[R] how to create data.frames from vectors with duplicates

[peter dalgaard]

On Sep 8, 2011, at 03:18 , zhenjiang xu wrote:

> Thanks for all your replies. I am using rowsum() and it looks efficient. I
> hope I could do some benchmark sometime in near future and let people know.
> Or is there any benchmark result available?

I'm a bit surprised that no-one thought of xtabs(x ~ y)

It won't win the speed competition, though.

-- 
Peter Dalgaard, Professor
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
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Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com