stable-baselines3/stable_baselines3/common/bit_flipping_env.py
Antonin RAFFIN 23afedb254
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2020-07-16 16:12:16 +02:00

124 lines
4.6 KiB
Python

from collections import OrderedDict
from typing import Optional, Union
import numpy as np
from gym import GoalEnv, spaces
from stable_baselines3.common.type_aliases import GymStepReturn
class BitFlippingEnv(GoalEnv):
"""
Simple bit flipping env, useful to test HER.
The goal is to flip all the bits to get a vector of ones.
In the continuous variant, if the ith action component has a value > 0,
then the ith bit will be flipped.
:param n_bits: (int) Number of bits to flip
:param continuous: (bool) Whether to use the continuous actions version or not,
by default, it uses the discrete one
:param max_steps: (Optional[int]) Max number of steps, by default, equal to n_bits
:param discrete_obs_space: (bool) Whether to use the discrete observation
version or not, by default, it uses the MultiBinary one
"""
def __init__(
self, n_bits: int = 10, continuous: bool = False, max_steps: Optional[int] = None, discrete_obs_space: bool = False
):
super(BitFlippingEnv, self).__init__()
# The achieved goal is determined by the current state
# here, it is a special where they are equal
if discrete_obs_space:
# In the discrete case, the agent act on the binary
# representation of the observation
self.observation_space = spaces.Dict(
{
"observation": spaces.Discrete(2 ** n_bits - 1),
"achieved_goal": spaces.Discrete(2 ** n_bits - 1),
"desired_goal": spaces.Discrete(2 ** n_bits - 1),
}
)
else:
self.observation_space = spaces.Dict(
{
"observation": spaces.MultiBinary(n_bits),
"achieved_goal": spaces.MultiBinary(n_bits),
"desired_goal": spaces.MultiBinary(n_bits),
}
)
self.obs_space = spaces.MultiBinary(n_bits)
if continuous:
self.action_space = spaces.Box(-1, 1, shape=(n_bits,), dtype=np.float32)
else:
self.action_space = spaces.Discrete(n_bits)
self.continuous = continuous
self.discrete_obs_space = discrete_obs_space
self.state = None
self.desired_goal = np.ones((n_bits,))
if max_steps is None:
max_steps = n_bits
self.max_steps = max_steps
self.current_step = 0
self.reset()
def convert_if_needed(self, state: np.ndarray) -> Union[int, np.ndarray]:
"""
Convert to discrete space if needed.
:param state: (np.ndarray)
:return: (np.ndarray or int)
"""
if self.discrete_obs_space:
# The internal state is the binary representation of the
# observed one
return int(sum([state[i] * 2 ** i for i in range(len(state))]))
return state
def _get_obs(self) -> OrderedDict:
"""
Helper to create the observation.
:return: (OrderedDict<int or ndarray>)
"""
return OrderedDict(
[
("observation", self.convert_if_needed(self.state.copy())),
("achieved_goal", self.convert_if_needed(self.state.copy())),
("desired_goal", self.convert_if_needed(self.desired_goal.copy())),
]
)
def reset(self) -> OrderedDict:
self.current_step = 0
self.state = self.obs_space.sample()
return self._get_obs()
def step(self, action: Union[np.ndarray, int]) -> GymStepReturn:
if self.continuous:
self.state[action > 0] = 1 - self.state[action > 0]
else:
self.state[action] = 1 - self.state[action]
obs = self._get_obs()
reward = self.compute_reward(obs["achieved_goal"], obs["desired_goal"], None)
done = reward == 0
self.current_step += 1
# Episode terminate when we reached the goal or the max number of steps
info = {"is_success": done}
done = done or self.current_step >= self.max_steps
return obs, reward, done, info
def compute_reward(self, achieved_goal: np.ndarray, desired_goal: np.ndarray, _info) -> float:
# Deceptive reward: it is positive only when the goal is achieved
if self.discrete_obs_space:
return 0.0 if achieved_goal == desired_goal else -1.0
return 0.0 if (achieved_goal == desired_goal).all() else -1.0
def render(self, mode: str = "human") -> Optional[np.ndarray]:
if mode == "rgb_array":
return self.state.copy()
print(self.state)
def close(self) -> None:
pass