Book Image

Deep Reinforcement Learning Hands-On

By : Maxim Lapan
Book Image

Deep Reinforcement Learning Hands-On

By: Maxim Lapan

Overview of this book

Deep Reinforcement Learning Hands-On is a comprehensive guide to the very latest DL tools and their limitations. You will evaluate methods including Cross-entropy and policy gradients, before applying them to real-world environments. Take on both the Atari set of virtual games and family favorites such as Connect4. The book provides an introduction to the basics of RL, giving you the know-how to code intelligent learning agents to take on a formidable array of practical tasks. Discover how to implement Q-learning on 'grid world' environments, teach your agent to buy and trade stocks, and find out how natural language models are driving the boom in chatbots.
Table of Contents (23 chapters)
Deep Reinforcement Learning Hands-On
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Prioritized replay buffer

The next very useful idea on how to improve DQN training was proposed in 2015 in the paper, Prioritized Experience Replay ([7] Schaul and others, 2015). This method tries to improve the efficiency of samples in the replay buffer by prioritizing those samples according to the training loss.

The basic DQN used the replay buffer to break the correlation between immediate transitions in our episodes. As we discussed in Chapter 6, Deep Q-Networks, the examples we experience during the episode will be highly correlated, as most of the time the environment is "smooth" and doesn't change much according to our actions. However, the SGD method assumes that the data we use for training has a i.i.d. property. To solve this problem, the classic DQN method used a large buffer of transitions, randomly sampled to get the next training batch.

The authors of the paper questioned this uniform random sample policy and proved that by assigning priorities to buffer samples, according to...