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how to define method for "+" function in a new class

4 messages · Martin Morgan, James Foadi

#
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")


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
#
I don't know why a "3D" appears instead of a "(".
Please, interpret a "( whenever you see a "3D".

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



-----Original Message-----
From: r-devel-bounces at r-project.org on behalf of james.foadi at diamond.ac.uk
Sent: Wed 07/07/2010 16:09
To: r-devel at r-project.org
Subject: [Rd] how to define method for "+" function in a new class
 


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")


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
#
On 07/07/2010 08:09 AM, james.foadi at diamond.ac.uk wrote:
If I
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
An object of class "A"
Slot "x":
[1] 6 6 6 6 6

but also
An object of class "A"
Slot "x":
[1] 5 8 9 8 5

Martin

  
    
#
Thank you, Martin! Very clear.

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



-----Original Message-----
From: Martin Morgan [mailto:mtmorgan at fhcrc.org]
Sent: Wed 07/07/2010 16:43
To: Foadi, James (Imperial Coll.,RAL,DIA)
Cc: r-devel at r-project.org
Subject: Re: [Rd] how to define method for "+" function in a new class
On 07/07/2010 08:09 AM, james.foadi at diamond.ac.uk wrote:
If I
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
An object of class "A"
Slot "x":
[1] 6 6 6 6 6

but also
An object of class "A"
Slot "x":
[1] 5 8 9 8 5

Martin
-- 
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