Book Image

Mastering PyTorch

By : Ashish Ranjan Jha
Book Image

Mastering PyTorch

By: Ashish Ranjan Jha

Overview of this book

Deep learning is driving the AI revolution, and PyTorch is making it easier than ever before for anyone to build deep learning applications. This PyTorch book will help you uncover expert techniques to get the most out of your data and build complex neural network models. The book starts with a quick overview of PyTorch and explores using convolutional neural network (CNN) architectures for image classification. You'll then work with recurrent neural network (RNN) architectures and transformers for sentiment analysis. As you advance, you'll apply deep learning across different domains, such as music, text, and image generation using generative models and explore the world of generative adversarial networks (GANs). You'll not only build and train your own deep reinforcement learning models in PyTorch but also deploy PyTorch models to production using expert tips and techniques. Finally, you'll get to grips with training large models efficiently in a distributed manner, searching neural architectures effectively with AutoML, and rapidly prototyping models using PyTorch and fast.ai. By the end of this PyTorch book, you'll be able to perform complex deep learning tasks using PyTorch to build smart artificial intelligence models.
Table of Contents (20 chapters)
1
Section 1: PyTorch Overview
4
Section 2: Working with Advanced Neural Network Architectures
8
Section 3: Generative Models and Deep Reinforcement Learning
13
Section 4: PyTorch in Production Systems

Discussing Q-learning

The key difference between policy optimization and Q-learning is the fact that in the latter, we are not directly optimizing the policy. Instead, we optimize a value function. What is a value function? We have already learned that RL is all about an agent learning to gain the maximum overall rewards while traversing a trajectory of states and actions. A value function is a function of a given state the agent is currently at, and this function outputs the expected sum of rewards the agent will receive by the end of the current episode.

In Q-learning, we optimize a specific type of value function, known as the action-value function, which depends on both the current state and the action. At a given state, S, the action-value function determines the long-term rewards (rewards until the end of the episode) the agent will receive for taking action a. This function is usually expressed as Q(S, a), and hence is also called the Q-function. The action-value is also...