[R] Noob question - Identity argument within aggregate function?
dwinsemius at comcast.net
Fri Mar 2 23:38:01 CET 2012
On Mar 2, 2012, at 3:51 PM, knavero wrote:
>> aggregate(z, identity, mean)
> 1 2 3 4 5
> 1.0 3.0 5.0 6.0 7.5
>> aggregate(z, mean)
> Error: length(time(x)) == length(by[]) is not TRUE
As generally happens when you call a function and fail to provide
enough arguments to fill up its formals list.
> Can someone help me understand the error above and why "identity" is
> necessary to satisfy the error
Well on my machine it throws an error, probably because you failed to
provide the requested code to create the objects you were working on.
Is 'z' so sort of special classed object for which there is an
aggregate method? Is 'identity' a list as expected by
aggregate.default or aggregate.data.frame? It would be an unfortunate
choice of an object name, since there is a function with that nam.
David Winsemius, MD
West Hartford, CT
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