>>>>> Ivan Krylov via R-devel writes:
Thanks: I just changed xtfrm.AsIs() as suggested.
Best
-k
> В Fri, 12 Jul 2024 17:35:19 +0200
> Hilmar Berger via R-devel <r-devel@r-project.org> пишет:
>> This can be finally traced to base::rank() (called from
>> xtfrm.default), where I found that
>>
>> "NB: rank is not itself generic but xtfrm is, and rank(xtfrm(x), ....)
>> will have the desired result if there is a xtfrm method. Otherwise,
>> rank will make use of ==, >, is.na and extraction methods for classed
>> objects, possibly rather slowly. "
> The problem is indeed that the vector reaches base::rank in both cases,
> but since it has a class, the function has to construct and evaluate a
> call to .gt every time it wants to compare two elements.
> xtfrm.AsIs even tries to remove the 'AsIs' class before continuing the
> method dispatch process:
>>> if (length(cl <- class(x)) > 1) oldClass(x) <- cl[-1L]
> It doesn't work in the (very contrived) case when 'AsIs' is not the
> first class and it doesn't remove 'AsIs' as the only class (making
> static int equal(...) take the slower branch). What's going to break if
> we allow removing the class attribute altogether? This seems to speed
> up xtfrm(I(x)) and survive LC_ALL=C.UTF-8 make check-devel:
> Index: src/library/base/R/sort.R
> ===================================================================
> --- src/library/base/R/sort.R (revision 86895)
> +++ src/library/base/R/sort.R (working copy)
> @@ -297,7 +297,8 @@
> xtfrm.AsIs <- function(x)
> {
> - if(length(cl <- class(x)) > 1) oldClass(x) <- cl[-1L]
> + cl <- oldClass(x)
> + oldClass(x) <- cl[cl != 'AsIs']
> NextMethod("xtfrm")
> }
> --
> Best regards,
> Ivan
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