Great!  This really helped!  One quick follow-up -- is there a trick to
placing a label wherever the line intersects the x-axis (either above or
below the plot)?


On Tue, Jan 22, 2013 at 11:49 PM, PIKAL Petr <petr.pikal@precheza.cz> wrote:

> Hi
> This function adds line to each panel
>
> addLine <- function (a = NULL, b = NULL, v = NULL, h = NULL, ..., once = F)
> {
>     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()
>     }
>   }
>
>
> addLine(v=2, col=2, lty=3)
>
> Petr
>
> > -----Original Message-----
> > From: r-help-bounces@r-project.org [mailto:r-help-bounces@r-
> > project.org] On Behalf Of Jonathan Greenberg
> > Sent: Tuesday, January 22, 2013 11:42 PM
> > To: r-help
> > Subject: [R] Adding a line to barchart
> >
> > R-helpers:
> >
> > I need a quick help with the following graph (I'm a lattice newbie):
> >
> > require("lattice")
> > npp=1:5
> > names(npp)=c("A","B","C","D","E")
> > barchart(npp,origin=0,box.width=1)
> >
> > # What I want to do, is add a single vertical line positioned at x = 2
> > that lays over the bars (say, using a dotted line).  How do I go about
> > doing this?
> >
> > --j
> >
> > --
> > Jonathan A. Greenberg, PhD
> > Assistant Professor
> > Global Environmental Analysis and Remote Sensing (GEARS) Laboratory
> > Department of Geography and Geographic Information Science University
> > of Illinois at Urbana-Champaign
> > 607 South Mathews Avenue, MC 150
> > Urbana, IL 61801
> > Phone: 217-300-1924
> > http://www.geog.illinois.edu/~jgrn/
> > AIM: jgrn307, MSN: jgrn307@hotmail.com, Gchat: jgrn307, Skype: jgrn3007
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > 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.
>



-- 
Jonathan A. Greenberg, PhD
Assistant Professor
Global Environmental Analysis and Remote Sensing (GEARS) Laboratory
Department of Geography and Geographic Information Science
University of Illinois at Urbana-Champaign
607 South Mathews Avenue, MC 150
Urbana, IL 61801
Phone: 217-300-1924
http://www.geog.illinois.edu/~jgrn/
AIM: jgrn307, MSN: jgrn307@hotmail.com, Gchat: jgrn307, Skype: jgrn3007

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