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from typing import List, Dict, Any, Tuple, Union
from collections import namedtuple
import copy
import torch
from torch.utils.data import Dataset, DataLoader
from ding.utils import POLICY_REGISTRY, split_data_generator, RunningMeanStd
from ding.utils.data import default_collate, default_decollate
from ding.torch_utils import Adam, to_device
from ding.rl_utils import get_gae_with_default_last_value, get_train_sample, gae, gae_data, get_gae, \
ppo_policy_data, ppo_policy_error, ppo_value_data, ppo_value_error, ppg_data, ppg_joint_error
from ding.model import model_wrap
from .base_policy import Policy
class ExperienceDataset(Dataset):
"""
Overview:
A dataset class for storing and accessing experience data.
Interface:
``__init__``, ``__len__``, ``__getitem__``.
"""
def __init__(self, data):
"""
Arguments:
- data (:obj:`dict`): A dictionary containing the experience data, where the keys represent the data types \
and the values are the corresponding data arrays.
"""
super().__init__()
self.data = data
def __len__(self):
return list(self.data.values())[0].shape[0]
def __getitem__(self, ind):
data = {}
for key in self.data.keys():
data[key] = self.data[key][ind]
return data
def create_shuffled_dataloader(data, batch_size):
ds = ExperienceDataset(data)
return DataLoader(ds, batch_size=batch_size, shuffle=True)
@POLICY_REGISTRY.register('ppg')
class PPGPolicy(Policy):
"""
Overview:
Policy class of PPG algorithm. PPG is a policy gradient algorithm with auxiliary phase training. \
The auxiliary phase training is proposed to distill the value into the policy network, \
while making sure the policy network does not change the action predictions (kl div loss). \
Paper link: https://arxiv.org/abs/2009.04416.
Interface:
``_init_learn``, ``_data_preprocess_learn``, ``_forward_learn``, ``_state_dict_learn``, \
``_load_state_dict_learn``, ``_init_collect``, ``_forward_collect``, ``_process_transition``, \
``_get_train_sample``, ``_get_batch_size``, ``_init_eval``, ``_forward_eval``, ``default_model``, \
``_monitor_vars_learn``, ``learn_aux``.
Config:
== ==================== ======== ============== ======================================== =======================
ID Symbol Type Default Value Description Other(Shape)
== ==================== ======== ============== ======================================== =======================
1 ``type`` str ppg | RL policy register name, refer to | this arg is optional,
| registry ``POLICY_REGISTRY`` | a placeholder
2 ``cuda`` bool False | Whether to use cuda for network | this arg can be diff-
| erent from modes
3 ``on_policy`` bool True | Whether the RL algorithm is on-policy
| or off-policy
4. ``priority`` bool False | Whether use priority(PER) | priority sample,
| update priority
5 | ``priority_`` bool False | Whether use Importance Sampling | IS weight
| ``IS_weight`` | Weight to correct biased update.
6 | ``learn.update`` int 5 | How many updates(iterations) to train | this args can be vary
| ``_per_collect`` | after collector's one collection. Only | from envs. Bigger val
| valid in serial training | means more off-policy
7 | ``learn.value_`` float 1.0 | The loss weight of value network | policy network weight
| ``weight`` | is set to 1
8 | ``learn.entropy_`` float 0.01 | The loss weight of entropy | policy network weight
| ``weight`` | regularization | is set to 1
9 | ``learn.clip_`` float 0.2 | PPO clip ratio
| ``ratio``
10 | ``learn.adv_`` bool False | Whether to use advantage norm in
| ``norm`` | a whole training batch
11 | ``learn.aux_`` int 5 | The frequency(normal update times)
| ``freq`` | of auxiliary phase training
12 | ``learn.aux_`` int 6 | The training epochs of auxiliary
| ``train_epoch`` | phase
13 | ``learn.aux_`` int 1 | The loss weight of behavioral_cloning
| ``bc_weight`` | in auxiliary phase
14 | ``collect.dis`` float 0.99 | Reward's future discount factor, aka. | may be 1 when sparse
| ``count_factor`` | gamma | reward env
15 | ``collect.gae_`` float 0.95 | GAE lambda factor for the balance
| ``lambda`` | of bias and variance(1-step td and mc)
== ==================== ======== ============== ======================================== =======================
"""
config = dict(
# (str) RL policy register name (refer to function "POLICY_REGISTRY").
type='ppg',
# (bool) Whether to use cuda for network.
cuda=False,
# (bool) Whether the RL algorithm is on-policy or off-policy. (Note: in practice PPO can be off-policy used)
on_policy=True,
priority=False,
# (bool) Whether use Importance Sampling Weight to correct biased update. If True, priority must be True.
priority_IS_weight=False,
learn=dict(
actor_epoch_per_collect=1,
critic_epoch_per_collect=1,
batch_size=64,
learning_rate=0.001,
# ==============================================================
# The following configs is algorithm-specific
# ==============================================================
# (float) The loss weight of value network, policy network weight is set to 1
value_weight=0.5,
# (float) The loss weight of entropy regularization, policy network weight is set to 1
entropy_weight=0.01,
# (float) PPO clip ratio, defaults to 0.2
clip_ratio=0.2,
value_norm=False,
# (bool) Whether to use advantage norm in a whole training batch
adv_norm=False,
# (int) The frequency(normal update times) of auxiliary phase training
aux_freq=8,
# (int) The training epochs of auxiliary phase
aux_train_epoch=6,
# (int) The loss weight of behavioral_cloning in auxiliary phase
aux_bc_weight=1,
grad_clip_type='clip_norm',
grad_clip_value=10,
ignore_done=False,
),
collect=dict(
# n_sample=64,
unroll_len=1,
# ==============================================================
# The following configs is algorithm-specific
# ==============================================================
# (float) Reward's future discount factor, aka. gamma.
discount_factor=0.99,
# (float) GAE lambda factor for the balance of bias and variance(1-step td and mc)
gae_lambda=0.95,
),
eval=dict(),
)
def default_model(self) -> Tuple[str, List[str]]:
"""
Overview:
Return this algorithm default neural network model setting for demonstration. ``__init__`` method will \
automatically call this method to get the default model setting and create model.
Returns:
- model_info (:obj:`Tuple[str, List[str]]`): The registered model name and model's import_names.
"""
return 'ppg', ['ding.model.template.ppg']
def _init_learn(self) -> None:
"""
Overview:
Initialize the learn mode of policy, including related attributes and modules. For PPG, it mainly \
contains optimizer, algorithm-specific arguments such as aux_bc_weight and aux_train_epoch. This method \
also executes some special network initializations and prepares running mean/std monitor for value. \
This method will be called in ``__init__`` method if ``learn`` field is in ``enable_field``.
.. note::
For the member variables that need to be saved and loaded, please refer to the ``_state_dict_learn`` \
and ``_load_state_dict_learn`` methods.
.. note::
For the member variables that need to be monitored, please refer to the ``_monitor_vars_learn`` method.
.. note::
If you want to set some spacial member variables in ``_init_learn`` method, you'd better name them \
with prefix ``_learn_`` to avoid conflict with other modes, such as ``self._learn_attr1``.
"""
# Optimizer
self._optimizer_ac = Adam(self._model.actor_critic.parameters(), lr=self._cfg.learn.learning_rate)
self._optimizer_aux_critic = Adam(self._model.aux_critic.parameters(), lr=self._cfg.learn.learning_rate)
self._learn_model = model_wrap(self._model, wrapper_name='base')
# Algorithm config
self._priority = self._cfg.priority
self._priority_IS_weight = self._cfg.priority_IS_weight
assert not self._priority and not self._priority_IS_weight, "Priority is not implemented in PPG"
self._value_weight = self._cfg.learn.value_weight
self._entropy_weight = self._cfg.learn.entropy_weight
self._value_norm = self._cfg.learn.value_norm
if self._value_norm:
self._running_mean_std = RunningMeanStd(epsilon=1e-4, device=self._device)
self._clip_ratio = self._cfg.learn.clip_ratio
self._adv_norm = self._cfg.learn.adv_norm
# Main model
self._learn_model.reset()
# Auxiliary memories
self._aux_train_epoch = self._cfg.learn.aux_train_epoch
self._train_iteration = 0
self._aux_memories = []
self._aux_bc_weight = self._cfg.learn.aux_bc_weight
def _data_preprocess_learn(self, data: List[Any]) -> dict:
"""
Overview:
Preprocess the data to fit the required data format for learning, including \
collate(stack data into batch), ignore done(in some fake terminate env),\
prepare loss weight per training sample, and cpu tensor to cuda.
Arguments:
- data (:obj:`List[Dict[str, Any]]`): The data collected from collect function.
Returns:
- data (:obj:`Dict[str, Any]`): The processed data, including at least ['done', 'weight'].
"""
# data preprocess
data = default_collate(data)
ignore_done = self._cfg.learn.ignore_done
if ignore_done:
data['done'] = None
else:
data['done'] = data['done'].float()
data['weight'] = None
if self._cuda:
data = to_device(data, self._device)
return data
def _forward_learn(self, data: dict) -> Dict[str, Any]:
"""
Overview:
Forward and backward function of learn mode.
Arguments:
- data (:obj:`Dict[str, Any]`): Input data used for policy forward, including the \
collected training samples from replay buffer. For each element in dict, the key of the \
dict is the name of data items and the value is the corresponding data. Usually, the value is \
torch.Tensor or np.ndarray or there dict/list combinations. In the ``_forward_learn`` method, data \
often need to first be stacked in the batch dimension by some utility functions such as \
``default_preprocess_learn``. \
For PPG, each element in list is a dict containing at least the following keys: ``obs``, ``action``, \
``reward``, ``logit``, ``value``, ``done``. Sometimes, it also contains other keys such as ``weight``.
Returns:
- info_dict (:obj:`Dict[str, Any]`): Dict type data, a info dict indicated training result, which will be \
recorded in text log and tensorboard, values are python scalar or a list of scalars. \
For the detailed definition of the dict, refer to the code of ``_monitor_vars_learn`` method.
.. note::
The input value can be torch.Tensor or dict/list combinations and current policy supports all of them. \
For the data type that not supported, the main reason is that the corresponding model does not support it. \
You can implement you own model rather than use the default model. For more information, please raise an \
issue in GitHub repo and we will continue to follow up.
.. note::
For more detailed examples, please refer to our unittest for PPGPolicy: ``ding.policy.tests.test_ppgs``.
"""
data = self._data_preprocess_learn(data)
# ====================
# PPG forward
# ====================
self._learn_model.train()
return_infos = []
if self._value_norm:
unnormalized_return = data['adv'] + data['value'] * self._running_mean_std.std
data['return'] = unnormalized_return / self._running_mean_std.std
self._running_mean_std.update(unnormalized_return.cpu().numpy())
else:
data['return'] = data['adv'] + data['value']
for epoch in range(self._cfg.learn.actor_epoch_per_collect):
for policy_data in split_data_generator(data, self._cfg.learn.batch_size, shuffle=True):
policy_adv = policy_data['adv']
if self._adv_norm:
# Normalize advantage in a total train_batch
policy_adv = (policy_adv - policy_adv.mean()) / (policy_adv.std() + 1e-8)
# Policy Phase(Policy)
policy_output = self._learn_model.forward(policy_data['obs'], mode='compute_actor')
policy_error_data = ppo_policy_data(
policy_output['logit'], policy_data['logit'], policy_data['action'], policy_adv,
policy_data['weight']
)
ppo_policy_loss, ppo_info = ppo_policy_error(policy_error_data, self._clip_ratio)
policy_loss = ppo_policy_loss.policy_loss - self._entropy_weight * ppo_policy_loss.entropy_loss
self._optimizer_ac.zero_grad()
policy_loss.backward()
self._optimizer_ac.step()
for epoch in range(self._cfg.learn.critic_epoch_per_collect):
for value_data in split_data_generator(data, self._cfg.learn.batch_size, shuffle=True):
value_adv = value_data['adv']
return_ = value_data['return']
if self._adv_norm:
# Normalize advantage in a total train_batch
value_adv = (value_adv - value_adv.mean()) / (value_adv.std() + 1e-8)
# Policy Phase(Value)
value_output = self._learn_model.forward(value_data['obs'], mode='compute_critic')
value_error_data = ppo_value_data(
value_output['value'], value_data['value'], return_, value_data['weight']
)
value_loss = self._value_weight * ppo_value_error(value_error_data, self._clip_ratio)
self._optimizer_aux_critic.zero_grad()
value_loss.backward()
self._optimizer_aux_critic.step()
data['return_'] = data['return']
self._aux_memories.append(copy.deepcopy(data))
self._train_iteration += 1
# ====================
# PPG update
# use aux loss after iterations and reset aux_memories
# ====================
# Auxiliary Phase
# record data for auxiliary head
if self._train_iteration % self._cfg.learn.aux_freq == 0:
aux_loss, bc_loss, aux_value_loss = self.learn_aux()
return {
'policy_cur_lr': self._optimizer_ac.defaults['lr'],
'value_cur_lr': self._optimizer_aux_critic.defaults['lr'],
'policy_loss': ppo_policy_loss.policy_loss.item(),
'value_loss': value_loss.item(),
'entropy_loss': ppo_policy_loss.entropy_loss.item(),
'policy_adv_abs_max': policy_adv.abs().max().item(),
'approx_kl': ppo_info.approx_kl,
'clipfrac': ppo_info.clipfrac,
'aux_value_loss': aux_value_loss,
'auxiliary_loss': aux_loss,
'behavioral_cloning_loss': bc_loss,
}
else:
return {
'policy_cur_lr': self._optimizer_ac.defaults['lr'],
'value_cur_lr': self._optimizer_aux_critic.defaults['lr'],
'policy_loss': ppo_policy_loss.policy_loss.item(),
'value_loss': value_loss.item(),
'entropy_loss': ppo_policy_loss.entropy_loss.item(),
'policy_adv_abs_max': policy_adv.abs().max().item(),
'approx_kl': ppo_info.approx_kl,
'clipfrac': ppo_info.clipfrac,
}
def _state_dict_learn(self) -> Dict[str, Any]:
"""
Overview:
Return the state_dict of learn mode, usually including model and optimizer.
Returns:
- state_dict (:obj:`Dict[str, Any]`): the dict of current policy learn state, for saving and restoring.
"""
return {
'model': self._learn_model.state_dict(),
'optimizer_ac': self._optimizer_ac.state_dict(),
'optimizer_aux_critic': self._optimizer_aux_critic.state_dict(),
}
def _load_state_dict_learn(self, state_dict: Dict[str, Any]) -> None:
"""
Overview:
Load the state_dict variable into policy learn mode.
Arguments:
- state_dict (:obj:`Dict[str, Any]`): the dict of policy learn state saved before.\
When the value is distilled into the policy network, we need to make sure the policy \
network does not change the action predictions, we need two optimizers, \
_optimizer_ac is used in policy net, and _optimizer_aux_critic is used in value net.
.. tip::
If you want to only load some parts of model, you can simply set the ``strict`` argument in \
load_state_dict to ``False``, or refer to ``ding.torch_utils.checkpoint_helper`` for more \
complicated operation.
"""
self._learn_model.load_state_dict(state_dict['model'])
self._optimizer_ac.load_state_dict(state_dict['optimizer_ac'])
self._optimizer_aux_critic.load_state_dict(state_dict['optimizer_aux_critic'])
def _init_collect(self) -> None:
"""
Overview:
Initialize the collect mode of policy, including related attributes and modules. For PPG, it contains the \
collect_model to balance the exploration and exploitation (e.g. the multinomial sample mechanism in \
discrete action space), and other algorithm-specific arguments such as unroll_len and gae_lambda.
This method will be called in ``__init__`` method if ``collect`` field is in ``enable_field``.
.. note::
If you want to set some spacial member variables in ``_init_collect`` method, you'd better name them \
with prefix ``_collect_`` to avoid conflict with other modes, such as ``self._collect_attr1``.
"""
self._unroll_len = self._cfg.collect.unroll_len
self._collect_model = model_wrap(self._model, wrapper_name='multinomial_sample')
# TODO continuous action space exploration
self._collect_model.reset()
self._gamma = self._cfg.collect.discount_factor
self._gae_lambda = self._cfg.collect.gae_lambda
def _forward_collect(self, data: dict) -> dict:
"""
Overview:
Policy forward function of collect mode (collecting training data by interacting with envs). Forward means \
that the policy gets some necessary data (mainly observation) from the envs and then returns the output \
data, such as the action to interact with the envs.
Arguments:
- data (:obj:`Dict[str, Any]`): Dict type data, stacked env data for predicting policy_output(action), \
values are torch.Tensor or np.ndarray or dict/list combinations, keys are env_id indicated by integer.
Returns:
- output (:obj:`Dict[int, Any]`): The output data of policy forward, including at least the action and \
other necessary data (action logit and value) for learn mode defined in \
``self._process_transition`` method. The key of the dict is the same as the input data, \
i.e. environment id.
.. tip::
If you want to add more tricks on this policy, like temperature factor in multinomial sample, you can pass \
related data as extra keyword arguments of this method.
.. note::
The input value can be torch.Tensor or dict/list combinations and current policy supports all of them. \
For the data type that not supported, the main reason is that the corresponding model does not support it. \
You can implement you own model rather than use the default model. For more information, please raise an \
issue in GitHub repo and we will continue to follow up.
.. note::
For more detailed examples, please refer to our unittest for PPGPolicy: ``ding.policy.tests.test_ppg``.
"""
data_id = list(data.keys())
data = default_collate(list(data.values()))
if self._cuda:
data = to_device(data, self._device)
self._collect_model.eval()
with torch.no_grad():
output = self._collect_model.forward(data, mode='compute_actor_critic')
if self._cuda:
output = to_device(output, 'cpu')
output = default_decollate(output)
return {i: d for i, d in zip(data_id, output)}
def _process_transition(self, obs: Any, model_output: dict, timestep: namedtuple) -> dict:
"""
Overview:
Process and pack one timestep transition data into a dict, which can be directly used for training and \
saved in replay buffer. For PPG, it contains obs, next_obs, action, reward, done, logit, value.
Arguments:
- obs (:obj:`Any`): Env observation
- model_output (:obj:`dict`): The output of the policy network with the observation \
as input. For PPG, it contains the state value, action and the logit of the action.
- timestep (:obj:`namedtuple`): The execution result namedtuple returned by the environment step \
method, except all the elements have been transformed into tensor data. Usually, it contains the next \
obs, reward, done, info, etc.
Returns:
- transition (:obj:`dict`): The processed transition data of the current timestep.
.. note::
``next_obs`` is used to calculate nstep return when necessary, so we place in into transition by default. \
You can delete this field to save memory occupancy if you do not need nstep return.
"""
transition = {
'obs': obs,
'next_obs': timestep.obs,
'logit': model_output['logit'],
'action': model_output['action'],
'value': model_output['value'],
'reward': timestep.reward,
'done': timestep.done,
}
return transition
def _get_train_sample(self, data: List[Dict[str, Any]]) -> Union[None, List[Any]]:
"""
Overview:
For a given trajectory (transitions, a list of transition) data, process it into a list of sample that \
can be used for training directly. In PPG, a train sample is a processed transition with new computed \
``adv`` field. This method is usually used in collectors to execute necessary. \
RL data preprocessing before training, which can help learner amortize revelant time consumption. \
In addition, you can also implement this method as an identity function and do the data processing \
in ``self._forward_learn`` method.
Arguments:
- data (:obj:`List[Dict[str, Any]]`): The trajectory data (a list of transition), each element is \
the same format as the return value of ``self._process_transition`` method.
Returns:
- samples (:obj:`dict`): The processed train samples, each element is the similar format \
as input transitions, but may contain more data for training, such as GAE advantage.
"""
data = to_device(data, self._device)
if self._cfg.learn.ignore_done:
data[-1]['done'] = False
if data[-1]['done']:
last_value = torch.zeros_like(data[-1]['value'])
else:
with torch.no_grad():
last_value = self._collect_model.forward(
data[-1]['next_obs'].unsqueeze(0), mode='compute_actor_critic'
)['value']
if self._value_norm:
last_value *= self._running_mean_std.std
for i in range(len(data)):
data[i]['value'] *= self._running_mean_std.std
data = get_gae(
data,
to_device(last_value, self._device),
gamma=self._gamma,
gae_lambda=self._gae_lambda,
cuda=False,
)
if self._value_norm:
for i in range(len(data)):
data[i]['value'] /= self._running_mean_std.std
return get_train_sample(data, self._unroll_len)
def _get_batch_size(self) -> Dict[str, int]:
"""
Overview:
Get learn batch size. In the PPG algorithm, different networks require different data.\
We need to get data['policy'] and data['value'] to train policy net and value net,\
this function is used to get the batch size of data['policy'] and data['value'].
Returns:
- output (:obj:`dict[str, int]`): Dict type data, including str type batch size and int type batch size.
"""
bs = self._cfg.learn.batch_size
return {'policy': bs, 'value': bs}
def _init_eval(self) -> None:
"""
Overview:
Initialize the eval mode of policy, including related attributes and modules. For PPG, it contains the \
eval model to select optimial action (e.g. greedily select action with argmax mechanism in discrete \
action). This method will be called in ``__init__`` method if ``eval`` field is in ``enable_field``.
.. note::
If you want to set some spacial member variables in ``_init_eval`` method, you'd better name them \
with prefix ``_eval_`` to avoid conflict with other modes, such as ``self._eval_attr1``.
"""
self._eval_model = model_wrap(self._model, wrapper_name='argmax_sample')
self._eval_model.reset()
def _forward_eval(self, data: dict) -> dict:
"""
Overview:
Policy forward function of eval mode (evaluation policy performance by interacting with envs). Forward \
means that the policy gets some necessary data (mainly observation) from the envs and then returns the \
action to interact with the envs. ``_forward_eval`` in PPG often uses deterministic sample method to get \
actions while ``_forward_collect`` usually uses stochastic sample method for balance exploration and \
exploitation.
Arguments:
- data (:obj:`Dict[str, Any]`): The input data used for policy forward, including at least the obs. The \
key of the dict is environment id and the value is the corresponding data of the env.
Returns:
- output (:obj:`Dict[int, Any]`): The output data of policy forward, including at least the action. The \
key of the dict is the same as the input data, i.e. environment id.
.. note::
The input value can be torch.Tensor or dict/list combinations and current policy supports all of them. \
For the data type that not supported, the main reason is that the corresponding model does not support it. \
You can implement you own model rather than use the default model. For more information, please raise an \
issue in GitHub repo and we will continue to follow up.
.. note::
For more detailed examples, please refer to our unittest for PPGPolicy: ``ding.policy.tests.test_ppg``.
"""
data_id = list(data.keys())
data = default_collate(list(data.values()))
if self._cuda:
data = to_device(data, self._device)
self._eval_model.eval()
with torch.no_grad():
output = self._eval_model.forward(data, mode='compute_actor')
if self._cuda:
output = to_device(output, 'cpu')
output = default_decollate(output)
return {i: d for i, d in zip(data_id, output)}
def _monitor_vars_learn(self) -> List[str]:
"""
Overview:
Return the necessary keys for logging the return dict of ``self._forward_learn``. The logger module, such \
as text logger, tensorboard logger, will use these keys to save the corresponding data.
Returns:
- vars (:obj:`List[str]`): The list of the necessary keys to be logged.
"""
return [
'policy_cur_lr',
'value_cur_lr',
'policy_loss',
'value_loss',
'entropy_loss',
'policy_adv_abs_max',
'approx_kl',
'clipfrac',
'aux_value_loss',
'auxiliary_loss',
'behavioral_cloning_loss',
]
def learn_aux(self) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
"""
Overview:
The auxiliary phase training, where the value is distilled into the policy network. In PPG algorithm, \
we use the value function loss as the auxiliary objective, thereby sharing features between the policy \
and value function while minimizing distortions to the policy. We also use behavioral cloning loss to \
optimize the auxiliary objective while otherwise preserving the original policy.
Returns:
- aux_loss (:obj:`Tuple[torch.Tensor, torch.Tensor, torch.Tensor]`): Including average auxiliary loss\
average behavioral cloning loss, and average auxiliary value loss.
"""
aux_memories = self._aux_memories
# gather states and target values into one tensor
data = {}
states = []
actions = []
return_ = []
old_values = []
weights = []
for memory in aux_memories:
# for memory in memories:
states.append(memory['obs'])
actions.append(memory['action'])
return_.append(memory['return_'])
old_values.append(memory['value'])
if memory['weight'] is None:
weight = torch.ones_like(memory['action'])
else:
weight = torch.tensor(memory['weight'])
weights.append(weight)
data['obs'] = torch.cat(states)
data['action'] = torch.cat(actions)
data['return_'] = torch.cat(return_)
data['value'] = torch.cat(old_values)
data['weight'] = torch.cat(weights).float()
# compute current policy logit_old
with torch.no_grad():
data['logit_old'] = self._model.forward(data['obs'], mode='compute_actor')['logit']
# prepared dataloader for auxiliary phase training
dl = create_shuffled_dataloader(data, self._cfg.learn.batch_size)
# the proposed auxiliary phase training
# where the value is distilled into the policy network,
# while making sure the policy network does not change the action predictions (kl div loss)
i = 0
auxiliary_loss_ = 0
behavioral_cloning_loss_ = 0
value_loss_ = 0
for epoch in range(self._aux_train_epoch):
for data in dl:
policy_output = self._model.forward(data['obs'], mode='compute_actor_critic')
# Calculate ppg error 'logit_new', 'logit_old', 'action', 'value_new', 'value_old', 'return_', 'weight'
data_ppg = ppg_data(
policy_output['logit'], data['logit_old'], data['action'], policy_output['value'], data['value'],
data['return_'], data['weight']
)
ppg_joint_loss = ppg_joint_error(data_ppg, self._clip_ratio)
wb = self._aux_bc_weight
total_loss = ppg_joint_loss.auxiliary_loss + wb * ppg_joint_loss.behavioral_cloning_loss
# # policy network loss copmoses of both the kl div loss as well as the auxiliary loss
# aux_loss = clipped_value_loss(policy_values, rewards, old_values, self.value_clip)
# loss_kl = F.kl_div(action_logprobs, old_action_probs, reduction='batchmean')
# policy_loss = aux_loss + loss_kl
self._optimizer_ac.zero_grad()
total_loss.backward()
self._optimizer_ac.step()
# paper says it is important to train the value network extra during the auxiliary phase
# Calculate ppg error 'value_new', 'value_old', 'return_', 'weight'
values = self._model.forward(data['obs'], mode='compute_critic')['value']
data_aux = ppo_value_data(values, data['value'], data['return_'], data['weight'])
value_loss = ppo_value_error(data_aux, self._clip_ratio)
self._optimizer_aux_critic.zero_grad()
value_loss.backward()
self._optimizer_aux_critic.step()
auxiliary_loss_ += ppg_joint_loss.auxiliary_loss.item()
behavioral_cloning_loss_ += ppg_joint_loss.behavioral_cloning_loss.item()
value_loss_ += value_loss.item()
i += 1
self._aux_memories = []
return auxiliary_loss_ / i, behavioral_cloning_loss_ / i, value_loss_ / i
@POLICY_REGISTRY.register('ppg_offpolicy')
class PPGOffPolicy(Policy):
"""
Overview:
Policy class of PPG algorithm with off-policy training mode. Off-policy PPG contains two different data \
max_use buffers. The policy buffer offers data for policy phase , while the value buffer provides auxiliary \
phase's data. The whole training procedure is similar to off-policy PPO but execute additional auxiliary \
phase with a fixed frequency.
Interface:
``_init_learn``, ``_data_preprocess_learn``, ``_forward_learn``, ``_state_dict_learn``, \
``_load_state_dict_learn``, ``_init_collect``, ``_forward_collect``, ``_process_transition``, \
``_get_train_sample``, ``_get_batch_size``, ``_init_eval``, ``_forward_eval``, ``default_model``, \
``_monitor_vars_learn``, ``learn_aux``.
Config:
== ==================== ======== ============== ======================================== =======================
ID Symbol Type Default Value Description Other(Shape)
== ==================== ======== ============== ======================================== =======================
1 ``type`` str ppg | RL policy register name, refer to | this arg is optional,
| registry ``POLICY_REGISTRY`` | a placeholder
2 ``cuda`` bool False | Whether to use cuda for network | this arg can be diff-
| erent from modes
3 ``on_policy`` bool True | Whether the RL algorithm is on-policy
| or off-policy
4. ``priority`` bool False | Whether use priority(PER) | priority sample,
| update priority
5 | ``priority_`` bool False | Whether use Importance Sampling | IS weight
| ``IS_weight`` | Weight to correct biased update.
6 | ``learn.update`` int 5 | How many updates(iterations) to train | this args can be vary
| ``_per_collect`` | after collector's one collection. Only | from envs. Bigger val
| valid in serial training | means more off-policy
7 | ``learn.value_`` float 1.0 | The loss weight of value network | policy network weight
| ``weight`` | is set to 1
8 | ``learn.entropy_`` float 0.01 | The loss weight of entropy | policy network weight
| ``weight`` | regularization | is set to 1
9 | ``learn.clip_`` float 0.2 | PPO clip ratio
| ``ratio``
10 | ``learn.adv_`` bool False | Whether to use advantage norm in
| ``norm`` | a whole training batch
11 | ``learn.aux_`` int 5 | The frequency(normal update times)
| ``freq`` | of auxiliary phase training
12 | ``learn.aux_`` int 6 | The training epochs of auxiliary
| ``train_epoch`` | phase
13 | ``learn.aux_`` int 1 | The loss weight of behavioral_cloning
| ``bc_weight`` | in auxiliary phase
14 | ``collect.dis`` float 0.99 | Reward's future discount factor, aka. | may be 1 when sparse
| ``count_factor`` | gamma | reward env
15 | ``collect.gae_`` float 0.95 | GAE lambda factor for the balance
| ``lambda`` | of bias and variance(1-step td and mc)
== ==================== ======== ============== ======================================== =======================
"""
config = dict(
# (str) RL policy register name (refer to function "POLICY_REGISTRY").
type='ppg_offpolicy',
# (bool) Whether to use cuda for network.
cuda=False,
# (bool) Whether the RL algorithm is on-policy or off-policy. (Note: in practice PPO can be off-policy used)
on_policy=False,
priority=False,
# (bool) Whether use Importance Sampling Weight to correct biased update. If True, priority must be True.
priority_IS_weight=False,
# (bool) Whether to need policy data in process transition
transition_with_policy_data=True,
learn=dict(
update_per_collect=5,
batch_size=64,
learning_rate=0.001,
# ==============================================================
# The following configs is algorithm-specific
# ==============================================================
# (float) The loss weight of value network, policy network weight is set to 1
value_weight=0.5,
# (float) The loss weight of entropy regularization, policy network weight is set to 1
entropy_weight=0.01,
# (float) PPO clip ratio, defaults to 0.2
clip_ratio=0.2,
# (bool) Whether to use advantage norm in a whole training batch
adv_norm=False,
# (int) The frequency(normal update times) of auxiliary phase training
aux_freq=5,
# (int) The training epochs of auxiliary phase
aux_train_epoch=6,
# (int) The loss weight of behavioral_cloning in auxiliary phase
aux_bc_weight=1,
ignore_done=False,
),
collect=dict(
# n_sample=64,
unroll_len=1,
# ==============================================================
# The following configs is algorithm-specific
# ==============================================================
# (float) Reward's future discount factor, aka. gamma.
discount_factor=0.99,
# (float) GAE lambda factor for the balance of bias and variance(1-step td and mc)
gae_lambda=0.95,
),
eval=dict(),
other=dict(
replay_buffer=dict(
# PPG use two separate buffer for different reuse
multi_buffer=True,
policy=dict(replay_buffer_size=1000, ),
value=dict(replay_buffer_size=1000, ),
),
),
)
def default_model(self) -> Tuple[str, List[str]]:
"""
Overview:
Return this algorithm default neural network model setting for demonstration. ``__init__`` method will \
automatically call this method to get the default model setting and create model.
Returns:
- model_info (:obj:`Tuple[str, List[str]]`): The registered model name and model's import_names.
.. note::
The user can define and use customized network model but must obey the same inferface definition indicated \
by import_names path.
"""
return 'ppg', ['ding.model.template.ppg']
def _init_learn(self) -> None:
"""
Overview:
Initialize the learn mode of policy, including related attributes and modules. For PPG, it mainly \
contains optimizer, algorithm-specific arguments such as aux_bc_weight and aux_train_epoch. This method \
also executes some special network initializations and prepares running mean/std monitor for value. \
This method will be called in ``__init__`` method if ``learn`` field is in ``enable_field``.
.. note::
For the member variables that need to be saved and loaded, please refer to the ``_state_dict_learn`` \
and ``_load_state_dict_learn`` methods.
.. note::
For the member variables that need to be monitored, please refer to the ``_monitor_vars_learn`` method.
.. note::
If you want to set some spacial member variables in ``_init_learn`` method, you'd better name them \
with prefix ``_learn_`` to avoid conflict with other modes, such as ``self._learn_attr1``.
"""
# Optimizer
self._optimizer_ac = Adam(self._model.actor_critic.parameters(), lr=self._cfg.learn.learning_rate)
self._optimizer_aux_critic = Adam(self._model.aux_critic.parameters(), lr=self._cfg.learn.learning_rate)
self._learn_model = model_wrap(self._model, wrapper_name='base')
# Algorithm config
self._priority = self._cfg.priority
self._priority_IS_weight = self._cfg.priority_IS_weight
assert not self._priority and not self._priority_IS_weight, "Priority is not implemented in PPG"
self._value_weight = self._cfg.learn.value_weight
self._entropy_weight = self._cfg.learn.entropy_weight
self._clip_ratio = self._cfg.learn.clip_ratio
self._adv_norm = self._cfg.learn.adv_norm
# Main model
self._learn_model.reset()
# Auxiliary memories
self._aux_train_epoch = self._cfg.learn.aux_train_epoch
self._train_iteration = 0
self._aux_memories = []
self._aux_bc_weight = self._cfg.learn.aux_bc_weight
def _data_preprocess_learn(self, data: List[Any]) -> dict:
"""
Overview:
Preprocess the data to fit the required data format for learning, including \
collate(stack data into batch), ignore done(in some fake terminate env),\
prepare loss weight per training sample, and cpu tensor to cuda.
Arguments:
- data (:obj:`List[Dict[str, Any]]`): The data collected from collect function.
Returns:
- data (:obj:`Dict[str, Any]`): The processed data, including at least ['done', 'weight'].
"""
# data preprocess
for k, data_item in data.items():
data_item = default_collate(data_item)
ignore_done = self._cfg.learn.ignore_done
if ignore_done:
data_item['done'] = None
else:
data_item['done'] = data_item['done'].float()
data_item['weight'] = None
data[k] = data_item
if self._cuda:
data = to_device(data, self._device)
return data
def _forward_learn(self, data: dict) -> Dict[str, Any]:
"""
Overview:
Forward and backward function of learn mode.
Arguments:
- data (:obj:`Dict[str, Any]`): Input data used for policy forward, including the \
collected training samples from replay buffer. For each element in dict, the key of the \
dict is the name of data items and the value is the corresponding data. Usually, \
the class type of value is either torch.Tensor or np.ndarray, or a dict/list containing \
either torch.Tensor or np.ndarray items In the ``_forward_learn`` method, data \
often need to first be stacked in the batch dimension by some utility functions such as \
``default_preprocess_learn``. \
For PPGOff, each element in list is a dict containing at least the following keys: ``obs``, \
``action``, ``reward``, ``logit``, ``value``, ``done``. Sometimes, it also contains other keys \
such as ``weight``.
Returns:
- info_dict (:obj:`Dict[str, Any]`): Dict type data, a info dict indicated training result, which will be \
recorded in text log and tensorboard, values are python scalar or a list of scalars. \
For the detailed definition of the dict, refer to the code of ``_monitor_vars_learn`` method.
ReturnsKeys:
- necessary: "current lr", "total_loss", "policy_loss", "value_loss", "entropy_loss", \
"adv_abs_max", "approx_kl", "clipfrac", \
"aux_value_loss", "auxiliary_loss", "behavioral_cloning_loss".
- current_lr (:obj:`float`): Current learning rate.
- total_loss (:obj:`float`): The calculated loss.
- policy_loss (:obj:`float`): The policy(actor) loss of ppg.
- value_loss (:obj:`float`): The value(critic) loss of ppg.
- entropy_loss (:obj:`float`): The entropy loss.
- auxiliary_loss (:obj:`float`): The auxiliary loss, we use the value function loss \
as the auxiliary objective, thereby sharing features between the policy and value function\
while minimizing distortions to the policy.
- aux_value_loss (:obj:`float`): The auxiliary value loss, we need to train the value network extra \
during the auxiliary phase, it's the value loss we train the value network during auxiliary phase.
- behavioral_cloning_loss (:obj:`float`): The behavioral cloning loss, used to optimize the auxiliary\
objective while otherwise preserving the original policy.
"""
data = self._data_preprocess_learn(data)
# ====================
# PPG forward
# ====================
self._learn_model.train()
policy_data, value_data = data['policy'], data['value']
policy_adv, value_adv = policy_data['adv'], value_data['adv']
return_ = value_data['value'] + value_adv
if self._adv_norm:
# Normalize advantage in a total train_batch
policy_adv = (policy_adv - policy_adv.mean()) / (policy_adv.std() + 1e-8)
value_adv = (value_adv - value_adv.mean()) / (value_adv.std() + 1e-8)
# Policy Phase(Policy)
policy_output = self._learn_model.forward(policy_data['obs'], mode='compute_actor')
policy_error_data = ppo_policy_data(
policy_output['logit'], policy_data['logit'], policy_data['action'], policy_adv, policy_data['weight']
)
ppo_policy_loss, ppo_info = ppo_policy_error(policy_error_data, self._clip_ratio)
policy_loss = ppo_policy_loss.policy_loss - self._entropy_weight * ppo_policy_loss.entropy_loss
self._optimizer_ac.zero_grad()
policy_loss.backward()
self._optimizer_ac.step()
# Policy Phase(Value)
value_output = self._learn_model.forward(value_data['obs'], mode='compute_critic')
value_error_data = ppo_value_data(value_output['value'], value_data['value'], return_, value_data['weight'])
value_loss = self._value_weight * ppo_value_error(value_error_data, self._clip_ratio)
self._optimizer_aux_critic.zero_grad()
value_loss.backward()
self._optimizer_aux_critic.step()
# ====================
# PPG update
# use aux loss after iterations and reset aux_memories
# ====================
# Auxiliary Phase
# record data for auxiliary head
data = data['value']
data['return_'] = return_.data
self._aux_memories.append(copy.deepcopy(data))
self._train_iteration += 1
total_loss = policy_loss + value_loss
if self._train_iteration % self._cfg.learn.aux_freq == 0:
aux_loss, bc_loss, aux_value_loss = self.learn_aux()
total_loss += aux_loss + bc_loss + aux_value_loss
return {
'policy_cur_lr': self._optimizer_ac.defaults['lr'],
'value_cur_lr': self._optimizer_aux_critic.defaults['lr'],
'policy_loss': ppo_policy_loss.policy_loss.item(),
'value_loss': value_loss.item(),
'entropy_loss': ppo_policy_loss.entropy_loss.item(),
'policy_adv_abs_max': policy_adv.abs().max().item(),
'approx_kl': ppo_info.approx_kl,
'clipfrac': ppo_info.clipfrac,
'aux_value_loss': aux_value_loss,
'auxiliary_loss': aux_loss,
'behavioral_cloning_loss': bc_loss,
'total_loss': total_loss.item(),
}
else:
return {
'policy_cur_lr': self._optimizer_ac.defaults['lr'],
'value_cur_lr': self._optimizer_aux_critic.defaults['lr'],
'policy_loss': ppo_policy_loss.policy_loss.item(),
'value_loss': value_loss.item(),
'entropy_loss': ppo_policy_loss.entropy_loss.item(),
'policy_adv_abs_max': policy_adv.abs().max().item(),
'approx_kl': ppo_info.approx_kl,
'clipfrac': ppo_info.clipfrac,
'total_loss': total_loss.item(),
}
def _state_dict_learn(self) -> Dict[str, Any]:
"""
Overview:
Return the state_dict of learn mode, usually including model and optimizer.
Returns:
- state_dict (:obj:`Dict[str, Any]`): the dict of current policy learn state, for saving and restoring.
"""
return {
'model': self._learn_model.state_dict(),
'optimizer_ac': self._optimizer_ac.state_dict(),
'optimizer_aux_critic': self._optimizer_aux_critic.state_dict(),
}
def _load_state_dict_learn(self, state_dict: Dict[str, Any]) -> None:
"""
Overview:
Load the state_dict variable into policy learn mode.
Arguments:
- state_dict (:obj:`Dict[str, Any]`): the dict of policy learn state saved before.\
When the value is distilled into the policy network, we need to make sure the policy \
network does not change the action predictions, we need two optimizers, \
_optimizer_ac is used in policy net, and _optimizer_aux_critic is used in value net.
.. tip::
If you want to only load some parts of model, you can simply set the ``strict`` argument in \
load_state_dict to ``False``, or refer to ``ding.torch_utils.checkpoint_helper`` for more \
complicated operation.
"""
self._learn_model.load_state_dict(state_dict['model'])
self._optimizer_ac.load_state_dict(state_dict['optimizer_ac'])
self._optimizer_aux_critic.load_state_dict(state_dict['optimizer_aux_critic'])
def _init_collect(self) -> None:
"""
Overview:
Initialize the collect mode of policy, including related attributes and modules. For PPO, it contains the \
collect_model to balance the exploration and exploitation (e.g. the multinomial sample mechanism in \
discrete action space), and other algorithm-specific arguments such as unroll_len and gae_lambda.
This method will be called in ``__init__`` method if ``collect`` field is in ``enable_field``.
.. note::
If you want to set some spacial member variables in ``_init_collect`` method, you'd better name them \
with prefix ``_collect_`` to avoid conflict with other modes, such as ``self._collect_attr1``.
"""
self._unroll_len = self._cfg.collect.unroll_len
self._collect_model = model_wrap(self._model, wrapper_name='multinomial_sample')
# TODO continuous action space exploration
self._collect_model.reset()
self._gamma = self._cfg.collect.discount_factor
self._gae_lambda = self._cfg.collect.gae_lambda
def _forward_collect(self, data: dict) -> dict:
"""
Overview:
Policy forward function of collect mode (collecting training data by interacting with envs). Forward means \
that the policy gets some necessary data (mainly observation) from the envs and then returns the output \
data, such as the action to interact with the envs.
Arguments:
- data (:obj:`Dict[str, Any]`): Dict type data, stacked env data for predicting policy_output(action), \
values are torch.Tensor or np.ndarray or dict/list combinations, keys are env_id indicated by integer.
Returns:
- output (:obj:`Dict[int, Any]`): The output data of policy forward, including at least the action and \
other necessary data (action logit and value) for learn mode defined in \
``self._process_transition`` method. The key of the dict is the same as the input data, \
i.e. environment id.
.. tip::
If you want to add more tricks on this policy, like temperature factor in multinomial sample, you can pass \
related data as extra keyword arguments of this method.
.. note::
The input value can be torch.Tensor or dict/list combinations and current policy supports all of them. \
For the data type that not supported, the main reason is that the corresponding model does not support it. \
You can implement you own model rather than use the default model. For more information, please raise an \
issue in GitHub repo and we will continue to follow up.
.. note::
For more detailed examples, please refer to our unittest for PPGOffPolicy: ``ding.policy.tests.test_ppg``.
"""
data_id = list(data.keys())
data = default_collate(list(data.values()))
if self._cuda:
data = to_device(data, self._device)
self._collect_model.eval()
with torch.no_grad():
output = self._collect_model.forward(data, mode='compute_actor_critic')
if self._cuda:
output = to_device(output, 'cpu')
output = default_decollate(output)
return {i: d for i, d in zip(data_id, output)}
def _process_transition(self, obs: Any, model_output: dict, timestep: namedtuple) -> dict:
"""
Overview:
Process and pack one timestep transition data into a dict, which can be directly used for training and \
saved in replay buffer. For PPG, it contains obs, next_obs, action, reward, done, logit, value.
Arguments:
- obs (:obj:`Any`): Env observation
- model_output (:obj:`dict`): The output of the policy network with the observation \
as input. For PPG, it contains the state value, action and the logit of the action.
- timestep (:obj:`namedtuple`): The execution result namedtuple returned by the environment step \
method, except all the elements have been transformed into tensor data. Usually, it contains the next \
obs, reward, done, info, etc.
Returns:
- transition (:obj:`dict`): The processed transition data of the current timestep.
.. note::
``next_obs`` is used to calculate nstep return when necessary, so we place in into transition by default. \
You can delete this field to save memory occupancy if you do not need nstep return.
"""
transition = {
'obs': obs,
'next_obs': timestep.obs,
'logit': model_output['logit'],
'action': model_output['action'],
'value': model_output['value'],
'reward': timestep.reward,
'done': timestep.done,
}
return transition
def _get_train_sample(self, data: list) -> Union[None, List[Any]]:
"""
Overview:
For a given trajectory (transitions, a list of transition) data, process it into a list of sample that \
can be used for training directly. In PPG, a train sample is a processed transition with new computed \
``adv`` field. This method is usually used in collectors to execute necessary. \
RL data preprocessing before training, which can help learner amortize revelant time consumption. \
In addition, you can also implement this method as an identity function and do the data processing \
in ``self._forward_learn`` method.
Arguments:
- data (:obj:`list`): The trajectory data (a list of transition), each element is \
the same format as the return value of ``self._process_transition`` method.
Returns:
- samples (:obj:`dict`): The processed train samples, each element is the similar format \
as input transitions, but may contain more data for training, such as GAE advantage.
"""
data = get_gae_with_default_last_value(
data,
data[-1]['done'],
gamma=self._gamma,
gae_lambda=self._gae_lambda,
cuda=False,
)
data = get_train_sample(data, self._unroll_len)
for d in data:
d['buffer_name'] = ["policy", "value"]
return data
def _get_batch_size(self) -> Dict[str, int]:
"""
Overview:
Get learn batch size. In the PPG algorithm, different networks require different data.\
We need to get data['policy'] and data['value'] to train policy net and value net,\
this function is used to get the batch size of data['policy'] and data['value'].
Returns:
- output (:obj:`dict[str, int]`): Dict type data, including str type batch size and int type batch size.
"""
bs = self._cfg.learn.batch_size
return {'policy': bs, 'value': bs}
def _init_eval(self) -> None:
"""
Overview:
Initialize the eval mode of policy, including related attributes and modules. For PPG, it contains the \
eval model to select optimial action (e.g. greedily select action with argmax mechanism in discrete \
action). This method will be called in ``__init__`` method if ``eval`` field is in ``enable_field``.
.. note::
If you want to set some spacial member variables in ``_init_eval`` method, you'd better name them \
with prefix ``_eval_`` to avoid conflict with other modes, such as ``self._eval_attr1``.
"""
self._eval_model = model_wrap(self._model, wrapper_name='argmax_sample')
self._eval_model.reset()
def _forward_eval(self, data: dict) -> dict:
r"""
Overview:
Policy forward function of eval mode (evaluation policy performance by interacting with envs). Forward \
means that the policy gets some necessary data (mainly observation) from the envs and then returns the \
action to interact with the envs. ``_forward_eval`` in PPG often uses deterministic sample method to get \
actions while ``_forward_collect`` usually uses stochastic sample method for balance exploration and \
exploitation.
Arguments:
- data (:obj:`Dict[str, Any]`): The input data used for policy forward, including at least the obs. The \
key of the dict is environment id and the value is the corresponding data of the env.
Returns:
- output (:obj:`Dict[int, Any]`): The output data of policy forward, including at least the action. The \
key of the dict is the same as the input data, i.e. environment id.
.. note::
The input value can be torch.Tensor or dict/list combinations and current policy supports all of them. \
For the data type that not supported, the main reason is that the corresponding model does not support it. \
You can implement you own model rather than use the default model. For more information, please raise an \
issue in GitHub repo and we will continue to follow up.
.. note::
For more detailed examples, please refer to our unittest for PPGOffPolicy: ``ding.policy.tests.test_ppg``.
"""
data_id = list(data.keys())
data = default_collate(list(data.values()))
if self._cuda:
data = to_device(data, self._device)
self._eval_model.eval()
with torch.no_grad():
output = self._eval_model.forward(data, mode='compute_actor')
if self._cuda:
output = to_device(output, 'cpu')
output = default_decollate(output)
return {i: d for i, d in zip(data_id, output)}
def _monitor_vars_learn(self) -> List[str]:
"""
Overview:
Return the necessary keys for logging the return dict of ``self._forward_learn``. The logger module, such \
as text logger, tensorboard logger, will use these keys to save the corresponding data.
Returns:
- vars (:obj:`List[str]`): The list of the necessary keys to be logged.
"""
return [
'policy_cur_lr',
'value_cur_lr',
'policy_loss',
'value_loss',
'entropy_loss',
'policy_adv_abs_max',
'approx_kl',
'clipfrac',
'aux_value_loss',
'auxiliary_loss',
'behavioral_cloning_loss',
]
def learn_aux(self) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
"""
Overview:
The auxiliary phase training, where the value is distilled into the policy network. In PPG algorithm, \
we use the value function loss as the auxiliary objective, thereby sharing features between the policy \
and value function while minimizing distortions to the policy. We also use behavioral cloning loss to \
optimize the auxiliary objective while otherwise preserving the original policy.
Returns:
- aux_loss (:obj:`Tuple[torch.Tensor, torch.Tensor, torch.Tensor]`): Including average auxiliary loss\
average behavioral cloning loss, and average auxiliary value loss.
"""
aux_memories = self._aux_memories
# gather states and target values into one tensor
data = {}
states = []
actions = []
return_ = []
old_values = []
weights = []
for memory in aux_memories:
# for memory in memories:
states.append(memory['obs'])
actions.append(memory['action'])
return_.append(memory['return_'])
old_values.append(memory['value'])
if memory['weight'] is None:
weight = torch.ones_like(memory['action'])
else:
weight = torch.tensor(memory['weight'])
weights.append(weight)
data['obs'] = torch.cat(states)
data['action'] = torch.cat(actions)
data['return_'] = torch.cat(return_)
data['value'] = torch.cat(old_values)
data['weight'] = torch.cat(weights)
# compute current policy logit_old
with torch.no_grad():
data['logit_old'] = self._model.forward(data['obs'], mode='compute_actor')['logit']
# prepared dataloader for auxiliary phase training
dl = create_shuffled_dataloader(data, self._cfg.learn.batch_size)
# the proposed auxiliary phase training
# where the value is distilled into the policy network,
# while making sure the policy network does not change the action predictions (kl div loss)
i = 0
auxiliary_loss_ = 0
behavioral_cloning_loss_ = 0
value_loss_ = 0
for epoch in range(self._aux_train_epoch):
for data in dl:
policy_output = self._model.forward(data['obs'], mode='compute_actor_critic')
# Calculate ppg error 'logit_new', 'logit_old', 'action', 'value_new', 'value_old', 'return_', 'weight'
data_ppg = ppg_data(
policy_output['logit'], data['logit_old'], data['action'], policy_output['value'], data['value'],
data['return_'], data['weight']
)
ppg_joint_loss = ppg_joint_error(data_ppg, self._clip_ratio)
wb = self._aux_bc_weight
total_loss = ppg_joint_loss.auxiliary_loss + wb * ppg_joint_loss.behavioral_cloning_loss
# # policy network loss copmoses of both the kl div loss as well as the auxiliary loss
# aux_loss = clipped_value_loss(policy_values, rewards, old_values, self.value_clip)
# loss_kl = F.kl_div(action_logprobs, old_action_probs, reduction='batchmean')
# policy_loss = aux_loss + loss_kl
self._optimizer_ac.zero_grad()
total_loss.backward()
self._optimizer_ac.step()
# paper says it is important to train the value network extra during the auxiliary phase
# Calculate ppg error 'value_new', 'value_old', 'return_', 'weight'
values = self._model.forward(data['obs'], mode='compute_critic')['value']
data_aux = ppo_value_data(values, data['value'], data['return_'], data['weight'])
value_loss = ppo_value_error(data_aux, self._clip_ratio)
self._optimizer_aux_critic.zero_grad()
value_loss.backward()
self._optimizer_aux_critic.step()
auxiliary_loss_ += ppg_joint_loss.auxiliary_loss.item()
behavioral_cloning_loss_ += ppg_joint_loss.behavioral_cloning_loss.item()
value_loss_ += value_loss.item()
i += 1
self._aux_memories = []
return auxiliary_loss_ / i, behavioral_cloning_loss_ / i, value_loss_ / i
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