R help - Oct 2008 - Histogram colours in lattice.

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.

Can I do what I want?  How?  Thanks for any advice (other than
``Go stick your head in a pig.'' :-) )

	cheers,

		Rolf Turner


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On Tue, Oct 7, 2008 at 8:54 PM, 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.
>
> Can I do what I want?  How?  Thanks for any advice (other than
> ``Go stick your head in a pig.'' :-) )
You could always use ggplot2:

library(ggplot2)
qplot(X, data=DF, geom="histogram", fill=A, facets = . ~ a,
binwidth=0.5)

Hadley

-- 
http://had.co.nz/

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