[R] question

peter dalgaard pdalgd at gmail.com
Wed Feb 15 21:11:13 CET 2012

On Feb 15, 2012, at 15:17 , R. Michael Weylandt wrote:

> But that's dropping unused factor levels, not the drop of `[`

Is there a good reason that nobody has suggested looking at aggregate()? There would seem to be a little red tape to sort out, but, I mean, this is generally speaking what aggregate() is intended for.

(And please choose an intelligent Subject: field next time. We now have two "question" threads mixed up, not to mention multiple other long-dead "question" threads from the last 1.5 years that get resurrected and inserted at the head of the thread.)  


> Michael
> On Wed, Feb 15, 2012 at 9:16 AM, David Winsemius <dwinsemius at comcast.net> wrote:
>> On Feb 15, 2012, at 7:19 AM, R. Michael Weylandt wrote:
>>> Sorry about that -- forgot the case where you might only have a
>>> certain entry once: try this,
>>> sapply(split(GS, rownames(GS)), function(x) colSums(as.matrix(x)))
>>> or
>>> sapply(split(GS, rownames(GS)), function(x) if(is.matrix(x)) colSums(x)
>>> else x)
>>> I'm not sure if there's a way to force split to give you matrix
>>> elements back but it would be nice.
>> The help(split) page says there is a 'drop' parameter. That would have been
>> what I tried first.
>> --
>> David Winsemius, MD
>> West Hartford, CT
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Peter Dalgaard, Professor
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

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