Book Image

Python Reinforcement Learning Projects

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

Python Reinforcement Learning Projects

By: Sean Saito, Yang Wenzhuo, Rajalingappaa Shanmugamani

Overview of this book

Reinforcement learning is one of the most exciting and rapidly growing fields in machine learning. This is due to the many novel algorithms developed and incredible results published in recent years. In this book, you will learn about the core concepts of RL including Q-learning, policy gradients, Monte Carlo processes, and several deep reinforcement learning algorithms. As you make your way through the book, you'll work on projects with datasets of various modalities including image, text, and video. You will gain experience in several domains, including gaming, image processing, and physical simulations. You'll explore technologies such as TensorFlow and OpenAI Gym to implement deep learning reinforcement learning algorithms that also predict stock prices, generate natural language, and even build other neural networks. By the end of this book, you will have hands-on experience with eight reinforcement learning projects, each addressing different topics and/or algorithms. We hope these practical exercises will provide you with better intuition and insight about the field of reinforcement learning and how to apply its algorithms to various problems in real life.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Implementation of DQN


This chapter will show you how to implement all the components, for example, Q-network, replay memory, trainer, and Q-learning optimizer, of the deep Q-learning algorithm with Python and TensorFlow.

We will  implement the QNetwork class for the Q-network that we discussed in the previous chapter, which is defined as follows:

class QNetwork:

    def __init__(self, input_shape=(84, 84, 4), n_outputs=4, 
                 network_type='cnn', scope='q_network'):

        self.width = input_shape[0]
        self.height = input_shape[1]
        self.channel = input_shape[2]
        self.n_outputs = n_outputs
        self.network_type = network_type
        self.scope = scope

        # Frame images
        self.x = tf.placeholder(dtype=tf.float32, 
                                shape=(None, self.channel, 
                                       self.width, self.height))
        # Estimates of Q-value
        self.y = tf.placeholder(dtype=tf.float32, shape=(None,))
       ...