[R] how to draw abline correctly?

Dieter Menne dieter.menne at menne-biomed.de
Mon Jan 4 09:17:40 CET 2010




aegea wrote:
> 
> 1, the red line is added on the graph but without any marker on the
> y-axis.  I want to display the number '.1361' on the y-axis. So people can
> easily tell 'method 2' gets a constant estimate, which is 0.1361.
> 
> 2, since 'method2' is a constant. I prefer in the legend area, it just
> shows 'method2' as a short red bar instead of a knot/spot in the middle of
> the red bar  in the legend area. How can I delete that spot?
> 
> 3, when I draw 'method1' in blue one, I prefer a filled/shaded circle
> instead of the unshaded circle. I tried pch='.', seems it does not really
> work.
> 
> 

Thanks for the nice example.

size=c(80, 40, 20, 16, 10, 8, 4, 2)
estimate=c(0.1353, 0.1337, 0.1237, 0.1164,  0.1058, 0.0983, 0.0759 , 0.0607)
plot(size, estimate, type="o", lwd=1.5, col="blue", ylim=c(0, 0.2),
xlim=c(0,80),pch=16)
abline(h=0.1361, col="red", lwd=1.5)
# use NA for no dot
legend(0, 0.2,c("method1","method2"), cex=0.8,    col=c("blue","red"),
pch=c(16,NA), lty=1);

# text inside it is easy
text(-0,0.134,"0.134",col="blue")
# outside you could use mtext, but not for exact position
mtext("0.134",2,adj=0.7,padj=-1,col="green")
# best is to plot another axis
#axis(2,0.134,"0.134") # ugly overprint
axis(2,0.134,"0.134",las=2,col="red")


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