# Copyright 2020,2021 Sony Corporation.
# Copyright 2021,2022,2023 Sony Group Corporation.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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from dataclasses import dataclass
from typing import Dict, Tuple, cast
import numpy as np
from nnabla_rl.environment_explorer import EnvironmentExplorer, EnvironmentExplorerConfig
from nnabla_rl.environments.environment_info import EnvironmentInfo
from nnabla_rl.typing import ActionSelector
@dataclass
class GaussianExplorerConfig(EnvironmentExplorerConfig):
"""List of configurations for gaussian explorer.
Args:
action_clip_low (float): Minimum noise value. Noise below this value will be clipped.
Defaults to np.finfo(np.float).min
action_clip_high (float): Maximum noise value. Noise above this value will be clipped.
Defaults to np.finfo(np.float).max
sigma (float): Standard deviation of gaussian noise. Must be positive. Defaults to 1.0.
"""
action_clip_low: float = cast(float, np.finfo(np.float32).min)
action_clip_high: float = cast(float, np.finfo(np.float32).max)
sigma: float = 1.0
def __post_init__(self):
self._assert_positive(self.sigma, 'sigma')
[docs]class GaussianExplorer(EnvironmentExplorer):
"""Gaussian explorer.
Explore using policy's action with gaussian noise appended to it. Policy's action must be continuous action.
Args:
policy_action_selector (:py:class:`ActionSelector <nnabla_rl.typing.ActionSelector>`):
callable which computes current policy's action with respect to current state.
env_info (:py:class:`EnvironmentInfo <nnabla_rl.environments.environment_info.EnvironmentInfo>`):
environment info
config (:py:class:`LinearDecayEpsilonGreedyExplorerConfig\
<nnabla_rl.environment_explorers.LinearDecayEpsilonGreedyExplorerConfig>`): the config of this class.
"""
# type declarations to type check with mypy
# NOTE: declared variables are instance variable and NOT class variable, unless it is marked with ClassVar
# See https://mypy.readthedocs.io/en/stable/class_basics.html for details
_config: GaussianExplorerConfig
def __init__(self,
policy_action_selector: ActionSelector,
env_info: EnvironmentInfo,
config: GaussianExplorerConfig = GaussianExplorerConfig()):
super().__init__(env_info, config)
self._policy_action_selector = policy_action_selector
[docs] def action(self, step: int, state: np.ndarray, *, begin_of_episode: bool = False) -> Tuple[np.ndarray, Dict]:
(action, info) = self._policy_action_selector(state, begin_of_episode=begin_of_episode)
return self._append_noise(action, self._config.action_clip_low, self._config.action_clip_high), info
def _append_noise(self, action, low, high):
noise = np.random.normal(loc=0.0, scale=self._config.sigma, size=action.shape).astype(np.float32)
return np.clip(action + noise, low, high)