plot spaghetti data
To elaborate a bit on Harold's reply, the use of a "spaghetti plot" for more than 4 or 5 groups is not recommended. Consider the longitudinal data "sleepstudy" in the Matrix package. A spaghetti plot can be produced by
data(sleepstudy, package = "Matrix")
library(lattice)
xyplot(Reaction ~ Days, sleepstudy, groups = Subject, type = c('g','l'), aspect = 'xy')
Now compare this to the result of
xyplot(Reaction ~ Days | Subject, sleepstudy, type = c('g','p','r'), aspect = 'xy')
which is a lattice plot with the data for each subject in a separate panel. Even better is to use
xyplot(Reaction ~ Days | Subject, sleepstudy, type = c('g','p','r'), aspect = 'xy',
+ index.cond = function(x, y) coef(lm(y ~ x))[1]) where the panels are ordered according to a characteristic of the data (the intercept for the per-subject regression line) rather than in the more-or-less random order created by the subject number. library(lattice) xyplot(Reaction ~ Days
On 9/16/05, Doran, Harold <HDoran at air.org> wrote:
There is interaction.plot(), but, the trellis graphics in lattice are
much better. You might want to check these out.
-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Marc Bernard
Sent: Friday, September 16, 2005 8:58 AM
To: r-help at stat.math.ethz.ch
Subject: [R] plot spaghetti data
Dear All,
I wonder if there is an R function to plot longitudinal data (spaghetti
plots)...
I've seen the function "is.longitudinal" but without any succes...
Thanks a lot in advance,
Bernard
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