Message-ID: <93d6f2a80911141600k7600cbf9n10b95bda2af9c287@mail.gmail.com>
Date: 2009-11-15T00:00:39Z
From: Juliet Hannah
Subject: when vectorising does not work: silent function fail?
In-Reply-To: <alpine.LRH.2.01.0911100916560.10481@hymn14.u.washington.edu>
>
> Also, you probably get less data copying by using a for() or while() loop
> than by using apply() in this context.
Why may there be less data copying with "for" and "while" compared to apply?
>
> Finally, the overhead of formula parsing and model matrix construction
> repeated thousands of times probably dominates this computation; if it isn't
> just a one-off it would probably be worth a lower-level implementation.
>
Does "lower-level implementation" mean code this outside of R.
Thanks!
Juliet