# [R] Newbie: how to calculate group averagege?

Mon Apr 10 13:47:50 CEST 2000

```Thanks a lot, this is exactly what I need.

Bye,

Sven

Peter Dalgaard BSA wrote:
>
>
> > For each combinations of the factors are 6 values of rt. I need the mean
> > of the six rt values for each factor combination. I´ve tried the ave()
> > function:
> >
> > > ave(rt, zf, xf, yf)
> >
> > but it returns a lot of NAs. Is there another r-function I´ve overlooked
> > or must I write my own function?
>
> I think you're looking for
>
> tapply(rt,list(zf, xf, yf), mean, na.rm=T)
>
> alternatively,
>
> ave(rt, zf, xf, yf, FUN=function(x)mean(x,na.rm=T))
>
> --
>    O__  ---- Peter Dalgaard             Blegdamsvej 3
>   c/ /'_ --- Dept. of Biostatistics     2200 Cph. N
>  (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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