[Rd] degraded performance with rank()

[Gabor Grothendieck]

On Sat, May 30, 2009 at 10:58 AM, Tim Bergsma <timb at metrumrg.com> wrote:
> Hi.
>
> I'm maintaining a package that creates an object that is essentially a
> classed version of numeric.  I updated recently from 2.7.1 to 2.9.0,
> and merges involving my class suddenly took a huge performance hit.
> I've traced the problem to something near rank().  From NEWS, it seems
> rank() etc. changed in 2.8.0.  Methods for xtfrm() are supposed to
> help, but I've had no success.  There was some chatter about this in
> the archives back in Sept 08 (though apparently regarding S4), with a
> suggestion that it is related to `[.` methods.  That has been my
> experience.  In the toy example below, the problem disappears if
> `[.my` is not defined.  Under R 2.7.1 on Mac, both cat() statements
> take the same amount of time, and that time depends very little on the
> length of x.  Under 2.9.0, the classed version takes much longer, and
> the time grows (more than?) exponentially with length(x).
>
> Is there something I can do to xtfrm.my() or [.my(), etc. to restore
> the performance?
>
> Thanks in advance,
>
> Tim.
>
> rm(...deleted rest of line...

OUCH!!!

Please don't post code like that.  Someone may wipe out valuable
objects in their workspace.