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Agent.py
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Agent.py
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#!/usr/bin/python
# -*- coding: utf-8 -*-
import torch
import torch.nn as nn
import numpy as np
import numpy.random as rd
from copy import deepcopy
from core import *
class AgentPPO:
def __init__(self):
super().__init__()
self.ratio_clip = 0.2 # ratio.clamp(1 - clip, 1 + clip)
self.lambda_entropy = 0.02 # could be 0.02
self.lambda_gae_adv = 0.98 # could be 0.95~0.99, GAE (Generalized Advantage Estimation. ICLR.2016.)
self.get_reward_sum = None
self.state = None
self.device = None
self.criterion = None
self.act = self.act_optimizer = None
self.cri = self.cri_optimizer = self.cri_target = None
def init(self, net_dim, state_dim, action_dim, learning_rate=1e-4, if_use_gae=False):
self.device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
self.get_reward_sum = self.get_reward_sum_gae if if_use_gae else self.get_reward_sum_raw
self.act = ActorPPO(net_dim, state_dim, action_dim).to(self.device)
self.cri = CriticAdv(net_dim, state_dim).to(self.device)
self.cri_target = deepcopy(self.cri) if self.cri_target is True else self.cri
self.criterion = torch.nn.SmoothL1Loss()
self.act_optimizer = torch.optim.Adam(self.act.parameters(), lr=learning_rate)
self.cri_optimizer = torch.optim.Adam(self.cri.parameters(), lr=learning_rate)
def select_action(self, state):
states = torch.as_tensor((state,), dtype=torch.float32, device=self.device)
actions, noises = self.act.get_action(states) # plan to be get_action_a_noise
return actions[0].detach().cpu().numpy(), noises[0].detach().cpu().numpy()
def explore_env(self, env, target_step, reward_scale, gamma):
trajectory_list = list()
state = self.state
for _ in range(target_step):
action, noise = self.select_action(state)
next_state, reward, done, _ = env.step(np.tanh(action))
other = (reward * reward_scale, 0.0 if done else gamma, *action, *noise)
trajectory_list.append((state, other))
state = env.reset() if done else next_state
self.state = state
return trajectory_list
def update_net(self, buffer, batch_size, repeat_times, soft_update_tau):
buffer.update_now_len()
buf_len = buffer.now_len
buf_state, buf_action, buf_r_sum, buf_logprob, buf_advantage = self.prepare_buffer(buffer)
buffer.empty_buffer()
'''PPO: Surrogate objective of Trust Region'''
obj_critic = obj_actor = logprob = None
for _ in range(int(buf_len / batch_size * repeat_times)):
indices = torch.randint(buf_len, size=(batch_size,), requires_grad=False, device=self.device)
state = buf_state[indices]
action = buf_action[indices]
r_sum = buf_r_sum[indices]
logprob = buf_logprob[indices]
advantage = buf_advantage[indices]
new_logprob, obj_entropy = self.act.get_logprob_entropy(state, action) # it is obj_actor
ratio = (new_logprob - logprob.detach()).exp()
surrogate1 = advantage * ratio
surrogate2 = advantage * ratio.clamp(1 - self.ratio_clip, 1 + self.ratio_clip)
obj_surrogate = -torch.min(surrogate1, surrogate2).mean()
obj_actor = obj_surrogate + obj_entropy * self.lambda_entropy
self.optim_update(self.act_optimizer, obj_actor)
value = self.cri(state).squeeze(1) # critic network predicts the reward_sum (Q value) of state
obj_critic = self.criterion(value, r_sum) / (r_sum.std() + 1e-6)
self.optim_update(self.cri_optimizer, obj_critic)
self.soft_update(self.cri_target, self.cri, soft_update_tau) if self.cri_target is not self.cri else None
return obj_critic.item(), obj_actor.item(), logprob.mean().item() # logging_tuple
def prepare_buffer(self, buffer):
buf_len = buffer.now_len
with torch.no_grad(): # compute reverse reward
reward, mask, action, a_noise, state = buffer.sample_all()
bs = 2 ** 10 # set a smaller 'BatchSize' when out of GPU memory.
value = torch.cat([self.cri_target(state[i:i + bs]) for i in range(0, state.size(0), bs)], dim=0)
logprob = self.act.get_old_logprob(action, a_noise)
pre_state = torch.as_tensor((self.state,), dtype=torch.float32, device=self.device)
pre_r_sum = self.cri(pre_state).detach()
r_sum, advantage = self.get_reward_sum(self, buf_len, reward, mask, value, pre_r_sum)
return state, action, r_sum, logprob, advantage
@staticmethod
def get_reward_sum_raw(self, buf_len, buf_reward, buf_mask, buf_value, pre_r_sum) -> (torch.Tensor, torch.Tensor):
buf_r_sum = torch.empty(buf_len, dtype=torch.float32, device=self.device) # reward sum
for i in range(buf_len - 1, -1, -1):
buf_r_sum[i] = buf_reward[i] + buf_mask[i] * pre_r_sum
pre_r_sum = buf_r_sum[i]
buf_advantage = buf_r_sum - (buf_mask * buf_value.squeeze(1))
buf_advantage = (buf_advantage - buf_advantage.mean()) / (buf_advantage.std() + 1e-5)
return buf_r_sum, buf_advantage
@staticmethod
def get_reward_sum_gae(self, buf_len, buf_reward, buf_mask, buf_value, pre_r_sum) -> (torch.Tensor, torch.Tensor):
buf_r_sum = torch.empty(buf_len, dtype=torch.float32, device=self.device) # old policy value
buf_advantage = torch.empty(buf_len, dtype=torch.float32, device=self.device) # advantage value
pre_advantage = 0 # advantage value of previous step
for i in range(buf_len - 1, -1, -1):
buf_r_sum[i] = buf_reward[i] + buf_mask[i] * pre_r_sum
pre_r_sum = buf_r_sum[i]
buf_advantage[i] = buf_reward[i] + buf_mask[i] * (pre_advantage - buf_value[i]) # fix a bug here
pre_advantage = buf_value[i] + buf_advantage[i] * self.lambda_gae_adv
buf_advantage = (buf_advantage - buf_advantage.mean()) / (buf_advantage.std() + 1e-5)
return buf_r_sum, buf_advantage
@staticmethod
def optim_update(optimizer, objective):
optimizer.zero_grad()
objective.backward()
optimizer.step()
@staticmethod
def soft_update(target_net, current_net, tau):
for tar, cur in zip(target_net.parameters(), current_net.parameters()):
tar.data.copy_(cur.data.__mul__(tau) + tar.data.__mul__(1 - tau))
class AgentDiscretePPO(AgentPPO):
def init(self, net_dim, state_dim, action_dim, learning_rate=1e-4, if_use_gae=False):
self.device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
self.get_reward_sum = self.get_reward_sum_gae if if_use_gae else self.get_reward_sum_raw
self.act = ActorDiscretePPO(net_dim, state_dim, action_dim).to(self.device)
self.cri = CriticAdv(net_dim, state_dim).to(self.device)
self.cri_target = deepcopy(self.cri) if self.cri_target is True else self.cri
self.criterion = torch.nn.SmoothL1Loss()
self.act_optimizer = torch.optim.Adam(self.act.parameters(), lr=learning_rate)
self.cri_optimizer = torch.optim.Adam(self.cri.parameters(), lr=learning_rate)
def explore_env(self, env, target_step, reward_scale, gamma):
trajectory_list = list()
state = self.state
for _ in range(target_step):
a_int, a_prob = self.select_action(state)
next_state, reward, done,_ = env.step(int(a_int))
other = (reward * reward_scale, 0.0 if done else gamma, a_int, *a_prob)
trajectory_list.append((state, other))
state = env.reset() if done else next_state
self.state = state
return trajectory_list