Addestrare il Double DQN

Ora modificherai il tuo codice per DQN per implementare il Double DQN.

Il Double DQN richiede solo un piccolo aggiornamento dell'algoritmo DQN, ma aiuta molto a risolvere il problema della sovrastima dei valori Q e spesso offre prestazioni migliori rispetto al DQN.

Questo esercizio fa parte del corso

Deep Reinforcement Learning in Python

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Istruzioni dell'esercizio

Calcola le prossime azioni per il calcolo del Q-target usando online_network(), assicurandoti di ottenere l'azione e la forma corrette.
Stima i valori Q per queste azioni con target_network(), anche qui assicurandoti di ottenere i valori e la forma corretti.

Esercizio pratico interattivo

Prova a risolvere questo esercizio completando il codice di esempio.

for episode in range(10):
    state, info = env.reset()
    done = False
    step = 0
    episode_reward = 0
    while not done:
        step += 1
        total_steps += 1
        q_values = online_network(state)
        action = select_action(q_values, total_steps, start=.9, end=.05, decay=1000)
        next_state, reward, terminated, truncated, _ = env.step(action)
        done = terminated or truncated
        replay_buffer.push(state, action, reward, next_state, done)        
        if len(replay_buffer) >= batch_size:
            states, actions, rewards, next_states, dones = replay_buffer.sample(64)
            q_values = online_network(states).gather(1, actions).squeeze(1)
            with torch.no_grad():
                # Obtain next actions for Q-target calculation
                next_actions = ____.____.____
                # Estimate next Q-values from these actions
                next_q_values = ____.____.____
                target_q_values = rewards + gamma * next_q_values * (1-dones)
            loss = nn.MSELoss()(q_values, target_q_values)
            optimizer.zero_grad()
            loss.backward()
            optimizer.step()
            update_target_network(target_network, online_network, tau=.005)
        state = next_state
        episode_reward += reward    
    describe_episode(episode, reward, episode_reward, step)

Modifica ed esegui il codice

Questo esercizio fa parte del corso

Deep Reinforcement Learning in Python

AvançadoNível de habilidade

4.8+

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Discover how deep reinforcement learning improves upon traditional Reinforcement Learning while studying and implementing your first Deep Q Learning algorithm.

Exercise 1: Introduction to deep reinforcement learning Exercise 2: Environment and neural network setup Exercise 3: DRL training loop Exercise 4: Introduction to deep Q learning Exercise 5: Deep learning and DQN Exercise 6: The Q-Network architecture Exercise 7: Instantiating the Q-Network Exercise 8: The barebone DQN algorithm Exercise 9: Barebone DQN action selection Exercise 10: Barebone DQN loss function Exercise 11: Training the barebone DQN

Dive into Deep Q-learning by implementing the original DQN algorithm, featuring Experience Replay, epsilon-greediness and fixed Q-targets. Beyond DQN, you will then explore two fascinating extensions that improve the performance and stability of Deep Q-learning: Double DQN and Prioritized Experience Replay.

Exercise 1: DQN con experience replay Exercise 2: La coda a due estremità Exercise 3: Experience replay buffer Exercise 4: DQN con experience replay Exercise 5: L'algoritmo DQN completo Exercise 6: Epsilon-greediness Exercise 7: Q-target fissi Exercise 8: Implementare l'algoritmo DQN completo Exercise 9: Double DQN Exercise 10: Rete online e rete target in DDQN Exercise 11: Addestrare il Double DQN

Esercizio in corso

Exercise 12: Prioritized experience replay Exercise 13: Prioritized experience replay buffer Exercise 14: Campionare dal buffer PER Exercise 15: DQN con prioritized experience replay

Learn about the foundational concepts of policy gradient methods found in DRL. You will begin with the policy gradient theorem, which forms the basis for these methods. Then, you will implement the REINFORCE algorithm, a powerful approach to learning policies. The chapter will then guide you through Actor-Critic methods, focusing on the Advantage Actor-Critic (A2C) algorithm, which combines the strengths of both policy gradient and value-based methods to enhance learning efficiency and stability.

Exercise 1: Introduction to policy gradient Exercise 2: The policy network architecture Exercise 3: Working with discrete distributions Exercise 4: Policy gradient and REINFORCE Exercise 5: Action selection in REINFORCE Exercise 6: Training the REINFORCE algorithm Exercise 7: Advantage Actor Critic Exercise 8: Critic network Exercise 9: Actor Critic loss calculations Exercise 10: Training the A2C algorithm

Explore Proximal Policy Optimization (PPO) for robust DRL performance. Next, you will examine using an entropy bonus in PPO, which encourages exploration by preventing premature convergence to deterministic policies. You'll also learn about batch updates in policy gradient methods. Finally, you will learn about hyperparameter optimization with Optuna, a powerful tool for optimizing performance in your DRL models.

Exercise 1: Proximal policy optimization Exercise 2: The clipped probability ratio Exercise 3: The clipped surrogate objective function Exercise 4: Entropy bonus and PPO Exercise 5: Entropy playground Exercise 6: Training the PPO algorithm Exercise 7: Batch updates in policy gradient Exercise 8: Minibatch and DRL Exercise 9: A2C with batch updates Exercise 10: Hyperparameter optimization with Optuna Exercise 11: Hyperparameter or not?Exercise 12: Hands-on with Optuna Exercise 13: Congratulations!