overlap different line in a xyplot (lattice)

On 2010-12-11 03:12, Francesco Nutini wrote:

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?

The idea is the same: you need to get your data
into "long" format with a grouping variable and
then use the 'groups' argument to xyplot.
Here's fake data frame (you should have provided one):

?DF <- data.frame(y1 = rnorm(30),
? ? ? ? ? ? ? ? ?y2 = rnorm(30) + 2,
? ? ? ? ? ? ? ? ?x ?= rep(1:10, 3),
? ? ? ? ? ? ? sites = gl(3, 10, lab=LETTERS[1:3]))

## Use the reshape2 package to melt the data:
## (or use reshape() in base R)
?require(reshape2)
?DF1 <- melt(DF, measure.vars = c('y1', 'y2'),
? ? ? ? ? ? variable.name = 'grp', value.name = 'y')

## and plot:
?require(lattice)
?p <- xyplot( y ~ x | sites, data = DF1, groups = grp,
? ? ? ? ? ? col = c("red", "blue"), type = "b")
?print(p)

Peter Ehlers

sorry for my ignorance!

Francesco Nutini

?> Date: Fri, 10 Dec 2010 10:13:00 -0800
?> From: ehlers at ucalgary.ca
?> To: nutini.francesco at gmail.com
?> CC: r-help at 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
?> >
?>