
mmmh, yes this method works...
but I have to overlap this two graphs:



> xyplot(  a ~  b |  sites, data=dataset,  col="red")



> xyplot(  c ~  b |  sites, data=dataset,  col="blue")


a, b and c are columns in the same dataset. "Sites" is also a column in the dataset, but it's a factorial variables.
How can I use your method?
sorry for my ignorance! 

Francesco Nutini

> Date: Fri, 10 Dec 2010 10:13:00 -0800
> From: ehlers@ucalgary.ca
> To: nutini.francesco@gmail.com
> CC: r-help@r-project.org
> Subject: Re: [R] [r] overlap different line in a xyplot (lattice)
> 
> On 2010-12-10 07:04, Francesco Nutini wrote:
> >
> > dear [R] users,
> > is there a way to plot different data (but with the same x-variables) in the same xyplot window?
> > There are already a similar question, but the answer is not enought explanatory...
> 
> Something like this?
> 
>   x <- rep(1:10, 2)
>   y1 <- rnorm(10); y2 <- rnorm(10) + 2
>   y <- c(y1, y2)
>   g <- gl(2, 10)
>   xyplot( y ~ x, groups = g, type = 'b')
> 
> Peter Ehlers
> 
> >
> >
> > Thanks a lot,
> > Francesco
> >
> 
 		 	   		  
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