Re: [R] Finding code for R functions

From: Berton Gunter <gunter.berton_at_gene.com>
Date: Wed 19 Oct 2005 - 07:38:38 EST


See chapter 5 on object oriented programming in the R language definition manual. Also the ?UseMethod man page. These will explain R's (S3) method dispatch procedures.

Finally, search on CRAN for the R New newsletter article on namespaces, which is where you'll find info on why you can't "see" certain functions. See ?getAnywhere to learn how to see code for functions in namespaces.

"The business of the statistician is to catalyze the scientific learning process." - George E. P. Box    

> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch
> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Wolfrum, Ed
> Sent: Tuesday, October 18, 2005 2:27 PM
> To: r-help@stat.math.ethz.ch
> Subject: [R] Finding code for R functions
>
> Greetings,
>
> I am trying to figure out how to find the source code for R
> functions. I
> am specifically interested in finding the code for the "prcomp"
> function. I know that typing the function name without
> parenthesis will
> lead to the code (or to a .Internal or .FORTRAN or .C call).
> However, I
> don't really understand what is going on. For example, typing "mean"
> gives a "UseMethod" response, while typing "mean.default" give the
> actual code:
>
> > mean
> function (x, ...)
> UseMethod("mean")
> <environment: namespace:base>
>
> > mean.default
> function (x, trim = 0, na.rm = FALSE, ...)
> ---SNIP---
> }
> <environment: namespace:base>
>
> Why is this? What does "mean.default" mean? I tried the same
> thing with
> "prcomp". With the stats package loaded, I cannot get to the
> source code
> for "prcomp".
>
> > require(stats)
> [1] TRUE
> > prcomp
> function (x, ...)
> UseMethod("prcomp")
> <environment: namespace:stats>

> > prcomp.default
> Error: object "prcomp.default" not found
>
> How do I find the prcomp code? Are there general rules for finding the
> source code for functions that I should know?
>
> Thanks in Advance,
>
> Edward J. Wolfrum, Ph.D.
> National Renewable Energy Laboratory
> Golden, Colorado
>
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R-help@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 Received on Wed Oct 19 07:42:52 2005

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