Book Image

Python Reinforcement Learning

By : Sudharsan Ravichandiran, Sean Saito, Rajalingappaa Shanmugamani, Yang Wenzhuo
Book Image

Python Reinforcement Learning

By: Sudharsan Ravichandiran, Sean Saito, Rajalingappaa Shanmugamani, Yang Wenzhuo

Overview of this book

Reinforcement Learning (RL) is the trending and most promising branch of artificial intelligence. This Learning Path will help you master not only the basic reinforcement learning algorithms but also the advanced deep reinforcement learning algorithms. The Learning Path starts with an introduction to RL followed by OpenAI Gym, and TensorFlow. You will then explore various RL algorithms, such as Markov Decision Process, Monte Carlo methods, and dynamic programming, including value and policy iteration. You'll also work on various datasets including image, text, and video. This example-rich guide will introduce you to deep RL algorithms, such as Dueling DQN, DRQN, A3C, PPO, and TRPO. You will gain experience in several domains, including gaming, image processing, and physical simulations. You'll explore TensorFlow and OpenAI Gym to implement algorithms that also predict stock prices, generate natural language, and even build other neural networks. You will also learn about imagination-augmented agents, learning from human preference, DQfD, HER, and many of the recent advancements in RL. By the end of the Learning Path, you will have all the knowledge and experience needed to implement RL and deep RL in your projects, and you enter the world of artificial intelligence to solve various real-life problems. This Learning Path includes content from the following Packt products: • Hands-On Reinforcement Learning with Python by Sudharsan Ravichandiran • Python Reinforcement Learning Projects by Sean Saito, Yang Wenzhuo, and Rajalingappaa Shanmugamani
Table of Contents (27 chapters)
Title Page
About Packt
Contributors
Preface
Index

Chapter 11. Policy Gradients and Optimization

In the last three chapters, we have learned about various deep reinforcement learning algorithms, such as Deep Q Network (DQN), Deep Recurrent Q Network (DRQN), and the Asynchronous Advantage Actor Critic (A3C) network. In all the algorithms, our goal is to find the correct policy so that we can maximize the rewards. We use the Q function to find the optimal policy as the Q function tells us which action is the best action to perform in a state. Do you think we can directly find the optimal policy without using Q function? Yes. We can. In policy gradient methods, we can find the optimal policy without using the Q function.

In this chapter, we will learn about policy gradients in detail. We will also look at different types of policy gradient methods such as deep deterministic policy gradients followed by state-of-the-art policy optimization methods such as trust region policy optimization and proximal policy optimization. 

In this chapter, you...