[R] add spline to longitudinal data - preferably similar to SAS's 'I=SM50S' routine

[Dylan Beaudette]

On Mon, Jan 18, 2010 at 3:25 PM, Eric Fail <e at 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")

Hi,

How about something like:

# your data
tolerance.pp <-
read.table("http://www.ats.ucla.edu/stat/R/examples/alda/tolerance1_pp.txt",
sep=",", header=T)

# almost works...
xyplot(tolerance ~ age, groups = id, data=tolerance.pp, type = c('l','smooth'))

see ?panel.loess for more ideas

Cheers,
Dylan

>
> This is where I want to add a overall spline.
>
> Hope someone out there can figure this out.
>
> Thanks
>
> Eric
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