[R] Sweave: infelicities with lattice graphics

[Michael Friendly]

In a paper I'm writing using Sweave, I make use of lattice graphics, but 
don't want to explicitly show (or explain)
in the article text the print() wrapper I need in code chunks for the 
graphs to appear. 
I can solve this by including each chunk twice, with different options, 
as in

<<ortho-xyplot1-code, keep.source=TRUE, eval=FALSE>>=
library(nlme)
library(lattice)
xyplot(distance ~ age|Sex, data=Orthodont, type='b', groups=Subject, 
pch=15:25,
    col=palette(), cex=1.3, main="Orthodont data")
@
<<ortho-xyplot1,fig=TRUE, include=FALSE, echo=FALSE, width=6, height=6>>=
library(nlme)
library(lattice)
print(xyplot(distance ~ age|Sex, data=Orthodont, type='b', 
groups=Subject, pch=15:25,
    col=palette(), cex=1.3, main="Orthodont data"))
@

but then, if I decide to change the plotting code, I have to make 
changes in two places.  Is there some
feature of Sweave or lattice I've missed that would simplify this? 
Re-use of code chunks doesn't seem
to apply here.

-Michael

-- 
Michael Friendly     Email: friendly AT yorku DOT ca 
Professor, Psychology Dept.
York University      Voice: 416 736-5115 x66249 Fax: 416 736-5814
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