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)

Actor-Critic algorithms and policy gradients

In this section, we will cover what Actor-Critic algorithms are. You will also see what policy gradients are and how they are useful to Actor-Critic algorithms.

How do students learn at school? Students normally make a lot of mistakes as they learn. When they do well at learning a task, their teacher provides positive feedback. On the other hand, if students do poorly at a task, the teacher provides negative feedback. This feedback serves as the learning signal for the student to get better at their tasks. This is the crux of Actor-Critic algorithms.

The following is a summary of the steps involved:

  • We will have two neural networks—one referred to as the actor, and the other as the critic
  • The actor is like the student, as we described previously, and takes an action at a given state
  • The critic is like the teacher, as we described...