This commit is contained in:
johnjim0816
2021-09-16 15:35:40 +08:00
parent 5085040330
commit 34fcebc4b8
31 changed files with 434 additions and 137 deletions

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@@ -5,7 +5,7 @@
@Email: johnjim0816@gmail.com
@Date: 2020-06-09 20:25:52
@LastEditor: John
LastEditTime: 2021-05-04 14:50:17
LastEditTime: 2021-09-16 00:55:30
@Discription:
@Environment: python 3.7.7
'''
@@ -26,7 +26,7 @@ class DDPG:
self.target_critic = Critic(state_dim, action_dim, cfg.hidden_dim).to(cfg.device)
self.target_actor = Actor(state_dim, action_dim, cfg.hidden_dim).to(cfg.device)
# copy parameters to target net
# 复制参数到目标网络
for target_param, param in zip(self.target_critic.parameters(), self.critic.parameters()):
target_param.data.copy_(param.data)
for target_param, param in zip(self.target_actor.parameters(), self.actor.parameters()):
@@ -37,7 +37,7 @@ class DDPG:
self.actor_optimizer = optim.Adam(self.actor.parameters(), lr=cfg.actor_lr)
self.memory = ReplayBuffer(cfg.memory_capacity)
self.batch_size = cfg.batch_size
self.soft_tau = cfg.soft_tau
self.soft_tau = cfg.soft_tau # 软更新参数
self.gamma = cfg.gamma
def choose_action(self, state):
@@ -46,11 +46,11 @@ class DDPG:
return action.detach().cpu().numpy()[0, 0]
def update(self):
if len(self.memory) < self.batch_size:
if len(self.memory) < self.batch_size: # 当 memory 中不满足一个批量时,不更新策略
return
state, action, reward, next_state, done = self.memory.sample(
self.batch_size)
# convert variables to Tensor
# 从经验回放中(replay memory)中随机采样一个批量的转移(transition)
state, action, reward, next_state, done = self.memory.sample(self.batch_size)
# 转变为张量
state = torch.FloatTensor(state).to(self.device)
next_state = torch.FloatTensor(next_state).to(self.device)
action = torch.FloatTensor(action).to(self.device)
@@ -70,10 +70,10 @@ class DDPG:
self.actor_optimizer.zero_grad()
policy_loss.backward()
self.actor_optimizer.step()
self.critic_optimizer.zero_grad()
value_loss.backward()
self.critic_optimizer.step()
# 软更新
for target_param, param in zip(self.target_critic.parameters(), self.critic.parameters()):
target_param.data.copy_(
target_param.data * (1.0 - self.soft_tau) +

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@@ -5,7 +5,7 @@
@Email: johnjim0816@gmail.com
@Date: 2020-06-10 15:28:30
@LastEditor: John
LastEditTime: 2021-03-19 19:56:46
LastEditTime: 2021-09-16 00:52:30
@Discription:
@Environment: python 3.7.7
'''
@@ -32,12 +32,12 @@ class NormalizedActions(gym.ActionWrapper):
return action
class OUNoise(object):
'''OrnsteinUhlenbeck
'''OrnsteinUhlenbeck噪声
'''
def __init__(self, action_space, mu=0.0, theta=0.15, max_sigma=0.3, min_sigma=0.3, decay_period=100000):
self.mu = mu
self.theta = theta
self.sigma = max_sigma
self.mu = mu # OU噪声的参数
self.theta = theta # OU噪声的参数
self.sigma = max_sigma # OU噪声的参数
self.max_sigma = max_sigma
self.min_sigma = min_sigma
self.decay_period = decay_period
@@ -45,17 +45,14 @@ class OUNoise(object):
self.low = action_space.low
self.high = action_space.high
self.reset()
def reset(self):
self.obs = np.ones(self.action_dim) * self.mu
def evolve_obs(self):
x = self.obs
dx = self.theta * (self.mu - x) + self.sigma * np.random.randn(self.action_dim)
self.obs = x + dx
return self.obs
def get_action(self, action, t=0):
ou_obs = self.evolve_obs()
self.sigma = self.max_sigma - (self.max_sigma - self.min_sigma) * min(1.0, t / self.decay_period)
return np.clip(action + ou_obs, self.low, self.high)
self.sigma = self.max_sigma - (self.max_sigma - self.min_sigma) * min(1.0, t / self.decay_period) # sigma会逐渐衰减
return np.clip(action + ou_obs, self.low, self.high) # 动作加上噪声后进行剪切

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@@ -5,14 +5,14 @@
@Email: johnjim0816@gmail.com
@Date: 2020-06-11 20:58:21
@LastEditor: John
LastEditTime: 2021-05-04 14:49:45
LastEditTime: 2021-09-16 01:31:33
@Discription:
@Environment: python 3.7.7
'''
import sys,os
curr_path = os.path.dirname(__file__)
parent_path = os.path.dirname(curr_path)
sys.path.append(parent_path) # add current terminal path to sys.path
curr_path = os.path.dirname(os.path.abspath(__file__)) # 当前文件所在绝对路径
parent_path = os.path.dirname(curr_path) # 父路径
sys.path.append(parent_path) # 添加父路径到系统路径sys.path
import datetime
import gym
@@ -21,49 +21,45 @@ import torch
from DDPG.env import NormalizedActions, OUNoise
from DDPG.agent import DDPG
from common.utils import save_results,make_dir
from common.plot import plot_rewards
curr_time = datetime.datetime.now().strftime(
"%Y%m%d-%H%M%S") # obtain current time
from common.plot import plot_rewards, plot_rewards_cn
curr_time = datetime.datetime.now().strftime("%Y%m%d-%H%M%S") # 获取当前时间
class DDPGConfig:
def __init__(self):
self.algo = 'DDPG'
self.env = 'Pendulum-v0' # env name
self.algo = 'DDPG' # 算法名称
self.env = 'Pendulum-v0' # 环境名称
self.result_path = curr_path+"/outputs/" + self.env + \
'/'+curr_time+'/results/' # path to save results
'/'+curr_time+'/results/' # 保存结果的路径
self.model_path = curr_path+"/outputs/" + self.env + \
'/'+curr_time+'/models/' # path to save results
self.gamma = 0.99
self.critic_lr = 1e-3
self.actor_lr = 1e-4
self.memory_capacity = 10000
'/'+curr_time+'/models/' # 保存模型的路径
self.train_eps = 300 # 训练的回合数
self.eval_eps = 50 # 测试的回合数
self.gamma = 0.99 # 折扣因子
self.critic_lr = 1e-3 # 评论家网络的学习率
self.actor_lr = 1e-4 # 演员网络的学习率
self.memory_capacity = 8000
self.batch_size = 128
self.train_eps = 300
self.eval_eps = 50
self.eval_steps = 200
self.target_update = 4
self.hidden_dim = 30
self.soft_tau = 1e-2
self.device = torch.device(
"cuda" if torch.cuda.is_available() else "cpu")
self.target_update = 2
self.hidden_dim = 256
self.soft_tau = 1e-2 # 软更新参数
self.device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
def env_agent_config(cfg,seed=1):
env = NormalizedActions(gym.make(cfg.env))
env.seed(seed)
env.seed(seed) # 随机种子
state_dim = env.observation_space.shape[0]
action_dim = env.action_space.shape[0]
agent = DDPG(state_dim,action_dim,cfg)
return env,agent
def train(cfg, env, agent):
print('Start to train ! ')
print(f'Env:{cfg.env}, Algorithm:{cfg.algo}, Device:{cfg.device}')
ou_noise = OUNoise(env.action_space) # action noise
rewards = []
ma_rewards = [] # moving average rewards
for i_episode in range(cfg.train_eps):
print('开始训练!')
print(f'环境:{cfg.env},算法:{cfg.algo},设备:{cfg.device}')
ou_noise = OUNoise(env.action_space) # 动作噪声
rewards = [] # 记录奖励
ma_rewards = [] # 记录滑动平均奖励
for i_ep in range(cfg.train_eps):
state = env.reset()
ou_noise.reset()
done = False
@@ -72,29 +68,29 @@ def train(cfg, env, agent):
while not done:
i_step += 1
action = agent.choose_action(state)
action = ou_noise.get_action(
action, i_step) # 即paper中的random process
action = ou_noise.get_action(action, i_step)
next_state, reward, done, _ = env.step(action)
ep_reward += reward
agent.memory.push(state, action, reward, next_state, done)
agent.update()
state = next_state
print('Episode:{}/{}, Reward:{}'.format(i_episode+1, cfg.train_eps, ep_reward))
if (i_ep+1)%10 == 0:
print('回合:{}/{},奖励:{:.2f}'.format(i_ep+1, cfg.train_eps, ep_reward))
rewards.append(ep_reward)
if ma_rewards:
ma_rewards.append(0.9*ma_rewards[-1]+0.1*ep_reward)
else:
ma_rewards.append(ep_reward)
print('Complete training')
print('完成训练')
return rewards, ma_rewards
def eval(cfg, env, agent):
print('Start to Eval ! ')
print(f'Env:{cfg.env}, Algorithm:{cfg.algo}, Device:{cfg.device}')
rewards = []
ma_rewards = [] # moving average rewards
for i_episode in range(cfg.eval_eps):
state = env.reset()
print('开始测试!')
print(f'环境:{cfg.env}, 算法:{cfg.algo}, 设备:{cfg.device}')
rewards = [] # 记录奖励
ma_rewards = [] # 记录滑动平均奖励
for i_ep in range(cfg.eval_eps):
state = env.reset()
done = False
ep_reward = 0
i_step = 0
@@ -104,32 +100,29 @@ def eval(cfg, env, agent):
next_state, reward, done, _ = env.step(action)
ep_reward += reward
state = next_state
print('Episode:{}/{}, Reward:{}'.format(i_episode+1, cfg.train_eps, ep_reward))
print('回合:{}/{}, 奖励:{}'.format(i_ep+1, cfg.train_eps, ep_reward))
rewards.append(ep_reward)
if ma_rewards:
ma_rewards.append(0.9*ma_rewards[-1]+0.1*ep_reward)
else:
ma_rewards.append(ep_reward)
print('Complete Eval')
print('完成测试')
return rewards, ma_rewards
if __name__ == "__main__":
cfg = DDPGConfig()
# train
# 训练
env,agent = env_agent_config(cfg,seed=1)
rewards, ma_rewards = train(cfg, env, agent)
make_dir(cfg.result_path, cfg.model_path)
agent.save(path=cfg.model_path)
save_results(rewards, ma_rewards, tag='train', path=cfg.result_path)
plot_rewards(rewards, ma_rewards, tag="train",
algo=cfg.algo, path=cfg.result_path)
# eval
plot_rewards_cn(rewards, ma_rewards, tag="train", env = cfg.env, algo=cfg.algo, path=cfg.result_path)
# 测试
env,agent = env_agent_config(cfg,seed=10)
agent.load(path=cfg.model_path)
rewards,ma_rewards = eval(cfg,env,agent)
save_results(rewards,ma_rewards,tag='eval',path=cfg.result_path)
plot_rewards(rewards,ma_rewards,tag="eval",env=cfg.env,algo = cfg.algo,path=cfg.result_path)
save_results(rewards,ma_rewards,tag = 'eval',path = cfg.result_path)
plot_rewards_cn(rewards,ma_rewards,tag = "eval",env = cfg.env,algo = cfg.algo,path=cfg.result_path)

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@@ -5,7 +5,7 @@
@Email: johnjim0816@gmail.com
@Date: 2020-06-12 00:50:49
@LastEditor: John
LastEditTime: 2021-09-15 02:18:56
LastEditTime: 2021-09-15 13:35:36
@Discription:
@Environment: python 3.7.7
'''
@@ -50,7 +50,7 @@ class DQN:
with torch.no_grad():
state = torch.tensor([state], device=self.device, dtype=torch.float32)
q_values = self.policy_net(state)
action = q_values.max(1)[1].item()
action = q_values.max(1)[1].item() # 选择Q值最大的动作
else:
action = random.randrange(self.action_dim)
return action
@@ -61,45 +61,33 @@ class DQN:
action = q_values.max(1)[1].item()
return action
def update(self):
if len(self.memory) < self.batch_size:
if len(self.memory) < self.batch_size: # 当memory中不满足一个批量时不更新策略
return
# 从memory中随机采样transition
# 从经验回放中(replay memory)中随机采样一个批量的转移(transition)
state_batch, action_batch, reward_batch, next_state_batch, done_batch = self.memory.sample(
self.batch_size)
'''转为张量
例如tensor([[-4.5543e-02, -2.3910e-01, 1.8344e-02, 2.3158e-01],...,[-1.8615e-02, -2.3921e-01, -1.1791e-02, 2.3400e-01]])'''
# 转为张量
state_batch = torch.tensor(
state_batch, device=self.device, dtype=torch.float)
action_batch = torch.tensor(action_batch, device=self.device).unsqueeze(
1) # 例如tensor([[1],...,[0]])
1)
reward_batch = torch.tensor(
reward_batch, device=self.device, dtype=torch.float) # tensor([1., 1.,...,1])
reward_batch, device=self.device, dtype=torch.float)
next_state_batch = torch.tensor(
next_state_batch, device=self.device, dtype=torch.float)
done_batch = torch.tensor(np.float32(
done_batch), device=self.device)
'''计算当前(s_t,a)对应的Q(s_t, a)'''
'''torch.gather:对于a=torch.Tensor([[1,2],[3,4]]),那么a.gather(1,torch.Tensor([[0],[1]]))=torch.Tensor([[1],[3]])'''
q_values = self.policy_net(state_batch).gather(
dim=1, index=action_batch) # 等价于self.forward
# 计算所有next states的V(s_{t+1})即通过target_net中选取reward最大的对应states
next_q_values = self.target_net(next_state_batch).max(
1)[0].detach() # 比如tensor([ 0.0060, -0.0171,...,])
# 计算 expected_q_value
# 对于终止状态此时done_batch[0]=1, 对应的expected_q_value等于reward
expected_q_values = reward_batch + \
self.gamma * next_q_values * (1-done_batch)
# self.loss = F.smooth_l1_loss(q_values,expected_q_values.unsqueeze(1)) # 计算 Huber loss
loss = nn.MSELoss()(q_values, expected_q_values.unsqueeze(1)) # 计算 均方误差loss
# 优化模型
self.optimizer.zero_grad() # zero_grad清除上一步所有旧的gradients from the last step
# loss.backward()使用backpropagation计算loss相对于所有parameters(需要gradients)的微分
q_values = self.policy_net(state_batch).gather(dim=1, index=action_batch) # 计算当前状态(s_t,a)对应的Q(s_t, a)
next_q_values = self.target_net(next_state_batch).max(1)[0].detach() # 计算下一时刻的状态(s_t_,a)对应的Q值
# 计算期望的Q值对于终止状态此时done_batch[0]=1, 对应的expected_q_value等于reward
expected_q_values = reward_batch + self.gamma * next_q_values * (1-done_batch)
loss = nn.MSELoss()(q_values, expected_q_values.unsqueeze(1)) # 计算均方根损失
# 优化更新模型
self.optimizer.zero_grad()
loss.backward()
# for param in self.policy_net.parameters(): # clip防止梯度爆炸
# param.grad.data.clamp_(-1, 1)
self.optimizer.step() # 更新模型
for param in self.policy_net.parameters(): # clip防止梯度爆炸
param.grad.data.clamp_(-1, 1)
self.optimizer.step()
def save(self, path):
torch.save(self.target_net.state_dict(), path+'dqn_checkpoint.pth')

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@@ -5,7 +5,7 @@
@Email: johnjim0816@gmail.com
@Date: 2020-06-12 00:48:57
@LastEditor: John
LastEditTime: 2021-09-15 02:19:54
LastEditTime: 2021-09-15 15:34:13
@Discription:
@Environment: python 3.7.7
'''
@@ -19,7 +19,7 @@ import torch
import datetime
from common.utils import save_results, make_dir
from common.plot import plot_rewards
from common.plot import plot_rewards,plot_rewards_cn
from DQN.agent import DQN
curr_time = datetime.datetime.now().strftime("%Y%m%d-%H%M%S") # 获取当前时间
@@ -29,21 +29,21 @@ class DQNConfig:
self.algo = "DQN" # 算法名称
self.env = 'CartPole-v0' # 环境名称
self.result_path = curr_path+"/outputs/" + self.env + \
'/'+curr_time+'/results/' # path to save results
'/'+curr_time+'/results/' # 保存结果的路径
self.model_path = curr_path+"/outputs/" + self.env + \
'/'+curr_time+'/models/' # path to save models
'/'+curr_time+'/models/' # 保存模型的路径
self.train_eps = 200 # 训练的回合数
self.eval_eps = 30 # 测试的回合数
self.gamma = 0.95
self.gamma = 0.95 # 强化学习中的折扣因子
self.epsilon_start = 0.90 # e-greedy策略中初始epsilon
self.epsilon_end = 0.01 # e-greedy策略中的终止epsilon
self.epsilon_decay = 500 # e-greedy策略中epsilon的衰减率
self.lr = 0.0001 # 学习率
self.memory_capacity = 100000 # capacity of Replay Memory
self.batch_size = 64
self.memory_capacity = 100000 # 经验回放的容量
self.batch_size = 64 # mini-batch SGD中的批量大小
self.target_update = 4 # 目标网络的更新频率
self.device = torch.device(
"cuda" if torch.cuda.is_available() else "cpu") # jian che
"cuda" if torch.cuda.is_available() else "cpu") # 检测GPU
self.hidden_dim = 256 # hidden size of net
def env_agent_config(cfg,seed=1):
@@ -55,10 +55,10 @@ def env_agent_config(cfg,seed=1):
return env,agent
def train(cfg, env, agent):
print('Start to train !')
print(f'Env: {cfg.env}, Algorithm: {cfg.algo}, Device: {cfg.device}')
rewards = []
ma_rewards = [] # moveing average reward
print('开始训练!')
print(f'环境:{cfg.env}, 算法:{cfg.algo}, 设备:{cfg.device}')
rewards = [] # 记录奖励
ma_rewards = [] # 记录滑动平均奖励
for i_ep in range(cfg.train_eps):
state = env.reset()
done = False
@@ -75,19 +75,19 @@ def train(cfg, env, agent):
if (i_ep+1) % cfg.target_update == 0:
agent.target_net.load_state_dict(agent.policy_net.state_dict())
if (i_ep+1)%10 == 0:
print('Episode:{}/{}, Reward:{}'.format(i_ep+1, cfg.train_eps, ep_reward))
print('回合:{}/{}, 奖励:{}'.format(i_ep+1, cfg.train_eps, ep_reward))
rewards.append(ep_reward)
# save ma_rewards
if ma_rewards:
ma_rewards.append(0.9*ma_rewards[-1]+0.1*ep_reward)
else:
ma_rewards.append(ep_reward)
print('Complete training')
print('完成训练')
return rewards, ma_rewards
def eval(cfg,env,agent):
print('Start to eval !')
print(f'Env: {cfg.env}, Algorithm: {cfg.algo}, Device: {cfg.device}')
print('开始测试!')
print(f'环境:{cfg.env}, 算法:{cfg.algo}, 设备:{cfg.device}')
rewards = []
ma_rewards = [] # moving average rewards
for i_ep in range(cfg.eval_eps):
@@ -105,24 +105,23 @@ def eval(cfg,env,agent):
ma_rewards.append(ma_rewards[-1]*0.9+ep_reward*0.1)
else:
ma_rewards.append(ep_reward)
print(f"Episode:{i_ep+1}/{cfg.eval_eps}, reward:{ep_reward:.1f}")
print('Complete evaling')
print(f"回合:{i_ep+1}/{cfg.eval_eps}, 奖励:{ep_reward:.1f}")
print('完成测试')
return rewards,ma_rewards
if __name__ == "__main__":
cfg = DQNConfig()
# train
# 训练
env,agent = env_agent_config(cfg,seed=1)
rewards, ma_rewards = train(cfg, env, agent)
make_dir(cfg.result_path, cfg.model_path)
agent.save(path=cfg.model_path)
save_results(rewards, ma_rewards, tag='train', path=cfg.result_path)
plot_rewards(rewards, ma_rewards, tag="train",
plot_rewards_cn(rewards, ma_rewards, tag="train",
algo=cfg.algo, path=cfg.result_path)
# eval
# 测试
env,agent = env_agent_config(cfg,seed=10)
agent.load(path=cfg.model_path)
rewards,ma_rewards = eval(cfg,env,agent)
save_results(rewards,ma_rewards,tag='eval',path=cfg.result_path)
plot_rewards(rewards,ma_rewards,tag="eval",env=cfg.env,algo = cfg.algo,path=cfg.result_path)
plot_rewards_cn(rewards,ma_rewards,tag="eval",env=cfg.env,algo = cfg.algo,path=cfg.result_path)

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@@ -0,0 +1,175 @@
前面项目讲的环境都是离散动作的但实际中也有很多连续动作的环境比如Open AI Gym中的[Pendulum-v0](https://github.com/openai/gym/wiki/Pendulum-v0)环境,它解决的是一个倒立摆问题,我们先对该环境做一个简要说明。
## Pendulum-v0简介
如果说 CartPole-v0 是一个离散动作的经典入门环境的话,那么对应 Pendulum-v0 就是连续动作的经典入门环境,如下图,我们通过施加力矩使其向上摆动并保持直立。
<img src="../../easy_rl_book/res/ch12/assets/pendulum_1.png" alt="image-20210915161550713" style="zoom:50%;" />
该环境的状态数有三个,设摆针竖直方向上的顺时针旋转角为$\theta$$\theta$设在$[-\pi,\pi]$之间,则相应的状态为$[cos\theta,sin\theta,\dot{\theta}]$,即表示角度和角速度,我们的动作则是一个-2到2之间的力矩它是一个连续量因而该环境不能用离散动作的算法比如 DQN 来解决。关于奖励是根据相关的物理原理而计算出的等式,如下:
$$
-\left(\theta^{2}+0.1 * \hat{\theta}^{2}+0.001 * \text { action }^{2}\right)
$$
对于每一步,其最低奖励为$-\left(\pi^{2}+0.1 * 8^{2}+0.001 * 2^{2}\right)= -16.2736044$最高奖励为0。同 CartPole-v0 环境一样达到最优算法的情况下每回合的步数是无限的因此这里设定每回合最大步数为200以便于训练。
## DDPG 基本接口
我们依然使用接口的概念,通过伪代码分析并实现 DDPG 的训练模式,如下:
> 初始化评论家网络$Q\left(s, a \mid \theta^{Q}\right)$和演员网络$\mu\left(s \mid \theta^{\mu}\right)$,其权重分别为$\theta^{Q}$和$\theta^{\mu}$
>
> 初始化目标网络$Q'$和$\mu'$,并复制权重$\theta^{Q^{\prime}} \leftarrow \theta^{Q}, \theta^{\mu^{\prime}} \leftarrow \theta^{\mu}$
>
> 初始化经验回放缓冲区$R$
>
> 执行$M$个回合循环,对于每个回合:
>
> * 初始化动作探索的的随机过程即噪声$\mathcal{N}$
>
> * 初始化状态$s_1$
>
> 循环$T$个时间步长,对于每个时步$
>
> * 根据当前策略和噪声选择动作$a_{t}=\mu\left(s_{t} \mid \theta^{\mu}\right)+\mathcal{N}_{t}$
> * 执行动作$a_t$并得到反馈$r_t$和下一个状态$s_{t+1}$
> * 存储转移$\left(s_{t}, a_{t}, r_{t}, s_{t+1}\right)$到经验缓冲$R$中
> * (更新策略)从$D$随机采样一个小批量的转移
> * (更新策略)计算实际的Q值$y_{i}=r_{i}+\gamma Q^{\prime}\left(s_{i+1}, \mu^{\prime}\left(s_{i+1} \mid \theta^{\mu^{\prime}}\right) \mid \theta^{Q^{\prime}}\right)$
> * (更新策略)对损失函数$L=\frac{1}{N} \sum_{i}\left(y_{i}-Q\left(s_{i}, a_{i} \mid \theta^{Q}\right)\right)^{2}$关于参数$\theta$做梯度下降用于更新评论家网络
> * (更新策略)使用采样梯度更新演员网络的策略:$\left.\left.\nabla_{\theta^{\mu}} J \approx \frac{1}{N} \sum_{i} \nabla_{a} Q\left(s, a \mid \theta^{Q}\right)\right|_{s=s_{i}, a=\mu\left(s_{i}\right)} \nabla_{\theta^{\mu}} \mu\left(s \mid \theta^{\mu}\right)\right|_{s_{i}}$
> * (更新策略)更新目标网络:$\theta^{Q^{\prime}} \leftarrow \tau \theta^{Q}+(1-\tau) \theta^{Q^{\prime}}$$\theta^{\mu^{\prime}} \leftarrow \tau \theta^{\mu}+(1-\tau) \theta^{\mu^{\prime}}$
代码如下:
```python
ou_noise = OUNoise(env.action_space) # 动作噪声
rewards = [] # 记录奖励
ma_rewards = [] # 记录滑动平均奖励
for i_ep in range(cfg.train_eps):
state = env.reset()
ou_noise.reset()
done = False
ep_reward = 0
i_step = 0
while not done:
i_step += 1
action = agent.choose_action(state)
action = ou_noise.get_action(action, i_step)
next_state, reward, done, _ = env.step(action)
ep_reward += reward
agent.memory.push(state, action, reward, next_state, done)
agent.update()
state = next_state
if (i_ep+1)%10 == 0:
print('回合:{}/{},奖励:{}'.format(i_ep+1, cfg.train_eps, ep_reward))
rewards.append(ep_reward)
if ma_rewards:
ma_rewards.append(0.9*ma_rewards[-1]+0.1*ep_reward)
else:
ma_rewards.append(ep_reward)
```
相比于 DQN DDPG 主要多了两处修改,一个是给动作施加噪声,另外一个是软更新策略,即最后一步。
## Ornstein-Uhlenbeck噪声
OU 噪声适用于惯性系统,尤其是时间离散化粒度较小的情况。 OU 噪声是一种随机过程,下面略去证明,直接给出公式:
$$
x(t+\Delta t)=x(t)-\theta(x(t)-\mu) \Delta t+\sigma W_t
$$
其中 $W_t$ 属于正太分布,进而代码实现如下:
```python
class OUNoise(object):
'''OrnsteinUhlenbeck噪声
'''
def __init__(self, action_space, mu=0.0, theta=0.15, max_sigma=0.3, min_sigma=0.3, decay_period=100000):
self.mu = mu # OU噪声的参数
self.theta = theta # OU噪声的参数
self.sigma = max_sigma # OU噪声的参数
self.max_sigma = max_sigma
self.min_sigma = min_sigma
self.decay_period = decay_period
self.action_dim = action_space.shape[0]
self.low = action_space.low
self.high = action_space.high
self.reset()
def reset(self):
self.obs = np.ones(self.action_dim) * self.mu
def evolve_obs(self):
x = self.obs
dx = self.theta * (self.mu - x) + self.sigma * np.random.randn(self.action_dim)
self.obs = x + dx
return self.obs
def get_action(self, action, t=0):
ou_obs = self.evolve_obs()
self.sigma = self.max_sigma - (self.max_sigma - self.min_sigma) * min(1.0, t / self.decay_period) # sigma会逐渐衰减
return np.clip(action + ou_obs, self.low, self.high) # 动作加上噪声后进行剪切
```
## DDPG算法
DDPG算法主要也包括两个功能一个是选择动作另外一个是更新策略首先看选择动作
```python
def choose_action(self, state):
state = torch.FloatTensor(state).unsqueeze(0).to(self.device)
action = self.actor(state)
return action.detach().cpu().numpy()[0, 0]
```
由于DDPG是直接从演员网络取得动作所以这里不用$\epsilon-greedy$策略。在更新策略函数中也会跟DQN稍有不同并且加入软更新
```python
def update(self):
if len(self.memory) < self.batch_size: # 当 memory 中不满足一个批量时,不更新策略
return
# 从经验回放中(replay memory)中随机采样一个批量的转移(transition)
state, action, reward, next_state, done = self.memory.sample(self.batch_size)
# 转变为张量
state = torch.FloatTensor(state).to(self.device)
next_state = torch.FloatTensor(next_state).to(self.device)
action = torch.FloatTensor(action).to(self.device)
reward = torch.FloatTensor(reward).unsqueeze(1).to(self.device)
done = torch.FloatTensor(np.float32(done)).unsqueeze(1).to(self.device)
policy_loss = self.critic(state, self.actor(state))
policy_loss = -policy_loss.mean()
next_action = self.target_actor(next_state)
target_value = self.target_critic(next_state, next_action.detach())
expected_value = reward + (1.0 - done) * self.gamma * target_value
expected_value = torch.clamp(expected_value, -np.inf, np.inf)
value = self.critic(state, action)
value_loss = nn.MSELoss()(value, expected_value.detach())
self.actor_optimizer.zero_grad()
policy_loss.backward()
self.actor_optimizer.step()
self.critic_optimizer.zero_grad()
value_loss.backward()
self.critic_optimizer.step()
# 软更新
for target_param, param in zip(self.target_critic.parameters(), self.critic.parameters()):
target_param.data.copy_(
target_param.data * (1.0 - self.soft_tau) +
param.data * self.soft_tau
)
for target_param, param in zip(self.target_actor.parameters(), self.actor.parameters()):
target_param.data.copy_(
target_param.data * (1.0 - self.soft_tau) +
param.data * self.soft_tau
)
```
## 结果分析
实现算法之后,我们先看看训练效果:
![train_rewards_curve_cn](../../easy_rl_book/res/ch12/assets/train_rewards_curve_cn-1760758.png)
可以看到算法整体上是达到收敛了的,但是稳定状态下波动还比较大,依然有提升的空间,限于笔者的精力,这里只是帮助赌注实现一个基础的代码演示,想要使得算法调到最优感兴趣的读者可以多思考实现。我们再来看看测试的结果:
![eval_rewards_curve_cn](../../easy_rl_book/res/ch12/assets/eval_rewards_curve_cn-1760950.png)
从图中看出测试的平均奖励在-150左右但其实训练的时候平均的稳态奖励在-300左右这是因为测试的时候我们舍去了OU噪声的缘故。

View File

@@ -2,7 +2,7 @@
在练习本项目之前可以先回顾一下之前的项目实战即使用Q学习解决悬崖寻路问题。本项目将具体实现DQN算法来解决推车杆问题对应的模拟环境为Open AI Gym中的[CartPole-v0](https://datawhalechina.github.io/easy-rl/#/chapter7/project2?id=cartpole-v0),我们同样先对该环境做一个简要说明。
## CartPole-v0环境简介
## CartPole-v0 简介
CartPole-v0是一个经典的入门环境如下图它通过向左(动作=0)或向右(动作=1)推动推车来实现竖直杆的平衡,每次实施一个动作后如果能够继续保持平衡就会得到一个+1的奖励否则杆将无法保持平衡而导致游戏结束。
@@ -28,15 +28,64 @@ print(f"初始状态:{state}")
初始状态:[ 0.03073904 0.00145001 -0.03088818 -0.03131252]
```
该环境状态数是四个,分别为车的位置、车的速度、杆的角度以及杆顶部的速度,动作数为两个,并且是离散的向左或者向右。
该环境状态数是四个,分别为车的位置、车的速度、杆的角度以及杆顶部的速度,动作数为两个,并且是离散的向左或者向右。理论上达到最优化算法的情况下推车杆是一直能保持平衡的也就是每回合的步数是无限但是这不方便训练所以环境内部设置了每回合的最大步数为200也就是说理想情况下只需要我们每回合的奖励达到200就算训练完成。
## DQN基本接口
介绍完环境之后我们沿用接口的概念通过分析伪代码来实现DQN的基本训练模式以及一些要素比如建立什么网络需要什么模块等等。我们现在常用的DQN伪代码如下
![image-20210915020027615](assets/image-20210915020027615.png)
> 初始化经验回放缓冲区(replay memory)$D$,容量(capacity)为$N$
>
> 初始化状态-动作函数,即带有初始随机权重$\theta$的$Q$网络
>
> 初始化目标状态-动作函数,即带有初始随机权重$\theta^-$的$\hat{Q}$网络,且$\theta^-=\theta$
>
> 执行$M$个回合循环,对于每个回合
>
> * 初始化环境,得到初始状态$s_1$
> * 循环$T$个时间步长,对于每个时步$t$
> * 使用$\epsilon-greedy$策略选择动作$a_t$
> * 环境根据$a_t$反馈当前的奖励$r_t$和下一个状态$s_{t+1}$
> * 更新状态$s_{t+1}=s_t$
> * 存储转移(transition)即$(s_t,a_t,r-t,s_{t+1})$到经验回放$D$中
> * (更新策略)从$D$随机采样一个小批量的转移
> * (更新策略)计算实际的Q值$y_{j}=\left\{\begin{array}{cc}r_{j} & \text { 如果回合在时步 j+1终止 }\\ r_{j}+\gamma \max _{a^{\prime}} \hat{Q}\left(\phi_{j+1}, a^{\prime} ; \theta^{-}\right) & \text {否则 }\end{array}\right.$
> * (更新策略)对损失函数$\left(y_{j}-Q\left(\phi_{j}, a_{j} ; \theta\right)\right)^{2}$关于参数$\theta$做梯度下降
> * (更新策略)每$C$步重置$\hat{Q}=Q$
与传统的Q学习算法相比DQN使用神经网络来代替之前的Q表格从而存储更多的信息且由于使用了神经网络所以我们一般需要利用随机梯度下降来优化Q值的预测。此外多了经验回放缓冲区(replay memory),并且使用两个网络,即目标网络和当前网络。
用代码来实现的话如下:
```python
rewards = [] # 记录奖励
ma_rewards = [] # 记录滑动平均奖励
for i_ep in range(cfg.train_eps):
state = env.reset()
done = False
ep_reward = 0
while True:
action = agent.choose_action(state)
next_state, reward, done, _ = env.step(action)
ep_reward += reward
agent.memory.push(state, action, reward, next_state, done)
state = next_state
agent.update()
if done:
break
if (i_ep+1) % cfg.target_update == 0:
agent.target_net.load_state_dict(agent.policy_net.state_dict())
if (i_ep+1)%10 == 0:
print('回合:{}/{}, 奖励:{}'.format(i_ep+1, cfg.train_eps, ep_reward))
rewards.append(ep_reward)
# save ma_rewards
if ma_rewards:
ma_rewards.append(0.9*ma_rewards[-1]+0.1*ep_reward)
else:
ma_rewards.append(ep_reward)
```
可以看到DQN的训练模式其实和大多强化学习算法是一样的套路但与传统的Q学习算法相比DQN使用神经网络来代替之前的Q表格从而存储更多的信息且由于使用了神经网络所以我们一般需要利用随机梯度下降来优化Q值的预测。此外多了经验回放缓冲区(replay memory),并且使用两个网络,即目标网络和当前网络。
## 经验回放缓冲区
@@ -62,5 +111,98 @@ class ReplayBuffer:
batch = random.sample(self.buffer, batch_size) # 随机采出小批量转移
state, action, reward, next_state, done = zip(*batch) # 解压成状态,动作等
return state, action, reward, next_state, done
def __len__(self):
''' 返回当前存储的量
'''
return len(self.buffer)
```
## Q网络
在DQN中我们使用神经网络替代原有的Q表从而能够存储更多的Q值实现更为高级的策略以便用于复杂的环境这里我们用的是一个三层的感知机或者说全连接网络
```python
class MLP(nn.Module):
def __init__(self, input_dim,output_dim,hidden_dim=128):
""" 初始化q网络为全连接网络
input_dim: 输入的特征数即环境的状态数
output_dim: 输出的动作维度
"""
super(MLP, self).__init__()
self.fc1 = nn.Linear(input_dim, hidden_dim) # 输入层
self.fc2 = nn.Linear(hidden_dim,hidden_dim) # 隐藏层
self.fc3 = nn.Linear(hidden_dim, output_dim) # 输出层
def forward(self, x):
# 各层对应的激活函数
x = F.relu(self.fc1(x))
x = F.relu(self.fc2(x))
return self.fc3(x)
```
学过深度学习的同学应该都对这个网络十分熟悉在强化学习中网络的输入一般是状态输出则是一个动作假如总共有两个动作那么这里的动作维度就是2可能的输出就是0或1一般我们用ReLU作为激活函数。根据实际需要也可以改变神经网络的模型结构等等比如若我们使用图像作为输入的话这里可以使用卷积神经网络(CNN)。
## DQN算法
跟前面的项目实战一样DQN算法一般也包括选择动作和更新策略两个函数首先我们看选择动作
```python
def choose_action(self, state):
'''选择动作
'''
self.frame_idx += 1
if random.random() > self.epsilon(self.frame_idx):
with torch.no_grad():
state = torch.tensor([state], device=self.device, dtype=torch.float32)
q_values = self.policy_net(state)
action = q_values.max(1)[1].item() # 选择Q值最大的动作
else:
action = random.randrange(self.action_dim)
```
可以看到跟Q学习算法其实是一样的都是用的$\epsilon-greedy$策略只是使用神经网络的话我们需要通过Torch或者Tensorflow工具来处理相应的数据。
而DQN更新策略的步骤稍微复杂一点主要包括三个部分随机采样计算期望Q值和梯度下降如下
```python
def update(self):
if len(self.memory) < self.batch_size: # 当memory中不满足一个批量时不更新策略
return
# 从经验回放中(replay memory)中随机采样一个批量的转移(transition)
state_batch, action_batch, reward_batch, next_state_batch, done_batch = self.memory.sample(
self.batch_size)
# 转为张量
state_batch = torch.tensor(
state_batch, device=self.device, dtype=torch.float)
action_batch = torch.tensor(action_batch, device=self.device).unsqueeze(
1)
reward_batch = torch.tensor(
reward_batch, device=self.device, dtype=torch.float)
next_state_batch = torch.tensor(
next_state_batch, device=self.device, dtype=torch.float)
done_batch = torch.tensor(np.float32(
done_batch), device=self.device)
q_values = self.policy_net(state_batch).gather(dim=1, index=action_batch) # 计算当前状态(s_t,a)对应的Q(s_t, a)
next_q_values = self.target_net(next_state_batch).max(1)[0].detach() # 计算下一时刻的状态(s_t_,a)对应的Q值
# 计算期望的Q值对于终止状态此时done_batch[0]=1, 对应的expected_q_value等于reward
expected_q_values = reward_batch + self.gamma * next_q_values * (1-done_batch)
loss = nn.MSELoss()(q_values, expected_q_values.unsqueeze(1)) # 计算均方根损失
# 优化更新模型
self.optimizer.zero_grad()
loss.backward()
for param in self.policy_net.parameters(): # clip防止梯度爆炸
param.grad.data.clamp_(-1, 1)
self.optimizer.step()
```
## 结果分析
完成代码之后我们先来看看DQN算法的训练效果曲线如下
![train_rewards_curve_cn](../../easy_rl_book/res/ch7/assets/train_rewards_curve_cn-1689150.png)
从图中看出算法其实已经在60回合左右达到收敛最后一直维持在最佳奖励200左右可能会有轻微的波动这是因为我们在收敛的情况下依然保持了一定的探索率即epsilon_end=0.01。现在我们可以载入模型看看测试的效果:
![eval_rewards_curve_cn](../../easy_rl_book/res/ch7/assets/eval_rewards_curve_cn-1689282.png)
我们测试了30个回合每回合都保持在200左右说明我们的模型学习得不错了

View File

@@ -5,7 +5,7 @@ Author: John
Email: johnjim0816@gmail.com
Date: 2020-09-11 23:03:00
LastEditor: John
LastEditTime: 2021-09-11 21:53:18
LastEditTime: 2021-09-15 13:18:37
Discription: use defaultdict to define Q table
Environment:
'''
@@ -26,7 +26,6 @@ class QLearning(object):
self.epsilon_end = cfg.epsilon_end
self.epsilon_decay = cfg.epsilon_decay
self.Q_table = defaultdict(lambda: np.zeros(action_dim)) # A nested dictionary that maps state -> (action -> action-value)
def choose_action(self, state):
self.sample_count += 1
self.epsilon = self.epsilon_end + (self.epsilon_start - self.epsilon_end) * \

View File

@@ -5,7 +5,7 @@ Author: John
Email: johnjim0816@gmail.com
Date: 2020-09-11 23:03:00
LastEditor: John
LastEditTime: 2021-09-12 01:29:40
LastEditTime: 2021-09-15 14:44:25
Discription:
Environment:
'''
@@ -57,11 +57,11 @@ def train(cfg,env,agent):
ma_rewards = [] # 滑动平均奖励
for i_ep in range(cfg.train_eps):
ep_reward = 0 # 记录每个回合的奖励
state = env.reset() # 重置环境, 重新开一局即开始新的一个episode
state = env.reset() # 重置环境,即开始新的回合
while True:
action = agent.choose_action(state) # 根据算法选择一个动作
next_state, reward, done, _ = env.step(action) # 与环境进行一次动作交互
agent.update(state, action, reward, next_state, done) # Q-learning算法更新
agent.update(state, action, reward, next_state, done) # Q学习算法更新
state = next_state # 更新状态
ep_reward += reward
if done:

View File

@@ -5,7 +5,7 @@
@Email: johnjim0816@gmail.com
@Date: 2020-06-10 15:27:16
@LastEditor: John
LastEditTime: 2021-09-15 02:17:59
LastEditTime: 2021-09-15 14:52:37
@Discription:
@Environment: python 3.7.7
'''
@@ -28,5 +28,9 @@ class ReplayBuffer:
batch = random.sample(self.buffer, batch_size) # 随机采出小批量转移
state, action, reward, next_state, done = zip(*batch) # 解压成状态,动作等
return state, action, reward, next_state, done
def __len__(self):
''' 返回当前存储的量
'''
return len(self.buffer)

View File

@@ -5,7 +5,7 @@ Author: John
Email: johnjim0816@gmail.com
Date: 2021-03-12 21:14:12
LastEditor: John
LastEditTime: 2021-05-04 02:45:27
LastEditTime: 2021-09-15 13:21:03
Discription:
Environment:
'''
@@ -17,8 +17,8 @@ from torch.distributions import Categorical
class MLP(nn.Module):
def __init__(self, input_dim,output_dim,hidden_dim=128):
""" 初始化q网络为全连接网络
input_dim: 输入的feature即环境的state数目
output_dim: 输出的action总个数
input_dim: 输入的特征数即环境的状态数
output_dim: 输出的动作维度
"""
super(MLP, self).__init__()
self.fc1 = nn.Linear(input_dim, hidden_dim) # 输入层

View File

@@ -5,7 +5,7 @@ Author: John
Email: johnjim0816@gmail.com
Date: 2020-10-07 20:57:11
LastEditor: John
LastEditTime: 2021-09-11 21:35:00
LastEditTime: 2021-09-15 14:56:15
Discription:
Environment:
'''
@@ -29,7 +29,7 @@ def plot_rewards_cn(rewards,ma_rewards,tag="train",env='CartPole-v0',algo = "DQN
''' 中文画图
'''
sns.set()
plt.title(u"{}环境下Q学习算法的学习曲线".format(env),fontproperties=chinese_font())
plt.title(u"{}环境下{}算法的学习曲线".format(env,algo),fontproperties=chinese_font())
plt.xlabel(u'回合数',fontproperties=chinese_font())
plt.plot(rewards)
plt.plot(ma_rewards)