[R] label points on a graph

Jim Lemon jim at bitwrit.com.au
Mon Jun 9 10:13:33 CEST 2008

Paul Adams wrote:
> Hello everyone,
> I have a plot and I am wanting to label points as 1 through 20
> I have the following code for the plot:
> dat<-read.table(file="C:\\Documents and Settings\\Owner\\My Documents\\colon cancer1.txt",header=T,row.names=1)
> file.show(file="C:\\Documents and Settings\\Owner\\My Documents\\colon cancer1.txt")
> plot(dat[1:20,1:2],type='p',xlab='normal1',ylab='normal2',main='Two normal samples--first 20 genes',pch=15,col='blue')
> grid(nx=5,ny=5,col="black",lty="dotted",lwd=2)
> Do I use the label function text(x,y,names)? If so do I specify to put 1-20 above the points as text(5,5,1:20,pos=3)?
> Any help would be much appreciated

Hi Paul,
The "thigmophobe.labels" function in the plotrix package is intended for 
this sort of labeling. As well as placing a label adjacent to each 
point, it offsets each label away from the nearest point. This avoids 
overlapping labels when two or three points are close together. You can 
also tweak the positioning manually if need be.


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