[R] showMethods()! Re: How to find S4 generics?

Martin Maechler maechler at stat.math.ethz.ch
Thu Jul 20 09:55:22 CEST 2006

>>>>> "SpG" == Spencer Graves <spencer.graves at pdf.com>
>>>>>     on Wed, 19 Jul 2006 15:23:58 -0700 writes:

    SpG> Hi, Thomas: Thanks very much.  I haven't tried it yet,
    SpG> but it looks very useful.  Best Wishes, Spencer Graves

Hmm,  ?methods  has been containing for a while

methods> Note:
methods>    This scheme is called _S3_ (S version 3).  For new projects, it is
methods>    recommended to use the more flexible and robust _S4_ scheme
methods>    provided in the 'methods' package.  Functions can have both S3 and
methods>    S4 methods, and function 'showMethods' will list the S4 methods
methods>    (possibly none).

So I wonder why nowbody mentioned the official


  (or are you all not reading the help pages  ;-\) )

It does  not always return / print what I want exactly, and in
the past, at one point I put some effort to make its output more
I didn't put that effort to the end (*)
but for the present case

    showMethods(class = "ddiMatrix", where = "package:Matrix")

at least is pretty useful.

(*)  I think I had added the  'showEmpty = TRUE'  argument
     where the current documentation says

 showM>   showEmpty: logical indicating if methods with empty
 showM>              method lists should be shown at all.  
 showM>     Note that 'FALSE' is _not yet implemented_.

and the non-implementation had a reason: implementation was
definitely much less simple than I had hoped ...


    SpG> Thomas Lumley wrote:
    >> On Wed, 19 Jul 2006, Spencer Graves wrote:
    >>> Am I correct then that the 'methods' function could, at
    >>> least theoretically, be revised so methods(class=...)
    >>> could identify both S3 and S4 methods (ignoring
    >>> inheritance, as it does now, I believe)?
    >>  Here is a function to find methods for a formal
    >> class. It returns a list with elements corresponding to a
    >> generic, and each element is a list of strings showing
    >> all the signatures that contain any of the specified
    >> classes.
    >> If super=TRUE it looks at all superclasses, if ANY=TRUE
    >> it also returns methods for ANY class.
    >> If you have lme4 loaded, try methods4("lmer"
    >> methods4("ddiMatrix") methods4("ddiMatrix",super=TRUE)
    >> -thomas
    >> methods4<-function(classes, super=FALSE, ANY=FALSE){ if
    >> (super) classes<-unlist(sapply(classes, function(cl)
    >> getAllSuperClasses(getClass(cl)))) if (ANY)
    >> classes<-c(classes,"ANY") gens<-allGenerics()@.Data
    >> sigs<-lapply(gens, function(g)
    >> linearizeMlist(getMethods(g))@classes)
    >> names(sigs)<-gens at .Data sigs<-lapply(sigs, function(gen){
    >> gen[unlist(sapply(gen, function(sig) any(sig %in%
    >> classes)))]}) sigs[sapply(sigs,length)>0] }
    >> Thomas Lumley Assoc. Professor, Biostatistics
    >> tlumley at u.washington.edu University of Washington,
    >> Seattle
    >> ______________________________________________
    >> 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 and provide
    >> commented, minimal, self-contained, reproducible code.

    SpG> ______________________________________________
    SpG> R-help at stat.math.ethz.ch mailing list
    SpG> https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do
    SpG> read the posting guide
    SpG> http://www.R-project.org/posting-guide.html and provide
    SpG> commented, minimal, self-contained, reproducible code.

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