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

Handling missing data and split and surrogate variables


Missing data can be a curse for analysis and prediction. It leads to an inaccurate inference from data. One simple way to handle missing data is to refuse to take missing data in to account by simply ignoring it or removing it from the dataset. This approach seems good, but not in an efficient way. If the number of missing values is less than 5 percent of a total dataset then discarding such data will not affect the whole dataset.

Getting ready

This recipe will familiarize us with using mice packages for filling missing values.

How to do it...

Perform the following steps in R:

  1. Find the minimum cross-validation error of the classification tree model:
        > install.packages("mice")
        > install.packages("randomForest")
        > install.packages("VIM")
        > t = data.frame(x=c(1:100), y=c(1:100))  
        > t$x[sample(1:100,10)]=NA
        > t$y[sample(1:100,20)]=NA
        > aggr(t)
  1. Tweaking the aggr function...