On 4/27/07, GOUACHE David <D.GOUACHE at arvalisinstitutduvegetal.fr>
wrote:> Hello Rhelpers,
>
> I am trying to represent the following data (hereafter named donnees) in a
barchart with a grouping variable :
>
>
> site traitement date s res
> 1 NT 17/10/2005 normal 76.2
> 1 T 17/10/2005 normal 103.2
> 1 NT 23/11/2005 tardif 81.6
> 1 T 23/11/2005 tardif 98
> 2 NT 15/10/2005 normal 72.71
> 2 T 15/10/2005 normal 94.47
> 2 NT 15/11/2005 tardif 79.65
> 2 T 15/11/2005 tardif 94.7
>
> barchart(res~s|site,groups=traitement,data=donnees)
>
> What I'd like to do is for each site represent with an arrow the
difference in value of variable res between normal and tardif values of variable
s.
> I've found one way of doing it:
>
>
> trellis.focus("panel",1,1)
> xx<-trellis.panelArgs()$x
> yy<-trellis.panelArgs()$y
>
panel.arrows(as.numeric(xx)[c(1,3)]-0.1,yy[c(1,3)],as.numeric(xx)[c(1,3)]-0.1,yy[c(2,4)],lwd=2,code=3)
>
panel.text(as.numeric(xx)[c(1,3)]-0.35,c(87,87),paste(yy[c(2,4)]-yy[c(1,3)],"\nq/ha"),font=2)
> trellis.focus("panel",2,1)
> xx<-trellis.panelArgs()$x
> yy<-trellis.panelArgs()$y
>
panel.arrows(as.numeric(xx)[c(1,3)]-0.1,yy[c(1,3)],as.numeric(xx)[c(1,3)]-0.1,yy[c(2,4)],lwd=2,code=3)
>
panel.text(as.numeric(xx)[c(1,3)]-0.35,c(87,87),paste(yy[c(2,4)]-yy[c(1,3)],"\nq/ha"),font=2)
> trellis.unfocus()
>
> But I would prefer doing this within a custom panel function so I can apply
it more generally, and I haven't been able to figure out how...
> Could anyone give me a hand?
The obvious analog (just copy/pasting your code) is:
my.panel <- function(x, y, ...)
{
panel.barchart(x, y, ...)
xx <- x
yy <- y
panel.arrows(as.numeric(xx)[c(1,3)]-0.1, yy[c(1,3)],
as.numeric(xx)[c(1,3)]-0.1, yy[c(2,4)],
lwd = 2, code = 3)
panel.text(as.numeric(xx)[c(1,3)] - 0.35, c(87,87),
paste(yy[c(2,4)] - yy[c(1,3)], "\nq/ha"),
font=2)
}
and this seems to work:
barchart(res~s|site,groups=traitement,data=donnees,
panel = my.panel)
barchart(res~s|site,groups=traitement,data=donnees,
panel = my.panel,
origin = 0)
I'm not sure what else you are looking for and what you mean by "more
general". For example, it's not clear what you want to happen If you
have more than 2 levels in 'groups', or if the second bar is not
always higher than the first.
-Deepayan