Book Image

R Graphs Cookbook Second Edition

Book Image

R Graphs Cookbook Second Edition

Overview of this book

Table of Contents (22 chapters)
R Graphs Cookbook
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Adding a legend to a pie chart


Sometimes, we might wish to use a legend to annotate a pie chart instead of using labels. In this recipe, we will learn how to do this using the legend() function.

Getting ready

Once again in this recipe, we will use the browsers.txt example dataset, which contains data about the usage percentage share of different Internet browsers.

How to do it...

First, we will load the browsers.txt dataset and then use the pie() function to draw a pie chart:

browsers<-read.table("browsers.txt",header=TRUE)
browsers<-browsers[order(browsers[,2]),]

pielabels <- sprintf("%s = %3.1f%s", browsers[,1],
100*browsers[,2]/sum(browsers[,2]), "%")

pie(browsers[,2],
labels=NA,
clockwise=TRUE,
col=brewer.pal(7,"Set1"),
border="white",
radius=0.7,
cex=0.8,
main="Percentage Share of Internet Browser usage")

legend("bottomright",legend=pielabels,bty="n",
fill=brewer.pal(7,"Set1"))

How it works...

Once again we ordered the browser dataset, created a vector of labels, and made the pie...