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distributions.py
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distributions.py
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import abc
from typing import Any, Union, Callable, TypeVar, Dict, Optional, cast
from collections import OrderedDict
import torch
import torch.nn as nn
from torch.distributions.utils import lazy_property
import gym
from allenact.base_abstractions.sensor import AbstractExpertActionSensor as Expert
from allenact.utils import spaces_utils as su
from allenact.utils.misc_utils import all_unique
TeacherForcingAnnealingType = TypeVar("TeacherForcingAnnealingType")
"""
Modify standard PyTorch distributions so they are compatible with this code.
"""
class Distr(abc.ABC):
@abc.abstractmethod
def log_prob(self, actions: Any):
"""Return the log probability/ies of the provided action/s."""
raise NotImplementedError()
@abc.abstractmethod
def entropy(self):
"""Return the entropy or entropies."""
raise NotImplementedError()
@abc.abstractmethod
def sample(self, sample_shape=torch.Size()):
"""Sample actions."""
raise NotImplementedError()
def mode(self):
"""If available, return the action(s) with highest probability.
It will only be called if using deterministic agents.
"""
raise NotImplementedError()
class CategoricalDistr(torch.distributions.Categorical, Distr):
"""A categorical distribution extending PyTorch's Categorical.
probs or logits are assumed to be passed with step and sampler
dimensions as in: [step, samplers, ...]
"""
def mode(self):
return self._param.argmax(dim=-1, keepdim=False) # match sample()'s shape
def log_prob(self, value: torch.Tensor):
if value.shape == self.logits.shape[:-1]:
return super(CategoricalDistr, self).log_prob(value=value)
elif value.shape == self.logits.shape[:-1] + (1,):
return (
super(CategoricalDistr, self)
.log_prob(value=value.squeeze(-1))
.unsqueeze(-1)
)
else:
raise NotImplementedError(
"Broadcasting in categorical distribution is disabled as it often leads"
f" to unexpected results. We have that `value.shape == {value.shape}` but"
f" expected a shape of "
f" `self.logits.shape[:-1] == {self.logits.shape[:-1]}` or"
f" `self.logits.shape[:-1] + (1,) == {self.logits.shape[:-1] + (1,)}`"
)
@lazy_property
def log_probs_tensor(self):
return torch.log_softmax(self.logits, dim=-1)
@lazy_property
def probs_tensor(self):
return torch.softmax(self.logits, dim=-1)
class ConditionalDistr(Distr):
"""Action distribution conditional which is conditioned on other information
(i.e. part of a hierarchical distribution)
# Attributes
action_group_name : the identifier of the group of actions (`OrderedDict`) produced by this `ConditionalDistr`
"""
action_group_name: str
def __init__(
self,
distr_conditioned_on_input_fn_or_instance: Union[Callable, Distr],
action_group_name: str,
*distr_conditioned_on_input_args,
**distr_conditioned_on_input_kwargs,
):
"""Initialize an ConditionalDistr
# Parameters
distr_conditioned_on_input_fn_or_instance : Callable to generate `ConditionalDistr` given sampled actions,
or given `Distr`.
action_group_name : the identifier of the group of actions (`OrderedDict`) produced by this `ConditionalDistr`
distr_conditioned_on_input_args : positional arguments for Callable `distr_conditioned_on_input_fn_or_instance`
distr_conditioned_on_input_kwargs : keyword arguments for Callable `distr_conditioned_on_input_fn_or_instance`
"""
self.distr: Optional[Distr] = None
self.distr_conditioned_on_input_fn: Optional[Callable] = None
self.distr_conditioned_on_input_args = distr_conditioned_on_input_args
self.distr_conditioned_on_input_kwargs = distr_conditioned_on_input_kwargs
if isinstance(distr_conditioned_on_input_fn_or_instance, Distr):
self.distr = distr_conditioned_on_input_fn_or_instance
else:
self.distr_conditioned_on_input_fn = (
distr_conditioned_on_input_fn_or_instance
)
self.action_group_name = action_group_name
def log_prob(self, actions):
return self.distr.log_prob(actions)
def entropy(self):
return self.distr.entropy()
def condition_on_input(self, **ready_actions):
if self.distr is None:
assert all(
key not in self.distr_conditioned_on_input_kwargs
for key in ready_actions
)
self.distr = self.distr_conditioned_on_input_fn(
*self.distr_conditioned_on_input_args,
**self.distr_conditioned_on_input_kwargs,
**ready_actions,
)
def reset(self):
if (self.distr is not None) and (
self.distr_conditioned_on_input_fn is not None
):
self.distr = None
def sample(self, sample_shape=torch.Size()) -> OrderedDict:
return OrderedDict([(self.action_group_name, self.distr.sample(sample_shape))])
def mode(self) -> OrderedDict:
return OrderedDict([(self.action_group_name, self.distr.mode())])
class SequentialDistr(Distr):
def __init__(self, *conditional_distrs: ConditionalDistr):
action_group_names = [cd.action_group_name for cd in conditional_distrs]
assert all_unique(
action_group_names
), f"All conditional distribution `action_group_name`, must be unique, given names {action_group_names}"
self.conditional_distrs = conditional_distrs
def sample(self, sample_shape=torch.Size()):
actions = OrderedDict()
for cd in self.conditional_distrs:
cd.condition_on_input(**actions)
actions.update(cd.sample(sample_shape=sample_shape))
return actions
def mode(self):
actions = OrderedDict()
for cd in self.conditional_distrs:
cd.condition_on_input(**actions)
actions.update(cd.mode())
return actions
def conditional_entropy(self):
sum = 0
for cd in self.conditional_distrs:
sum = sum + cd.entropy()
return sum
def entropy(self):
raise NotImplementedError(
"Please use 'conditional_entropy' instead of 'entropy' as the `entropy_method_name` "
"parameter in your loss when using `SequentialDistr`."
)
def log_prob(
self, actions: Dict[str, Any], return_dict: bool = False
) -> Union[torch.Tensor, Dict[str, torch.Tensor]]:
assert len(actions) == len(
self.conditional_distrs
), f"{len(self.conditional_distrs)} conditional distributions for {len(actions)} action groups"
res: Union[
int, torch.Tensor, Dict[str, torch.Tensor]
] = 0 if not return_dict else OrderedDict()
for cd in self.conditional_distrs:
cd.condition_on_input(**actions)
current_log_prob = cd.log_prob(actions[cd.action_group_name])
if not return_dict:
res = res + current_log_prob
else:
res[cd.action_group_name] = current_log_prob
return res
class TeacherForcingDistr(Distr):
def __init__(
self,
distr: Distr,
obs: Dict[str, Any],
action_space: gym.spaces.Space,
num_active_samplers: Optional[int],
approx_steps: Optional[int],
teacher_forcing: Optional[TeacherForcingAnnealingType],
tracking_info: Optional[Dict[str, Any]],
always_enforce: bool = False,
):
self.distr = distr
self.is_sequential = isinstance(self.distr, SequentialDistr)
# action_space is a gym.spaces.Dict for SequentialDistr, or any gym.Space for other Distr
self.action_space = action_space
self.num_active_samplers = num_active_samplers
self.approx_steps = approx_steps
self.teacher_forcing = teacher_forcing
self.tracking_info = tracking_info
self.always_enforce = always_enforce
assert (
"expert_action" in obs
), "When using teacher forcing, obs must contain an `expert_action` uuid"
obs_space = Expert.flagged_space(
self.action_space, use_dict_as_groups=self.is_sequential
)
self.expert = su.unflatten(obs_space, obs["expert_action"])
def enforce(
self,
sample: Any,
action_space: gym.spaces.Space,
teacher: OrderedDict,
teacher_force_info: Optional[Dict[str, Any]],
action_name: Optional[str] = None,
):
actions = su.flatten(action_space, sample)
assert (
len(actions.shape) == 3
), f"Got flattened actions with shape {actions.shape} (it should be [1 x `samplers` x `flatdims`])"
if self.num_active_samplers is not None:
assert actions.shape[1] == self.num_active_samplers
expert_actions = su.flatten(action_space, teacher[Expert.ACTION_POLICY_LABEL])
assert (
expert_actions.shape == actions.shape
), f"expert actions shape {expert_actions.shape} doesn't match the model's {actions.shape}"
# expert_success is 0 if the expert action could not be computed and otherwise equals 1.
expert_action_exists_mask = teacher[Expert.EXPERT_SUCCESS_LABEL]
if not self.always_enforce:
teacher_forcing_mask = (
torch.distributions.bernoulli.Bernoulli(
torch.tensor(self.teacher_forcing(self.approx_steps))
)
.sample(expert_action_exists_mask.shape)
.long()
.to(actions.device)
) * expert_action_exists_mask
else:
teacher_forcing_mask = expert_action_exists_mask
if teacher_force_info is not None:
teacher_force_info[
"teacher_ratio/sampled{}".format(
f"_{action_name}" if action_name is not None else ""
)
] = (teacher_forcing_mask.float().mean().item())
extended_shape = teacher_forcing_mask.shape + (1,) * (
len(actions.shape) - len(teacher_forcing_mask.shape)
)
actions = torch.where(
teacher_forcing_mask.byte().view(extended_shape), expert_actions, actions
)
return su.unflatten(action_space, actions)
def log_prob(self, actions: Any):
return self.distr.log_prob(actions)
def entropy(self):
return self.distr.entropy()
def conditional_entropy(self):
return self.distr.conditional_entropy()
def sample(self, sample_shape=torch.Size()):
teacher_force_info: Optional[Dict[str, Any]] = None
if self.approx_steps is not None:
teacher_force_info = {
"teacher_ratio/enforced": self.teacher_forcing(self.approx_steps),
}
if self.is_sequential:
res = OrderedDict()
for cd in cast(SequentialDistr, self.distr).conditional_distrs:
cd.condition_on_input(**res)
action_group_name = cd.action_group_name
res[action_group_name] = self.enforce(
cd.sample(sample_shape)[action_group_name],
cast(gym.spaces.Dict, self.action_space)[action_group_name],
self.expert[action_group_name],
teacher_force_info,
action_group_name,
)
else:
res = self.enforce(
self.distr.sample(sample_shape),
self.action_space,
self.expert,
teacher_force_info,
)
if self.tracking_info is not None and self.num_active_samplers is not None:
self.tracking_info["teacher"].append(
("teacher_package", teacher_force_info, self.num_active_samplers)
)
return res
class AddBias(nn.Module):
"""Adding bias parameters to input values."""
def __init__(self, bias: torch.FloatTensor):
"""Initializer.
# Parameters
bias : data to use as the initial values of the bias.
"""
super(AddBias, self).__init__()
self._bias = nn.Parameter(bias.unsqueeze(1), requires_grad=True)
def forward(self, x: torch.FloatTensor) -> torch.FloatTensor: # type: ignore
"""Adds the stored bias parameters to `x`."""
assert x.dim() in [2, 4]
if x.dim() == 2:
bias = self._bias.t().view(1, -1)
else:
bias = self._bias.t().view(1, -1, 1, 1)
return x + bias # type:ignore