[R] aggregation with two statistical functions - mean and variance

[Gabor Grothendieck]

See summaryBy in the doBy package.

On Dec 24, 2007 4:27 PM, Agrarimmobilien
<ralf.pfeiffer at agrarimmobilien.info> wrote:
> Hello,
>
> using the syntax
>
> aggregate(daten[,c(3,4)], list(A,B), mean)
>
> I'm getting the following data.frame:
>
>
>    A     B        C                    D
> 1  35    1         6.16000          5
> 2  47    1        31.24333         20
> 3  54    1        26.81773         2
> 4   3     2        12.99000         7
> 5   4     2         6.49000          1
>
> C and D are both means. But now I want to have: C is mean, D is variance.
>
> How can I do this by using/ changing the aggregation syntax?
>
> Thanks!
>
> Macki
>
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