Yes. One usually creates a call object when one need to modify it  in some
way -- e.g. alter arguments, change the function -- prior to evaluation.
That doesn't seem to be the case here.

Why isn't  plot(pcal) acceptable?

?do.call

is also a more straightforward way to create and evaluate a call in one go.

-- Bert

On Thu, Jun 28, 2012 at 8:15 AM, Joshua Wiley <jwiley.psych@gmail.com>wrote:

> Hi Jessica,
>
> x <- call("plot", quote(pcaI))
> eval(x)
>
> that said, I suspect you would be better off avoiding this idiom
> altogether.  Storing unevaluated calls is akin to putting tomatoes on
> your sandwich before packing it for work---you can do it but you end
> up with a soggy sandwich by the time you are eating it.  Better to
> store the bread and tomatoe separately and put them together when you
> want a delicious sandwich.
>
> Cheers,
>
> Josh
>
> On Thu, Jun 28, 2012 at 8:03 AM, Jessica Streicher
> <j.streicher@micromata.de> wrote:
> > Hi!
> >
> > I am getting a lot of numbers in the background of the pca screeplots if
> i use call("plot") and eval(somecall).
> > Til now, creating the calls and plotting later on this way worked fine.
> Example:
> >
> >  pcaI<-prcomp(iris[,1:4])
> >  plot(pcaI)
> >
> >  x<-call("plot",pcaI)
> >  eval(x)
> >
> > Anyone got an idea how i can avoid that? (also it might take a second or
> so for the numbers to appear, so wait a bit before you tell me everythings
> fine ^^)
> >        [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
>
>
> --
> Joshua Wiley
> Ph.D. Student, Health Psychology
> Programmer Analyst II, Statistical Consulting Group
> University of California, Los Angeles
> https://joshuawiley.com/
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 

Bert Gunter
Genentech Nonclinical Biostatistics

Internal Contact Info:
Phone: 467-7374
Website:
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm

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