[R] How to change the type of segments ends?

[Lu, Jiang Jane]

Hi,

I am trying to plot odds ratios and the corresponding confidence
intervals in horizontal segments. It would be ideal if the confidence
interval segment can be drawn with little vertical bars at both ends. I
have tried very hard to change the type of ends by using 'lend'
arguments, but cannot make it. I even tried 'arrows()', but still
failed. Following is the code I use:
====================================================
drug.or <- c(1.017,1.437,1.427,2.211)
drug.orl <- c(0.715,1.075,1.103,1.696)
drug.oru <- c(1.446,1.922,1.845,2.882)

yaxis <- seq(1,4,by=1)

plot(x=drug.or,y=yaxis,type='p',pch=17,xlim=c(0,3),axes=FALSE,
     xlab='Odds Ratio',ylab='',main='Reference Group: A only')
axis(1,at=seq(0,3,by=0.5),labels=paste(seq(0,3,by=0.5)))
axis(2,at=yaxis,las=2)


segments(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,col=4,lend=2)

# or try
#arrows(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,length=0.1,angle=0,cod
e=3,col=4,lend=2)

box()
=====================================================


Any comments or suggestions would be greatly appreciated.


Jane

University of Pittsburgh
Pittsburgh, PA 15261