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296 行
12 KiB
296 行
12 KiB
from typing import List, Optional, Tuple
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import torch
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import numpy as np
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from torch import nn
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from mlagents.trainers.torch.encoders import (
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SimpleVisualEncoder,
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ResNetVisualEncoder,
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NatureVisualEncoder,
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VectorEncoder,
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VectorAndUnnormalizedInputEncoder,
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)
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from mlagents.trainers.settings import EncoderType, ScheduleType
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from mlagents.trainers.exception import UnityTrainerException
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from mlagents_envs.base_env import BehaviorSpec
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from mlagents.trainers.torch.distributions import DistInstance, DiscreteDistInstance
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class ModelUtils:
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# Minimum supported side for each encoder type. If refactoring an encoder, please
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# adjust these also.
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MIN_RESOLUTION_FOR_ENCODER = {
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EncoderType.SIMPLE: 20,
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EncoderType.NATURE_CNN: 36,
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EncoderType.RESNET: 15,
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}
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class ActionFlattener:
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def __init__(self, behavior_spec: BehaviorSpec):
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self._specs = behavior_spec
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@property
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def flattened_size(self) -> int:
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if self._specs.is_action_continuous():
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return self._specs.action_size
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else:
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return sum(self._specs.discrete_action_branches)
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def forward(self, action: torch.Tensor) -> torch.Tensor:
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if self._specs.is_action_continuous():
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return action
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else:
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return torch.cat(
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ModelUtils.actions_to_onehot(
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torch.as_tensor(action, dtype=torch.long),
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self._specs.discrete_action_branches,
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),
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dim=1,
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)
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@staticmethod
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def update_learning_rate(optim: torch.optim.Optimizer, lr: float) -> None:
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"""
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Apply a learning rate to a torch optimizer.
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:param optim: Optimizer
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:param lr: Learning rate
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"""
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for param_group in optim.param_groups:
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param_group["lr"] = lr
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class DecayedValue:
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def __init__(
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self,
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schedule: ScheduleType,
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initial_value: float,
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min_value: float,
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max_step: int,
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):
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"""
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Object that represnets value of a parameter that should be decayed, assuming it is a function of
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global_step.
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:param schedule: Type of learning rate schedule.
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:param initial_value: Initial value before decay.
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:param min_value: Decay value to this value by max_step.
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:param max_step: The final step count where the return value should equal min_value.
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:param global_step: The current step count.
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:return: The value.
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"""
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self.schedule = schedule
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self.initial_value = initial_value
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self.min_value = min_value
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self.max_step = max_step
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def get_value(self, global_step: int) -> float:
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"""
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Get the value at a given global step.
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:param global_step: Step count.
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:returns: Decayed value at this global step.
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"""
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if self.schedule == ScheduleType.CONSTANT:
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return self.initial_value
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elif self.schedule == ScheduleType.LINEAR:
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return ModelUtils.polynomial_decay(
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self.initial_value, self.min_value, self.max_step, global_step
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)
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else:
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raise UnityTrainerException(f"The schedule {self.schedule} is invalid.")
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@staticmethod
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def polynomial_decay(
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initial_value: float,
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min_value: float,
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max_step: int,
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global_step: int,
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power: float = 1.0,
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) -> float:
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"""
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Get a decayed value based on a polynomial schedule, with respect to the current global step.
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:param initial_value: Initial value before decay.
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:param min_value: Decay value to this value by max_step.
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:param max_step: The final step count where the return value should equal min_value.
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:param global_step: The current step count.
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:param power: Power of polynomial decay. 1.0 (default) is a linear decay.
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:return: The current decayed value.
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"""
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global_step = min(global_step, max_step)
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decayed_value = (initial_value - min_value) * (
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1 - float(global_step) / max_step
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) ** (power) + min_value
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return decayed_value
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@staticmethod
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def get_encoder_for_type(encoder_type: EncoderType) -> nn.Module:
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ENCODER_FUNCTION_BY_TYPE = {
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EncoderType.SIMPLE: SimpleVisualEncoder,
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EncoderType.NATURE_CNN: NatureVisualEncoder,
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EncoderType.RESNET: ResNetVisualEncoder,
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}
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return ENCODER_FUNCTION_BY_TYPE.get(encoder_type)
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@staticmethod
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def _check_resolution_for_encoder(
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height: int, width: int, vis_encoder_type: EncoderType
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) -> None:
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min_res = ModelUtils.MIN_RESOLUTION_FOR_ENCODER[vis_encoder_type]
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if height < min_res or width < min_res:
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raise UnityTrainerException(
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f"Visual observation resolution ({width}x{height}) is too small for"
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f"the provided EncoderType ({vis_encoder_type.value}). The min dimension is {min_res}"
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)
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@staticmethod
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def create_encoders(
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observation_shapes: List[Tuple[int, ...]],
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h_size: int,
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num_layers: int,
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vis_encode_type: EncoderType,
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unnormalized_inputs: int = 0,
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normalize: bool = False,
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) -> Tuple[nn.ModuleList, nn.ModuleList]:
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"""
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Creates visual and vector encoders, along with their normalizers.
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:param observation_shapes: List of Tuples that represent the action dimensions.
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:param action_size: Number of additional un-normalized inputs to each vector encoder. Used for
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conditioining network on other values (e.g. actions for a Q function)
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:param h_size: Number of hidden units per layer.
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:param num_layers: Depth of MLP per encoder.
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:param vis_encode_type: Type of visual encoder to use.
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:param unnormalized_inputs: Vector inputs that should not be normalized, and added to the vector
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obs.
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:param normalize: Normalize all vector inputs.
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:return: Tuple of visual encoders and vector encoders each as a list.
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"""
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visual_encoders: List[nn.Module] = []
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vector_encoders: List[nn.Module] = []
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visual_encoder_class = ModelUtils.get_encoder_for_type(vis_encode_type)
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vector_size = 0
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for i, dimension in enumerate(observation_shapes):
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if len(dimension) == 3:
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ModelUtils._check_resolution_for_encoder(
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dimension[0], dimension[1], vis_encode_type
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)
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visual_encoders.append(
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visual_encoder_class(
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dimension[0], dimension[1], dimension[2], h_size
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)
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)
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elif len(dimension) == 1:
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vector_size += dimension[0]
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else:
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raise UnityTrainerException(
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f"Unsupported shape of {dimension} for observation {i}"
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)
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if vector_size + unnormalized_inputs > 0:
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if unnormalized_inputs > 0:
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vector_encoders.append(
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VectorAndUnnormalizedInputEncoder(
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vector_size, h_size, unnormalized_inputs, num_layers, normalize
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)
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)
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else:
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vector_encoders.append(
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VectorEncoder(vector_size, h_size, num_layers, normalize)
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)
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return nn.ModuleList(visual_encoders), nn.ModuleList(vector_encoders)
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@staticmethod
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def list_to_tensor(
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ndarray_list: List[np.ndarray], dtype: Optional[torch.dtype] = None
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) -> torch.Tensor:
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"""
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Converts a list of numpy arrays into a tensor. MUCH faster than
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calling as_tensor on the list directly.
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"""
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return torch.as_tensor(np.asanyarray(ndarray_list), dtype=dtype)
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@staticmethod
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def break_into_branches(
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concatenated_logits: torch.Tensor, action_size: List[int]
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) -> List[torch.Tensor]:
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"""
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Takes a concatenated set of logits that represent multiple discrete action branches
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and breaks it up into one Tensor per branch.
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:param concatenated_logits: Tensor that represents the concatenated action branches
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:param action_size: List of ints containing the number of possible actions for each branch.
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:return: A List of Tensors containing one tensor per branch.
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"""
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action_idx = [0] + list(np.cumsum(action_size))
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branched_logits = [
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concatenated_logits[:, action_idx[i] : action_idx[i + 1]]
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for i in range(len(action_size))
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]
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return branched_logits
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@staticmethod
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def actions_to_onehot(
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discrete_actions: torch.Tensor, action_size: List[int]
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) -> List[torch.Tensor]:
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"""
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Takes a tensor of discrete actions and turns it into a List of onehot encoding for each
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action.
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:param discrete_actions: Actions in integer form.
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:param action_size: List of branch sizes. Should be of same size as discrete_actions'
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last dimension.
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:return: List of one-hot tensors, one representing each branch.
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"""
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onehot_branches = [
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torch.nn.functional.one_hot(_act.T, action_size[i]).float()
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for i, _act in enumerate(discrete_actions.long().T)
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]
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return onehot_branches
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@staticmethod
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def dynamic_partition(
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data: torch.Tensor, partitions: torch.Tensor, num_partitions: int
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) -> List[torch.Tensor]:
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"""
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Torch implementation of dynamic_partition :
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https://www.tensorflow.org/api_docs/python/tf/dynamic_partition
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Splits the data Tensor input into num_partitions Tensors according to the indices in
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partitions.
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:param data: The Tensor data that will be split into partitions.
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:param partitions: An indices tensor that determines in which partition each element
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of data will be in.
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:param num_partitions: The number of partitions to output. Corresponds to the
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maximum possible index in the partitions argument.
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:return: A list of Tensor partitions (Their indices correspond to their partition index).
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"""
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res: List[torch.Tensor] = []
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for i in range(num_partitions):
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res += [data[(partitions == i).nonzero().squeeze(1)]]
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return res
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@staticmethod
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def get_probs_and_entropy(
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action_list: List[torch.Tensor], dists: List[DistInstance]
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) -> Tuple[torch.Tensor, torch.Tensor, Optional[torch.Tensor]]:
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log_probs_list = []
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all_probs_list = []
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entropies_list = []
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for action, action_dist in zip(action_list, dists):
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log_prob = action_dist.log_prob(action)
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log_probs_list.append(log_prob)
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entropies_list.append(action_dist.entropy())
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if isinstance(action_dist, DiscreteDistInstance):
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all_probs_list.append(action_dist.all_log_prob())
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log_probs = torch.stack(log_probs_list, dim=-1)
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entropies = torch.stack(entropies_list, dim=-1)
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if not all_probs_list:
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log_probs = log_probs.squeeze(-1)
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entropies = entropies.squeeze(-1)
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all_probs = None
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else:
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all_probs = torch.cat(all_probs_list, dim=-1)
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return log_probs, entropies, all_probs
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@staticmethod
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def masked_mean(tensor: torch.Tensor, masks: torch.Tensor) -> torch.Tensor:
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"""
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Returns the mean of the tensor but ignoring the values specified by masks.
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Used for masking out loss functions.
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:param tensor: Tensor which needs mean computation.
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:param masks: Boolean tensor of masks with same dimension as tensor.
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"""
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return (tensor * masks).sum() / torch.clamp(masks.float().sum(), min=1.0)
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