from typing import Dict, Optional, Tuple, List from mlagents.torch_utils import torch import numpy as np from collections import defaultdict from mlagents.trainers.buffer import AgentBuffer, AgentBufferField from mlagents.trainers.trajectory import ObsUtil from mlagents.trainers.torch.components.bc.module import BCModule from mlagents.trainers.torch.components.reward_providers import create_reward_provider from mlagents.trainers.policy.torch_policy import TorchPolicy from mlagents.trainers.optimizer import Optimizer from mlagents.trainers.settings import ( TrainerSettings, RewardSignalSettings, RewardSignalType, ) from mlagents.trainers.torch.utils import ModelUtils class TorchOptimizer(Optimizer): def __init__(self, policy: TorchPolicy, trainer_settings: TrainerSettings): super().__init__() self.policy = policy self.trainer_settings = trainer_settings self.update_dict: Dict[str, torch.Tensor] = {} self.value_heads: Dict[str, torch.Tensor] = {} self.memory_in: torch.Tensor = None self.memory_out: torch.Tensor = None self.m_size: int = 0 self.global_step = torch.tensor(0) self.bc_module: Optional[BCModule] = None self.create_reward_signals(trainer_settings.reward_signals) self.critic_memory_dict: Dict[str, torch.Tensor] = {} if trainer_settings.behavioral_cloning is not None: self.bc_module = BCModule( self.policy, trainer_settings.behavioral_cloning, policy_learning_rate=trainer_settings.hyperparameters.learning_rate, default_batch_size=trainer_settings.hyperparameters.batch_size, default_num_epoch=3, ) @property def critic(self): raise NotImplementedError def update(self, batch: AgentBuffer, num_sequences: int) -> Dict[str, float]: pass def create_reward_signals( self, reward_signal_configs: Dict[RewardSignalType, RewardSignalSettings] ) -> None: """ Create reward signals :param reward_signal_configs: Reward signal config. """ for reward_signal, settings in reward_signal_configs.items(): # Name reward signals by string in case we have duplicates later self.reward_signals[reward_signal.value] = create_reward_provider( reward_signal, self.policy.behavior_spec, settings ) def _evaluate_by_sequence( self, tensor_obs: List[torch.Tensor], initial_memory: torch.Tensor ) -> Tuple[Dict[str, torch.Tensor], AgentBufferField, torch.Tensor]: """ Evaluate a trajectory sequence-by-sequence, assembling the result. This enables us to get the intermediate memories for the critic. :param tensor_obs: A List of tensors of shape (trajectory_len, ) that are the agent's observations for this trajectory. :param initial_memory: The memory that preceeds this trajectory. Of shape (1,1,), i.e. what is returned as the output of a MemoryModules. :return: A Tuple of the value estimates as a Dict of [name, tensor], an AgentBufferField of the initial memories to be used during value function update, and the final memory at the end of the trajectory. """ num_experiences = tensor_obs[0].shape[0] all_next_memories = AgentBufferField() # When using LSTM, we need to divide the trajectory into sequences of equal length. Sometimes, # that division isn't even, and we must pad the leftover sequence. # When it is added to the buffer, the last sequence will be padded. So if seq_len = 3 and # trajectory is of length 10, the last sequence is [obs,pad,pad] once it is added to the buffer. # Compute the number of elements in this sequence that will end up being padded. leftover_seq_len = num_experiences % self.policy.sequence_length all_values: Dict[str, List[np.ndarray]] = defaultdict(list) _mem = initial_memory # Evaluate other trajectories, carrying over _mem after each # trajectory for seq_num in range(num_experiences // self.policy.sequence_length): seq_obs = [] for _ in range(self.policy.sequence_length): all_next_memories.append(ModelUtils.to_numpy(_mem.squeeze())) start = seq_num * self.policy.sequence_length end = (seq_num + 1) * self.policy.sequence_length for _obs in tensor_obs: seq_obs.append(_obs[start:end]) values, _mem = self.critic.critic_pass( seq_obs, _mem, sequence_length=self.policy.sequence_length ) for signal_name, _val in values.items(): all_values[signal_name].append(_val) # Compute values for the potentially truncated last sequence. Note that this # sequence isn't padded yet, but will be. seq_obs = [] if leftover_seq_len > 0: for _obs in tensor_obs: last_seq_obs = _obs[-leftover_seq_len:] seq_obs.append(last_seq_obs) # For the last sequence, the initial memory should be the one at the # end of this trajectory. for _ in range(leftover_seq_len): all_next_memories.append(ModelUtils.to_numpy(_mem.squeeze())) last_values, _mem = self.critic.critic_pass( seq_obs, _mem, sequence_length=leftover_seq_len ) for signal_name, _val in last_values.items(): all_values[signal_name].append(_val) # Create one tensor per reward signal all_value_tensors = { signal_name: torch.cat(value_list, dim=0) for signal_name, value_list in all_values.items() } next_mem = _mem return all_value_tensors, all_next_memories, next_mem def get_trajectory_value_estimates( self, batch: AgentBuffer, next_obs: List[np.ndarray], done: bool, agent_id: str = "", ) -> Tuple[Dict[str, np.ndarray], Dict[str, float], Optional[AgentBufferField]]: """ Get value estimates and memories for a trajectory, in batch form. :param batch: An AgentBuffer that consists of a trajectory. :param next_obs: the next observation (after the trajectory). Used for boostrapping if this is not a termiinal trajectory. :param done: Set true if this is a terminal trajectory. :param agent_id: Agent ID of the agent that this trajectory belongs to. :returns: A Tuple of the Value Estimates as a Dict of [name, np.ndarray(trajectory_len)], the final value estimate as a Dict of [name, float], and optionally (if using memories) an AgentBufferField of initial critic memories to be used during update. """ n_obs = len(self.policy.behavior_spec.observation_specs) if agent_id in self.critic_memory_dict: memory = self.critic_memory_dict[agent_id] else: memory = ( torch.zeros((1, 1, self.critic.memory_size)) if self.policy.use_recurrent else None ) # Convert to tensors current_obs = [ ModelUtils.list_to_tensor(obs) for obs in ObsUtil.from_buffer(batch, n_obs) ] next_obs = [ModelUtils.list_to_tensor(obs) for obs in next_obs] next_obs = [obs.unsqueeze(0) for obs in next_obs] # If we're using LSTM, we want to get all the intermediate memories. all_next_memories: Optional[AgentBufferField] = None # To prevent memory leak and improve performance, evaluate with no_grad. with torch.no_grad(): if self.policy.use_recurrent: ( value_estimates, all_next_memories, next_memory, ) = self._evaluate_by_sequence(current_obs, memory) else: value_estimates, next_memory = self.critic.critic_pass( current_obs, memory, sequence_length=batch.num_experiences ) # Store the memory for the next trajectory. This should NOT have a gradient. self.critic_memory_dict[agent_id] = next_memory next_value_estimate, _ = self.critic.critic_pass( next_obs, next_memory, sequence_length=1 ) for name, estimate in value_estimates.items(): value_estimates[name] = ModelUtils.to_numpy(estimate) next_value_estimate[name] = ModelUtils.to_numpy(next_value_estimate[name]) if done: for k in next_value_estimate: if not self.reward_signals[k].ignore_done: next_value_estimate[k] = 0.0 if agent_id in self.critic_memory_dict: self.critic_memory_dict.pop(agent_id) return value_estimates, next_value_estimate, all_next_memories