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

Creating correlation heat maps


In this recipe, we will learn how to make a correlation heat map from a matrix of correlation coefficients.

Getting ready

We will only use the base graphics functions for this recipe. So, just open up the R prompt and type in the following code. We will use the genes.csv example dataset for this recipe. So, let's first load it:

genes<-read.csv("genes.csv")

How to do it...

Let's make a heat map showing the correlation between genes in a matrix:

rownames(genes)<-genes[,1]
data_matrix<-data.matrix(genes[,-1])

pal=heat.colors(5)

breaks<-seq(0,1,0.2)

layout(matrix(data=c(1,2), nrow=1, ncol=2), widths=c(8,1), heights=c(1,1))

par(mar = c(3,7,12,2),oma=c(0.2,0.2,0.2,0.2),mex=0.5) 

image(x=1:nrow(data_matrix),y=1:ncol(data_matrix),
z=data_matrix,xlab="",ylab="",breaks=breaks,
col=pal,axes=FALSE)


text(x=1:nrow(data_matrix)+0.75, y=par("usr")[4] + 1.25, 
srt = 45, adj = 1, labels = rownames(data_matrix), 
xpd = TRUE)

axis(2,at=1:ncol(data_matrix),labels...