From jeffrey.ryan at lemnica.com  Sat Nov  5 17:45:14 2011
From: jeffrey.ryan at lemnica.com (Jeffrey Ryan)
Date: Sat, 5 Nov 2011 11:45:14 -0500
Subject: [Rd] Efficiency of factor objects
In-Reply-To: <1320510627.31269.26.camel@milan>
References: <CACLVabVigMZ-YNr2NP_wmbs6YQhMr-LVULetnEgs8yLGPheftA@mail.gmail.com>
	<1320510627.31269.26.camel@milan>
Message-ID: <CABDUZc8n8CV8LgsUbm2UUaUGfu7wfNqVjbAiZOW7-UwJczaHsw@mail.gmail.com>

Or better still, extend R via the mechanisms in place.  Something akin
to a fast factor package.  Any change to R causes downstream issues in
(hundreds of?) millions of lines of deployed code.

It almost seems hard to fathom that a package for this doesn't already
exist. Have you searched CRAN?

Jeff



On Sat, Nov 5, 2011 at 11:30 AM, Milan Bouchet-Valat <nalimilan at club.fr> wrote:
> Le vendredi 04 novembre 2011 ? 19:19 -0400, Stavros Macrakis a ?crit :
>> R factors are the natural way to represent factors -- and should be
>> efficient since they use small integers. ?But in fact, for many (but
>> not all) operations, R factors are considerably slower than integers,
>> or even character strings. ?This appears to be because whenever a
>> factor vector is subsetted, the entire levels vector is copied.
> Is it so common for a factor to have so many levels? One can probably
> argue that, in that case, using a numeric or character vector is
> preferred - factors are no longer the "natural way" of representing this
> kind of data.
>
> Adding code to fix a completely theoretical problem is generally not a
> good idea. I think you'd have to come up with a real use case to hope
> convincing the developers a change is needed. There are probably many
> more interesting areas where speedups can be gained than that.
>
>
> Regards
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>



-- 
Jeffrey Ryan
jeffrey.ryan at lemnica.com

www.lemnica.com
www.esotericR.com



[Rd] Efficiency of factor objects
Jeffrey Ryan