[R] Plot.lme error

[Yang, Richard]

Dear All;

	Attempting to reproduce Figure 4.15 of MEMSS (p. 171) in R using

             plot(Wafer, outer = ~ Wafer)
yields an error:

> plot(Wafer, outer = ~ Wafer)
Error in order(na.last, decreasing, ...) : 
        Argument lengths differ

	The plot() produces the figure without problems for all versions of
Splus (4.5 to 6.2) on  Windows. Noticing that the plot() differs slightly
between R and Splus, I copied the function from Splus, renamed it myplot()
in R and ran but without luck;

> myplot(Wafer, outer = ~ Wafer)
Error in myplot(Wafer, outer = ~Wafer) : Covariate must be numeric.

Coercing the covariate into numeric, but...

> myplot(Wafer, outer = ~ Wafer)
Error in !outer : invalid argument type

	Any suggestions and work around for the problem? I found the problem
dated back to R.1.4.1

	TIA,

Richard