import torch
import numpy as np
from copy import deepcopy
import torch.nn.functional as F
from tianshou.data import Batch
from tianshou.policy import BasePolicy
# from tianshou.exploration import OUNoise
[docs]class DDPGPolicy(BasePolicy):
"""Implementation of Deep Deterministic Policy Gradient. arXiv:1509.02971
:param torch.nn.Module actor: the actor network following the rules in
:class:`~tianshou.policy.BasePolicy`. (s -> logits)
:param torch.optim.Optimizer actor_optim: the optimizer for actor network.
:param torch.nn.Module critic: the critic network. (s, a -> Q(s, a))
:param torch.optim.Optimizer critic_optim: the optimizer for critic
network.
:param float tau: param for soft update of the target network, defaults to
0.005.
:param float gamma: discount factor, in [0, 1], defaults to 0.99.
:param float exploration_noise: the noise intensity, add to the action,
defaults to 0.1.
:param action_range: the action range (minimum, maximum).
:type action_range: [float, float]
:param bool reward_normalization: normalize the reward to Normal(0, 1),
defaults to ``False``.
:param bool ignore_done: ignore the done flag while training the policy,
defaults to ``False``.
.. seealso::
Please refer to :class:`~tianshou.policy.BasePolicy` for more detailed
explanation.
"""
def __init__(self, actor, actor_optim, critic, critic_optim,
tau=0.005, gamma=0.99, exploration_noise=0.1,
action_range=None, reward_normalization=False,
ignore_done=False, **kwargs):
super().__init__(**kwargs)
if actor is not None:
self.actor, self.actor_old = actor, deepcopy(actor)
self.actor_old.eval()
self.actor_optim = actor_optim
if critic is not None:
self.critic, self.critic_old = critic, deepcopy(critic)
self.critic_old.eval()
self.critic_optim = critic_optim
assert 0 <= tau <= 1, 'tau should in [0, 1]'
self._tau = tau
assert 0 <= gamma <= 1, 'gamma should in [0, 1]'
self._gamma = gamma
assert 0 <= exploration_noise, 'noise should not be negative'
self._eps = exploration_noise
assert action_range is not None
self._range = action_range
self._action_bias = (action_range[0] + action_range[1]) / 2
self._action_scale = (action_range[1] - action_range[0]) / 2
# it is only a little difference to use rand_normal
# self.noise = OUNoise()
self._rm_done = ignore_done
self._rew_norm = reward_normalization
self.__eps = np.finfo(np.float32).eps.item()
[docs] def set_eps(self, eps):
"""Set the eps for exploration."""
self._eps = eps
[docs] def train(self):
"""Set the module in training mode, except for the target network."""
self.training = True
self.actor.train()
self.critic.train()
[docs] def eval(self):
"""Set the module in evaluation mode, except for the target network."""
self.training = False
self.actor.eval()
self.critic.eval()
[docs] def sync_weight(self):
"""Soft-update the weight for the target network."""
for o, n in zip(self.actor_old.parameters(), self.actor.parameters()):
o.data.copy_(o.data * (1 - self._tau) + n.data * self._tau)
for o, n in zip(
self.critic_old.parameters(), self.critic.parameters()):
o.data.copy_(o.data * (1 - self._tau) + n.data * self._tau)
[docs] def process_fn(self, batch, buffer, indice):
if self._rew_norm:
bfr = buffer.rew[:min(len(buffer), 1000)] # avoid large buffer
mean, std = bfr.mean(), bfr.std()
if std > self.__eps:
batch.rew = (batch.rew - mean) / std
if self._rm_done:
batch.done = batch.done * 0.
return batch
[docs] def forward(self, batch, state=None,
model='actor', input='obs', eps=None, **kwargs):
"""Compute action over the given batch data.
:param float eps: in [0, 1], for exploration use.
:return: A :class:`~tianshou.data.Batch` which has 2 keys:
* ``act`` the action.
* ``state`` the hidden state.
.. seealso::
Please refer to :meth:`~tianshou.policy.BasePolicy.forward` for
more detailed explanation.
"""
model = getattr(self, model)
obs = getattr(batch, input)
logits, h = model(obs, state=state, info=batch.info)
logits += self._action_bias
if eps is None:
eps = self._eps
if eps > 0:
# noise = np.random.normal(0, eps, size=logits.shape)
# logits += torch.tensor(noise, device=logits.device)
# noise = self.noise(logits.shape, eps)
logits += torch.randn(
size=logits.shape, device=logits.device) * eps
logits = logits.clamp(self._range[0], self._range[1])
return Batch(act=logits, state=h)
[docs] def learn(self, batch, **kwargs):
with torch.no_grad():
target_q = self.critic_old(batch.obs_next, self(
batch, model='actor_old', input='obs_next', eps=0).act)
dev = target_q.device
rew = torch.tensor(batch.rew,
dtype=torch.float, device=dev)[:, None]
done = torch.tensor(batch.done,
dtype=torch.float, device=dev)[:, None]
target_q = (rew + (1. - done) * self._gamma * target_q)
current_q = self.critic(batch.obs, batch.act)
critic_loss = F.mse_loss(current_q, target_q)
self.critic_optim.zero_grad()
critic_loss.backward()
self.critic_optim.step()
actor_loss = -self.critic(batch.obs, self(batch, eps=0).act).mean()
self.actor_optim.zero_grad()
actor_loss.backward()
self.actor_optim.step()
self.sync_weight()
return {
'loss/actor': actor_loss.item(),
'loss/critic': critic_loss.item(),
}