Book Image

Scala for Machine Learning, Second Edition - Second Edition

Book Image

Scala for Machine Learning, Second Edition - Second Edition

Overview of this book

The discovery of information through data clustering and classification is becoming a key differentiator for competitive organizations. Machine learning applications are everywhere, from self-driving cars, engineering design, logistics, manufacturing, and trading strategies, to detection of genetic anomalies. The book is your one stop guide that introduces you to the functional capabilities of the Scala programming language that are critical to the creation of machine learning algorithms such as dependency injection and implicits. You start by learning data preprocessing and filtering techniques. Following this, you'll move on to unsupervised learning techniques such as clustering and dimension reduction, followed by probabilistic graphical models such as Naïve Bayes, hidden Markov models and Monte Carlo inference. Further, it covers the discriminative algorithms such as linear, logistic regression with regularization, kernelization, support vector machines, neural networks, and deep learning. You’ll move on to evolutionary computing, multibandit algorithms, and reinforcement learning. Finally, the book includes a comprehensive overview of parallel computing in Scala and Akka followed by a description of Apache Spark and its ML library. With updated codes based on the latest version of Scala and comprehensive examples, this book will ensure that you have more than just a solid fundamental knowledge in machine learning with Scala.
Table of Contents (27 chapters)
Scala for Machine Learning Second Edition
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface
Index

Chapter 5. Dimension Reduction

As described in the Assessing a model/overfitting section of Chapter 2, Data Pipelines, the indiscriminative reliance of a large number of features may cause overfitting; the model may become so tightly coupled with the training set that different validation sets will generate a vastly different outcome and quality metrics such as AuROC.

Dimension reduction techniques alleviate these problems by detecting features that have little influence on the overall model behavior.

This chapter introduces three categories of dimension reduction techniques with two implementations in Scala:

  • Divergence with an implementation of the Kullback-Leibler distance

  • Principal components analysis

  • Estimation of low dimension feature space for nonlinear models

Other types of methodologies used to reduce the number of features such as regularization or singular value decomposition are discussed in future chapters.

But first, let's start our investigation by defining the problem.