[R] Sweave: infelicities with lattice graphics

[Duncan Murdoch]

On 12/09/2010 11:41 AM, Michael Friendly wrote:
> Just a follow-up on this thread, now with R 2.11.1.  I was happy back 
> then to use Deepayan's solution for this, under earlier R versions; but 
> it now gives an error and the Sweave-generated .tex file no longer compiles.
> 
> <<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>>=
> plot(trellis.last.object())
> @
> 
> Now, I get the following from Sweave:
> 
> Error:  chunk 46 (label=ortho-xyplot1)
> Error in !lattice.getStatus("current.plot.saved", prefix = prefix) :
>    invalid argument type
> 
> Did something in lattice change so that plot(trellis.last.object()) no 
> longer works or needs to be specified differently?

I don't know if something in lattice has changed, but that doesn't look 
as though it should work:  the code to do the plot was never evaluated. 
  I think you would need eval=TRUE in the first chunk, or
<<ortho-xyplot1-code>>
ahead of the plot command in the second.

Duncan Murdoch

> 
> -Michael
> 
> 
> 
> On 7/16/2010 1:14 AM, Deepayan Sarkar wrote:
>> On Thu, Jul 15, 2010 at 1:51 PM, Michael Friendly<friendly at yorku.ca>  wrote:
>>> 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.
>> I usually use this variant of Duncan's suggestion:
>>
>> <<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>>=
>> plot(trellis.last.object())
>> @
>>
>> -Deepayan
>>
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> 
>