Book Image

Mastering Predictive Analytics with R - Second Edition

By : James D. Miller, Rui Miguel Forte
Book Image

Mastering Predictive Analytics with R - Second Edition

By: James D. Miller, Rui Miguel Forte

Overview of this book

R offers a free and open source environment that is perfect for both learning and deploying predictive modeling solutions. With its constantly growing community and plethora of packages, R offers the functionality to deal with a truly vast array of problems. The book begins with a dedicated chapter on the language of models and the predictive modeling process. You will understand the learning curve and the process of tidying data. Each subsequent chapter tackles a particular type of model, such as neural networks, and focuses on the three important questions of how the model works, how to use R to train it, and how to measure and assess its performance using real-world datasets. How do you train models that can handle really large datasets? This book will also show you just that. Finally, you will tackle the really important topic of deep learning by implementing applications on word embedding and recurrent neural networks. By the end of this book, you will have explored and tested the most popular modeling techniques in use on real- world datasets and mastered a diverse range of techniques in predictive analytics using R.
Table of Contents (22 chapters)
Mastering Predictive Analytics with R Second Edition
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
8
Dimensionality Reduction
Index

Rating matrix


A recommendation system usually involves having a set of users, U = {u1 , u2 , …, um }, that have varying preferences on a set of items, I = {i1, i2, …, in }. The number of users, |U| = m, is usually different from the number of items, |I| = n. In addition, users can often express their preference by rating items on some scale. As an example, we can think of users as being restaurant patrons in a city, and the items being the restaurants that they visit. Under this setup, the preferences of the users could be expressed as ratings on a five-star scale. Of course, our generalization does not require that the items be physical items or that the users be actual people—this is simply an abstraction that is commonly used for the recommender system problem.

As an illustration, think of a dating website in which users rate other users; here, the items that are being rated are the profiles of the actual users themselves. Let's return to our example of a restaurant recommender system...