[R] is library loaded

[John Fox]

Dear Robert,

packageLoaded() may well be a bad name but loadedNamespaces() won't detect a
package without a namespace. It therefore seemed safe to me to check the
path, which would include both packages with and without namespaces. With
respect to loading and attaching, I thought that library() both loaded a
package (with or without a namespace) and attached it to the search path,
but I must admit that I'm easily confused about these distinctions. 

Regards,
 John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox 
-------------------------------- 

> -----Original Message-----
> From: Robert Gentleman [mailto:rgentlem at fhcrc.org] 
> Sent: Tuesday, September 13, 2005 3:53 PM
> To: John Fox
> Cc: uofiowa at gmail.com; r-help at stat.math.ethz.ch
> Subject: Re: [R] is library loaded
> 
> Hi,
> 
>   Almost surely this is a bad name. With the advent of name 
> spaces it is important to distinguish between loading and 
> attaching. This function tests for attached packages. To test 
> for loaded packages we already have
>   loadedNamespaces.
> 
>   Best wishes,
>     Robert
> 
> John Fox wrote:
> > Dear Omar,
> > 
> > The following function tests whether a package is in the 
> search path 
> > (with the package name given in quotes):
> > 
> > packageLoaded <- function(name) 0 != length(grep(paste("^package:", 
> > name, "$", sep=""), search()))
> > 
> > I hope this helps,
> >  John
> > 
> > --------------------------------
> > John Fox
> > Department of Sociology
> > McMaster University
> > Hamilton, Ontario
> > Canada L8S 4M4
> > 905-525-9140x23604
> > http://socserv.mcmaster.ca/jfox
> > --------------------------------
> > 
> > 
> >>-----Original Message-----
> >>From: r-help-bounces at stat.math.ethz.ch 
> >>[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Omar Lakkis
> >>Sent: Tuesday, September 13, 2005 2:09 PM
> >>To: r-help at stat.math.ethz.ch
> >>Subject: [R] is library loaded
> >>
> >>Is there a way to test if a library has been loaded?
> >>
> >>is.loaded does not give me what I want, I am looking to say:
> >>
> >>if loaded(Rdbi) dbSendQuery(conn, q)
> >>if loaded(RODBC) sqlQuery(conn, q)
> >>
> >>I need this to support both unix and windows platforms as I 
> could not 
> >>find a windows distribution for RdbiPgSQL. I am using R 2.1.0 and 
> >>postgresql. I will be connecting to the database using Rdbi and 
> >>RdbiPgSQL and have other developers using windows connect 
> with RODBC, 
> >>unless someone can suggest a better solution.
> >>
> >>______________________________________________
> >>R-help at stat.math.ethz.ch mailing list
> >>https://stat.ethz.ch/mailman/listinfo/r-help
> >>PLEASE do read the posting guide! 
> >>http://www.R-project.org/posting-guide.html
> > 
> > 
> > ______________________________________________
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> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide! 
> > http://www.R-project.org/posting-guide.html
> > 
> 
> --
> Robert Gentleman, PhD
> Program in Computational Biology
> Division of Public Health Sciences
> Fred Hutchinson Cancer Research Center
> 1100 Fairview Ave. N, M2-B876
> PO Box 19024
> Seattle, Washington 98109-1024
> 206-667-7700
> rgentlem at fhcrc.org