强化学习算法实例DQN代码PyTorch实现
前言
实例参考MorvanZhou/Reinforcement-learning-with-tensorflow,
更改为PyTorch实现，并增加了几处优化。实现效果如下。
其中,红色方块作为探索的智能体,到达黄色圆形块reward=1,到达黑色方块区域reward=-1.
代码
- 程序主循环
from dqn.maze_env import Maze
from dqn.RL_brain import DQN
import time
def run_maze():
print("====Game Start====")
step = 0
max_episode = 500
for episode in range(max_episode):
state = env.reset() # 重置智能体位置
step_every_episode = 0
epsilon = episode / max_episode # 动态变化随机值
while True:
if episode < 10:
time.sleep(0.1)
if episode > 480:
time.sleep(0.5)
env.render() # 显示新位置
action = model.choose_action(state, epsilon) # 根据状态选择行为
# 环境根据行为给出下一个状态，奖励，是否结束。
next_state, reward, terminal = env.step(action)
model.store_transition(state, action, reward, next_state) # 模型存储经历
# 控制学习起始时间(先积累记忆再学习)和控制学习的频率(积累多少步经验学习一次)
if step > 200 and step % 5 == 0:
model.learn()
# 进入下一步
state = next_state
if terminal:
print("episode=", episode, end=",")
print("step=", step_every_episode)
break
step += 1
step_every_episode += 1
# 游戏环境结束
print("====Game Over====")
env.destroy()
if __name__ == "__main__":
env = Maze() # 环境
model = DQN(
n_states=env.n_states,
n_actions=env.n_actions
) # 算法模型
run_maze()
env.mainloop()
model.plot_cost() # 误差曲线
- 环境模块maze_env.py
import tkinter as tk
import sys
import numpy as np
UNIT = 40 # pixels
MAZE_H = 4 # grid height
MAZE_W = 4 # grid width
class Maze(tk.Tk, object):
def __init__(self):
print("<env init>")
super(Maze, self).__init__()
# 动作空间(定义智能体可选的行为),action=0-3
self.action_space = ['u', 'd', 'l', 'r']
# 使用变量
self.n_actions = len(self.action_space)
self.n_states = 2
# 配置信息
self.title('maze')
self.geometry("160x160")
# 初始化操作
self.__build_maze()
def render(self):
# time.sleep(0.1)
self.update()
def reset(self):
# 智能体回到初始位置
# time.sleep(0.1)
self.update()
self.canvas.delete(self.rect)
origin = np.array([20, 20])
self.rect = self.canvas.create_rectangle(
origin[0] - 15, origin[1] - 15,
origin[0] + 15, origin[1] + 15,
fill='red')
# return observation
return (np.array(self.canvas.coords(self.rect)[:2]) - np.array(self.canvas.coords(self.oval)[:2])) / (MAZE_H * UNIT)
def step(self, action):
# 智能体向前移动一步：返回next_state,reward,terminal
s = self.canvas.coords(self.rect)
base_action = np.array([0, 0])
if action == 0: # up
if s[1] > UNIT:
base_action[1] -= UNIT
elif action == 1: # down
if s[1] < (MAZE_H - 1) * UNIT:
base_action[1] += UNIT
elif action == 2: # right
if s[0] < (MAZE_W - 1) * UNIT:
base_action[0] += UNIT
elif action == 3: # left
if s[0] > UNIT:
base_action[0] -= UNIT
self.canvas.move(self.rect, base_action[0], base_action[1]) # move agent
next_coords = self.canvas.coords(self.rect) # next state
# reward function
if next_coords == self.canvas.coords(self.oval):
reward = 1
print("victory")
done = True
elif next_coords in [self.canvas.coords(self.hell1)]:
reward = -1
print("defeat")
done = True
else:
reward = 0
done = False
s_ = (np.array(next_coords[:2]) - np.array(self.canvas.coords(self.oval)[:2])) / (MAZE_H * UNIT)
return s_, reward, done
def __build_maze(self):
self.canvas = tk.Canvas(self, bg='white',
height=MAZE_H * UNIT,
width=MAZE_W * UNIT)
# create grids
for c in range(0, MAZE_W * UNIT, UNIT):
x0, y0, x1, y1 = c, 0, c, MAZE_H * UNIT
self.canvas.create_line(x0, y0, x1, y1)
for r in range(0, MAZE_H * UNIT, UNIT):
x0, y0, x1, y1 = 0, r, MAZE_W * UNIT, r
self.canvas.create_line(x0, y0, x1, y1)
origin = np.array([20, 20])
hell1_center = origin + np.array([UNIT * 2, UNIT])
self.hell1 = self.canvas.create_rectangle(
hell1_center[0] - 15, hell1_center[1] - 15,
hell1_center[0] + 15, hell1_center[1] + 15,
fill='black')
oval_center = origin + UNIT * 2
self.oval = self.canvas.create_oval(
oval_center[0] - 15, oval_center[1] - 15,
oval_center[0] + 15, oval_center[1] + 15,
fill='yellow')
self.rect = self.canvas.create_rectangle(
origin[0] - 15, origin[1] - 15,
origin[0] + 15, origin[1] + 15,
fill='red')
self.canvas.pack()
- DQN模型RL_brain.py
class Net(nn.Module):
def __init__(self, n_states, n_actions):
super(Net, self).__init__()
self.fc1 = nn.Linear(n_states, 10)
self.fc2 = nn.Linear(10, n_actions)
self.fc1.weight.data.normal_(0, 0.1)
self.fc2.weight.data.normal_(0, 0.1)
def forward(self, x):
x = self.fc1(x)
x = F.relu(x)
out = self.fc2(x)
return out
class DQN:
def __init__(self, n_states, n_actions):
print("<DQN init>")
# DQN有两个net:target net和eval net,具有选动作，存经历，学习三个基本功能
self.eval_net, self.target_net = Net(n_states, n_actions), Net(n_states, n_actions)
self.loss = nn.MSELoss()
self.optimizer = torch.optim.Adam(self.eval_net.parameters(), lr=0.01)
self.n_actions = n_actions
self.n_states = n_states
# 使用变量
self.learn_step_counter = 0 # target网络学习计数
self.memory_counter = 0 # 记忆计数
self.memory = np.zeros((2000, 2 * 2 + 2)) # 2*2(state和next_state,每个x,y坐标确定)+2(action和reward),存储2000个记忆体
self.cost = [] # 记录损失值
def choose_action(self, x, epsilon):
# print("<choose_action>")
x = torch.unsqueeze(torch.FloatTensor(x), 0) # (1,2)
if np.random.uniform() < epsilon:
action_value = self.eval_net.forward(x)
action = torch.max(action_value, 1)[1].data.numpy()[0]
else:
action = np.random.randint(0, self.n_actions)
# print("action=", action)
return action
def store_transition(self, state, action, reward, next_state):
# print("<store_transition>")
transition = np.hstack((state, [action, reward], next_state))
index = self.memory_counter % 200 # 满了就覆盖旧的
self.memory[index, :] = transition
self.memory_counter += 1
def learn(self):
# print("<learn>")
# target net 更新频率,用于预测，不会及时更新参数
if self.learn_step_counter % 100 == 0:
self.target_net.load_state_dict((self.eval_net.state_dict()))
self.learn_step_counter += 1
# 使用记忆库中批量数据
sample_index = np.random.choice(200, 16) # 2000个中随机抽取32个作为batch_size
memory = self.memory[sample_index, :] # 抽取的记忆单元，并逐个提取
state = torch.FloatTensor(memory[:, :2])
action = torch.LongTensor(memory[:, 2:3])
reward = torch.LongTensor(memory[:, 3:4])
next_state = torch.FloatTensor(memory[:, 4:6])
# 计算loss,q_eval:所采取动作的预测value,q_target:所采取动作的实际value
q_eval = self.eval_net(state).gather(1, action) # eval_net->(64,4)->按照action索引提取出q_value
q_next = self.target_net(next_state).detach()
# torch.max->[values=[],indices=[]] max(1)[0]->values=[]
q_target = reward + 0.9 * q_next.max(1)[0].unsqueeze(1) # label
loss = self.loss(q_eval, q_target)
self.cost.append(loss)
# 反向传播更新
self.optimizer.zero_grad() # 梯度重置
loss.backward() # 反向求导
self.optimizer.step() # 更新模型参数
def plot_cost(self):
plt.plot(np.arange(len(self.cost)), self.cost)
plt.xlabel("step")
plt.ylabel("cost")
plt.show()
参考
