Book Image

Machine Learning with R Cookbook, Second Edition - Second Edition

By : Yu-Wei, Chiu (David Chiu)
Book Image

Machine Learning with R Cookbook, Second Edition - Second Edition

By: Yu-Wei, Chiu (David Chiu)

Overview of this book

Big data has become a popular buzzword across many industries. An increasing number of people have been exposed to the term and are looking at how to leverage big data in their own businesses, to improve sales and profitability. However, collecting, aggregating, and visualizing data is just one part of the equation. Being able to extract useful information from data is another task, and a much more challenging one. Machine Learning with R Cookbook, Second Edition uses a practical approach to teach you how to perform machine learning with R. Each chapter is divided into several simple recipes. Through the step-by-step instructions provided in each recipe, you will be able to construct a predictive model by using a variety of machine learning packages. In this book, you will first learn to set up the R environment and use simple R commands to explore data. The next topic covers how to perform statistical analysis with machine learning analysis and assess created models, covered in detail later on in the book. You'll also learn how to integrate R and Hadoop to create a big data analysis platform. The detailed illustrations provide all the information required to start applying machine learning to individual projects. With Machine Learning with R Cookbook, machine learning has never been easier.
Table of Contents (21 chapters)
Title Page
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

Working with Pearson's Chi-squared test


In this recipe, we introduce Pearson's Chi-squared test, which is used to examine whether the distributions of categorical variables of two groups differ. We will discuss how to conduct Pearson's Chi-squared Test in R.

Getting ready

Ensure that mtcars has already been loaded into a DataFrame within an R session. Since the chisq.test function is originated from the stats? package, and make sure the library, stats, is loaded.

How to do it...

Perform the following steps:

  1. To make the counting table, we first use the contingency table built with the inputs of the transmission type and number of forward gears:

        > ftable = table(mtcars$am, mtcars$gear)
        > ftable
         Output:
            3 4 5
         0 15 4 0
         1 0 8 5
  1. We then plot the mosaic plot of the contingency table:
        > mosaicplot(ftable, main="Number of Forward Gears Within Automatic 
        and Manual Cars", color = TRUE)

Number of forward gears in automatic and manual...