Book Image

Learning Predictive Analytics with R

By : Eric Mayor
Book Image

Learning Predictive Analytics with R

By: Eric Mayor

Overview of this book

This book is packed with easy-to-follow guidelines that explain the workings of the many key data mining tools of R, which are used to discover knowledge from your data. You will learn how to perform key predictive analytics tasks using R, such as train and test predictive models for classification and regression tasks, score new data sets and so on. All chapters will guide you in acquiring the skills in a practical way. Most chapters also include a theoretical introduction that will sharpen your understanding of the subject matter and invite you to go further. The book familiarizes you with the most common data mining tools of R, such as k-means, hierarchical regression, linear regression, association rules, principal component analysis, multilevel modeling, k-NN, Naïve Bayes, decision trees, and text mining. It also provides a description of visualization techniques using the basic visualization tools of R as well as lattice for visualizing patterns in data organized in groups. This book is invaluable for anyone fascinated by the data mining opportunities offered by GNU R and its packages.
Table of Contents (23 chapters)
Learning Predictive Analytics with R
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Exercises and Solutions
Index

Chapter 5. Agglomerative Clustering Using hclust()

Unlike partition clustering, which requires the user to specify the number of k clusters and create homogeneous k groups, hierarchical clustering defines clusters without user intervention from distances in the data and defines a tree of clusters from this. Hierarchical clustering is particularly useful when the data is suspected to be hierarchical (leaves nested in nodes nested in higher level nodes). It can also be used to determine the number of clusters to be used in k-means clustering. Hierarchical clustering can be agglomerative or divisive. Agglomerative clustering usually yields a higher number of clusters, with less leaf nodes by cluster.

Agglomerative clustering refers to the use of algorithms, which start with a number of clusters that is equal to the number of cases (each case being a cluster) and merges clusters iteratively one by one, until there is only one cluster that corresponds to the entire dataset. Divisive cluster is...