From rksh1 at cam.ac.uk  Tue Oct 26 12:53:49 2010
From: rksh1 at cam.ac.uk (Robin Hankin)
Date: Tue, 26 Oct 2010 11:53:49 +0100
Subject: [Rd] S4 methods for rbind()
Message-ID: <4CC6B33D.5050106@cam.ac.uk>

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
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



[Rd] S4 methods for rbind()
Robin Hankin