[R] lattice: showing panels for factor levels with no values

[Deepayan Sarkar]

On Thursday 12 February 2004 03:12, Wolfram Fischer - Z/I/M wrote:
> How to show panels for factor levels of conditioning variables
> which do have no values?
>
> E.g. there are panels for "Grand Rapids" when they have values:
> 	data( barley )
> 	with( barley, dotplot(variety ~ yield | year * site, layout=c(6,2) ) )
>
> There are no panels for "Grand Rapids"
> when there are no values for "Grand Rapids":
> 	my.barley <- subset( barley, ! ( site == "Grand Rapids" ) )
> 	with( my.barley, dotplot(variety ~ yield | year * site, layout=c(6,2) ) )
>
> But there is a level "Grand Rapids":
> 	levels( my.barley$site )
> 	[1] "Grand Rapids"    "Duluth"
> 	[3] "University Farm" "Morris"
> 	[5] "Crookston"       "Waseca"
>
> Is there an option to show empty panels for "Grand Rapids" in
> ``my.barley''?

No, unused factor levels are dropped. I'll see if adding an option for this is 
feasible.

Deepayan