On 05/02/2011 5:58 PM, Bogaso Christofer wrote:
Thanks Martin for your help. Although your suggestion is working for
somewhat restrictive case, I would like to make thing more generic. For
example:
setMethod("Arith", c("Me", "Me"), function(e1, e2) callGeneric(e1@x1,
e2@x1))
with in (new1 + new2) is working perfectly, however if I want to add
arbitrary number of objects then it fails:
new1 + new2 - new1
Error in new1 + new2 - new1 : non-numeric argument to binary operator
What can I do to handle this?
Your function returns a number, not a Me object, so R ends up with a
number minus a Me. You could define what to do in that case,
or have your function construct a Me object and return that, in which
case you'll only see the signature (Me, Me). In the latter case you
won't be able to handle things like (new1 + 1).
Duncan Murdoch
Thanks and regards,
-----Original Message-----
From: Martin Morgan [mailto:mtmor...@fhcrc.org]
Sent: 06 February 2011 03:57
To: Bogaso Christofer
Cc: r-help@r-project.org
Subject: Re: [R] Seeking help to define method for '+'
On 02/05/2011 02:19 PM, Bogaso Christofer wrote:
Dear all, I am trying to define "+" method for my newly defined s4 class
which is as follows:
setClass("Me", sealed=F,representation(x1 = "numeric", x2 = "character"))
new1<- new("Me", x1=2, x2="comment1")
new2<- new("Me", x1=3, x2="comment1")
setMethod("+", "Me", definition=function(x,y) cat(x@x1 + y@x1, "\n"))
However while am trying to set method, it fails:
Error in conformMethod(signature, mnames, fnames, f, fdef, definition) :
in method for '+' with signature 'e1="Me"': formal arguments (e1 = "Me",
e2 = "Me") omitted in the method definition cannot be in the signature
From
getGeneric("+")
standardGeneric for "+" defined from package "base"
belonging to group(s): Arith
function (e1, e2)
standardGeneric("+", .Primitive("+"))
<environment: 0x19a9918>
Methods may be defined for arguments: e1, e2
Use showMethods("+") for currently available ones.
you can see that the generic is defined to dispatch on two arguments in
a signature function(e1, e2). So
setMethod("+", c("Me", "Me"), function(e1, e2) e1@x1 + e2@x1)
but S4 also has group generics, and
setMethod("Arith", c("Me", "Me"),
function(e2, e2) callGeneric(e1@x1, e2@x1))
will define not just + but also - and other functions in the 'Arith'
group. See
?GroupGenericFunctions
Martin
I am just started learning s4 class system therefore please forgive me if
I
have some any bad mistakes. Anyway I would really appreciate if someone
point me how should I proceed.
Thanks and reagrds,
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