[Rd] relist, an inverse operator to unlist

[Andrew Clausen]

Hi Gabor,

Can you suggest some examples of how your proposal could be used?
Reshape never returns a vector.

Cheers,
Andrew

On Tue, May 22, 2007 at 07:36:56PM -0400, Gabor Grothendieck wrote:
> One additional idea.
> 
> I wonder if reshape might be promoted to a generic and relist made
> into methods for it.  The unlisted version of an object would be the "long"
> version and the original version of the list would be the "wide" version.
> 
> This would consolidate the two concepts together and make it
> easier to use since the user could leverage his knowledge of
> how reshape works to lists where it would work analogously.
> 
> Essentially reshape(myList, direction = "long") would be
> similar to unlist but would add the attributes need to reverse
> the procedure and reshape(myList, direction = "wide")
> would perform the inversion.
> 
> I am not sure if the reshape package has any bearing here
> as well.
> 
> On 5/22/07, Andrew Clausen <clausen at econ.upenn.edu> wrote:
> >Hi Seth,
> >
> >On Mon, May 21, 2007 at 05:15:10PM -0700, Seth Falcon wrote:
> >> I will also add that the notion of a default argument on a generic
> >> function seems a bit odd to me.  If an argument is available for
> >> dispatch, I just don't see what sense it makes to have a default.  In
> >> those cases, the default should be handled by the method that has a
> >> signature with said argument matching the "missing" class.
> >>
> >> What often does make sense is to define a generic function where some
> >> argument are not available for dispatch.  For example:
> >>
> >> setGeneric("foo", signature="flesh",
> >>            function(flesh, skeleton=attr(flesh, "skeleton")
> >>                standardGeneric("foo")))
> >
> >That's an excellent suggestion.  Thanks!  However, I had to set the 
> >signature
> >to c("numeric", "missing") rather than just "numeric".
> >
> >I have uploaded a new version here:
> >
> >       http://www.econ.upenn.edu/~clausen/computing/relist.R
> >
> >Cheers,
> >Andrew
> >
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