Hi:

There is a very similar example in the ggplot book by Hadley Wickham
(section 4.5, pp. 50-52). Here's
one approach using ggplot:

library(ggplot2)
p <- ggplot(tolerance.pp, aes(age, tolerance, group = id)) + geom_line()
p + geom_smooth(aes(group = 1), size = 2)

The second command adds a smoothing spline in blue, with twice the line
width as the
individual spaghetti plots, and by default, a confidence envelope  around
it. To get rid
of the envelope, include se = FALSE as an argument to geom_smooth(); to
change the
color, add the argument colour = 'red', for example.

HTH,
Dennis

On Mon, Jan 18, 2010 at 3:25 PM, Eric Fail <e@it.dk> wrote:

> Hi Ruser
>
> I'm trying to replicate some SAS code. I have to add a spline to my
> longitudinal spaghetti plot.
>
> I have the plot, but I can't add the spline, a overall trend line. In the
> SAS code they use the command   'I=SM50S' and I would prefer something
> similar. I’m using R 2.10.1 on windows XP…
>
> I have made this working example.
>
> tolerance.pp <- read.table("
> http://www.ats.ucla.edu/stat/R/examples/alda/tolerance1_pp.txt", sep=",",
> header=T)
> # install.packages("lattice", dep = T)
> library(lattice)
> xyplot(tolerance ~ age, groups = id, data=tolerance.pp, type = "l")
>
> This is where I want to add a overall spline.
>
> Hope someone out there can figure this out.
>
> Thanks
>
> Eric
> ______________________________________________
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>

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