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

Understanding data sampling in R


Sampling is a method to select a subset of data from a statistical population, which can use the characteristics of the population to estimate the whole population. The following recipe will demonstrate how to generate samples in R.

Getting ready

Make sure that you have an R working environment for the following recipe.

How to do it...

Perform the following steps to understand data sampling in R:

  1. To generate random samples of a given population, the user can simply use the sample function:
> sample(1:10)
  1. To specify the number of items returned, the user can set the assigned value to the size argument:
> sample(1:10, size = 5)
  1. Moreover, the sample can also generate Bernoulli trials by specifying replace = TRUE (default is FALSE):
> sample(c(0,1), 10, replace = TRUE)
  1. If we want to do a coin flipping trail, where the outcome is Head or Tail, we can use:
  > outcome <- c("Head","Tail")  > sample(outcome, size=1)
  1. To generate result for 100 times, we can use...