Re: [R] trouble with S4 methods for group "Summary"

From: Martin Maechler <>
Date: Fri 30 Dec 2005 - 08:22:56 EST

Yes, setting 'Summary' S4 group methods is a bit painful, because the S3 generic starts with "...".

In the 'Matrix' CRAN package,
we do the following {thanks to hints by John Chambers IIRC}:

Our AllGeneric.R file
( ends with

###---- Group Generics ----
## The following are **WORKAROUND** s currently needed for all non-Primitives:

## "Math"

setGeneric("log", group="Math")
setGeneric("gamma", group="Math")
setGeneric("lgamma", group="Math")

## "Math2"
setGeneric("round", group="Math2")
setGeneric("signif", group="Math2")

## "Summary" --- this needs some hoop jumping that may become unnecessary ## in a future version of R (>= 2.3.x):

.max_def <- function(x, ..., na.rm = FALSE) base::max(x, ..., na.rm = na.rm)
.min_def <- function(x, ..., na.rm = FALSE) base::min(x, ..., na.rm = na.rm)
.range_def <- function(x, ..., na.rm = FALSE) base::range(x, ..., na.rm = na.rm)
.prod_def <- function(x, ..., na.rm = FALSE) base::prod(x, ..., na.rm = na.rm)
.sum_def <- function(x, ..., na.rm = FALSE) base::sum(x, ..., na.rm = na.rm)
.any_def <- function(x, ..., na.rm = FALSE) base::any(x, ..., na.rm = na.rm)
.all_def <- function(x, ..., na.rm = FALSE) base::all(x, ..., na.rm = na.rm)

setGeneric("max", function(x, ..., na.rm = FALSE) standardGeneric("max"),

           useAsDefault = .max_def, group = "Summary") setGeneric("min", function(x, ..., na.rm = FALSE) standardGeneric("min"),

           useAsDefault = .min_def, group="Summary") setGeneric("range", function(x, ..., na.rm = FALSE) standardGeneric("range"),

           useAsDefault = .range_def, group="Summary") setGeneric("prod", function(x, ..., na.rm = FALSE) standardGeneric("prod"),

           useAsDefault = .prod_def, group="Summary")

setGeneric("sum", function(x, ..., na.rm = FALSE) standardGeneric("sum"),
           useAsDefault = .sum_def, group="Summary")
setGeneric("any", function(x, ..., na.rm = FALSE) standardGeneric("any"),
           useAsDefault = .any_def, group="Summary")
setGeneric("all", function(x, ..., na.rm = FALSE) standardGeneric("all"),
           useAsDefault = .all_def, group="Summary")


and then in dMatrix.R we have

## This needs extra work in ./AllGeneric.R : setMethod("Summary", signature(x = "dMatrix", na.rm = "ANY"),

          function(x, ..., na.rm) callGeneric(x@x, ..., na.rm = na.rm))

I think you can safely follow this recipe;

Martin Maechler, ETH Zurich

>>>>> "Parlamis" == Parlamis Franklin <> >>>>> on Wed, 28 Dec 2005 19:52:00 -1000 writes:

    Parlamis> Hello.  This question concerns the Methods
    Parlamis> package.  I have created a new class and am trying
    Parlamis> to set a method for it for S4 group generic
    Parlamis> "Summary".  I have run into some signature
    Parlamis> problems.  An example:

    >> setClass("track", representation(x="numeric",     >> y="character"))
    Parlamis> [1] "track"
    >> setGeneric("max", group="Summary")     Parlamis> [1] "max"
    >> setMethod("Summary", signature(x="track"), function(x,     >> ..., na.rm)
    Parlamis> callGeneric(x@x, ..., na.rm)) [1] "Summary"     >> dd<-new("track", x=c(1,2), y="abc") max(dd)     Parlamis> [1] -Inf Warning message: no finite arguments to     Parlamis> max; returning -Inf
    >> showMethods("max")         

    Parlamis> Function "max": na.rm = "ANY" na.rm = "track"     Parlamis> na.rm = "missing" (inherited from na.rm = "ANY")

    Parlamis> As you can see from the above, the method I tried
    Parlamis> to set for "max" (via "Summary") was defined for
    Parlamis> the formal argument "na.rm" not "x".  This makes
    Parlamis> sense because the standardGeneric created for max
    Parlamis> only allows methods to be defined for argument
    Parlamis> "na.rm"

    >> max
    Parlamis> 	standardGeneric for "max" defined from package
    Parlamis> "base" belonging to group(s): Summary         
    Parlamis> 	function (..., na.rm = FALSE)
    Parlamis> standardGeneric("max") <environment: 0x19447a28>
    Parlamis> Methods may be defined for arguments: na.rm

    Parlamis> However, group "Summary" purports to allow you to     Parlamis> define methods for arguments "x" and "na.rm".

    >> Summary
    Parlamis> groupGenericFunction for "Summary" defined from     Parlamis> package "base"         

    Parlamis> 	function (x, ..., na.rm = FALSE) stop("function
    Parlamis> 'Summary' is a group generic; do not call it
    Parlamis> directly", domain = NA) <environment: 0x16aef098>
    Parlamis> Methods may be defined for arguments: x, na.rm

    Parlamis> How does this work?  Can someone point me to where
    Parlamis> I am going wrong, and explain how to define S4
    Parlamis> methods for group "Summary" for argument "x"?
    Parlamis> Perhaps I need to do more in my "setGeneric" call?     Parlamis> Thanks in advance.
    Parlamis> ______________________________________________
    Parlamis> mailing list
    Parlamis> PLEASE do read the posting guide!     Parlamis> mailing list PLEASE do read the posting guide! Received on Fri Dec 30 08:29:20 2005

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