thank you very much Petr. Yes, I meant densityplot form lattice.

The code I gave plots the densities of both x1 and x2 in one panel.
Could you show me how to integrate the function addline into the code so
that a vertical line v=0 is added?



On 4 January 2012 15:55, Petr PIKAL <petr.pikal@precheza.cz> wrote:

> Hi
>
> >
> > Hi,
> > A simple question I hope. I wish to add a single vertical line to a plot
> > with several density plots.
> > Here is a simplified example.
> >
> > ############
> > thedata <- data.frame(x1=rnorm(100,1,1),x2=rnorm(100,3,1)) #create data
> > thedata.m<-melt(thedata)
> > densityplot(~value, thedata.m, groups=variable,auto.key=list(columns=2))
> > #this gives the two density plots
> > #########
> >
> > what I wish now is to add a vertical line, for example v=2.
>
> If you mean densityplot from lattice here is a function (addapted from
> Gabor Grothendieck's code] which adds arbitrary line(s) into panels. Is
> options are similar to abline and once=TRUE means you want different lines
> to different panels.
>
> > addLine
> function (a = NULL, b = NULL, v = NULL, h = NULL, ..., once = FALSE)
> {
>    tcL <- trellis.currentLayout()
>    k <- 0
>    for (i in 1:nrow(tcL)) for (j in 1:ncol(tcL)) if (tcL[i,
>        j] > 0) {
>        k <- k + 1
>        trellis.focus("panel", j, i, highlight = FALSE)
>        if (once)
>            panel.abline(a = a[k], b = b[k], v = v[k], h = h[k],
>                ...)
>        else panel.abline(a = a, b = b, v = v, h = h, ...)
>        trellis.unfocus()
>    }
> }
>
> Regards
> Petr
>
>
>
> >
> > Many thanks,
> > Josh.
> >
> >    [[alternative HTML version deleted]]
> >
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> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
>

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