# -*- coding:utf-8 -*-
#
# Copyright (C) 2019-2021, Saarland University
# Copyright (C) 2019-2021, Maximilian Köhl <koehl@cs.uni-saarland.de>
from __future__ import annotations
import dataclasses as d
import typing as t
import abc
StateVector = t.Sequence[float]
AvailableVector = t.Sequence[bool]
@d.dataclass(frozen=True)
class Destination:
state: StateVector
reward: float
probability: float
@d.dataclass(frozen=True)
class Transition:
action: int
destinations: t.Sequence[Destination]
[docs]class Explorer(abc.ABC):
"""State space explorer for training decision agents."""
@property
@abc.abstractmethod
def num_actions(self) -> int:
"""The number of *actions*."""
raise NotImplementedError()
@property
@abc.abstractmethod
def num_features(self) -> int:
"""The number of features of the state vector."""
raise NotImplementedError()
@property
@abc.abstractmethod
def has_terminated(self) -> bool:
"""Indicates whether the explorer is in a terminal state."""
raise NotImplementedError()
@property
@abc.abstractmethod
def state_vector(self) -> StateVector:
"""The state vector of the current explorer state."""
raise NotImplementedError()
@property
@abc.abstractmethod
def available_actions(self) -> AvailableVector:
"""A boolean vector indicating which actions are available."""
raise NotImplementedError()
@property
@abc.abstractmethod
def available_transitions(self) -> t.Sequence[Transition]:
"""A sequence of available transitions."""
raise NotImplementedError()
[docs] @abc.abstractmethod
def step(self, action: int) -> float:
"""
Takes a step with the given action and returns the reward.
Precondition: The explorer must not be in a terminal state.
"""
raise NotImplementedError()
[docs] @abc.abstractmethod
def reset(self) -> None:
"""Resets the explorer to the initial state."""
raise NotImplementedError()
[docs] @abc.abstractmethod
def fork(self) -> Explorer:
"""Forks the explorer with the current state."""
raise NotImplementedError()
[docs]class Oracle(t.Protocol):
"""An *oracle* selects an action based on the state and the available actions."""
def __call__(self, state: StateVector, available: AvailableVector) -> int:
pass
