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283 行
11 KiB
283 行
11 KiB
from typing import List, Optional, Tuple
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from mlagents.torch_utils import torch, nn
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import numpy as np
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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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SmallVisualEncoder,
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VectorInput,
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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 ObservationSpec
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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.MATCH3: 5,
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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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@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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EncoderType.MATCH3: SmallVisualEncoder,
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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 get_encoder_for_obs(
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shape: Tuple[int, ...],
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normalize: bool,
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h_size: int,
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vis_encode_type: EncoderType,
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) -> Tuple[nn.Module, int]:
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"""
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Returns the encoder and the size of the appropriate encoder.
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:param shape: Tuples that represent the observation dimension.
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:param normalize: Normalize all vector inputs.
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:param h_size: Number of hidden units per layer.
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:param vis_encode_type: Type of visual encoder to use.
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"""
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if len(shape) == 1:
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# Case rank 1 tensor
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return (VectorInput(shape[0], normalize), shape[0])
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if len(shape) == 3:
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ModelUtils._check_resolution_for_encoder(
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shape[0], shape[1], vis_encode_type
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)
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visual_encoder_class = ModelUtils.get_encoder_for_type(vis_encode_type)
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return (visual_encoder_class(shape[0], shape[1], shape[2], h_size), h_size)
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raise UnityTrainerException(f"Unsupported shape of {shape} for observation")
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@staticmethod
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def create_input_processors(
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observation_specs: List[ObservationSpec],
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h_size: int,
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vis_encode_type: EncoderType,
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normalize: bool = False,
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) -> Tuple[nn.ModuleList, List[int]]:
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"""
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Creates visual and vector encoders, along with their normalizers.
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:param observation_specs: List of ObservationSpec that represent the observation dimensions.
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:param action_size: Number of additional un-normalized inputs to each vector encoder. Used for
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conditioning 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 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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encoders: List[nn.Module] = []
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embedding_sizes: List[int] = []
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for obs_spec in observation_specs:
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encoder, embedding_size = ModelUtils.get_encoder_for_obs(
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obs_spec.shape, normalize, h_size, vis_encode_type
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)
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encoders.append(encoder)
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embedding_sizes.append(embedding_size)
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return (nn.ModuleList(encoders), embedding_sizes)
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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] = torch.float32
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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 to_numpy(tensor: torch.Tensor) -> np.ndarray:
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"""
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Converts a Torch Tensor to a numpy array. If the Tensor is on the GPU, it will
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be brought to the CPU.
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"""
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return tensor.detach().cpu().numpy()
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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 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.T * masks).sum() / torch.clamp(
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(torch.ones_like(tensor.T) * masks).float().sum(), min=1.0
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)
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@staticmethod
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def soft_update(source: nn.Module, target: nn.Module, tau: float) -> None:
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"""
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Performs an in-place polyak update of the target module based on the source,
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by a ratio of tau. Note that source and target modules must have the same
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parameters, where:
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target = tau * source + (1-tau) * target
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:param source: Source module whose parameters will be used.
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:param target: Target module whose parameters will be updated.
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:param tau: Percentage of source parameters to use in average. Setting tau to
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1 will copy the source parameters to the target.
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"""
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with torch.no_grad():
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for source_param, target_param in zip(
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source.parameters(), target.parameters()
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):
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target_param.data.mul_(1.0 - tau)
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torch.add(
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target_param.data,
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source_param.data,
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alpha=tau,
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out=target_param.data,
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)
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