[R] problem with xyplot

[Carlisle Thacker]

Dear Rlisters,

When trying to indicate which data belong to which of 7 groups, the
following plot shows only 5 groups:

ss <- trellis.par.get("superpose.symbol")
ss$col <- c("red","blue","green","yellow","orange","magenta","cyan")
ss$pch <- format(1:7)
ss$cex <- 1.2
ss <- trellis.par.get("background")
ss$col <- "white"
trellis.par.set("background",ss)

xyplot(t~s,data=P0,
  subset = p==1500 & whichLonP==2 & whichLatP==3 & t<6 & id>100000000,
  groups = id%/%1000)
# don't see groups 6 and 7 ?????????????

But groups can be put into separate panels:

xyplot(t~s|factor(id%/%1000),data=P0,as.table=TRUE,
  subset = p==1500 & whichLonP==2 & whichLatP==3 & t<6 & id>100000000)

And using a smaller dataframe helps:

temp <- P0[P0$p==1500 & whichLonP==2 & whichLatP==3 & P0$t<6,]
xyplot(t~s,data=temp,
  subset = id>100000000,
  groups = id%/%1000)
# get different labels but all groups

Also, for other plots involving large dataframes, specifying groups made
the plotting very slow.

Is there a bug, or am I screwing up?

Thanks,

Carlisle