import os
import typing
import warnings
from abc import ABC, abstractmethod
from typing import Any, Dict, List, Optional, Union
import gym
import numpy as np
from stable_baselines3.common import logger
from stable_baselines3.common.evaluation import evaluate_policy
from stable_baselines3.common.vec_env import DummyVecEnv, VecEnv, sync_envs_normalization
if typing.TYPE_CHECKING:
from stable_baselines3.common.base_class import BaseAlgorithm # pytype: disable=pyi-error
[docs]class BaseCallback(ABC):
"""
Base class for callback.
:param verbose: (int)
"""
def __init__(self, verbose: int = 0):
super(BaseCallback, self).__init__()
# The RL model
self.model = None # type: Optional[BaseAlgorithm]
# An alias for self.model.get_env(), the environment used for training
self.training_env = None # type: Union[gym.Env, VecEnv, None]
# Number of time the callback was called
self.n_calls = 0 # type: int
# n_envs * n times env.step() was called
self.num_timesteps = 0 # type: int
self.verbose = verbose
self.locals = None # type: Optional[Dict[str, Any]]
self.globals = None # type: Optional[Dict[str, Any]]
self.logger = None
# Sometimes, for event callback, it is useful
# to have access to the parent object
self.parent = None # type: Optional[BaseCallback]
# Type hint as string to avoid circular import
[docs] def init_callback(self, model: "BaseAlgorithm") -> None:
"""
Initialize the callback by saving references to the
RL model and the training environment for convenience.
"""
self.model = model
self.training_env = model.get_env()
self.logger = logger
self._init_callback()
def _init_callback(self) -> None:
pass
def on_training_start(self, locals_: Dict[str, Any], globals_: Dict[str, Any]) -> None:
# Those are reference and will be updated automatically
self.locals = locals_
self.globals = globals_
self._on_training_start()
def _on_training_start(self) -> None:
pass
def on_rollout_start(self) -> None:
self._on_rollout_start()
def _on_rollout_start(self) -> None:
pass
@abstractmethod
def _on_step(self) -> bool:
"""
:return: (bool) If the callback returns False, training is aborted early.
"""
return True
[docs] def on_step(self) -> bool:
"""
This method will be called by the model after each call to ``env.step()``.
For child callback (of an ``EventCallback``), this will be called
when the event is triggered.
:return: (bool) If the callback returns False, training is aborted early.
"""
self.n_calls += 1
# timesteps start at zero
self.num_timesteps = self.model.num_timesteps + 1
return self._on_step()
def on_training_end(self) -> None:
self._on_training_end()
def _on_training_end(self) -> None:
pass
def on_rollout_end(self) -> None:
self._on_rollout_end()
def _on_rollout_end(self) -> None:
pass
[docs]class EventCallback(BaseCallback):
"""
Base class for triggering callback on event.
:param callback: (Optional[BaseCallback]) Callback that will be called
when an event is triggered.
:param verbose: (int)
"""
def __init__(self, callback: Optional[BaseCallback] = None, verbose: int = 0):
super(EventCallback, self).__init__(verbose=verbose)
self.callback = callback
# Give access to the parent
if callback is not None:
self.callback.parent = self
[docs] def init_callback(self, model: "BaseAlgorithm") -> None:
super(EventCallback, self).init_callback(model)
if self.callback is not None:
self.callback.init_callback(self.model)
def _on_training_start(self) -> None:
if self.callback is not None:
self.callback.on_training_start(self.locals, self.globals)
def _on_event(self) -> bool:
if self.callback is not None:
return self.callback.on_step()
return True
def _on_step(self) -> bool:
return True
[docs]class CallbackList(BaseCallback):
"""
Class for chaining callbacks.
:param callbacks: (List[BaseCallback]) A list of callbacks that will be called
sequentially.
"""
def __init__(self, callbacks: List[BaseCallback]):
super(CallbackList, self).__init__()
assert isinstance(callbacks, list)
self.callbacks = callbacks
def _init_callback(self) -> None:
for callback in self.callbacks:
callback.init_callback(self.model)
def _on_training_start(self) -> None:
for callback in self.callbacks:
callback.on_training_start(self.locals, self.globals)
def _on_rollout_start(self) -> None:
for callback in self.callbacks:
callback.on_rollout_start()
def _on_step(self) -> bool:
continue_training = True
for callback in self.callbacks:
# Return False (stop training) if at least one callback returns False
continue_training = callback.on_step() and continue_training
return continue_training
def _on_rollout_end(self) -> None:
for callback in self.callbacks:
callback.on_rollout_end()
def _on_training_end(self) -> None:
for callback in self.callbacks:
callback.on_training_end()
[docs]class CheckpointCallback(BaseCallback):
"""
Callback for saving a model every ``save_freq`` steps
:param save_freq: (int)
:param save_path: (str) Path to the folder where the model will be saved.
:param name_prefix: (str) Common prefix to the saved models
"""
def __init__(self, save_freq: int, save_path: str, name_prefix="rl_model", verbose=0):
super(CheckpointCallback, self).__init__(verbose)
self.save_freq = save_freq
self.save_path = save_path
self.name_prefix = name_prefix
def _init_callback(self) -> None:
# Create folder if needed
if self.save_path is not None:
os.makedirs(self.save_path, exist_ok=True)
def _on_step(self) -> bool:
if self.n_calls % self.save_freq == 0:
path = os.path.join(self.save_path, f"{self.name_prefix}_{self.num_timesteps}_steps")
self.model.save(path)
if self.verbose > 1:
print(f"Saving model checkpoint to {path}")
return True
[docs]class ConvertCallback(BaseCallback):
"""
Convert functional callback (old-style) to object.
:param callback: (callable)
:param verbose: (int)
"""
def __init__(self, callback, verbose=0):
super(ConvertCallback, self).__init__(verbose)
self.callback = callback
def _on_step(self) -> bool:
if self.callback is not None:
return self.callback(self.locals, self.globals)
return True
[docs]class EvalCallback(EventCallback):
"""
Callback for evaluating an agent.
:param eval_env: (Union[gym.Env, VecEnv]) The environment used for initialization
:param callback_on_new_best: (Optional[BaseCallback]) Callback to trigger
when there is a new best model according to the ``mean_reward``
:param n_eval_episodes: (int) The number of episodes to test the agent
:param eval_freq: (int) Evaluate the agent every eval_freq call of the callback.
:param log_path: (str) Path to a folder where the evaluations (``evaluations.npz``)
will be saved. It will be updated at each evaluation.
:param best_model_save_path: (str) Path to a folder where the best model
according to performance on the eval env will be saved.
:param deterministic: (bool) Whether the evaluation should
use a stochastic or deterministic actions.
:param deterministic: (bool) Whether to render or not the environment during evaluation
:param render: (bool) Whether to render or not the environment during evaluation
:param verbose: (int)
"""
def __init__(
self,
eval_env: Union[gym.Env, VecEnv],
callback_on_new_best: Optional[BaseCallback] = None,
n_eval_episodes: int = 5,
eval_freq: int = 10000,
log_path: str = None,
best_model_save_path: str = None,
deterministic: bool = True,
render: bool = False,
verbose: int = 1,
):
super(EvalCallback, self).__init__(callback_on_new_best, verbose=verbose)
self.n_eval_episodes = n_eval_episodes
self.eval_freq = eval_freq
self.best_mean_reward = -np.inf
self.last_mean_reward = -np.inf
self.deterministic = deterministic
self.render = render
# Convert to VecEnv for consistency
if not isinstance(eval_env, VecEnv):
eval_env = DummyVecEnv([lambda: eval_env])
if isinstance(eval_env, VecEnv):
assert eval_env.num_envs == 1, "You must pass only one environment for evaluation"
self.eval_env = eval_env
self.best_model_save_path = best_model_save_path
# Logs will be written in ``evaluations.npz``
if log_path is not None:
log_path = os.path.join(log_path, "evaluations")
self.log_path = log_path
self.evaluations_results = []
self.evaluations_timesteps = []
self.evaluations_length = []
def _init_callback(self):
# Does not work in some corner cases, where the wrapper is not the same
if not isinstance(self.training_env, type(self.eval_env)):
warnings.warn("Training and eval env are not of the same type" f"{self.training_env} != {self.eval_env}")
# Create folders if needed
if self.best_model_save_path is not None:
os.makedirs(self.best_model_save_path, exist_ok=True)
if self.log_path is not None:
os.makedirs(os.path.dirname(self.log_path), exist_ok=True)
def _on_step(self) -> bool:
if self.eval_freq > 0 and self.n_calls % self.eval_freq == 0:
# Sync training and eval env if there is VecNormalize
sync_envs_normalization(self.training_env, self.eval_env)
episode_rewards, episode_lengths = evaluate_policy(
self.model,
self.eval_env,
n_eval_episodes=self.n_eval_episodes,
render=self.render,
deterministic=self.deterministic,
return_episode_rewards=True,
)
if self.log_path is not None:
self.evaluations_timesteps.append(self.num_timesteps)
self.evaluations_results.append(episode_rewards)
self.evaluations_length.append(episode_lengths)
np.savez(
self.log_path,
timesteps=self.evaluations_timesteps,
results=self.evaluations_results,
ep_lengths=self.evaluations_length,
)
mean_reward, std_reward = np.mean(episode_rewards), np.std(episode_rewards)
mean_ep_length, std_ep_length = np.mean(episode_lengths), np.std(episode_lengths)
self.last_mean_reward = mean_reward
if self.verbose > 0:
print(f"Eval num_timesteps={self.num_timesteps}, " f"episode_reward={mean_reward:.2f} +/- {std_reward:.2f}")
print(f"Episode length: {mean_ep_length:.2f} +/- {std_ep_length:.2f}")
# Add to current Logger
self.logger.record("eval/mean_reward", float(mean_reward))
self.logger.record("eval/mean_ep_length", mean_ep_length)
if mean_reward > self.best_mean_reward:
if self.verbose > 0:
print("New best mean reward!")
if self.best_model_save_path is not None:
self.model.save(os.path.join(self.best_model_save_path, "best_model"))
self.best_mean_reward = mean_reward
# Trigger callback if needed
if self.callback is not None:
return self._on_event()
return True
[docs]class StopTrainingOnRewardThreshold(BaseCallback):
"""
Stop the training once a threshold in episodic reward
has been reached (i.e. when the model is good enough).
It must be used with the ``EvalCallback``.
:param reward_threshold: (float) Minimum expected reward per episode
to stop training.
:param verbose: (int)
"""
def __init__(self, reward_threshold: float, verbose: int = 0):
super(StopTrainingOnRewardThreshold, self).__init__(verbose=verbose)
self.reward_threshold = reward_threshold
def _on_step(self) -> bool:
assert self.parent is not None, "``StopTrainingOnMinimumReward`` callback must be used " "with an ``EvalCallback``"
# Convert np.bool to bool, otherwise callback() is False won't work
continue_training = bool(self.parent.best_mean_reward < self.reward_threshold)
if self.verbose > 0 and not continue_training:
print(
f"Stopping training because the mean reward {self.parent.best_mean_reward:.2f} "
f" is above the threshold {self.reward_threshold}"
)
return continue_training
[docs]class EveryNTimesteps(EventCallback):
"""
Trigger a callback every ``n_steps`` timesteps
:param n_steps: (int) Number of timesteps between two trigger.
:param callback: (BaseCallback) Callback that will be called
when the event is triggered.
"""
def __init__(self, n_steps: int, callback: BaseCallback):
super(EveryNTimesteps, self).__init__(callback)
self.n_steps = n_steps
self.last_time_trigger = 0
def _on_step(self) -> bool:
if (self.num_timesteps - self.last_time_trigger) >= self.n_steps:
self.last_time_trigger = self.num_timesteps
return self._on_event()
return True