Book Image

TensorFlow Reinforcement Learning Quick Start Guide

By : Kaushik Balakrishnan
Book Image

TensorFlow Reinforcement Learning Quick Start Guide

By: Kaushik Balakrishnan

Overview of this book

Advances in reinforcement learning algorithms have made it possible to use them for optimal control in several different industrial applications. With this book, you will apply Reinforcement Learning to a range of problems, from computer games to autonomous driving. The book starts by introducing you to essential Reinforcement Learning concepts such as agents, environments, rewards, and advantage functions. You will also master the distinctions between on-policy and off-policy algorithms, as well as model-free and model-based algorithms. You will also learn about several Reinforcement Learning algorithms, such as SARSA, Deep Q-Networks (DQN), Deep Deterministic Policy Gradients (DDPG), Asynchronous Advantage Actor-Critic (A3C), Trust Region Policy Optimization (TRPO), and Proximal Policy Optimization (PPO). The book will also show you how to code these algorithms in TensorFlow and Python and apply them to solve computer games from OpenAI Gym. Finally, you will also learn how to train a car to drive autonomously in the Torcs racing car simulator. By the end of the book, you will be able to design, build, train, and evaluate feed-forward neural networks and convolutional neural networks. You will also have mastered coding state-of-the-art algorithms and also training agents for various control problems.
Table of Contents (11 chapters)

Summary

In this chapter, we were introduced to the TRPO and PPO RL algorithms. TRPO involves two equations that need to be solved, with the first equation being the policy objective and the second equation being a constraint on how much we can update. TRPO requires second-order optimization methods, such as conjugate gradient. To simplify this, the PPO algorithm was introduced, where the policy ratio is clipped within a certain user-specified range so as to keep the update gradual. In addition, we also saw the use of data samples collected from experience to update the actor and the critic for multiple iteration steps. We trained the PPO agent on the MountainCar problem, which is a challenging problem, as the actor must first drive the car backward up the left mountain, and then accelerate to gain sufficient momentum to overcome gravity and reach the flag point on the right mountain...