[R] Fast method to compute average values of duplicated IDs

[Greg Snow]

?tapply
?aggregate

--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
(801) 408-8111



> -----Original Message-----
> From: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org] On Behalf Of Daren Tan
> Sent: Tuesday, June 10, 2008 9:37 AM
> To: r-help at r-project.org
> Subject: [R] Fast method to compute average values of duplicated IDs
>
>
> Hi,
>
> How do I collapse (average in the simplest case) the values
> of those duplicated ids (i.e., 2, 5, 6, 9) to give a table of
> unique ids ?
>
> t <- cbind(id=c(1:10, 2,5,6,9), value=rnorm(14))
>
>
>
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