# [R] Lattice histogram with vertical lines

Petr PIKAL petr.pikal at precheza.cz
Tue Feb 3 10:21:50 CET 2009

```Hi

r-help-bounces at r-project.org napsal dne 03.02.2009 09:20:25:

> David Scott <d.scott <at> auckland.ac.nz> writes:
>
> >
> >
> > I would like to add some vertical lines to a lattice plot of
histograms.
> > What I am after is a lattice version of abline(v = 1234). The lattice
> > histogram plot is just:
> >
> > histogram( ~ LTSE | approach, data = arrivals)
> >
>
> As a little variation on the histogram docs example:
>
> histogram( ~ height | voice.part, data = singer,
>           xlab = "Height (inches)", type = "density",
>           panel = function(x, ...) {
>               panel.histogram(x, ...)
>               panel.abline(v= 70)
>               panel.mathdensity(dmath = dnorm, col = "black",
>                                 args = list(mean=mean(x),sd=sd(x)))
>           } )
>
>

Or if you want add lines at different places in each panel use this
function and set once =T

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()
}
}

Regards
Petr

> Dieter
>
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