[R] Problem with llines in lattice

[John Fox]

Dear Deepayan,

The application in which I encountered the problem is much more complicated,
so I'm not sure whether using groups will work there, but I'll give it a
try. 

Thanks for this,
 John

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Deepayan Sarkar
> Sent: Saturday, October 29, 2005 6:01 PM
> To: John Fox
> Cc: r-help at stat.math.ethz.ch
> Subject: Re: [R] Problem with llines in lattice
> 
> On 10/29/05, John Fox <jfox at mcmaster.ca> wrote:
> > Dear r-help list members,
> >
> > I'm experiencing problems getting type="b" (or "o" or "c") 
> to work in 
> > llines(). Try, e.g., the following scaled-down example:
> >
> > x <- factor(c("a", "b", "a", "b"))
> > y <- c(1,2,1,2)
> > z <- factor(c("A", "A", "B", "B"))
> > symbols <- 1:2
> > lines <- 1:2
> > colors <- 1:2
> > zvals <- levels(z)
> > xyplot(y~x|z, panel = function(x, y, subscripts, ...) {
> >     for (i in 1:length(zvals)) {
> >         sub <- z[subscripts] == zvals[i]
> >         llines(x[sub], y[sub], lwd = 2, type = "b",
> >           col = colors[i], pch = symbols[i], lty = lines[i])
> >         }
> >     })
> >
> > Only the lines (properly coloured with correct line types) 
> appear, but 
> > no symbols are plotted.
> 
> It's bug in lplot.xy. Fortunately, panel.xyplot will do the 
> same thing, so you can use it instead of llines.
> 
> One comment: I'm not sure if this would work in your real 
> application, but for your toy example a more direct approach would be
> 
> xyplot(y ~ x | z, type = 'b', groups = z,
>        col = colors, pch = symbols, lty = lines,
>        lwd = 2)
> 
> -Deepayan
> 
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