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

[Martin Maechler]

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
(https://svn.R-project.org/R-packages/trunk/Matrix/R/AllGeneric.R)
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 at x, ..., na.rm = na.rm))


I think you can safely follow this recipe;

Regards,
Martin Maechler, ETH Zurich


>>>>> "Parlamis" == Parlamis Franklin <fparlamis at mac.com>
>>>>>     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 at 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> ______________________________________________
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