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)

Learning TRPO

TRPO is a very popular on-policy algorithm from OpenAI and the University of California, Berkeley, and was introduced in 2015. There are many flavors of TRPO, but we will learn about the vanilla TRPO version from the paper Trust Region Policy Optimization, by John Schulman, Sergey Levine, Philipp Moritz, Michael I. Jordan, and Pieter Abbeel, arXiv:1502.05477: https://arxiv.org/abs/1502.05477.

TRPO involves solving a policy optimization equation subject to an additional constraint on the size of the policy update. We will see these equations now.

TRPO equations

TRPO involves the maximization of the expectation of the ratio of the current policy distribution, πθ, to the old policy distribution, π...