[R] homogenity inside groups

[Petr PIKAL]

Dear all

I would like to show my audience that some variables are homogenous inside 
groups but different outside. I can use by with summary for all variables

 by(iris[,1:4],  iris$Species, summary)

what can be quite messy in case of more than few variables and about 8 
groups

or densityplot for one variable

densityplot(~Petal.Length | Species, iris)

I have two questions:

1.      Is there any other plot to show all variables at once? Something 
like

densityplot(~iris[,1:4] | Species, iris)

2.      Is it possible to evaluate homogenity of many (20-30) variables 
inside groups by some other function/table/graph?

Thank you

Petr Pikal
petr.pikal at precheza.cz