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Deep Reinforcement Learning Hands-On

You're reading from   Deep Reinforcement Learning Hands-On Apply modern RL methods to practical problems of chatbots, robotics, discrete optimization, web automation, and more

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Product type Paperback
Published in Jan 2020
Publisher Packt
ISBN-13 9781838826994
Length 826 pages
Edition 2nd Edition
Languages
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Author (1):
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Maxim Lapan Maxim Lapan
Author Profile Icon Maxim Lapan
Maxim Lapan
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Table of Contents (28) Chapters Close

Preface 1. What Is Reinforcement Learning? 2. OpenAI Gym FREE CHAPTER 3. Deep Learning with PyTorch 4. The Cross-Entropy Method 5. Tabular Learning and the Bellman Equation 6. Deep Q-Networks 7. Higher-Level RL Libraries 8. DQN Extensions 9. Ways to Speed up RL 10. Stocks Trading Using RL 11. Policy Gradients – an Alternative 12. The Actor-Critic Method 13. Asynchronous Advantage Actor-Critic 14. Training Chatbots with RL 15. The TextWorld Environment 16. Web Navigation 17. Continuous Action Space 18. RL in Robotics 19. Trust Regions – PPO, TRPO, ACKTR, and SAC 20. Black-Box Optimization in RL 21. Advanced Exploration 22. Beyond Model-Free – Imagination 23. AlphaGo Zero 24. RL in Discrete Optimization 25. Multi-agent RL 26. Other Books You May Enjoy
27. Index

Models

In this example, two architectures of DQN are used: a simple feed-forward network with three layers and a network with 1D convolution as a feature extractor, followed by two fully connected layers to output Q-values. Both of them use the dueling architecture described in Chapter 8, DQN Extensions. Double DQN and two-step Bellman unrolling have also been used. The rest of the process is the same as in a classical DQN (from Chapter 6, Deep Q-Networks).

Both models are in Chapter10/lib/models.py and are very simple.

class SimpleFFDQN(nn.Module):
    def __init__(self, obs_len, actions_n):
        super(SimpleFFDQN, self).__init__()
        self.fc_val = nn.Sequential(
            nn.Linear(obs_len, 512),
            nn.ReLU(),
            nn.Linear(512, 512),
            nn.ReLU(),
            nn.Linear(512, 1)
        )
        self.fc_adv = nn.Sequential(
            nn.Linear(obs_len, 512),
            nn.ReLU(),
            nn.Linear(512, 512),
            nn.ReLU(),...
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