[R] barplot at specific x values

[Richard M. Heiberger]

Bastian Pöschl wrote:
> Dear useRs,
>
> I search for a possibillity to plot stacked bars at specific x positions.
> I tried and tried, but the only way i got something adequate was by using lowlevel plots segments(). That is quiet ok, but will not please eyes without a lot of par() lines.
>
> dh<-data.frame(longitude=abs(rnorm(5)),deers=abs(rnorm(5)),humans=abs(rnorm(5)))
>
> plot(dh$longitude,apply(dh[,2:3], 1, sum),type="n",ylim=c(0,max(apply(dh[,2:3], 1, sum))))
> segments(dh$longitude,0,dh$longitude,dh$deers, col="green", lwd=12)
> segments(dh$longitude,dh$deers,dh$longitude,dh$deers+dh$humans, col="red", lwd=12)
>
> I hope somebody is experienced in doing such plots or somebody just knows how to do it.
>
> Bastian
>
>   
tmp.lattice <- barchart(deers+humans ~ longitude, data=dh, stack=TRUE, 
horizontal=FALSE, auto.key=TRUE, box.ratio=.03)
tmp.lattice$panel.args[[1]]$x <- 
rep(dh$longitude,2)[tmp.lattice$panel.args[[1]]$subscripts]
tmp.lattice$x.limits <- range(pretty(dh$longitude))
tmp.lattice

This works.  I don't like this solution because I had to modify the 
trellis object after the fact instead of
specifying it with commands.  The panel.barchart says
|     y| 	Horizontal location of bars, possibly factor

which implies that numeric values would be acceptable, but the barchart 
function coerces the values to effectively
  as.numeric(factor(longitude))
so they appear in the panel function as 1 1 2 2 3 3 4 4 5 5

I tried a few ways to make the longitude stay numeric and didn't hit on 
any that worked.

Deepayan, can you help here?

Rich