Dear Julia,
Try also
x=read.table(textConnection("ID value
111 5
111 6
111 2
178 7
178 3
138 3
138 8
138 7
138 6"),header=TRUE)
closeAllConnections()
attach(x)
do.call(rbind,tapply(value,ID, function(x){
res=c(mean(x,na.rm=TRUE),var(x,na.rm=TRUE))
names(res)=c('Mean','Variance')
res
}
)
)
HTH,
Jorge
On Thu, Sep 11, 2008 at 1:45 PM, liujb <[EMAIL PROTECTED]> wrote:
>
> Hello,
>
> I have a data set that looks like this.
> ID value
> 111 5
> 111 6
> 111 2
> 178 7
> 178 3
> 138 3
> 138 8
> 138 7
> 138 6
> .
> .
> .
>
> I'd like to calculate the mean and var for each object identified by the
> ID.
> I can in theory just loop through the whole thing..., but is there a easier
> way/command which let me calculate the mean/var by ID?
>
> Thanks,
> Julia
> --
> View this message in context:
> http://www.nabble.com/Calculate-mean-var-by-ID-tp19440461p19440461.html
> Sent from the R help mailing list archive at Nabble.com.
>
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