[R] lattice histogram and grouping

[Evans, David G (DFG)]

Hi,
>From the following pseudo-code (tweaked from another user): 
library(lattice)
variable<-sample(rep(1:2,100))
individual<-rep(1:3, length(variable))
group<-rep(LETTERS[1:2],length(variable)/2)
mydata<-data.frame(variable,individual,group)
individual<-as.factor(individual)
group<-as.factor(group)
histogram(~variable|individual+group)

I get six panels, one for each of  individuals 1-3 in group A and one
for each of individuals 1-3 in group B .  
What I want is three panels, one for each individual, but with  A and B
paired in the same panel.  I think the "groups="argument does this sort
of superposition for other lattice functions, but is apparently
unavailable for histogram().  

Thanks very much for any help.