Le code est basé sur le PPO de Mofan Python et fait également référence au flux d'algorithme du code réseau. Il n'utilise pas de mémoire. Les données utilisées pour chaque mise à jour du PPO sont une transition continue (y compris l'état actuel, l'action d'exécution et la récompense de remise cumulée valeur). Il utilise deux réseaux d'acteurs (un acteur_old et un acteur), hors politique est implémenté. Les deux scripts de code sont PPO_clip_ok.py et PPO_kl_pen_ok.py. Il s'agit de l'algorithme de clip et de l'algorithme de pénalité KL pour mettre à jour le neurone PPO. réseau. Après avoir pratiqué le code suivant, tout peut être exécuté via
Agrafe
"""
A simple version of Proximal Policy Optimization (PPO) using single thread.
Based on:
1. Emergence of Locomotion Behaviours in Rich Environments (Google Deepmind): [https://arxiv.org/abs/1707.02286]
2. Proximal Policy Optimization Algorithms (OpenAI): [https://arxiv.org/abs/1707.06347]
pytorch
gym 0.26.2
连续动作
"""
import gym
import numpy as np
import torch
import torch.nn as nn
import matplotlib.pyplot as plt
import torch.nn.functional as F
from torch.distributions import Normal
GAMMA = 0.9 # 折扣率
EP_MAX = 1000 # episode循环次数 # 默认是1000
EP_LEN = 200 # 一个回合规定的长度 # 默认是200
A_LR = 0.0001 # actor的学习率 默认是0.0001
C_LR = 0.0002 # critic的学习率 默认是0.0002
BATCH = 32 # 缓冲池长度
A_UPDATE_STEPS = 10 # 在多少步数之后更新actor
C_UPDATE_STEPS = 10 # 在多少步数之后更新critic
S_DIM, A_DIM = 3, 1 # state维度是3， action维度是1
METHOD = [
dict(name='kl_pen', kl_target=0.01, lam=0.5), # KL penalty # 0.5
dict(name='clip', epsilon=0.2) # clip
][1] # choose the method for optimization
# METHOD[0]是Adaptive KL penalty Coefficient
# METHOD[1]是Clipped Surrogate Objective
# 结果证明，clip的这个方法更好
class Actor(nn.Module):
"""
神经网络结构
# 全连接1
# 全连接2
# ReLU
网络输出是动作的mu和sigma
"""
def __init__(self,
n_features,
n_neuron):
super(Actor, self).__init__()
self.linear = nn.Sequential(
nn.Linear(in_features=n_features,
out_features=n_neuron,
bias=True),
nn.ReLU()
)
self.mu = nn.Sequential(
nn.Linear(in_features=n_neuron,
out_features=1,
bias=True),
nn.Tanh()
)
self.sigma = nn.Sequential(
nn.Linear(in_features=n_neuron,
out_features=1,
bias=True),
nn.Softplus()
)
def forward(self, x):
y = self.linear(x)
mu = 2 * self.mu(y)
sigma = self.sigma(y)
return mu, sigma
class Critic(nn.Module):
"""
神经网络结构
# 全连接1
# 全连接2
# ReLU
输出是状态价值
"""
def __init__(self,
n_features,
n_neuron):
super(Critic, self).__init__()
self.net = nn.Sequential(
nn.Linear(in_features=n_features,
out_features=n_neuron,
bias=True),
nn.ReLU(),
nn.Linear(in_features=n_neuron,
out_features=1,
bias=True),
)
def forward(self, x):
return self.net(x)
class PPO(object):
def __init__(self,
n_features,
n_neuron,
actor_learning_rate,
critic_learning_rate,
max_grad_norm=0.5 # 梯度剪裁参数
):
self.actor_lr = actor_learning_rate
self.critic_lr = critic_learning_rate
self.actor_old = Actor(n_features, n_neuron)
self.actor = Actor(n_features, n_neuron)
self.critic = Critic(n_features, n_neuron)
self.actor_optimizer = torch.optim.Adam(params=self.actor.parameters(),
lr=self.actor_lr)
self.critic_optimizer = torch.optim.Adam(params=self.critic.parameters(),
lr=self.critic_lr)
self.max_grad_norm = max_grad_norm # 梯度剪裁参数
def update(self, s, a, r, log_old, br_next_state):
"""
:param s: np.array(buffer_s)
:param a: np.array(buffer_a)
:param r: np.array(buffer_r)
:param log_old: np.array(buffer_log_old)
:param next_state: np.array(buffer_next_state)
:return: update actor net and critic net
"""
self.actor_old.load_state_dict(self.actor.state_dict())
# 从buffer中取出state, action, reward, old_action_log_prob, next_state放在tensor上
state = torch.FloatTensor(s)
action = torch.FloatTensor(a)
discounted_r = torch.FloatTensor(r) # discounted_r是target_v
next_state = torch.FloatTensor(br_next_state)
# 使用actor_old得到old_action_log_prob
mu_old, sigma_old = self.actor_old(state)
dist_old = Normal(mu_old, sigma_old)
old_action_log_prob = dist_old.log_prob(action).detach()
# target_v也是累积折扣奖励
target_v = discounted_r
# 优势函数advantage，也是td_error
advantage = (target_v - self.critic(state)).detach()
#advantage = (advantage - advantage.mean()) / (advantage.std()+1e-6) # sometimes helpful by movan
# update actor net，METHOD[0]是KL penalty，METHOD[1]是clip
if METHOD['name'] == 'kl_pen':
for _ in range(A_UPDATE_STEPS):
# compute new_action_log_prob
mu, sigma = self.actor(state)
dist = Normal(mu, sigma)
new_action_log_prob = dist.log_prob(action) # !!!划重点，新策略动作值的log_prob，是新策略得到的分布上找到action对应的log_prob值
new_action_prob = torch.exp(new_action_log_prob)
old_action_prob = torch.exp(old_action_log_prob)
# KL散度
kl = nn.KLDivLoss()(old_action_prob, new_action_prob)
# 计算loss
ratio = new_action_prob / old_action_prob
actor_loss = -torch.mean(ratio * advantage - METHOD['lam'] * kl)
# 梯度下降
self.actor_optimizer.zero_grad()
actor_loss.backward()
nn.utils.clip_grad_norm_(self.actor.parameters(), self.max_grad_norm) # 梯度剪裁，只解决梯度爆炸问题，不解决梯度消失问题
self.actor_optimizer.step()
if kl > 4*METHOD['kl_target']:
# this in google's paper
break
if kl < METHOD['kl_target'] / 1.5:
# 散度较小，需要弱化惩罚力度
# adaptive lambda, this is in OpenAI's paper
METHOD['lam'] /= 2
elif kl > METHOD['kl_target'] * 1.5:
# 散度较大，需要增强惩罚力度
METHOD['lam'] *= 2
# sometimes explode, this clipping is my solution
METHOD['lam'] = np.clip(METHOD['lam'], 1e-4, 10)
else:
# clipping method, find this is better (OpenAI's paper)
# update actor net
for _ in range(A_UPDATE_STEPS):
## update step as follows:
# compute new_action_log_prob
mu, sigma = self.actor(state)
n = Normal(mu, sigma)
new_action_log_prob = n.log_prob(action) # !!!划重点，新策略动作值的log_prob，是新策略得到的分布上找到action对应的log_prob值
# ratio = new_action_prob / old_action_prob
ratio = torch.exp(new_action_log_prob - old_action_log_prob)
# L1 = ratio * td_error, td_error也叫作advatange
L1 = ratio * advantage
# L2 = clip(ratio, 1-epsilon, 1+epsilon) * td_error
L2 = torch.clamp(ratio, 1-METHOD['epsilon'], 1+METHOD['epsilon']) * advantage
# loss_actor = -min(L1, L2)
actor_loss = -torch.min(L1, L2).mean()
# optimizer.zero_grad()
self.actor_optimizer.zero_grad()
# actor_loss.backward()
actor_loss.backward()
# 梯度裁剪,只解决梯度爆炸问题，不解决梯度消失问题
nn.utils.clip_grad_norm_(self.actor.parameters(), self.max_grad_norm)
# actor_optimizer.step()
self.actor_optimizer.step()
# update critic net
for _ in range(C_UPDATE_STEPS):
# critic的loss是td_error也就是advantage，可以是td_error的L1范数也可以是td_error的L2范数
critic_loss = nn.MSELoss(reduction='mean')(self.critic(state), target_v)
# optimizer.zero_grad()
self.critic_optimizer.zero_grad()
# 反向传播
critic_loss.backward()
# 梯度裁剪,只解决梯度爆炸问题，不解决梯度消失问题
nn.utils.clip_grad_norm_(self.critic.parameters(), self.max_grad_norm)
# optimizer.step()
self.critic_optimizer.step()
def choose_action(self, s):
"""
选择动作
:param s:
:return:
"""
# 状态s放在torch.tensor上
# actor net输出mu和sigma
# 根据mu和sigma采样动作
# 返回动作和动作的log概率值
s = torch.FloatTensor(s)
with torch.no_grad():
mu, sigma = self.actor(s)
# print(s, mu, sigma)
dist = Normal(mu, sigma)
action = dist.sample()
action_log_prob = dist.log_prob(action)
action = action.clamp(-2, 2)
return action.item(), action_log_prob.item()
def get_v(self, s):
"""
状态价值函数
:param s:
:return:
"""
# 状态s放在torch.tensor上
# critic net输出value
s = torch.FloatTensor(s)
with torch.no_grad():
value = self.critic(s)
return value.item()
env = gym.make('Pendulum-v1').unwrapped
env.reset(seed=0)
torch.manual_seed(0)
ppo = PPO(n_features=S_DIM, n_neuron=50,
actor_learning_rate=A_LR, critic_learning_rate=C_LR)
all_ep_r = [] # 记录每个回合的累积reward值，当前回合的累积reward值 = 上一回合reward*0.9 + 当前回合reward*0.1
for ep in range(EP_MAX):
s, info = env.reset()
buffer_s, buffer_a, buffer_r = [], [], []
buffer_log_old = [] # revised by lihan
buffer_next_state = []
ep_r = 0 # 每个回合的reward值，是回合每步的reward值的累加
for t in range(EP_LEN):
# in one episode
# env.render()
a, a_log_prob_old = ppo.choose_action(s)
s_, r, done, truncated, info = env.step([a])
buffer_s.append(s)
buffer_a.append(a)
buffer_r.append((r+8)/8) # normalize reward, find to be useful
buffer_log_old.append(a_log_prob_old)
buffer_next_state.append(s_)
s = s_
ep_r += r
# 如果buffer收集一个batch了或者episode完了，那么update ppo
if (t+1) % BATCH == 0 or t == EP_LEN - 1:
# print('update *****')
v_s_ = ppo.get_v(s_)
discounted_r = []
for r in buffer_r[::-1]:
v_s_ = r + GAMMA * v_s_
discounted_r.append(v_s_)
discounted_r.reverse()
# discounted_r是target_v
bs, ba = np.vstack(buffer_s), np.vstack(buffer_a)
br_next_state = np.vstack(buffer_next_state)
br = np.array(discounted_r)[:, np.newaxis]
blog_old = np.vstack(buffer_log_old) # revised by lihan
# 清空buffer
buffer_s, buffer_a, buffer_r = [], [], []
buffer_log_old = [] # revised by lihan
buffer_next_state = []
ppo.update(bs, ba, br, blog_old, br_next_state) # 更新PPO
if ep == 0:
all_ep_r.append(ep_r)
else:
all_ep_r.append(all_ep_r[-1]*0.9 + ep_r*0.1)
print(
'EP: %i' % ep,
"|EP_r %i" % ep_r,
("|Lam: %.4f" % METHOD['lam']) if METHOD['name']=='kl_pen' else '',
)
plt.plot(np.arange(len(all_ep_r)), all_ep_r)
plt.xlabel('Episode')
plt.ylabel('Moving averaged episode reward')
plt.show()
Pénalité de KL
"""
A simple version of Proximal Policy Optimization (PPO) using single thread.
Based on:
1. Emergence of Locomotion Behaviours in Rich Environments (Google Deepmind): [https://arxiv.org/abs/1707.02286]
2. Proximal Policy Optimization Algorithms (OpenAI): [https://arxiv.org/abs/1707.06347]
pytorch
gym 0.26.2
连续动作
"""
import gym
import numpy as np
import torch
import torch.nn as nn
import matplotlib.pyplot as plt
import torch.nn.functional as F
from torch.distributions import Normal
GAMMA = 0.9 # 折扣率
EP_MAX = 1000 # episode循环次数 # 默认是1000
EP_LEN = 200 # 一个回合规定的长度 # 默认是200
A_LR = 0.0001 # actor的学习率 默认是0.0001
C_LR = 0.0002 # critic的学习率 默认是0.0002
BATCH = 32 # 缓冲池长度
A_UPDATE_STEPS = 10 # 在多少步数之后更新actor
C_UPDATE_STEPS = 10 # 在多少步数之后更新critic
S_DIM, A_DIM = 3, 1 # state维度是3， action维度是1
METHOD = [
dict(name='kl_pen', kl_target=0.01, lam=0.5), # KL penalty # 0.5
dict(name='clip', epsilon=0.2) # clip
][0] # choose the method for optimization
# METHOD[0]是Adaptive KL penalty Coefficient
# METHOD[1]是Clipped Surrogate Objective
# 结果证明，clip的这个方法更好
class Actor(nn.Module):
"""
神经网络结构
# 全连接1
# 全连接2
# ReLU
网络输出是动作的mu和sigma
"""
def __init__(self,
n_features,
n_neuron):
super(Actor, self).__init__()
self.linear = nn.Sequential(
nn.Linear(in_features=n_features,
out_features=n_neuron,
bias=True),
nn.ReLU()
)
self.mu = nn.Sequential(
nn.Linear(in_features=n_neuron,
out_features=1,
bias=True),
nn.Tanh()
)
self.sigma = nn.Sequential(
nn.Linear(in_features=n_neuron,
out_features=1,
bias=True),
nn.Softplus()
)
def forward(self, x):
y = self.linear(x)
mu = 2 * self.mu(y)
sigma = self.sigma(y)
return mu, sigma
class Critic(nn.Module):
"""
神经网络结构
# 全连接1
# 全连接2
# ReLU
输出是状态价值
"""
def __init__(self,
n_features,
n_neuron):
super(Critic, self).__init__()
self.net = nn.Sequential(
nn.Linear(in_features=n_features,
out_features=n_neuron,
bias=True),
nn.ReLU(),
nn.Linear(in_features=n_neuron,
out_features=1,
bias=True),
)
def forward(self, x):
return self.net(x)
class PPO(object):
def __init__(self,
n_features,
n_neuron,
actor_learning_rate,
critic_learning_rate,
max_grad_norm=0.5 # 梯度剪裁参数
):
self.actor_lr = actor_learning_rate
self.critic_lr = critic_learning_rate
self.actor_old = Actor(n_features, n_neuron)
self.actor = Actor(n_features, n_neuron)
self.critic = Critic(n_features, n_neuron)
self.actor_optimizer = torch.optim.Adam(params=self.actor.parameters(),
lr=self.actor_lr)
self.critic_optimizer = torch.optim.Adam(params=self.critic.parameters(),
lr=self.critic_lr)
self.max_grad_norm = max_grad_norm # 梯度剪裁参数
def update(self, s, a, r, log_old, br_next_state):
"""
:param s: np.array(buffer_s)
:param a: np.array(buffer_a)
:param r: np.array(buffer_r)
:param log_old: np.array(buffer_log_old)
:param next_state: np.array(buffer_next_state)
:return: update actor net and critic net
"""
self.actor_old.load_state_dict(self.actor.state_dict())
# 从buffer中取出state, action, reward, old_action_log_prob, next_state放在tensor上
state = torch.FloatTensor(s)
action = torch.FloatTensor(a)
discounted_r = torch.FloatTensor(r) # discounted_r是target_v
next_state = torch.FloatTensor(br_next_state)
mu_old, sigma_old = self.actor_old(state)
dist_old = Normal(mu_old, sigma_old)
old_action_log_prob = dist_old.log_prob(action).detach()
# discounted_r是target_v
target_v = discounted_r
# 优势函数advantage，也是td_error
advantage = (target_v - self.critic(state)).detach()
#advantage = (advantage - advantage.mean()) / (advantage.std()+1e-6) # sometimes helpful by movan
# update actor net，METHOD[0]是KL penalty，METHOD[1]是clip
if METHOD['name'] == 'kl_pen':
for _ in range(A_UPDATE_STEPS):
# compute new_action_log_prob
mu, sigma = self.actor(state)
dist = Normal(mu, sigma)
new_action_log_prob = dist.log_prob(action) # !!!划重点，新策略动作值的log_prob，是新策略得到的分布上找到action对应的log_prob值
new_action_prob = torch.exp(new_action_log_prob)
old_action_prob = torch.exp(old_action_log_prob)
# KL散度
kl = nn.KLDivLoss()(old_action_prob, new_action_prob)
# 计算loss
ratio = new_action_prob / old_action_prob
actor_loss = -torch.mean(ratio * advantage - METHOD['lam'] * kl)
# 梯度下降
self.actor_optimizer.zero_grad()
actor_loss.backward()
nn.utils.clip_grad_norm_(self.actor.parameters(), self.max_grad_norm) # 梯度剪裁，只解决梯度爆炸问题，不解决梯度消失问题
self.actor_optimizer.step()
if kl > 4*METHOD['kl_target']:
# this in google's paper
break
if kl < METHOD['kl_target'] / 1.5:
# 散度较小，需要弱化惩罚力度
# adaptive lambda, this is in OpenAI's paper
METHOD['lam'] /= 2
elif kl > METHOD['kl_target'] * 1.5:
# 散度较大，需要增强惩罚力度
METHOD['lam'] *= 2
# sometimes explode, this clipping is my solution
METHOD['lam'] = np.clip(METHOD['lam'], 1e-4, 10)
else:
# clipping method, find this is better (OpenAI's paper)
# update actor net
for _ in range(A_UPDATE_STEPS):
## update step as follows:
# compute new_action_log_prob
mu, sigma = self.actor(state)
n = Normal(mu, sigma)
new_action_log_prob = n.log_prob(action) # !!!划重点，新策略动作值的log_prob，是新策略得到的分布上找到action对应的log_prob值
# ratio = new_action_prob / old_action_prob
ratio = torch.exp(new_action_log_prob - old_action_log_prob)
# L1 = ratio * td_error, td_error也叫作advatange
L1 = ratio * advantage
# L2 = clip(ratio, 1-epsilon, 1+epsilon) * td_error
L2 = torch.clamp(ratio, 1-METHOD['epsilon'], 1+METHOD['epsilon']) * advantage
# loss_actor = -min(L1, L2)
actor_loss = -torch.min(L1, L2).mean()
# optimizer.zero_grad()
self.actor_optimizer.zero_grad()
# actor_loss.backward()
actor_loss.backward()
# 梯度裁剪,只解决梯度爆炸问题，不解决梯度消失问题
nn.utils.clip_grad_norm_(self.actor.parameters(), self.max_grad_norm)
# actor_optimizer.step()
self.actor_optimizer.step()
# update critic net
for _ in range(C_UPDATE_STEPS):
# critic的loss是td_error也就是advantage，可以是td_error的L1范数也可以是td_error的L2范数
critic_loss = nn.MSELoss(reduction='mean')(self.critic(state), target_v)
# optimizer.zero_grad()
self.critic_optimizer.zero_grad()
# 反向传播
critic_loss.backward()
# 梯度裁剪,只解决梯度爆炸问题，不解决梯度消失问题
nn.utils.clip_grad_norm_(self.critic.parameters(), self.max_grad_norm)
# optimizer.step()
self.critic_optimizer.step()
def choose_action(self, s):
"""
选择动作
:param s:
:return:
"""
# 状态s放在torch.tensor上
# actor net输出mu和sigma
# 根据mu和sigma采样动作
# 返回动作和动作的log概率值
s = torch.FloatTensor(s)
with torch.no_grad():
mu, sigma = self.actor(s)
# print(s, mu, sigma)
dist = Normal(mu, sigma)
action = dist.sample()
action_log_prob = dist.log_prob(action)
action = action.clamp(-2, 2)
return action.item(), action_log_prob.item()
def get_v(self, s):
"""
状态价值函数
:param s:
:return:
"""
# 状态s放在torch.tensor上
# critic net输出value
s = torch.FloatTensor(s)
with torch.no_grad():
value = self.critic(s)
return value.item()
env = gym.make('Pendulum-v1').unwrapped
env.reset(seed=0)
torch.manual_seed(0)
ppo = PPO(n_features=S_DIM, n_neuron=50,
actor_learning_rate=A_LR, critic_learning_rate=C_LR)
all_ep_r = [] # 记录每个回合的累积reward值，当前回合的累积reward值 = 上一回合reward*0.9 + 当前回合reward*0.1
for ep in range(EP_MAX):
s, info = env.reset()
buffer_s, buffer_a, buffer_r = [], [], []
buffer_log_old = [] # revised by lihan
buffer_next_state = []
ep_r = 0 # 每个回合的reward值，是回合每步的reward值的累加
for t in range(EP_LEN):
# in one episode
env.render()
# print(ep, t)
a, a_log_prob_old = ppo.choose_action(s)
s_, r, done, truncated, info = env.step([a])
buffer_s.append(s)
buffer_a.append(a)
buffer_r.append((r+8)/8) # normalize reward, find to be useful
buffer_log_old.append(a_log_prob_old)
buffer_next_state.append(s_)
s = s_
ep_r += r
# 如果buffer收集一个batch了或者episode完了，那么update ppo
if (t+1) % BATCH == 0 or t == EP_LEN - 1:
# print('update *****')
v_s_ = ppo.get_v(s_)
discounted_r = []
for r in buffer_r[::-1]:
v_s_ = r + GAMMA * v_s_
discounted_r.append(v_s_)
discounted_r.reverse()
# discounted_r是target_v
bs, ba = np.vstack(buffer_s), np.vstack(buffer_a)
br_next_state = np.vstack(buffer_next_state)
br = np.array(discounted_r)[:, np.newaxis]
blog_old = np.vstack(buffer_log_old) # revised by lihan
# 清空buffer
buffer_s, buffer_a, buffer_r = [], [], []
buffer_log_old = [] # revised by lihan
buffer_next_state = []
ppo.update(bs, ba, br, blog_old, br_next_state) # 更新PPO
if ep == 0:
all_ep_r.append(ep_r)
else:
all_ep_r.append(all_ep_r[-1]*0.9 + ep_r*0.1)
print(
'EP: %i' % ep,
"|EP_r %i" % ep_r,
("|Lam: %.4f" % METHOD['lam']) if METHOD['name']=='kl_pen' else '',
)
plt.plot(np.arange(len(all_ep_r)), all_ep_r)
plt.xlabel('Episode')
plt.ylabel('Moving averaged episode reward')
plt.show()
Les références
Tutoriel vidéo PPO de MofanPython sur Bilibili