Re: [R] Overloading %*%

From: Martin Morgan <mtmorgan_at_fhcrc.org>
Date: Sun, 16 Mar 2008 19:43:11 -0700

Spencer Graves wrote:
> 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

Use the 'classes' argument to showMethods, either with or without a function as first argument.

> 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

use includeDef=TRUE with showMethods, or getMethod to get a specific method, or, for some fun, selectMethod to find the method to which object dispatch occurs. I'm not sure how to dump the method to a file.

Martin

> "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
>>
>> ______________________________________________
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>>

>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


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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 and provide commented, minimal, self-contained, reproducible code. Received on Mon 17 Mar 2008 - 02:51:47 GMT

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