[R] Overloading %*%

[Spencer Graves]

Thanks, Ken. 

      1.  How can I find S4 methods for a given function given class(es) 
of objects?  The 'showMethods' function lists available generics for a 
given function;  "showMethods('%*%')" just produced for me a list of 52 
different signatures for "%*%".  However, I don't know how to find the 
functions with methods for a particular class.  The 'methods' function 
will produce either S3 methods for a given function or S3 functions for 
a given class.  It would help me if the 'methods' help page included 
"See Also" and "Examples" for S4 classes also, but it doesn't. 

      2.  How can I find source code for S4 methods?  I tried 
"dumpMethods('%*%', 'mmult.R')" and got an apparently empty file of 0 
KB.  Then I tried 'dumpMethod("%*%", c(x="TsparseMatrix", y="ANY"))' and 
got a file with the following: 

setMethod("%*%", structure(c("TsparseMatrix", "ANY"), .Names = c("x", "y")),
NULL
)

      Thanks again for your reply regarding "%*%". 
      Spencer Graves   

knoblauch wrote:
> Joe Cainey <jcainey <at> gmail.com> writes:
>   
>> Is it possible to supply a new method for the %*% operator? 
>>     
> clipped
>   
>> I've tried to do the same thing with %*%:
>>
>> "%*%.ad" <- function(a,b)
>> {
>>     # further code here
>> }
>> However this doesn't work; the new method is never called and the standard
>> %*% operator is used instead. I've had a look at the documentation and it
>> appears to be because the %*% operator is not part of the "Math", "Ops",
>> "Summary" or "Complex" groups. I was wondering if anybody knew of a
>> work-around for this?
>>     
> According to the help page for %*%, it is S4 generic but not S3, so
> you might make further progress using S4 methods.
>
>   
>> Thanks,
>>
>> Joe Cainey
>>
>>     
> best,
>
> Ken
>
> ______________________________________________
> R-help at 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.
>