Re: [Rd] S4 methods for rbind()

From: Robin Hankin <rksh1_at_cam.ac.uk>
Date: Tue, 26 Oct 2010 14:34:07 +0100

Thank you very much for this Martin.

It works!

There were two gotchas:

  1. One has to add 'deparse.level=1' to the setMethod() function argument list
  2. Adding deparse.level=1 increments nargs() ...so the 3 should be 4.

But now it works!

Best wishes

Robin

On 26/10/10 13:49, Martin Morgan wrote:

> On 10/26/2010 03:53 AM, Robin Hankin wrote:
>   

>> Hello.
>>
>> I am trying to write an S4 method for rbind(). I have a class of objects
>> called 'mdm', and I want to be able to rbind() them to one another.
>>
>> I do not want the method for rbind() to coerce anything to an mdm object.
>> I want rbind(x1,x2,x1,x2) to work as expected [ie rbind() should take any
>> number of arguments].
>>
>> This is what I have so far:
>>
>>
>> setGeneric(".rbind_pair", function(x,y){standardGeneric(".rbind_pair")})
>> setMethod(".rbind_pair", c("mdm", "mdm"), function(x,y){.mdm.cPair(x,y)})
>> setMethod(".rbind_pair", c("mdm", "ANY"),
>> function(x,y){.mdm_rbind_error(x,y)})
>> setMethod(".rbind_pair", c("ANY", "mdm"),
>> function(x,y){.mdm_rbind_error(x,y)})
>> setMethod(".rbind_pair", c("ANY", "ANY"),
>> function(x,y){.mdm_rbind_error(x,y)})
>>
>> ".mdm_rbind_error" <- function(x,y){
>> stop("an mdm object may only be rbinded to another mdm object")
>> }
>>
>> ".mdm.rbind_pair" <- function(x,y){
>> stopifnot(compatible(x,y))
>> mdm(rbind(xold(x),xold(y)),c(types(x),types(y))) # this is the "meat" of
>> the rbind functionality
>> }
>>
>> setGeneric("rbind")
>> setMethod("rbind", signature="mdm", function(x, ...) {
>> if(nargs()<3)
>> .mdm_rbind_pair(x,...)
>> else
>> .mdm_rbind_pair(x, Recall(...))
>> })
>>
>>
>> But
>>
>>
>> LE223:~/packages% sudo R CMD INSTALL ./multivator
>> [snip]
>> Creating a new generic function for "tail" in "multivator"
>> Error in conformMethod(signature, mnames, fnames, f, fdef, definition) :
>> in method for ‘rbind’ with signature ‘deparse.level="mdm"’: formal
>> arguments (... = "mdm", deparse.level = "mdm") omitted in the method
>> definition cannot be in the signature
>>
> Hi Robin
>
> try getGeneric("rbind") and showMethods("rbind") after your setGeneric;.
> The generic is dispatching on 'deparse.level'. 'deparse.level' is
> missing from your method definition, and so can't be used as the
> signature for your method. Try to set the ... explicitly as the
> signature to be used for dispatch.
>
> setGeneric("rbind",
>     function(..., deparse.level=1) standardGeneric("rbind"),
>     signature = "...")
>
> Martin
>
>   

>> Error : unable to load R code in package 'multivator'
>> ERROR: lazy loading failed for package ‘multivator’
>> * removing ‘/usr/local/lib64/R/library/multivator’
>> * restoring previous ‘/usr/local/lib64/R/library/multivator’
>> LE223:~/packages%
>>
>>
>> I can't understand what the error message is trying to say.
>>
>> Can anyone advise on a fix for this?
>>
>>
>>
>
>
-- 
Robin K. S. Hankin
Uncertainty Analyst
University of Cambridge
19 Silver Street
Cambridge CB3 9EP
01223-764877

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