[R] how do I calculate means or cov matrix for multivariate groups

[Henrique Dallazuanna]

Try this:

lapply(list(mean, cov), by, data = d[,1:2], INDICES = d[,'class'])

On Mon, Feb 22, 2010 at 6:13 AM, mirauta <bmirauta at yahoo.com> wrote:
>
> Hello,
>
> Having the matrix d
>> d
>   value value2 class
> 1      1      1     x
> 2      2      2     x
> 3      3      3     x
> 4      4      2     x
> 5      5      1     y
> 6     11      3     y
> 7     12      4     z
> 8     13      5     z
> 9     14      6     z
> 10    15      7     z
>
> I want to calculate the means and cov matrix for groups x,y,z.
> I know how to do it the long way.
> I tried to use tapply and kmeans but no good results.
> (tapply is a good solution for only 1 variable)
>
>
> Thank you
>
> Bogdan
>
>
> --
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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O