Re: [R] How to build a package which loads Rgraphviz (if installed)...

From: William Revelle <lists_at_revelle.net>
Date: Sat, 12 Jul 2008 16:47:54 -0500

Soren,
When I had an almost identical problem last year. I also wanted to use Rraphviz but only if people had it.

Kurt Hornik suggested that I replace a direct call to the function, foo, that uses Rgraphviz with

if(require("Rgraphviz")) foo()

Bill

At 10:23 PM +0200 7/12/08, Søren Højsgaard wrote:
>Dear List,
>I use Rgraphviz for display of graphs in some
>packages. Since Rgraphviz is no longer on CRAN
>it needs to be installed from Bioconductor and
>that is fine, but I have trouble figureing out
>the following: I create a plot method which - if
>Rgraphviz is installed - uses Rgraphviz for
>displaying and otherwise does nothing. This is
>implemented as:
>
>
> if (!("package:Rgraphviz" %in% search())){
> if("Rgraphviz" %in% installed.packages()){
> require(Rgraphviz)
> } else {
> cat("The Rgraphviz package (from
>Bioconductor) must be installed to display the
>models\n")
> return()
> }
> }
> ... else go on and do the plotting...
>
>When I run rcmd check packagename (on Windows XP, using R.2.7.1) I get
>
>* checking for unstated dependencies in R code ... WARNING
>'library' or 'require' calls not declared from:
> Rgraphviz
>See the information on DESCRIPTION files in the chapter 'Creating R
>packages' of the 'Writing R Extensions' manual.
>
>I can not state Rgraphviz in the Depends-field
>of the DESCRIPTION file because then the package
>does not pass the windows checks for going on
>CRAN. I can not see any solution from "writing R
>extensions", but I apologize if I have
>overlooked it. Does anyone have a suggestion on
>what to do?
>
>Cheers
>Søren
>
>
>
>______________________________________________
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-- 
William Revelle		http://personality-project.org/revelle.html
Professor			http://personality-project.org/personality.html
Department of Psychology             http://www.wcas.northwestern.edu/psych/
Northwestern University	http://www.northwestern.edu/
Attend  ISSID/ARP:2009               http://issid.org/issid.2009/

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Received on Sat 12 Jul 2008 - 21:53:33 GMT

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