Book Image

Applied Unsupervised Learning with R

By : Alok Malik, Bradford Tuckfield
Book Image

Applied Unsupervised Learning with R

By: Alok Malik, Bradford Tuckfield

Overview of this book

Starting with the basics, Applied Unsupervised Learning with R explains clustering methods, distribution analysis, data encoders, and features of R that enable you to understand your data better and get answers to your most pressing business questions. This book begins with the most important and commonly used method for unsupervised learning - clustering - and explains the three main clustering algorithms - k-means, divisive, and agglomerative. Following this, you'll study market basket analysis, kernel density estimation, principal component analysis, and anomaly detection. You'll be introduced to these methods using code written in R, with further instructions on how to work with, edit, and improve R code. To help you gain a practical understanding, the book also features useful tips on applying these methods to real business problems, including market segmentation and fraud detection. By working through interesting activities, you'll explore data encoders and latent variable models. By the end of this book, you will have a better understanding of different anomaly detection methods, such as outlier detection, Mahalanobis distances, and contextual and collective anomaly detection.
Table of Contents (9 chapters)

Introduction


This chapter presents techniques for unsupervised learning that accomplish something called dimension reduction. First, we will discuss what a dimension is, why we want to avoid having too many dimensions, and the basic idea of dimension reduction. The chapter then covers two dimension reduction techniques in detail: market basket analysis and Principal Component Analysis (PCA). Market basket analysis is a technique for generating associative rules in datasets. The chapter will contain a walk-through of detailed R code that accomplishes this. PCA, a very common dimension reduction technique, comes from theoretical linear algebra. The chapter will also show a detailed walk-through of how to accomplish PCA with R.

The Idea of Dimension Reduction

The dimensions of a dataset are nothing more than the collection of distinct numbers that are required to describe observations in it. For example, consider the position of Pac-Man in the game named after him. Pac-Man is a game that was...