dqn算法python实现

DQN（Deep Q-Network）是一种基于深度学习的强化学习算法。它通过神经网络估计每个动作的Q值，从而实现智能体对环境的决策。下面是DQN算法的Python实现步骤：

1.导入必要的库和环境

import gym
import numpy as np
import tensorflow as tf
from collections import deque

env = gym.make('CartPole-v0')
state_size = env.observation_space.shape
action_size = env.action_space.n

2.定义DQN模型，包括网络结构和训练方法

class DQNAgent:
    def __init__(self, state_size, action_size):
        self.state_size = state_size
        self.action_size = action_size
        self.memory = deque(maxlen=2000)
        self.gamma = 0.95
        self.epsilon = 1.0
        self.epsilon_decay = 0.995
        self.epsilon_min = 0.01
        self.learning_rate = 0.001
        self.model = self._build_model()

    def _build_model(self):
        model = tf.keras.models.Sequential()
        model.add(tf.keras.layers.Dense(24, input_dim=self.state_size, activation='relu'))
        model.add(tf.keras.layers.Dense(24, activation='relu'))
        model.add(tf.keras.layers.Dense(self.action_size, activation='linear'))
        model.compile(loss='mse', optimizer=tf.keras.optimizers.Adam(lr=self.learning_rate))
        return model

    def remember(self, state, action, reward, next_state, done):
        self.memory.append((state, action, reward, next_state, done))

    def act(self, state):
        if np.random.rand() <= self.epsilon:
            return np.random.choice(self.action_size)
        act_values = self.model.predict(state)
        return np.argmax(act_values)

    def replay(self, batch_size):
        minibatch = np.array(random.sample(self.memory, batch_size))
        for state, action, reward, next_state, done in minibatch:
            target = reward
            if not done:
                target = (reward + self.gamma * np.amax(self.model.predict(next_state)))
            target_f = self.model.predict(state)
            target_f[action] = target
            self.model.fit(state, target_f, epochs=1, verbose=0)
        if self.epsilon > self.epsilon_min:
            self.epsilon *= self.epsilon_decay

    def load(self, name):
        self.model.load_weights(name)

    def save(self, name):
        self.model.save_weights(name)

3.训练DQN模型并测试

agent = DQNAgent(state_size, action_size)
done = False
batch_size = 32
EPISODES = 100

for e in range(EPISODES):
    state = env.reset()
    state = np.reshape(state, [1, state_size])
    for time in range(500):
        action = agent.act(state)
        next_state, reward, done, _ = env.step(action)
        reward = reward if not done else -10
        next_state = np.reshape(next_state, [1, state_size])
        agent.remember(state, action, reward, next_state, done)
        state = next_state
        if done:
            print("episode: {}/{}, score: {}, e: {:.2}"
                  .format(e, EPISODES, time, agent.epsilon))
            break
    if len(agent.memory) > batch_size:
        agent.replay(batch_size)
    if e % 10 == 0:
        agent.save("./dqn.h5")

# test the trained DQN model
agent.load("./dqn.h5")
state = env.reset()
state = np.reshape(state, [1, state_size])
for time in range(500):
    env.render()
    action = agent.act(state)
    next_state, reward, done, _ = env.step(action)
    state = np.reshape(next_state, [1, state_size])
    if done:
        break
env.close()