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ddpg_agent.py
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ddpg_agent.py
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# -*- coding: utf-8 -*-
"""Behaviour Cloning with DDPG agent for episodic tasks in OpenAI Gym.
- Author: Kh Kim
- Contact: kh.kim@medipixel.io
- Paper: https://arxiv.org/pdf/1709.10089.pdf
"""
import argparse
import pickle
from typing import Tuple
import gym
import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F
import wandb
from algorithms.common.abstract.her import HER
from algorithms.common.buffer.replay_buffer import ReplayBuffer
import algorithms.common.helper_functions as common_utils
from algorithms.common.noise import OUNoise
from algorithms.ddpg.agent import DDPGAgent
device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
class BCDDPGAgent(DDPGAgent):
"""BC with DDPG agent interacting with environment.
Attributes:
her (HER): hinsight experience replay
transitions_epi (list): transitions per episode (for HER)
desired_state (np.ndarray): desired state of current episode
memory (ReplayBuffer): replay memory
demo_memory (ReplayBuffer): replay memory for demo
lambda1 (float): proportion of policy loss
lambda2 (float): proportion of BC loss
"""
def __init__(
self,
env: gym.Env,
args: argparse.Namespace,
hyper_params: dict,
models: tuple,
optims: tuple,
noise: OUNoise,
her: HER,
):
"""Initialization.
Args:
her (HER): hinsight experience replay
"""
self.her = her
DDPGAgent.__init__(self, env, args, hyper_params, models, optims, noise)
# pylint: disable=attribute-defined-outside-init
def _initialize(self):
"""Initialize non-common things."""
# load demo replay memory
with open(self.args.demo_path, "rb") as f:
demo = list(pickle.load(f))
# HER
if self.hyper_params["USE_HER"]:
if self.hyper_params["DESIRED_STATES_FROM_DEMO"]:
self.her.fetch_desired_states_from_demo(demo)
self.transitions_epi: list = list()
self.desired_state = np.zeros((1,))
demo = self.her.generate_demo_transitions(demo)
if not self.args.test:
# Replay buffers
demo_batch_size = self.hyper_params["DEMO_BATCH_SIZE"]
self.demo_memory = ReplayBuffer(len(demo), demo_batch_size)
self.demo_memory.extend(demo)
self.memory = ReplayBuffer(
self.hyper_params["BUFFER_SIZE"], self.hyper_params["BATCH_SIZE"]
)
# set hyper parameters
self.lambda1 = self.hyper_params["LAMBDA1"]
self.lambda2 = self.hyper_params["LAMBDA2"] / demo_batch_size
def _preprocess_state(self, state: np.ndarray) -> torch.Tensor:
"""Preprocess state so that actor selects an action."""
if self.hyper_params["USE_HER"]:
self.desired_state = self.her.get_desired_state()
state = np.concatenate((state, self.desired_state), axis=-1)
state = torch.FloatTensor(state).to(device)
return state
def _add_transition_to_memory(self, transition: Tuple[np.ndarray, ...]):
"""Add 1 step and n step transitions to memory."""
if self.hyper_params["USE_HER"]:
self.transitions_epi.append(transition)
done = transition[-1] or self.episode_step == self.args.max_episode_steps
if done:
# insert generated transitions if the episode is done
transitions = self.her.generate_transitions(
self.transitions_epi,
self.desired_state,
self.hyper_params["SUCCESS_SCORE"],
)
self.memory.extend(transitions)
self.transitions_epi.clear()
else:
self.memory.add(transition)
def update_model(self) -> Tuple[torch.Tensor, ...]:
"""Train the model after each episode."""
experiences = self.memory.sample()
demos = self.demo_memory.sample()
exp_states, exp_actions, exp_rewards, exp_next_states, exp_dones = experiences
demo_states, demo_actions, demo_rewards, demo_next_states, demo_dones = demos
states = torch.cat((exp_states, demo_states), dim=0)
actions = torch.cat((exp_actions, demo_actions), dim=0)
rewards = torch.cat((exp_rewards, demo_rewards), dim=0)
next_states = torch.cat((exp_next_states, demo_next_states), dim=0)
dones = torch.cat((exp_dones, demo_dones), dim=0)
# G_t = r + gamma * v(s_{t+1}) if state != Terminal
# = r otherwise
masks = 1 - dones
next_actions = self.actor_target(next_states)
next_values = self.critic_target(torch.cat((next_states, next_actions), dim=-1))
curr_returns = rewards + (self.hyper_params["GAMMA"] * next_values * masks)
curr_returns = curr_returns.to(device)
# critic loss
values = self.critic(torch.cat((states, actions), dim=-1))
critic_loss = F.mse_loss(values, curr_returns)
# train critic
gradient_clip_cr = self.hyper_params["GRADIENT_CLIP_CR"]
self.critic_optimizer.zero_grad()
critic_loss.backward()
nn.utils.clip_grad_norm_(self.critic.parameters(), gradient_clip_cr)
self.critic_optimizer.step()
# policy loss
actions = self.actor(states)
policy_loss = -self.critic(torch.cat((states, actions), dim=-1)).mean()
# bc loss
pred_actions = self.actor(demo_states)
qf_mask = torch.gt(
self.critic(torch.cat((demo_states, demo_actions), dim=-1)),
self.critic(torch.cat((demo_states, pred_actions), dim=-1)),
).to(device)
qf_mask = qf_mask.float()
n_qf_mask = int(qf_mask.sum().item())
if n_qf_mask == 0:
bc_loss = torch.zeros(1, device=device)
else:
bc_loss = (
torch.mul(pred_actions, qf_mask) - torch.mul(demo_actions, qf_mask)
).pow(2).sum() / n_qf_mask
# train actor: pg loss + BC loss
actor_loss = self.lambda1 * policy_loss + self.lambda2 * bc_loss
gradient_clip_ac = self.hyper_params["GRADIENT_CLIP_AC"]
self.actor_optimizer.zero_grad()
actor_loss.backward()
nn.utils.clip_grad_norm_(self.actor.parameters(), gradient_clip_ac)
self.actor_optimizer.step()
# update target networks
tau = self.hyper_params["TAU"]
common_utils.soft_update(self.actor, self.actor_target, tau)
common_utils.soft_update(self.critic, self.critic_target, tau)
return actor_loss.item(), critic_loss.item(), n_qf_mask
def write_log(self, i: int, loss: np.ndarray, score: int, avg_time_cost):
"""Write log about loss and score"""
total_loss = loss.sum()
print(
"[INFO] episode %d, episode step: %d, total step: %d, total score: %d\n"
"total loss: %f actor_loss: %.3f critic_loss: %.3f, n_qf_mask: %d "
"(spent %.6f sec/step)\n"
% (
i,
self.episode_step,
self.total_step,
score,
total_loss,
loss[0],
loss[1],
loss[2],
avg_time_cost,
) # actor loss # critic loss
)
if self.args.log:
wandb.log(
{
"score": score,
"total loss": total_loss,
"actor loss": loss[0],
"critic loss": loss[1],
"time per each step": avg_time_cost,
}
)