[R] Histogram colours in lattice.

[Deepayan Sarkar]

On 10/7/08, Rolf Turner <r.turner at auckland.ac.nz> wrote:
>
>  I am trying to do a histogram lattice plot and I would like the
>  histogram to be filled with a different colour in each panel.
>
>  Note:  I want every bar in each histogram to be the same colour,
>  but that there should be different colours *between* histograms.
>
>  Can't seem to get this to work.  I thought that something like
>  the following would be a goer:
>
>  set.seed(42)
>  X <- rnorm(200)
>  A <- factor(sample(letters[1:5],200,TRUE))
>  DF <- data.frame(x=X,a=A)
>  print(histogram(~x|a,data=DF,col=2:6,type="count",
>  panel=function(x,...,subscripts,col) {
>         panel.histogram(x,...,col=col[subscripts])
>  }))
>
>  However it somewhat mysteriously colours the first bar/rectangle
>  of the histogram appropriately in the last three panels, leaving
>  all of the others blank, and leaves all bars blank in the first
>  two panels.

That's because you are ending up with 'col[subscripts]' being a
vector, most elements of which are NA.

>  Can I do what I want?  How?

print(histogram(~x|a,data=DF,col=2:6,type="count",
  panel=function(x,...,col) {
     panel.histogram(x,...,col=col[packet.number()])
}))

-Deepayan