numpy.ndarray with shape (x, y, 3),
representing RGB values for an x-by-y pixel image, suitable
for turning into a video.
- ansi: Return a string (str) or StringIO.StringIO containing a
terminal-style text representation. The text can include newlines
and ANSI escape sequences (e.g. for colors).
Note:
Make sure that your class's metadata 'render_modes' key includes
the list of supported modes. It's recommended to call super()
in implementations to use the functionality of this method.
Args:
mode (str): the mode to render with
Example:
class MyEnv(Env):
metadata = {'render_modes': ['human', 'rgb_array']}
def render(self, mode='human'):
if mode == 'rgb_array':
return np.array(...) # return RGB frame suitable for video
elif mode == 'human':
... # pop up a window and render
else:
super(MyEnv, self).render(mode=mode) # just raise an exception
"""
raise NotImplementedError
def close(self):
"""Override close in your subclass to perform any necessary cleanup.
Environments will automatically close() themselves when
garbage collected or when the program exits.
"""
pass
def seed(self, seed=None):
"""Sets the seed for this env's random number generator(s).
Note:
Some environments use multiple pseudorandom number generators.
We want to capture all such seeds used in order to ensure that
there aren't accidental correlations between multiple generators.
Returns:
list<bigint>: Returns the list of seeds used in this env's random
number generators. The first value in the list should be the
"main" seed, or the value which a reproducer should pass to
'seed'. Often, the main seed equals the provided 'seed', but
this won't be true if seed=None, for example.
"""
deprecation(
"Function `env.seed(seed)` is marked as deprecated and will be removed in the future. "
"Please use `env.reset(seed=seed) instead."
)
self._np_random, seed = seeding.np_random(seed)
return [seed]
@property
def unwrapped(self) -> Env:
"""Completely unwrap this env.
Returns:
gym.Env: The base non-wrapped gym.Env instance
"""
return self
def __str__(self):
if self.spec is None:
return f"<{type(self).__name__} instance>"
else:
return f"<{type(self).__name__}<{self.spec.id}>>"
def __enter__(self):
"""Support with-statement for the environment."""
return self
def __exit__(self, *args):
"""Support with-statement for the environment."""
self.close()
# propagate exception
return False
class Wrapper(Env[ObsType, ActType]):
"""Wraps the environment to allow a modular transformation.
This class is the base class for all wrappers. The subclass could override
some methods to change the behavior of the original environment without touching the
original code.
.. note::
Don't forget to call ``super().__init__(env)`` if the subclass overrides :meth:`__init__`.
"""
def __init__(self, env: Env):
self.env = env
self._action_space: spaces.Space | None = None
self._observation_space: spaces.Space | None = None
self._reward_range: tuple[SupportsFloat, SupportsFloat] | None = None
self._metadata: dict | None = None
def __getattr__(self, name):
if name.startswith("_"):
raise AttributeError(f"accessing private attribute '{name}' is prohibited")
return getattr(self.env, name)
@property
def spec(self):
return self.env.spec
@classmethod
def class_name(cls):
return cls.__name__
@property
def action_space(self) -> spaces.Space[ActType]:
if self._action_space is None:
return self.env.action_space
return self._action_space
@action_space.setter
def action_space(self, space):
self._action_space = space
@property
def observation_space(self) -> spaces.Space:
if self._observation_space is None:
return self.env.observation_space
return self._observation_space
@observation_space.setter
def observation_space(self, space):
self._observation_space = space
@property
def reward_range(self) -> tuple[SupportsFloat, SupportsFloat]:
if self._reward_range is None:
return self.env.reward_range
return self._reward_range
@reward_range.setter
def reward_range(self, value):
self._reward_range = value
@property
def metadata(self) -> dict:
if self._metadata is None:
return self.env.metadata
return self._metadata
@metadata.setter
def metadata(self, value):
self._metadata = value
def step(self, action: ActType) -> Tuple[ObsType, float, bool, dict]:
return self.env.step(action)
def reset(self, **kwargs) -> Union[ObsType, tuple[ObsType, dict]]:
return self.env.reset(**kwargs)
def render(self, mode="human", **kwargs):
return self.env.render(mode, **kwargs)
def close(self):
return self.env.close()
def seed(self, seed=None):
return self.env.seed(seed)
def __str__(self):
return f"<{type(self).__name__}{self.env}>"
def __repr__(self):
return str(self)
@property
def unwrapped(self) -> Env:
return self.env.unwrapped
class ObservationWrapper(Wrapper):
def reset(self, **kwargs):
if kwargs.get("return_info", False):
obs, info = self.env.reset(**kwargs)
return self.observation(obs), info
else:
return self.observation(self.env.reset(**kwargs))
def step(self, action):
observation, reward, done, info = self.env.step(action)
return self.observation(observation), reward, done, info
@abstractmethod
def observation(self, observation):
raise NotImplementedError
class RewardWrapper(Wrapper):
def reset(self, **kwargs):
return self.env.reset(**kwargs)
def step(self, action):
observation, reward, done, info = self.env.step(action)
return observation, self.reward(reward), done, info
@abstractmethod
def reward(self, reward):
raise NotImplementedError
class ActionWrapper(Wrapper):
def reset(self, **kwargs):
return self.env.reset(**kwargs)
def step(self, action):
return self.env.step(self.action(action))
@abstractmethod
def action(self, action):
raise NotImplementedError
@abstractmethod
def reverse_action(self, action):
raise NotImplementedError