def predict_batch(self, states):
batch_size = states.shape[0]
actions = self.action_sampler.sample((self.horizon, batch_size, self.num_random_action_selection))
states = np.expand_dims(states, axis=1)
states = (states, (1, self.num_random_action_selection, 1))
states = convert_to_tensor(states)
actions = convert_to_tensor(actions)
cost = torch.zeros(size=(batch_size, self.num_random_action_selection)).type(FloatTensor)
for i in range(self.horizon):
# reshape states and actions
states = states.view(-1, *states.shape[2:]) # (b, K, ob_dim) -> (b * K, ob_dim)
current_action = actions[i].view(-1, *actions[i][2:])
# predict next states and rewards
next_states, rewards = self.model.predict_next_states_rewards(states, current_action)
# reshape back
rewards = rewards.view(batch_size, self.num_random_action_selection)
next_states = next_states.view(batch_size, self.num_random_action_selection, *states.shape[2:])
cost += -rewards * self.gamma_inverse
states = next_states
best_action = torch.gather(actions[0], dim=1, index=torch.argmin(cost, dim=1, keepdim=True))
best_action = best_action.cpu().numpy()
return best_action
def predict_next_state(self, state, action):
states = np.expand_dims(state, axis=0)
actions = np.expand_dims(action, axis=0)
states = convert_to_tensor(states)
actions = convert_to_tensor(actions)
next_state = self.predict_next_states(states, actions).cpu().numpy()[0]
return next_state
def predict(self, state):
state = np.expand_dims(state, axis=0)
with torch.no_grad():
state = convert_to_tensor(state)
state = (state - self.state_mean) / self.state_std
action = self.model.forward(state)
return action.cpu().numpy()[0]
def update(self,
replay_buffer,
num_updates,
action_limit,
policy_freq=2,
batch_size=128,
target_noise=0.2,
clip_noise=0.5,
tau=5e-3,
gamma=0.99):
for i in range(num_updates):
transition = replay_buffer.sample(batch_size)
s_batch, a_batch, s2_batch, r_batch, t_batch = convert_to_tensor(
transition, location='gpu')
r_batch = r_batch.type(FloatTensor)
t_batch = t_batch.type(FloatTensor)
# get ground truth q value
with torch.no_grad():
target_action_noise = torch.clamp(torch.randn_like(a_batch) *
target_noise,
min=-clip_noise,
max=clip_noise)
target_action = torch.clamp(
self.target_actor_module.forward(s2_batch) +
target_action_noise,
min=-action_limit,
max=action_limit)
target_q = self.target_critic_module.forward(
state=s2_batch, action=target_action, minimum=True)
q_target = r_batch + gamma * target_q * (1 - t_batch)
# critic loss
q_values, q_values2 = self.critic_module.forward(s_batch,
a_batch,
minimum=False)
q_values_loss = F.mse_loss(q_values, q_target) + F.mse_loss(
q_values2, q_target)
self.critic_optimizer.zero_grad()
q_values_loss.backward()
self.critic_optimizer.step()
if i % policy_freq == 0:
action = self.actor_module.forward(s_batch)
q_values = self.critic_module.forward(s_batch,
action,
minimum=False)[0]
loss = -torch.mean(q_values)
self.actor_optimizer.zero_grad()
loss.backward()
self.actor_optimizer.step()
soft_update(self.target_critic_module, self.critic_module, tau)
soft_update(self.target_actor_module, self.actor_module, tau)
def set_statistics(self, dataset: ReplayBuffer):
state_mean, state_std = dataset.state_mean_std
self.state_mean = convert_to_tensor(state_mean).unsqueeze(dim=0)
self.state_std = convert_to_tensor(state_std).unsqueeze(dim=0)
if self.dynamics_model.discrete:
self.action_mean = None
self.action_std = None
else:
action_mean, action_std = dataset.action_mean_std
self.action_mean = convert_to_tensor(action_mean).unsqueeze(dim=0)
self.action_std = convert_to_tensor(action_std).unsqueeze(dim=0)
delta_state_mean, delta_state_std = dataset.delta_state_mean_std
self.delta_state_mean = convert_to_tensor(delta_state_mean).unsqueeze(
dim=0)
self.delta_state_std = convert_to_tensor(delta_state_std).unsqueeze(
dim=0)
if self.cost_fn_batch is None:
reward_mean, reward_std = dataset.reward_mean_std
self.reward_mean = reward_mean
self.reward_std = reward_std
def update(self, obs, actions, next_obs, done, reward):
""" Sample a mini-batch from replay buffer and update the network
Args:
obs: (batch_size, ob_dim)
actions: (batch_size, action_dim)
next_obs: (batch_size, ob_dim)
done: (batch_size,)
reward: (batch_size,)
Returns: None
"""
obs = convert_to_tensor(obs)
actions = convert_to_tensor(actions)
next_obs = convert_to_tensor(next_obs)
done = convert_to_tensor(done).type(FloatTensor)
reward = convert_to_tensor(reward)
# q loss
q_values, q_values2 = self.q_network.forward(obs, actions, False)
with torch.no_grad():
next_action_distribution = self.policy_net.forward_action(next_obs)
next_action = next_action_distribution.sample()
next_action_log_prob = next_action_distribution.log_prob(
next_action)
target_q_values = self.target_q_network.forward(
next_obs, next_action,
True) - self.alpha * next_action_log_prob
q_target = reward + self.gamma * (1.0 - done) * target_q_values
q_values_loss = F.mse_loss(q_values, q_target) + F.mse_loss(
q_values2, q_target)
# policy loss
if self.discrete:
# for discrete action space, we can directly compute kl divergence analytically without sampling
action_distribution = self.policy_net.forward_action(obs)
q_values_min = self.q_network.forward(obs, None,
True) # (batch_size, ac_dim)
probs = F.softmax(q_values_min, dim=-1)
target_distribution = torch.distributions.Categorical(probs=probs)
policy_loss = torch.distributions.kl_divergence(
action_distribution, target_distribution).mean()
log_prob = -action_distribution.entropy()
else:
action_distribution = self.policy_net.forward_action(obs)
pi = action_distribution.rsample()
log_prob = action_distribution.log_prob(
pi) # should be shape (batch_size,)
q_values_pi_min = self.q_network.forward(obs, pi, True)
policy_loss = torch.mean(log_prob * self.alpha - q_values_pi_min)
# alpha loss
if self.log_alpha_tensor is not None:
alpha_loss = -(self.log_alpha_tensor *
(log_prob + self.target_entropy).detach()).mean()
self.alpha_optimizer.zero_grad()
alpha_loss.backward()
self.alpha_optimizer.step()
self.alpha = self.log_alpha_tensor.exp().item()
self.q_optimizer.zero_grad()
q_values_loss.backward()
self.q_optimizer.step()
self.policy_optimizer.zero_grad()
policy_loss.backward()
self.policy_optimizer.step()
def predict_batch(self, states):
states = convert_to_tensor(states.astype(np.float32))
action_distribution = self.policy_net.forward_action(states)
return action_distribution.sample().cpu().numpy()
def predict_batch(self, state):
state = convert_to_tensor(state.astype(np.float32))
return self.actor_module.forward(state).cpu().numpy()
def set_state_stats(self, state_mean, state_std):
self.state_mean = convert_to_tensor(state_mean).unsqueeze(dim=0)
self.state_std = convert_to_tensor(state_std).unsqueeze(dim=0)