def sac_q_loss(
self,
q1_out: Dict[str, torch.Tensor],
q2_out: Dict[str, torch.Tensor],
target_values: Dict[str, torch.Tensor],
dones: torch.Tensor,
rewards: Dict[str, torch.Tensor],
loss_masks: torch.Tensor,
) -> Tuple[torch.Tensor, torch.Tensor]:
q1_losses = []
q2_losses = []
# Multiple q losses per stream
for i, name in enumerate(q1_out.keys()):
q1_stream = q1_out[name].squeeze()
q2_stream = q2_out[name].squeeze()
with torch.no_grad():
q_backup = rewards[name] + (
(1.0 - self.use_dones_in_backup[name] * dones) *
self.gammas[i] * target_values[name])
_q1_loss = 0.5 * ModelUtils.masked_mean(
torch.nn.functional.mse_loss(q_backup, q1_stream), loss_masks)
_q2_loss = 0.5 * ModelUtils.masked_mean(
torch.nn.functional.mse_loss(q_backup, q2_stream), loss_masks)
q1_losses.append(_q1_loss)
q2_losses.append(_q2_loss)
q1_loss = torch.mean(torch.stack(q1_losses))
q2_loss = torch.mean(torch.stack(q2_losses))
return q1_loss, q2_loss
def sac_entropy_loss(
self, log_probs: torch.Tensor, loss_masks: torch.Tensor, discrete: bool
) -> torch.Tensor:
if not discrete:
with torch.no_grad():
target_current_diff = torch.sum(log_probs + self.target_entropy, dim=1)
entropy_loss = -1 * ModelUtils.masked_mean(
self._log_ent_coef * target_current_diff, loss_masks
)
else:
with torch.no_grad():
branched_per_action_ent = ModelUtils.break_into_branches(
log_probs * log_probs.exp(), self.act_size
)
target_current_diff_branched = torch.stack(
[
torch.sum(_lp, axis=1, keepdim=True) + _te
for _lp, _te in zip(
branched_per_action_ent, self.target_entropy
)
],
axis=1,
)
target_current_diff = torch.squeeze(
target_current_diff_branched, axis=2
)
entropy_loss = -1 * ModelUtils.masked_mean(
torch.mean(self._log_ent_coef * target_current_diff, axis=1), loss_masks
)
return entropy_loss
def sac_policy_loss(
self,
log_probs: torch.Tensor,
q1p_outs: Dict[str, torch.Tensor],
loss_masks: torch.Tensor,
discrete: bool,
) -> torch.Tensor:
_ent_coef = torch.exp(self._log_ent_coef)
mean_q1 = torch.mean(torch.stack(list(q1p_outs.values())), axis=0)
if not discrete:
mean_q1 = mean_q1.unsqueeze(1)
batch_policy_loss = torch.mean(_ent_coef * log_probs - mean_q1, dim=1)
policy_loss = ModelUtils.masked_mean(batch_policy_loss, loss_masks)
else:
action_probs = log_probs.exp()
branched_per_action_ent = ModelUtils.break_into_branches(
log_probs * action_probs, self.act_size
)
branched_q_term = ModelUtils.break_into_branches(
mean_q1 * action_probs, self.act_size
)
branched_policy_loss = torch.stack(
[
torch.sum(_ent_coef[i] * _lp - _qt, dim=1, keepdim=True)
for i, (_lp, _qt) in enumerate(
zip(branched_per_action_ent, branched_q_term)
)
],
dim=1,
)
batch_policy_loss = torch.squeeze(branched_policy_loss)
policy_loss = ModelUtils.masked_mean(batch_policy_loss, loss_masks)
return policy_loss
def test_masked_mean():
test_input = torch.tensor([1, 2, 3, 4, 5])
masks = torch.ones_like(test_input).bool()
mean = ModelUtils.masked_mean(test_input, masks=masks)
assert mean == 3.0
masks = torch.tensor([False, False, True, True, True])
mean = ModelUtils.masked_mean(test_input, masks=masks)
assert mean == 4.0
# Make sure it works if all masks are off
masks = torch.tensor([False, False, False, False, False])
mean = ModelUtils.masked_mean(test_input, masks=masks)
assert mean == 0.0
def ppo_policy_loss(
self,
advantages: torch.Tensor,
log_probs: torch.Tensor,
old_log_probs: torch.Tensor,
loss_masks: torch.Tensor,
) -> torch.Tensor:
"""
Evaluate PPO policy loss.
:param advantages: Computed advantages.
:param log_probs: Current policy probabilities
:param old_log_probs: Past policy probabilities
:param loss_masks: Mask for losses. Used with LSTM to ignore 0'ed out experiences.
"""
advantage = advantages.unsqueeze(-1)
decay_epsilon = self.hyperparameters.epsilon
r_theta = torch.exp(log_probs - old_log_probs)
p_opt_a = r_theta * advantage
p_opt_b = (
torch.clamp(r_theta, 1.0 - decay_epsilon, 1.0 + decay_epsilon) *
advantage)
policy_loss = -1 * ModelUtils.masked_mean(torch.min(p_opt_a, p_opt_b),
loss_masks)
return policy_loss
def ppo_value_loss(
self,
values: Dict[str, torch.Tensor],
old_values: Dict[str, torch.Tensor],
returns: Dict[str, torch.Tensor],
epsilon: float,
loss_masks: torch.Tensor,
) -> torch.Tensor:
"""
Evaluates value loss for PPO.
:param values: Value output of the current network.
:param old_values: Value stored with experiences in buffer.
:param returns: Computed returns.
:param epsilon: Clipping value for value estimate.
:param loss_mask: Mask for losses. Used with LSTM to ignore 0'ed out experiences.
"""
value_losses = []
for name, head in values.items():
old_val_tensor = old_values[name]
returns_tensor = returns[name]
clipped_value_estimate = old_val_tensor + torch.clamp(
head - old_val_tensor, -1 * epsilon, epsilon)
v_opt_a = (returns_tensor - head)**2
v_opt_b = (returns_tensor - clipped_value_estimate)**2
value_loss = ModelUtils.masked_mean(torch.max(v_opt_a, v_opt_b),
loss_masks)
value_losses.append(value_loss)
value_loss = torch.mean(torch.stack(value_losses))
return value_loss
def sac_entropy_loss(
self, log_probs: ActionLogProbs, loss_masks: torch.Tensor
) -> torch.Tensor:
_cont_ent_coef, _disc_ent_coef = (
self._log_ent_coef.continuous,
self._log_ent_coef.discrete,
)
entropy_loss = 0
if self._action_spec.discrete_size > 0:
with torch.no_grad():
# Break continuous into separate branch
disc_log_probs = log_probs.all_discrete_tensor
branched_per_action_ent = ModelUtils.break_into_branches(
disc_log_probs * disc_log_probs.exp(),
self._action_spec.discrete_branches,
)
target_current_diff_branched = torch.stack(
[
torch.sum(_lp, axis=1, keepdim=True) + _te
for _lp, _te in zip(
branched_per_action_ent, self.target_entropy.discrete
)
],
axis=1,
)
target_current_diff = torch.squeeze(
target_current_diff_branched, axis=2
)
entropy_loss += -1 * ModelUtils.masked_mean(
torch.mean(_disc_ent_coef * target_current_diff, axis=1), loss_masks
)
if self._action_spec.continuous_size > 0:
with torch.no_grad():
cont_log_probs = log_probs.continuous_tensor
target_current_diff = torch.sum(
cont_log_probs + self.target_entropy.continuous, dim=1
)
# We update all the _cont_ent_coef as one block
entropy_loss += -1 * ModelUtils.masked_mean(
_cont_ent_coef * target_current_diff, loss_masks
)
return entropy_loss
def test_masked_mean():
test_input = torch.tensor([1, 2, 3, 4, 5])
masks = torch.ones_like(test_input).bool()
mean = ModelUtils.masked_mean(test_input, masks=masks)
assert mean == 3.0
masks = torch.tensor([False, False, True, True, True])
mean = ModelUtils.masked_mean(test_input, masks=masks)
assert mean == 4.0
# Make sure it works if all masks are off
masks = torch.tensor([False, False, False, False, False])
mean = ModelUtils.masked_mean(test_input, masks=masks)
assert mean == 0.0
# Make sure it works with 2d arrays of shape (mask_length, N)
test_input = torch.tensor([1, 2, 3, 4, 5]).repeat(2, 1).T
masks = torch.tensor([False, False, True, True, True])
mean = ModelUtils.masked_mean(test_input, masks=masks)
assert mean == 4.0
def sac_policy_loss(
self,
log_probs: ActionLogProbs,
q1p_outs: Dict[str, torch.Tensor],
loss_masks: torch.Tensor,
) -> torch.Tensor:
_cont_ent_coef, _disc_ent_coef = (
self._log_ent_coef.continuous,
self._log_ent_coef.discrete,
)
_cont_ent_coef = _cont_ent_coef.exp()
_disc_ent_coef = _disc_ent_coef.exp()
mean_q1 = torch.mean(torch.stack(list(q1p_outs.values())), axis=0)
batch_policy_loss = 0
if self._action_spec.discrete_size > 0:
disc_log_probs = log_probs.all_discrete_tensor
disc_action_probs = disc_log_probs.exp()
branched_per_action_ent = ModelUtils.break_into_branches(
disc_log_probs * disc_action_probs,
self._action_spec.discrete_branches)
branched_q_term = ModelUtils.break_into_branches(
mean_q1 * disc_action_probs,
self._action_spec.discrete_branches)
branched_policy_loss = torch.stack(
[
torch.sum(
_disc_ent_coef[i] * _lp - _qt, dim=1, keepdim=False)
for i, (_lp, _qt) in enumerate(
zip(branched_per_action_ent, branched_q_term))
],
dim=1,
)
batch_policy_loss += torch.sum(branched_policy_loss, dim=1)
all_mean_q1 = torch.sum(disc_action_probs * mean_q1, dim=1)
else:
all_mean_q1 = mean_q1
if self._action_spec.continuous_size > 0:
cont_log_probs = log_probs.continuous_tensor
batch_policy_loss += torch.mean(_cont_ent_coef * cont_log_probs -
all_mean_q1.unsqueeze(1),
dim=1)
policy_loss = ModelUtils.masked_mean(batch_policy_loss, loss_masks)
return policy_loss
def update(self, batch: AgentBuffer,
num_sequences: int) -> Dict[str, float]:
"""
Performs update on model.
:param batch: Batch of experiences.
:param num_sequences: Number of sequences to process.
:return: Results of update.
"""
# Get decayed parameters
decay_lr = self.decay_learning_rate.get_value(
self.policy.get_current_step())
decay_eps = self.decay_epsilon.get_value(
self.policy.get_current_step())
decay_bet = self.decay_beta.get_value(self.policy.get_current_step())
returns = {}
old_values = {}
for name in self.reward_signals:
old_values[name] = ModelUtils.list_to_tensor(
batch[f"{name}_value_estimates"])
returns[name] = ModelUtils.list_to_tensor(batch[f"{name}_returns"])
vec_obs = [ModelUtils.list_to_tensor(batch["vector_obs"])]
act_masks = ModelUtils.list_to_tensor(batch["action_mask"])
if self.policy.use_continuous_act:
actions = ModelUtils.list_to_tensor(batch["actions"]).unsqueeze(-1)
else:
actions = ModelUtils.list_to_tensor(batch["actions"],
dtype=torch.long)
memories = [
ModelUtils.list_to_tensor(batch["memory"][i]) for i in range(
0, len(batch["memory"]), self.policy.sequence_length)
]
if len(memories) > 0:
memories = torch.stack(memories).unsqueeze(0)
if self.policy.use_vis_obs:
vis_obs = []
for idx, _ in enumerate(
self.policy.actor_critic.network_body.visual_encoders):
vis_ob = ModelUtils.list_to_tensor(batch["visual_obs%d" % idx])
vis_obs.append(vis_ob)
else:
vis_obs = []
log_probs, entropy, values = self.policy.evaluate_actions(
vec_obs,
vis_obs,
masks=act_masks,
actions=actions,
memories=memories,
seq_len=self.policy.sequence_length,
)
loss_masks = ModelUtils.list_to_tensor(batch["masks"],
dtype=torch.bool)
value_loss = self.ppo_value_loss(values, old_values, returns,
decay_eps, loss_masks)
policy_loss = self.ppo_policy_loss(
ModelUtils.list_to_tensor(batch["advantages"]),
log_probs,
ModelUtils.list_to_tensor(batch["action_probs"]),
loss_masks,
)
loss = (policy_loss + 0.5 * value_loss -
decay_bet * ModelUtils.masked_mean(entropy, loss_masks))
# Set optimizer learning rate
ModelUtils.update_learning_rate(self.optimizer, decay_lr)
self.optimizer.zero_grad()
loss.backward()
self.optimizer.step()
update_stats = {
"Losses/Policy Loss": abs(policy_loss.detach().cpu().numpy()),
"Losses/Value Loss": value_loss.detach().cpu().numpy(),
"Policy/Learning Rate": decay_lr,
"Policy/Epsilon": decay_eps,
"Policy/Beta": decay_bet,
}
for reward_provider in self.reward_signals.values():
update_stats.update(reward_provider.update(batch))
return update_stats
def update(self, batch: AgentBuffer,
num_sequences: int) -> Dict[str, float]:
"""
Performs update on model.
:param batch: Batch of experiences.
:param num_sequences: Number of sequences to process.
:return: Results of update.
"""
# Get decayed parameters
decay_lr = self.decay_learning_rate.get_value(
self.policy.get_current_step())
decay_eps = self.decay_epsilon.get_value(
self.policy.get_current_step())
decay_bet = self.decay_beta.get_value(self.policy.get_current_step())
returns = {}
old_values = {}
for name in self.reward_signals:
old_values[name] = ModelUtils.list_to_tensor(
batch[RewardSignalUtil.value_estimates_key(name)])
returns[name] = ModelUtils.list_to_tensor(
batch[RewardSignalUtil.returns_key(name)])
n_obs = len(self.policy.behavior_spec.observation_specs)
current_obs = ObsUtil.from_buffer(batch, n_obs)
# Convert to tensors
current_obs = [ModelUtils.list_to_tensor(obs) for obs in current_obs]
act_masks = ModelUtils.list_to_tensor(batch[BufferKey.ACTION_MASK])
actions = AgentAction.from_buffer(batch)
memories = [
ModelUtils.list_to_tensor(batch[BufferKey.MEMORY][i]) for i in
range(0, len(batch[BufferKey.MEMORY]), self.policy.sequence_length)
]
if len(memories) > 0:
memories = torch.stack(memories).unsqueeze(0)
# Get value memories
value_memories = [
ModelUtils.list_to_tensor(batch[BufferKey.CRITIC_MEMORY][i])
for i in range(0, len(batch[BufferKey.CRITIC_MEMORY]),
self.policy.sequence_length)
]
if len(value_memories) > 0:
value_memories = torch.stack(value_memories).unsqueeze(0)
log_probs, entropy = self.policy.evaluate_actions(
current_obs,
masks=act_masks,
actions=actions,
memories=memories,
seq_len=self.policy.sequence_length,
)
values, _ = self.critic.critic_pass(
current_obs,
memories=value_memories,
sequence_length=self.policy.sequence_length,
)
old_log_probs = ActionLogProbs.from_buffer(batch).flatten()
log_probs = log_probs.flatten()
loss_masks = ModelUtils.list_to_tensor(batch[BufferKey.MASKS],
dtype=torch.bool)
value_loss = self.ppo_value_loss(values, old_values, returns,
decay_eps, loss_masks)
policy_loss = self.ppo_policy_loss(
ModelUtils.list_to_tensor(batch[BufferKey.ADVANTAGES]),
log_probs,
old_log_probs,
loss_masks,
)
loss = (policy_loss + 0.5 * value_loss -
decay_bet * ModelUtils.masked_mean(entropy, loss_masks))
# Set optimizer learning rate
ModelUtils.update_learning_rate(self.optimizer, decay_lr)
self.optimizer.zero_grad()
loss.backward()
self.optimizer.step()
update_stats = {
# NOTE: abs() is not technically correct, but matches the behavior in TensorFlow.
# TODO: After PyTorch is default, change to something more correct.
"Losses/Policy Loss": torch.abs(policy_loss).item(),
"Losses/Value Loss": value_loss.item(),
"Policy/Learning Rate": decay_lr,
"Policy/Epsilon": decay_eps,
"Policy/Beta": decay_bet,
}
for reward_provider in self.reward_signals.values():
update_stats.update(reward_provider.update(batch))
return update_stats
def sac_value_loss(
self,
log_probs: ActionLogProbs,
values: Dict[str, torch.Tensor],
q1p_out: Dict[str, torch.Tensor],
q2p_out: Dict[str, torch.Tensor],
loss_masks: torch.Tensor,
) -> torch.Tensor:
min_policy_qs = {}
with torch.no_grad():
_cont_ent_coef = self._log_ent_coef.continuous.exp()
_disc_ent_coef = self._log_ent_coef.discrete.exp()
for name in values.keys():
if self._action_spec.discrete_size <= 0:
min_policy_qs[name] = torch.min(q1p_out[name],
q2p_out[name])
else:
disc_action_probs = log_probs.all_discrete_tensor.exp()
_branched_q1p = ModelUtils.break_into_branches(
q1p_out[name] * disc_action_probs,
self._action_spec.discrete_branches,
)
_branched_q2p = ModelUtils.break_into_branches(
q2p_out[name] * disc_action_probs,
self._action_spec.discrete_branches,
)
_q1p_mean = torch.mean(
torch.stack([
torch.sum(_br, dim=1, keepdim=True)
for _br in _branched_q1p
]),
dim=0,
)
_q2p_mean = torch.mean(
torch.stack([
torch.sum(_br, dim=1, keepdim=True)
for _br in _branched_q2p
]),
dim=0,
)
min_policy_qs[name] = torch.min(_q1p_mean, _q2p_mean)
value_losses = []
if self._action_spec.discrete_size <= 0:
for name in values.keys():
with torch.no_grad():
v_backup = min_policy_qs[name] - torch.sum(
_cont_ent_coef * log_probs.continuous_tensor, dim=1)
value_loss = 0.5 * ModelUtils.masked_mean(
torch.nn.functional.mse_loss(values[name], v_backup),
loss_masks)
value_losses.append(value_loss)
else:
disc_log_probs = log_probs.all_discrete_tensor
branched_per_action_ent = ModelUtils.break_into_branches(
disc_log_probs * disc_log_probs.exp(),
self._action_spec.discrete_branches,
)
# We have to do entropy bonus per action branch
branched_ent_bonus = torch.stack([
torch.sum(_disc_ent_coef[i] * _lp, dim=1, keepdim=True)
for i, _lp in enumerate(branched_per_action_ent)
])
for name in values.keys():
with torch.no_grad():
v_backup = min_policy_qs[name] - torch.mean(
branched_ent_bonus, axis=0)
# Add continuous entropy bonus to minimum Q
if self._action_spec.continuous_size > 0:
v_backup += torch.sum(
_cont_ent_coef * log_probs.continuous_tensor,
dim=1,
keepdim=True,
)
value_loss = 0.5 * ModelUtils.masked_mean(
torch.nn.functional.mse_loss(values[name],
v_backup.squeeze()),
loss_masks,
)
value_losses.append(value_loss)
value_loss = torch.mean(torch.stack(value_losses))
if torch.isinf(value_loss).any() or torch.isnan(value_loss).any():
raise UnityTrainerException("Inf found")
return value_loss
def sac_value_loss(
self,
log_probs: torch.Tensor,
values: Dict[str, torch.Tensor],
q1p_out: Dict[str, torch.Tensor],
q2p_out: Dict[str, torch.Tensor],
loss_masks: torch.Tensor,
discrete: bool,
) -> torch.Tensor:
min_policy_qs = {}
with torch.no_grad():
_ent_coef = torch.exp(self._log_ent_coef)
for name in values.keys():
if not discrete:
min_policy_qs[name] = torch.min(q1p_out[name], q2p_out[name])
else:
action_probs = log_probs.exp()
_branched_q1p = ModelUtils.break_into_branches(
q1p_out[name] * action_probs, self.act_size
)
_branched_q2p = ModelUtils.break_into_branches(
q2p_out[name] * action_probs, self.act_size
)
_q1p_mean = torch.mean(
torch.stack(
[
torch.sum(_br, dim=1, keepdim=True)
for _br in _branched_q1p
]
),
dim=0,
)
_q2p_mean = torch.mean(
torch.stack(
[
torch.sum(_br, dim=1, keepdim=True)
for _br in _branched_q2p
]
),
dim=0,
)
min_policy_qs[name] = torch.min(_q1p_mean, _q2p_mean)
value_losses = []
if not discrete:
for name in values.keys():
with torch.no_grad():
v_backup = min_policy_qs[name] - torch.sum(
_ent_coef * log_probs, dim=1
)
value_loss = 0.5 * ModelUtils.masked_mean(
torch.nn.functional.mse_loss(values[name], v_backup), loss_masks
)
value_losses.append(value_loss)
else:
branched_per_action_ent = ModelUtils.break_into_branches(
log_probs * log_probs.exp(), self.act_size
)
# We have to do entropy bonus per action branch
branched_ent_bonus = torch.stack(
[
torch.sum(_ent_coef[i] * _lp, dim=1, keepdim=True)
for i, _lp in enumerate(branched_per_action_ent)
]
)
for name in values.keys():
with torch.no_grad():
v_backup = min_policy_qs[name] - torch.mean(
branched_ent_bonus, axis=0
)
value_loss = 0.5 * ModelUtils.masked_mean(
torch.nn.functional.mse_loss(values[name], v_backup.squeeze()),
loss_masks,
)
value_losses.append(value_loss)
value_loss = torch.mean(torch.stack(value_losses))
if torch.isinf(value_loss).any() or torch.isnan(value_loss).any():
raise UnityTrainerException("Inf found")
return value_loss
