[R] rbind and data.frame

[Göran Broström]

On Fri, 7 Dec 2001, Prof Brian Ripley wrote:

> 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!

I know that book too (thanks!). I did what you suggest, and that took 7 
hours to run. Definitely.

Göran

> >
> > 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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> 
> 

-- 
 Göran Broström                      tel: +46 90 786 5223
 professor                           fax: +46 90 786 6614
 Department of Statistics            http://www.stat.umu.se/egna/gb/
 Umeå University
 SE-90187 Umeå, Sweden             e-mail: gb at stat.umu.se

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