how to define method for "+" function in a new class
On 07/07/2010 08:09 AM, james.foadi at diamond.ac.uk wrote:
Dear R developers,
I have a new class, which I called "Molecule", and have tried to define =
a "+" operation for 2 objects of this class.
This is what I have written so far, although the method is not complete =
(I'm trying to look at it at intermediate stages):
setMethod(
f=3D"+",
signature(x=3D"Molecule",y=3D"Molecule"),
definition=3Dfunction(x,y,...)
{
# Check both objects are correct
checkMolecule(x)
checkMolecule(y)
# Extract chains information
ch1 <- getMoleculeChains(x)
ch2 <- getMoleculeChains(y)
union_ch <- unique(c(ch1,ch2))
not_used <- .ALPHABET
for (i in seq(along =3D union_ch))
{
idx <- which(not_used !=3D union_ch[i])
if (length(idx) !=3D 0) not_used <- not_used[idx]
}
return(not_used)
}
)
The definition of class Molecule is included earlier in the same file. =
When I source it, I get the following error message:
Error in match.call(fun, fcall) :=20
unused argument(s) (x =3D "Molecule", y =3D "Molecule")
If I
getGeneric("+")
standardGeneric for "+" defined from package "base"
belonging to group(s): Arith
function (e1, e2)
standardGeneric("+", .Primitive("+"))
<environment: 0xb432f8>
Methods may be defined for arguments: e1, e2
Use showMethods("+") for currently available ones.
I see that the generic is defined to take two arguments e1 and e2. So
setMethod("+", c("Molecule", "Molecule"), function(e1, e2) {
## ...
})
but actually here it might often pay to discover ?GroupGenericFunctions
and end up with something like
setClass("A", representation=representation(x="numeric"))
setMethod("Arith", c("A", "A"), function(e1, e2) {
new(class(e1), x=callGeneric(e1=e1 at x, e2=e2 at x))
})
and then
new("A", x=1:5) + new("A", x=5:1)
An object of class "A" Slot "x": [1] 6 6 6 6 6 but also
new("A", x=1:5) * new("A", x=5:1)
An object of class "A" Slot "x": [1] 5 8 9 8 5 Martin
I can't see what's wrong in my method definition. Can anyone help me = with this? J Dr James Foadi PhD Membrane Protein Laboratory (MPL) Diamond Light Source Ltd Diamond House Harewell Science and Innovation Campus Chilton, Didcot Oxfordshire OX11 0DE Email : james.foadi at diamond.ac.uk Alt Email: j.foadi at imperial.ac.uk
Martin Morgan Computational Biology / Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N. PO Box 19024 Seattle, WA 98109 Location: Arnold Building M1 B861 Phone: (206) 667-2793