Re: [Rd] question about trailing arguments in an S4 method

From: Seth Falcon <sfalcon_at_fhcrc.org>
Date: Sun 17 Dec 2006 - 00:06:57 GMT

Ben Bolker <bolker@zoo.ufl.edu> writes:

> I'm trying to add arguments to the AIC method
> for some classes -- things like
> weights=TRUE to calculate AIC weights
> corr=TRUE, nobs to calculate AICc
> delta=TRUE to put a delta-AIC column in the output.
>
> The problem is that AIC is defined as
> AIC(object, ..., k=2) where k is the constant associated
> with the penalty term and ... is a list of objects
> that will have their AICs calculated and listed.
> Thus I'm not allowed (I think) to extend the definition to
>
> AIC(object, ..., nobs, corr=FALSE, delta=FALSE, weights=FALSE, k=2)

I think you can add args before the '...'. However, you will need to provide values for them in all calls or else they will steal a fit from the '...' args.

I don't understand really what you are trying to achieve, so this may not be helpful. Nevertheless, here is a dummy example that you may find useful.

setClass("Foo",

         representation=representation(
           fit="lm"))

setMethod("AIC", "Foo",
          function(object, weights=TRUE, delta=TRUE, ..., k=2) {
              ans <- AIC(object=object@fit, k=k, ...)
              args1 <- list(weights=weights, delta=delta, k=k)
              cat("args\n")
              print(args1)
              cat("answer:\n")
              print(ans)
          })

example("AIC")
foo <- new("Foo", fit=lm1)
AIC(foo)
## AIC(foo, lm1) # this doesn't work, lm1 gets picked up as the weights arg AIC(foo, weights=FALSE, delta=TRUE, lm1, lm1, lm1)

+ seth



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