[R] lme: Plot colours based on variable?

[Duncan Murdoch]

On 2025-12-02 3:39 a.m., Leo Mada via R-help wrote:
> Dear R-Users,
> 
> Is there a quick solution to plot colours based on a variable?
> 
> I tried something like this:
> 
> library(nlme)
> 
> plot(BodyWeight)
> 
> # Does NOT work!
> colDiet = c(2:4)[BodyWeight$Diet]
> plot(BodyWeight, col = colDiet)
> 
> # Wastes space
> rat.fit = lme(weight ~ Time + Diet, data = BodyWeight, random = ~ Time|Rat)
> plot(rat.fit, weight ~ Time | Rat + Diet)
> 
> Is there a quick way to base the colour on the Diet variable?

   plot(BodyWeight, ...)

dispatches to plot.nfnGroupedData(), which uses lattice::xyplot() 
graphics rather than base graphics. I don't know lattice well enough to 
answer your question, but maybe this will give you a hint...

Duncan Murdoch