>>>>> Michael Lawrence <lawrence.mich...@gene.com> >>>>> on Thu, 1 Feb 2018 06:12:20 -0800 writes:
> On Thu, Feb 1, 2018 at 1:21 AM, Martin Maechler <maech...@stat.math.ethz.ch> > wrote: >> >>>>> Michael Lawrence <lawrence.mich...@gene.com> >> >>>>> on Tue, 30 Jan 2018 10:37:38 -0800 writes: >> >> > I agree that it would make sense for the object to have c("by", >> "list") as >> > its class attribute, since the object is known to behave as a list. >> >> Well, but that (list behavior) applies to most non-simple S3 >> classed objects, say "data.frame", say "lm" to start with real basic ones. >> >> The later part of the discussion, seems more relevant to me. >> Adding "list" to the class attribute seems as wrong to me as >> e.g. adding "double" to "Date" or "POSIXct" (and many more such cases). >> >> > There's a distinction though. Date and POSIXct should not really behave as > double values (an implementation detail), but "by" is expected to behave as > a list (when it is one). yes, you are right.... As I'm "never"(*) using by(), I'm glad to leave this issue to you. Martin --- *) Never .... [James Bond, 1983] > For the present case, we should stay with focusing on is.list() >> being true after as.list() .. the same we would do with >> as.numeric() and is.numeric(). >> >> Martin >> >> > However, it would may be too disruptive to make this change at this >> point. >> > Hard to predict. >> >> > Michael >> >> > On Mon, Jan 29, 2018 at 5:00 PM, Dario Strbenac < >> dstr7...@uni.sydney.edu.au> >> > wrote: >> >> >> Good day, >> >> >> >> I'd like to suggest the addition of an as.list method for a by >> object that >> >> actually returns a list of class "list". This would make it safer >> to do >> >> type-checking, because is.list also returns TRUE for a data.frame >> variable >> >> and using class(result) == "list" is an alternative that only >> returns TRUE >> >> for lists. It's also confusing initially that >> >> >> >> > class(x) >> >> [1] "by" >> >> > is.list(x) >> >> [1] TRUE >> >> >> >> since there's no explicit class definition for "by" and no mention >> if it >> >> has any superclasses. >> >> >> >> -------------------------------------- >> >> Dario Strbenac >> >> University of Sydney >> >> Camperdown NSW 2050 >> >> Australia >> >> >> >> ______________________________________________ >> >> R-devel@r-project.org mailing list >> >> https://stat.ethz.ch/mailman/listinfo/r-devel >> >> >> >> >> >> > [[alternative HTML version deleted]] >> >> > ______________________________________________ >> > R-devel@r-project.org mailing list >> > https://stat.ethz.ch/mailman/listinfo/r-devel >> >> > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel