[R] lattice draw.key(): position of key in panels

[Boris.Vasiliev at forces.gc.ca]

Good morning,

This problem was already addressed in a previous post:

https://stat.ethz.ch/pipermail/r-help/2009-February/187244.html

In the call to draw.key() use
'vp=viewport(x=unit(0.1,"npc"),y=unit(0.1,"npc"))'.
Prior to calling viewport() make sure grid package is loaded.

Apologies for cluttering the mail list.
Regards,
Boris Vasiliev.


> -----Original Message-----
> From: Vasiliev B at CEFCOM HQ at Ottawa-Hull 
> Sent: Tuesday, 25, January, 2011 16:22 PM
> To: 'r-help at r-project.org'
> Subject: lattice draw.key(): position of key in panels
> 
> Good afternoon,
> 
> I am working on a plot that requires custom legends to be 
> placed in some panels of the plot; other panels do not 
> contain legends.  The problem that I run into is positioning 
> of the legend in individual panels. In particular, the 'x' 
> and 'y' elements of the key-list are ignored by draw.key() 
> when it is called from inside a panel function.  As a result, 
> the legend is placed in the middle of the panel.  The example 
> below illustrates this problem.
> 
> df <- data.frame(x=c(1,1),y=c(1,2),type=c("A","B"))
> 
> panel.xyplot.x <- function(...) {
>   # draw data
>   panel.xyplot(...)
> 
>   # create key-list
>   pnlid <- panel.number()
>   lbl <- ifelse(pnlid==1,"AA","BB")
>   pts <- Rows(trellis.par.get("superpose.symbol"),pnlid)
>   key <- list(points=pts,text=list(lbl),x=0.1,y=0.9,corner=c(0,1))
> 
>   # draw key
>   draw.key(key,draw=TRUE)
> }
> 
> oltc <- xyplot(y~x|type,data=df,panel=panel.xyplot.x)
> print(oltc)
> 
> I tried using 'vp=current.viewport()' in the call to 
> draw.key() but it did not help.  Can anybody suggest the 
> proper way to specify position of the key-list so that it is 
> respected by draw.key() when called within a panel function?
> 
> Sincerely,
> Boris Vasiliev.