[R] Does anybody know how to control the appearance of the end of the line in lattice?

[George Chen]

Hi All,

I am plotting vertical lines using xyplot in lattice and type="h".
It works well, but the problem is that the tops of the lines are convex and the bottoms are concave.
Is there a way to flatten the tops and bottoms?

Here's my code:

Source<-matrix(1:30,10,3)
colnames(Source)<-c("x","y1","y2")
Source<-data.frame(Source)

xyplot(y2+y1~x,
	data=Source,
	distribute.type=TRUE,
	type=c("h","h"),
	col=c("black","white"),
        lwd=20)
graphics.off()

Thanks.

George Chen