[R] rbind and data.frame

[Prof Brian Ripley]

On Fri, 7 Dec 2001, [iso-8859-1] Göran Broström wrote:

> On Wed, 5 Dec 2001, Göran Broström wrote:
>
> [...]
>
> > My real problem is how to create a data frame in a sequentially growing
> > manner, when I know the final size (no of cases). I want to avoid to
> > call 'rbind' many times, and instead create an 'empty' data frame in
> > one call, and then fill it. Are there better ways of doing this?
>
> Got no answer to this one, so I provide one myself:

The usual answer is to create a data frame of the desired size and
populate it via indexing.  That's in some books I know!

>
> The answer is: Yes, definitely. I did this, with pure  R  code, and
> created a new data frame with around 58000 records. It took 7 hours to
> run. I then did it with compiled code (Fortran), and that made a slight
> difference:  It took 4.8 seconds(!).
>
> Göran
>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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