def _preprocess_states_actions(actions, states, device):
# Process states and actions
states = [''.join(list(state)) for state in states]
states, states_len = pad_sequences(states)
states, _ = seq2tensor(states, get_default_tokens())
states = torch.from_numpy(states).long().to(device)
states_len = torch.tensor(states_len).long().to(device)
actions, _ = seq2tensor(actions, get_default_tokens())
actions = torch.from_numpy(actions.reshape(-1)).long().to(device)
return (states, states_len), actions
def forward(self, x):
"""
Performs forward propagation to get predictions.
Arguments:
----------
:param x: list
A list of SMILES strings as input to the model.
:return: tensor
predictions corresponding to x.
"""
batch_size = len(x)
x, states_len = pad_sequences(x)
x, _ = seq2tensor(x, self.tokens)
x = torch.from_numpy(x).long().to(self.device)
x = self.encoder(x)
x = x.permute(1, 0, 2)
h0 = torch.zeros(self.num_layers * self.num_directions, batch_size,
self.d_model).to(self.device)
if self.unit_type == 'lstm':
c0 = torch.zeros(self.num_layers * self.num_directions, batch_size,
self.d_model).to(self.device)
h0 = (h0, c0)
x, hidden = self.rnn(x, h0)
x = x[-1, :, :].reshape(batch_size, -1)
x = self.read_out(x)
return x
def calc_adv_ref(self, trajectory):
states, actions, _ = unpack_batch([trajectory], self.gamma)
last_state = ''.join(list(states[-1]))
inp, _ = seq2tensor([last_state], tokens=get_default_tokens())
inp = torch.from_numpy(inp).long().to(self.device)
values_v = self.critic(inp)
values = values_v.view(-1, ).data.cpu().numpy()
last_gae = 0.0
result_adv = []
result_ref = []
for val, next_val, exp in zip(reversed(values[:-1]),
reversed(values[1:]),
reversed(trajectory[:-1])):
if exp.last_state is None: # for terminal state
delta = exp.reward - val
last_gae = delta
else:
delta = exp.reward + self.gamma * next_val - val
last_gae = delta + self.gamma * self.gae_lambda * last_gae
result_adv.append(last_gae)
result_ref.append(last_gae + val)
adv_v = torch.FloatTensor(list(reversed(result_adv))).to(self.device)
ref_v = torch.FloatTensor(list(reversed(result_ref))).to(self.device)
return states[:-1], actions[:-1], adv_v, ref_v
def smiles_to_tensor(smiles):
smiles = list(smiles)
_, valid_vec = canonical_smiles(smiles)
valid_vec = torch.tensor(valid_vec).view(-1, 1).float().to(device)
smiles, _ = pad_sequences(smiles)
inp, _ = seq2tensor(smiles, tokens=get_default_tokens())
inp = torch.from_numpy(inp).long().to(device)
return inp, valid_vec
def random_training_set(self, batch_size=None, return_seq_len=False):
if batch_size is None:
batch_size = self.batch_size
assert (batch_size > 0)
inp, target = self.random_chunk(batch_size)
inp_padded, inp_seq_len = pad_sequences(inp)
inp_tensor, self.all_characters = seq2tensor(
inp_padded, tokens=self.all_characters, flip=False)
target_padded, target_seq_len = pad_sequences(target)
target_tensor, self.all_characters = seq2tensor(
target_padded, tokens=self.all_characters, flip=False)
self.n_characters = len(self.all_characters)
inp_tensor = torch.tensor(inp_tensor).long()
target_tensor = torch.tensor(target_tensor).long()
if self.use_cuda:
inp_tensor = inp_tensor.cuda()
target_tensor = target_tensor.cuda()
if return_seq_len:
return inp_tensor, target_tensor, (inp_seq_len, target_seq_len)
return inp_tensor, target_tensor
def fit(self, trajectories):
"""Train the reward function / model using the GRL algorithm."""
"""Train the reward function / model using the GRL algorithm."""
if self.use_buffer:
extra_trajs = self.replay_buffer.sample(self.batch_size)
trajectories.extend(extra_trajs)
self.replay_buffer.populate(trajectories)
d_traj, d_traj_probs = [], []
for traj in trajectories:
d_traj.append(''.join(list(traj.terminal_state.state)) +
traj.terminal_state.action)
d_traj_probs.append(traj.traj_prob)
_, valid_vec_samp = canonical_smiles(d_traj)
valid_vec_samp = torch.tensor(valid_vec_samp).view(-1, 1).float().to(
self.device)
d_traj, _ = pad_sequences(d_traj)
d_samp, _ = seq2tensor(d_traj, tokens=get_default_tokens())
d_samp = torch.from_numpy(d_samp).long().to(self.device)
losses = []
for i in trange(self.k, desc='IRL optimization...'):
# D_demo processing
demo_states, demo_actions = self.demo_gen_data.random_training_set(
)
d_demo = torch.cat(
[demo_states, demo_actions[:, -1].reshape(-1, 1)],
dim=1).to(self.device)
valid_vec_demo = torch.ones(d_demo.shape[0]).view(
-1, 1).float().to(self.device)
d_demo_out = self.model([d_demo, valid_vec_demo])
# D_samp processing
d_samp_out = self.model([d_samp, valid_vec_samp])
d_out_combined = torch.cat([d_samp_out, d_demo_out], dim=0)
if d_samp_out.shape[0] < 1000:
d_samp_out = torch.cat([d_samp_out, d_demo_out], dim=0)
z = torch.ones(d_samp_out.shape[0]).float().to(
self.device) # dummy importance weights TODO: replace this
d_samp_out = z.view(-1, 1) * torch.exp(d_samp_out)
# objective
loss = torch.mean(d_demo_out) - torch.log(torch.mean(d_samp_out))
losses.append(loss.item())
loss = -loss # for maximization
# update params
self.optimizer.zero_grad()
loss.backward()
self.optimizer.step()
# self.lr_sch.step()
return np.mean(losses)
def __call__(self, x, use_mc):
"""
Calculates the reward function of a given state.
:param x:
The state to be used in calculating the reward.
:param use_mc:
Whether Monte Carlo Tree Search or the parameterized reward function should be used
:return: float
A scalar value representing the reward w.r.t. the given state x.
"""
if use_mc:
if self.mc_enabled:
mc_node = MoleculeMonteCarloTreeSearchNode(
x,
self,
self.mc_policy,
self.actions,
self.max_len,
end_char=self.end_char)
mcts = MonteCarloTreeSearch(mc_node)
reward = mcts(simulations_number=self.mc_max_sims)
return reward
else:
return self.no_mc_fill_val
else:
# Get reward of completed string using the reward net or a given reward function.
state = ''.join(x.tolist())
if self.use_true_reward:
state = state[1:-1].replace('\n', '-')
reward = self.true_reward_func(state, self.expert_func)
else:
smiles, valid_vec = canonical_smiles([state])
valid_vec = torch.tensor(valid_vec).view(-1, 1).float().to(
self.device)
inp, _ = seq2tensor([state], tokens=self.actions)
inp = torch.from_numpy(inp).long().to(self.device)
reward = self.model([inp, valid_vec]).squeeze().item()
return self.reward_wrapper(reward)
def fit(self, trajectories):
sq2ten = lambda x: torch.from_numpy(
seq2tensor(x, get_default_tokens())[0]).long().to(self.device)
t_states, t_actions, t_adv, t_ref = [], [], [], []
t_old_probs = []
for traj in trajectories:
states, actions, adv_v, ref_v = self.calc_adv_ref(traj)
if len(states) == 0:
continue
t_states.append(states)
t_actions.append(actions)
t_adv.append(adv_v)
t_ref.append(ref_v)
with torch.set_grad_enabled(False):
hidden_states = self.initial_states_func(
batch_size=1, **self.initial_states_args)
trajectory_input = sq2ten(states[-1])
actions = sq2ten(actions)
old_probs = []
for p in range(len(trajectory_input)):
outputs = self.model([trajectory_input[p].reshape(1, 1)] +
hidden_states)
output, hidden_states = outputs[0], outputs[1:]
log_prob = torch.log_softmax(output.view(1, -1), dim=1)
old_probs.append(log_prob[0, actions[p]].item())
t_old_probs.append(old_probs)
if len(t_states) == 0:
return 0., 0.
for epoch in trange(self.ppo_epochs, desc='PPO optimization...'):
cr_loss = 0.
ac_loss = 0.
for i in range(len(t_states)):
traj_last_state = t_states[i][-1]
traj_actions = t_actions[i]
traj_adv = t_adv[i]
traj_ref = t_ref[i]
traj_old_probs = t_old_probs[i]
hidden_states = self.initial_states_func(
1, **self.initial_states_args)
for p in range(len(traj_last_state)):
state, action, adv = traj_last_state[p], traj_actions[
p], traj_adv[p]
old_log_prob = traj_old_probs[p]
state, action = sq2ten(state), sq2ten(action)
# Critic
pred = self.critic(state)
cr_loss = cr_loss + F.mse_loss(pred.reshape(-1, 1),
traj_ref[p].reshape(-1, 1))
# Actor
outputs = self.actor([state] + hidden_states)
output, hidden_states = outputs[0], outputs[1:]
logprob_pi_v = torch.log_softmax(output.view(1, -1),
dim=-1)
logprob_pi_v = logprob_pi_v[0, action]
ratio_v = torch.exp(logprob_pi_v - old_log_prob)
surr_obj_v = adv * ratio_v
clipped_surr_v = adv * torch.clamp(
ratio_v, 1.0 - self.ppo_eps, 1.0 + self.ppo_eps)
loss_policy_v = torch.min(surr_obj_v, clipped_surr_v)
# Maximize entropy
prob = torch.softmax(output.view(1, -1), dim=1)
prob = prob[0, action]
entropy = prob * logprob_pi_v
entropy_loss = self.entropy_beta * entropy
ac_loss = ac_loss - (loss_policy_v + entropy_loss)
# Update weights
self.critic_opt.zero_grad()
self.actor_opt.zero_grad()
cr_loss = cr_loss / len(trajectories)
ac_loss = ac_loss / len(trajectories)
cr_loss.backward()
ac_loss.backward()
self.critic_opt.step()
self.actor_opt.step()
return cr_loss.item(), -ac_loss.item()