def update(
self,
actor: Actor,
critic: Critic,
train_critic_iters: int = 80,
gamma: float = 0.99,
lam: float = 0.97,
):
"""Performs A2C update at the end of each epoch using training samples
that have been collected in `self.replay`.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
critic: (base.Critic) Critic network to optimize.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
train_critic_iters: (int, optional) Max number of critic training steps
per epoch. Default: 80.
lam: (float, optional) Hyperparameter for GAE-Lambda calaulation.
Range: (0, 1). Default: 0.97
"""
device = utils.get_device(actor)
batch = self.replay.sample(device=device)
self.actor_optimizer.zero_grad()
actor_loss(batch, actor, critic, gamma=gamma, lam=lam).backward()
self.actor_optimizer.step()
for i in range(train_critic_iters):
self.critic_optimizer.zero_grad()
critic_loss(batch, critic, gamma=gamma).backward()
self.critic_optimizer.step()
def update(
self,
iteration: int,
dqns: Sequence[DQN],
batch_size: int = 128,
gamma: float = 0.99,
):
"""Samples from the experience replay and performs a single DDPG update.
Parameters
----------
iteration: (int) Number of update iterations that have been performed
during this update step. Used for updating target DQN network.
dqns: (Sequence[DQN]) List or tuple of all DQN networks used for training.
Must contain a *minimum of two* DQN networks (as in the original DDQN
paper). In general, this function will accept more than two. In
that case, network (i + 1) acts as the Double DQN for network (i)
during training -- the Double DQN relationship becomes circular.
batch_size: (int, optional) Minibatch size for SGD. Default: 128.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99.
"""
device = utils.get_device(dqns[0])
batch = self.replay.sample(batch_size, device=device)
dqn = dqns[iteration % len(dqns)]
optimizer = self.optimizers[iteration % len(dqns)]
double_dqn = dqns[(iteration + 1) % len(dqns)]
optimizer.zero_grad()
self.dqn_loss(batch, dqn, double_dqn, gamma=gamma).backward()
optimizer.step()
def update(
self,
iteration: int,
dqn: agents.DQN,
batch_size: int = 128,
gamma: float = 0.99,
target_update: int = 10,
):
"""Samples from the experience replay and performs a single update.
Parameters
----------
iteration: (int) Number of update iterations that have been performed
during this update step. Used for updating target DQN network.
dqn: (agents.DQN) DQN network used to select training actions, which will
have its parameters updated directly.
batch_size: (int, optional) Minibatch size for SGD. Default: 128.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99.
target_update: (int, optional) Frequency at which the target DQN network
should be updated. Should generally be larger than 1. Default: 10.
"""
device = utils.get_device(dqn)
batch = self.replay.sample(batch_size, device=device)
self.optimizer.zero_grad()
self.dqn_loss(batch, dqn, gamma=gamma).backward()
self.optimizer.step()
if iteration % target_update == 0:
self.target_dqn.load_state_dict(dqn.state_dict())
def train(
self,
actor: Actor,
replay: Replay = None,
lr: float = 3e-4,
epochs: int = 200,
steps_per_epoch: int = 4000,
max_ep_len: int = 1000,
gamma: float = 0.99,
callbacks: Iterable[Callable] = (),
):
"""Vanilla Policy Gradients algorithm with no added bells or whistles.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
replay: (base.Replay, optional) Experience replay object for sampling
previous experiences. If not provided, defaults to 'ExperienceReplay'
with a buffer size of 1,000,000. Users can provide a replay object,
which is pre-populated with experiences (for specific use cases).
steps_per_epoch: (int, optional) Number of steps of interaction
for the agent and the environment in each epoch. Default: 4000.
epochs: (int, optional) Number of training epochs. Default: 100.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
max_ep_len: (int, optional) Maximum length of episode. Defaults to 1000,
but *this should be provided for each unique environment!* This
has an effect on how end-of-episode rewards are computed.
callbacks: (Iterable[Callable], optional) callback functions to execute
at the end of each training epoch.
"""
device = utils.get_device(actor)
self.optimizer = Adam(actor.parameters(), lr=lr)
self.replay = NoReplay(steps_per_epoch) if replay is None else replay
for epoch in range(1, epochs + 1):
state = self.env.reset()
ep_reward, ep_length = 0, 0
num_episodes = 0
for t in range(1, steps_per_epoch + 1):
action, _ = actor(state.to(device))
state, reward, done, _ = self.env.step(action)
self.replay.append([state, action, reward, done])
ep_reward += reward
ep_length += 1
if done or (ep_length == max_ep_len):
num_episodes += 1
self.ep_rewards.append(ep_reward)
state = self.env.reset()
ep_reward, ep_length = 0, 0
self.update(actor, gamma=gamma)
avg_reward = sum(self.ep_rewards[-num_episodes:]) / num_episodes
print(f"\rEpoch {epoch} | Avg Reward {avg_reward}", end="")
for callback in callbacks:
callback(self)
def update(
self,
iteration: int,
actor: Actor,
critics: Iterable[Critic],
batch_size: int = 128,
gamma: float = 0.99,
target_noise: float = 0.2,
noise_clip: float = 0.5,
policy_delay: int = 2,
polyak: float = 0.995,
):
"""Samples from the experience replay and performs a single TD3 update.
Parameters
----------
iteration: (int) Number of update iterations that have been performed
during this update step. Used for monitoring policy update delays.
actor: (base.Actor) Actor (policy) network to optimize.
critics: (Iterable[base.Critic]) Critic networks to optimize. In standard
SAC there are *two* critics, but this method only requires that *two or
more* critics are provided.
batch_size: (int, optional) Minibatch size for SGD. Default: 128.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
target_noise: (float, optional) Stddev for smoothing noise added to
target policy. Default: 0.2.
noise_clip: (float, optional) Max absolute value of target policy
smoothing noise. Default: 0.5.
policy_delay: (int, optional) Policy will only be updated once every
policy_delay times for each update of the Q-networks. Default: 2.
polyak: (float, optional) Interpolation factor in polyak averaging for
target networks. Range: (0, 1). Default: 0.995
"""
device = utils.get_device(actor)
batch = self.replay.sample(batch_size, device=device)
self.critic_optimizer.zero_grad()
self.critic_loss(
batch,
critics,
gamma=gamma,
target_noise=target_noise,
noise_clip=noise_clip,
).backward()
self.critic_optimizer.step()
if iteration % policy_delay != 0:
return
self.actor_optimizer.zero_grad()
actor_loss(batch, actor, critics).backward()
self.actor_optimizer.step()
for p, pt in zip(actor.parameters(), self.target_actor.parameters()):
pt.data = pt.data * polyak + (1 - polyak) * p.data
for critic, target in zip(critics, self.target_critics):
for p, pt in zip(critic.parameters(), target.parameters()):
pt.data = pt.data * polyak + (1 - polyak) * p.data
def update(
self,
actor,
critic,
train_actor_iters: int = 80,
train_critic_iters: int = 80,
clip_ratio: float = 0.2,
gamma: float = 0.99,
lam: float = 0.97,
target_kl: float = 0.01,
):
"""Performs PPO update at the end of each epoch using training samples
that have been collected in `self.replay`.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
critic: (base.Critic) Critic network to optimize.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
train_actor_iters: (int, optional) Max number of actor training steps
per epoch. Default: 80.
train_critic_iters: (int, optional) Max number of critic training steps
per epoch. Default: 80.
clip_ratio: (float, optional) Hyperparameter for clipping in the policy
objective. Scales how much the policy is allowed change per
training update. Default: 0.2.
lam: (float, optional) Hyperparameter for GAE-Lambda calaulation.
Range: (0, 1). Default: 0.97
target_kl: (float, optional) Max KL divergence between new and old
policies after an update. Used for early stopping. Typically in
range (0.01, 0.05). Default: 0.01.
"""
device = utils.get_device(actor)
batch = self.replay.sample(device=device)
for i in range(train_actor_iters):
self.actor_optimizer.zero_grad()
loss_pi, approx_kl = actor_loss(batch,
actor,
critic,
clip_ratio=clip_ratio,
gamma=gamma,
lam=lam)
if approx_kl > 1.5 * target_kl:
break
loss_pi.backward()
self.actor_optimizer.step()
for i in range(train_critic_iters):
self.critic_optimizer.zero_grad()
critic_loss(batch, critic, gamma=gamma).backward()
self.critic_optimizer.step()
def update(self, actor: Actor, gamma: float = 0.99):
"""Performs PG update at the end of each epoch using training samples
that have been collected in `self.replay`.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99.
"""
device = utils.get_device(actor)
batch = self.replay.sample(device=device)
assert len(batch) == 4
self.optimizer.zero_grad()
actor_loss(batch, actor, gamma=gamma).backward()
self.optimizer.step()
def update(
self,
actor: Actor,
critics: Iterable[Critic],
batch_size: int = 128,
gamma: float = 0.99,
alpha: Union[float, Tensor] = 0.2,
polyak: float = 0.995,
):
"""Samples from the experience replay and performs a single SAC update.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
critics: (Iterable[base.Critic]) Critic networks to optimize. In standard
SAC there are *two* critics, but this method only requires that *two or
more* critics are provided.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
polyak: (float, optional) Interpolation factor in polyak averaging for
target networks. Range: (0, 1). Default: 0.995
alpha: (float, optional) Entropy regularization coefficient. (Equivalent to
inverse of reward scale in the original SAC paper.) Default: 0.2.
batch_size: (int, optional) Minibatch size for SGD. Default: 128.
"""
device = utils.get_device(actor)
batch = self.replay.sample(batch_size, device=device)
self.critic_optimizer.zero_grad()
if any(isinstance(c, DQNCritic) for c in critics):
self.q_network_loss(batch, actor, critics, alpha=alpha).backward()
else:
self.critic_loss(batch, actor, critics, gamma=gamma,
alpha=alpha).backward()
self.critic_optimizer.step()
self.actor_optimizer.zero_grad()
actor_loss(batch, actor, critics, alpha=alpha).backward()
self.actor_optimizer.step()
for critic, target in zip(critics, self.target_critics):
for p, pt in zip(critic.parameters(), target.parameters()):
pt.data = (1 - polyak) * p.data + polyak * pt.data
def update(
self,
actor: Actor,
critic: Critic,
batch_size: int = 128,
gamma: float = 0.99,
polyak: float = 0.995,
):
"""Samples from the experience replay and performs a single DDPG update.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
critic: (Iterable[base.Critic]) Critic networks to optimize. In standard
SAC there are *two* critics, but this method only requires that *two or
more* critics are provided.
batch_size: (int, optional) Minibatch size for SGD. Default: 128.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
polyak: (float, optional) Interpolation factor in polyak averaging for
target networks. Range: (0, 1). Default: 0.995
"""
device = utils.get_device(actor)
batch = self.replay.sample(batch_size, device=device)
self.critic_optimizer.zero_grad()
self.critic_loss(
batch,
critic,
gamma=gamma,
).backward()
self.critic_optimizer.step()
self.actor_optimizer.zero_grad()
actor_loss(batch, actor, critic).backward()
self.actor_optimizer.step()
for p, pt in zip(actor.parameters(), self.target_actor.parameters()):
pt.data = pt.data * polyak + (1 - polyak) * p.data
for p, pt in zip(critic.parameters(), self.target_critic.parameters()):
pt.data = pt.data * polyak + (1 - polyak) * p.data
def train(
self,
dqns: Sequence[DQN],
replay: Replay = None,
steps_per_epoch: int = 4000,
epochs: int = 100,
gamma: float = 0.99,
lr: float = 1e-3,
batch_size: int = 128,
max_ep_len: int = 1000,
callbacks: Iterable[Callable] = (),
):
"""
Parameters
----------
dqns: (Sequence[DQN]) List or tuple of all DQN networks used for training.
Must contain a *minimum of two* DQN networks (as in the original DDQN
paper). In general, this function will accept more than two. In
that case, network (i + 1) acts as the Double DQN for network (i)
during training -- the Double DQN relationship becomes circular.
replay: (base.Replay, optional) Experience replay object for sampling
previous experiences. If not provided, defaults to 'PER'
with a buffer size of 1,000,000. Users can provide a replay object,
which is pre-populated with experiences (for specific use cases).
steps_per_epoch: (int, optional) Number of steps of interaction
for the agent and the environment in each epoch. Default: 4000.
epochs: (int, optional) Number of training epochs. Default: 100.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
lr: (float, optional) Learning rate critic optimizer. Default: 1e-3.
batch_size: (int, optional) Minibatch size for SGD. Default: 128.
max_ep_len: (int, optional) Maximum length of episode. Defaults to 1000,
but *this should be provided for each unique environment!* This
has an effect on how end-of-episode rewards are computed.
callbacks: (Iterable[Callable], optional) callback functions to execute
at the end of each training epoch.
"""
device = utils.get_device(dqns[0])
self.replay = replay
if replay is None:
self.replay = PER(int(1e6))
self.optimizers = [Adam(dqn.parameters(), lr=lr) for dqn in dqns]
total_steps = steps_per_epoch * epochs
state, ep_reward, ep_length = self.env.reset(), 0, 0
for step in range(1, total_steps + 1):
eps = 0.05 + (0.9 - 0.05) * exp(-step / 1000)
if torch.rand(1).item() < eps:
action = self.env.action_space.sample()
else:
dqn_idx = step % len(dqns)
action, _ = dqns[dqn_idx](state.to(device))
next_state, reward, done, _ = self.env.step(action)
done = False if ep_length == max_ep_len else done
self.replay.append([state, action, reward, done, next_state])
state = next_state
ep_reward += reward
ep_length += 1
if len(self.replay) >= batch_size:
self.update(
step,
dqns,
batch_size=batch_size,
gamma=gamma,
)
if step % steps_per_epoch == 0:
for callback in callbacks:
callback(self)
if done or (ep_length == max_ep_len):
self.ep_rewards.append(ep_reward)
epoch = (step + 1) // steps_per_epoch
print(f"\rEpoch {epoch} | Step {step} | Reward {ep_reward}",
end="")
state, ep_reward, ep_length = self.env.reset(), 0, 0
def train(
self,
actor: Actor,
critic: Critic,
replay: Replay = None,
actor_lr: float = 3e-4,
critic_lr: float = 1e-3,
train_actor_iters: int = 80,
train_critic_iters: int = 80,
epochs: int = 200,
steps_per_epoch: int = 4000,
clip_ratio: float = 0.2,
gamma: float = 0.99,
lam: float = 0.97,
target_kl: float = 0.01,
max_ep_len: int = 1000,
callbacks: Iterable[Callable] = (),
):
"""Proximal Policy Optimization (via objective clipping) with early
stopping based on approximate KL divergence of the policy network.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
critic: (base.Critic) Critic network to optimize.
replay: (base.Replay, optional) Experience replay object for sampling
previous experiences. If not provided, defaults to 'ExperienceReplay'
with a buffer size of 1,000,000. Users can provide a replay object,
which is pre-populated with experiences (for specific use cases).
steps_per_epoch: (int, optional) Number of steps of interaction
for the agent and the environment in each epoch. Default: 4000.
epochs: (int, optional) Number of training epochs. Default: 100.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
actor_lr: (float, optional) Learning rate actor optimizer. Default: 1e-3.
critic_lr: (float, optional) Learning rate critic optimizer. Default: 1e-3.
train_actor_iters: (int, optional) Max number of actor training steps
per epoch. Default: 80.
train_critic_iters: (int, optional) Max number of critic training steps
per epoch. Default: 80.
clip_ratio: (float, optional) Hyperparameter for clipping in the policy
objective. Scales how much the policy is allowed change per
training update. Default: 0.2.
lam: (float, optional) Hyperparameter for GAE-Lambda calaulation.
Range: (0, 1). Default: 0.97
target_kl: (float, optional) Max KL divergence between new and old
policies after an update. Used for early stopping. Typically in
range (0.01, 0.05). Default: 0.01.
max_ep_len: (int, optional) Maximum length of episode. Defaults to 1000,
but *this should be provided for each unique environment!* This
has an effect on how end-of-episode rewards are computed.
callbacks: (Iterable[Callable], optional) callback functions to execute
at the end of each training epoch.
"""
device = utils.get_device(actor)
self.actor_optimizer = Adam(actor.parameters(), lr=actor_lr)
self.critic_optimizer = Adam(critic.parameters(), lr=critic_lr)
self.replay = NoReplay(steps_per_epoch) if replay is None else replay
for epoch in range(1, epochs + 1):
state = self.env.reset()
ep_reward, ep_length = 0, 0
num_episodes = 0
for t in range(1, steps_per_epoch + 1):
action, logprob = actor(state.to(device))
next_state, reward, done, _ = self.env.step(action)
done = False if ep_length == max_ep_len else done
self.replay.append(
[state, action, logprob, reward, done, next_state])
state = next_state
ep_reward += reward
ep_length += 1
if done or (ep_length == max_ep_len):
num_episodes += 1
self.ep_rewards.append(ep_reward)
state = self.env.reset()
ep_reward, ep_length = 0, 0
self.update(
actor,
critic,
train_actor_iters=train_actor_iters,
train_critic_iters=train_critic_iters,
clip_ratio=clip_ratio,
gamma=gamma,
lam=lam,
target_kl=target_kl,
)
avg_reward = sum(self.ep_rewards[-num_episodes:]) / num_episodes
print(f"\rEpoch {epoch} | Avg Reward {avg_reward}", end="")
for callback in callbacks:
callback(self)
def train(
self,
actor: Actor,
critics: Iterable[Critic],
replay: Replay = None,
steps_per_epoch: int = 4000,
epochs: int = 100,
gamma: float = 0.99,
polyak: float = 0.995,
actor_lr: float = 5e-4,
critic_lr: float = 1e-3,
alpha: float = 0.2,
batch_size: int = 128,
start_steps: int = 4000,
update_after: int = 1000,
update_every: int = 1,
max_ep_len: int = 1000,
callbacks: Iterable[Callable] = (),
):
"""Soft actor-critic (SAC) training algorithm. Supports both continuous
and discrete action spaces.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
critics: (Iterable[base.Critic]) Critic networks to optimize. In standard
SAC there are *two* critics, but this method only requires that *two or
more* critics are provided.
replay: (base.Replay, optional) Experience replay object for sampling
previous experiences. If not provided, defaults to 'ExperienceReplay'
with a buffer size of 1,000,000. Users can provide a replay object,
which is pre-populated with experiences (for specific use cases).
steps_per_epoch: (int, optional) Number of steps of interaction
for the agent and the environment in each epoch. Default: 4000.
epochs: (int, optional) Number of training epochs. Default: 100.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
polyak: (float, optional) Interpolation factor in polyak averaging for
target networks. Range: (0, 1). Default: 0.995
actor_lr: (float, optional) Learning rate actor optimizer. Default: 1e-3.
critic_lr: (float, optional) Learning rate critic optimizer. Default: 1e-3.
alpha: (float, optional) Entropy regularization coefficient. (Equivalent to
inverse of reward scale in the original SAC paper.) Default: 0.2.
batch_size: (int, optional) Minibatch size for SGD. Default: 128.
start_steps: (int, optional) Number of steps for random action selection
before running real policy (helps exploration). Default: 1000.
update_after: (int, optional) Number of env interactions to collect before
starting to do gradient descent updates. Ensures replay buffer
is full enough for useful updates. Default: 5000.
update_every: (int, optional) Number of env interactions that should elapse
between gradient descent updates. Note: Regardless of how long
you wait between updates, the ratio of env steps to gradient steps
is locked to 1. Default: 1.
max_ep_len: (int, optional) Maximum length of episode. Defaults to 1000,
but *this should be provided for each unique environment!* This
has an effect on how end-of-episode rewards are computed.
callbacks: (Iterable[Callable], optional) callback functions to execute
at the end of each training epoch.
"""
device = utils.get_device(actor)
self.replay = replay
if replay is None:
self.replay = ExperienceReplay(int(1e6))
critic_params = chain(*[c.parameters() for c in critics])
self.critic_optimizer = torch.optim.Adam(critic_params, lr=critic_lr)
self.actor_optimizer = torch.optim.Adam(actor.parameters(),
lr=actor_lr)
self.target_critics = deepcopy(critics)
state = self.env.reset()
ep_reward, ep_length = 0, 0
total_steps = steps_per_epoch * epochs
for step in range(1, total_steps + 1):
if step < start_steps:
action = self.env.action_space.sample()
else:
action, _ = actor(state.to(device))
next_state, reward, done, _ = self.env.step(action)
done = False if ep_length == max_ep_len else done
self.replay.append([state, action, reward, done, next_state])
state = next_state
ep_reward += reward
ep_length += 1
if step > update_after and step % update_every == 0:
for j in range(update_every):
self.update(
actor,
critics,
batch_size=batch_size,
gamma=gamma,
alpha=alpha,
polyak=polyak,
)
if step % steps_per_epoch == 0:
for callback in callbacks:
callback(self)
if done or (ep_length == max_ep_len):
self.ep_rewards.append(ep_reward)
epoch = (step + 1) // steps_per_epoch
print(f"\rEpoch {epoch} | Step {step} | Reward {ep_reward}",
end="")
state, ep_reward, ep_length = self.env.reset(), 0, 0
def train(
self,
dqn: agents.DQN,
replay: Replay = None,
steps_per_epoch: int = 4000,
epochs: int = 100,
gamma: float = 0.99,
lr: float = 1e-3,
batch_size: int = 128,
target_update: int = 10,
max_ep_len: int = 1000,
callbacks: Iterable[Callable] = (),
):
"""Deep Q-Network (DQN) training algorithm for RL agents in discrete
action spaces.
Parameters
----------
dqn: (agents.DQN) DQN network used to select training actions, which will
have its parameters updated directly.
replay: (base.Replay, optional) Experience replay object for sampling
previous experiences. If not provided, defaults to 'ExperienceReplay'
with a buffer size of 1,000,000. Users can provide a replay object,
which is pre-populated with experiences (for specific use cases).
steps_per_epoch: (int, optional) Number of steps of interaction
for the agent and the environment in each epoch. Default: 4000.
epochs: (int, optional) Number of training epochs. Default: 100.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
lr: (float, optional) Learning rate critic optimizer. Default: 1e-3.
batch_size: (int, optional) Minibatch size for SGD. Default: 128.
target_update: (int, optional) Frequency at which the target DQN network
should be updated. Should generally be larger than 1. Default: 10.
max_ep_len: (int, optional) Maximum length of episode. Defaults to 1000,
but *this should be provided for each unique environment!* This
has an effect on how end-of-episode rewards are computed.
callbacks: (Iterable[Callable], optional) callback functions to execute
at the end of each training epoch.
"""
device = utils.get_device(dqn)
self.replay = replay
if replay is None:
self.replay = PER(int(1e6))
self.optimizer = Adam(dqn.parameters(), lr=lr)
self.target_dqn = deepcopy(dqn)
total_steps = steps_per_epoch * epochs
state, ep_reward, ep_length = self.env.reset(), 0, 0
for step in range(1, total_steps + 1):
eps = 0.05 + (0.9 - 0.05) * exp(-step / 1000)
if torch.rand(1).item() < eps:
action = self.env.action_space.sample()
else:
action, _ = dqn(state.to(device))
next_state, reward, done, _ = self.env.step(action)
done = False if ep_length == max_ep_len else done
self.replay.append([state, action, reward, done, next_state])
state = next_state
ep_reward += reward
ep_length += 1
if len(self.replay) >= batch_size:
self.update(
step,
dqn,
batch_size=batch_size,
gamma=gamma,
target_update=target_update,
)
if step % steps_per_epoch == 0:
for callback in callbacks:
callback(self)
if done or (ep_length == max_ep_len):
self.ep_rewards.append(ep_reward)
epoch = (step + 1) // steps_per_epoch
print(f"\rEpoch {epoch} | Step {step} | Reward {ep_reward}", end="")
state, ep_reward, ep_length = self.env.reset(), 0, 0
def train(
self,
actor: Actor,
critic: Critic,
replay: Replay = None,
actor_lr: float = 3e-4,
critic_lr: float = 1e-3,
train_critic_iters: int = 10,
epochs: int = 200,
steps_per_epoch: int = 4000,
max_ep_len: int = 1000,
gamma: float = 0.99,
lam: float = 0.97,
callbacks: Iterable[Callable] = (),
):
"""Advantage Actor-Critic (A2C) algorithm for training RL agents in both
continuous and discrete action spaces.
**NOTE:** Synchronous A2C was chosen over the asynchronous version (A3C)
due to its simplicity. It's also questionable that A3C performs better
than A2C in the first place (in terms of the resulting trained policy,
not training speed in Python). Other people/organizations have also
pointed this out, including OpenAI.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
critic: (base.Critic) Critic network to optimize.
replay: (base.Replay, optional) Experience replay object for sampling
previous experiences. If not provided, defaults to 'ExperienceReplay'
with a buffer size of 1,000,000. Users can provide a replay object,
which is pre-populated with experiences (for specific use cases).
steps_per_epoch: (int, optional) Number of steps of interaction
for the agent and the environment in each epoch. Default: 4000.
epochs: (int, optional) Number of training epochs. Default: 100.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
actor_lr: (float, optional) Learning rate actor optimizer. Default: 1e-3.
critic_lr: (float, optional) Learning rate critic optimizer. Default: 1e-3.
train_critic_iters: (int, optional) Max number of critic training steps
per epoch. Default: 10.
lam: (float, optional) Hyperparameter for GAE-Lambda calaulation.
Range: (0, 1). Default: 0.97.
max_ep_len: (int, optional) Maximum length of episode. Defaults to 1000,
but *this should be provided for each unique environment!* This
has an effect on how end-of-episode rewards are computed.
callbacks: (Iterable[Callable], optional) callback functions to execute
at the end of each training epoch.
"""
device = utils.get_device(actor)
self.actor_optimizer = Adam(actor.parameters(), lr=actor_lr)
self.critic_optimizer = Adam(critic.parameters(), lr=critic_lr)
self.replay = NoReplay(steps_per_epoch) if replay is None else replay
for epoch in range(1, epochs + 1):
state = self.env.reset()
ep_reward, ep_length = 0, 0
num_episodes = 0
for t in range(1, steps_per_epoch + 1):
action, logprob = actor(state.to(device))
next_state, reward, done, _ = self.env.step(action)
self.replay.append([state, action, logprob, reward, done, next_state])
state = next_state
ep_reward += reward
ep_length += 1
if done or (ep_length == max_ep_len):
num_episodes += 1
self.ep_rewards.append(ep_reward)
state = self.env.reset()
ep_reward, ep_length = 0, 0
self.update(
actor,
critic,
train_critic_iters=train_critic_iters,
gamma=gamma,
lam=lam,
)
avg_reward = sum(self.ep_rewards[-num_episodes:]) / num_episodes
print(f"\rEpoch {epoch} | Avg Reward {avg_reward}", end="")
for callback in callbacks:
callback(self)
def train(
self,
actor: Actor,
critics: Iterable[Critic],
replay: Replay = None,
steps_per_epoch: int = 4000,
epochs: int = 100,
gamma: float = 0.99,
polyak: float = 0.995,
actor_lr: float = 5e-4,
critic_lr: float = 1e-3,
batch_size: int = 128,
start_steps: int = 5000,
update_after: int = 1000,
update_every: int = 50,
act_noise: float = 0.1,
target_noise: float = 0.2,
noise_clip: float = 0.5,
policy_delay: int = 2,
max_ep_len: int = 1000,
callbacks: Iterable[Callable] = (),
):
"""Twin-Delayed Deep Deterministic (TD3) Policy Gradients training
algorithm. Supports only *deterministic* policies in *continuous*
action spaces.
Parameters
----------
actor: (base.Actor) Actor (policy) network to optimize.
critics: (Iterable[base.Critic]) Critic networks to optimize. In standard
SAC there are *two* critics, but this method only requires that *two or
more* critics are provided.
replay: (base.Replay, optional) Experience replay object for sampling
previous experiences. If not provided, defaults to 'ExperienceReplay'
with a buffer size of 1,000,000. Users can provide a replay object,
which is pre-populated with experiences (for specific use cases).
steps_per_epoch: (int, optional) Number of steps of interaction
for the agent and the environment in each epoch. Default: 4000.
epochs: (int, optional) Number of training epochs. Default: 100.
gamma: (float, optional) Discount factor. Range: (0, 1). Default: 0.99
polyak: (float, optional) Interpolation factor in polyak averaging for
target networks. Range: (0, 1). Default: 0.995
actor_lr: (float, optional) Learning rate actor optimizer. Default: 1e-3.
critic_lr: (float, optional) Learning rate critic optimizer. Default: 1e-3.
batch_size: (int, optional) Minibatch size for SGD. Default: 128.
start_steps: (int, optional) Number of steps for random action selection
before running real policy (helps exploration). Default: 1000.
update_after: (int, optional) Number of env interactions to collect before
starting to do gradient descent updates. Ensures replay buffer
is full enough for useful updates. Default: 5000.
update_every: (int, optional) Number of env interactions that should elapse
between gradient descent updates. Note: Regardless of how long
you wait between updates, the ratio of env steps to gradient steps
is locked to 1. Default: 1.
act_noise: (float, optional) Stddev for Gaussian exploration noise added
to policy at training time. Default: 0.1.
target_noise: (float, optional) Stddev for smoothing noise added to
target policy. Default: 0.2.
noise_clip: (float, optional) Max absolute value of target policy
smoothing noise. Default: 0.5.
policy_delay: (int, optional) Policy will only be updated once every
policy_delay times for each update of the Q-networks. Default: 2.
max_ep_len: (int, optional) Maximum length of episode. Defaults to 1000,
but *this should be provided for each unique environment!* This
has an effect on how end-of-episode rewards are computed.
callbacks: (Iterable[Callable], optional) callback functions to execute
at the end of each training epoch.
"""
device = utils.get_device(actor)
self.replay = replay
if replay is None:
self.replay = ExperienceReplay(int(1e6))
critic_params = chain(*[c.parameters() for c in critics])
self.critic_optimizer = Adam(critic_params, lr=critic_lr)
self.actor_optimizer = Adam(actor.parameters(), lr=actor_lr)
self.target_actor = deepcopy(actor)
self.target_critics = deepcopy(critics)
total_steps = steps_per_epoch * epochs
state, ep_reward, ep_length = self.env.reset(), 0, 0
for step in range(1, total_steps + 1):
if step < start_steps:
action = self.env.action_space.sample()
else:
action, _ = actor(state.to(device))
action += act_noise * torch.randn_like(action)
next_state, reward, done, _ = self.env.step(action)
done = False if ep_length == max_ep_len else done
self.replay.append([state, action, reward, done, next_state])
state = next_state
ep_reward += reward
ep_length += 1
if step >= update_after and step % update_every == 0:
for iter in range(update_every):
self.update(
iter,
actor,
critics,
batch_size=batch_size,
gamma=gamma,
target_noise=target_noise,
noise_clip=noise_clip,
policy_delay=policy_delay,
polyak=polyak,
)
if step % steps_per_epoch == 0:
for callback in callbacks:
callback(self)
if done or (ep_length == max_ep_len):
self.ep_rewards.append(ep_reward)
epoch = (step + 1) // steps_per_epoch
print(f"\rEpoch {epoch} | Step {step} | Reward {ep_reward}",
end="")
state, ep_reward, ep_length = self.env.reset(), 0, 0