R help - Jun 2008 - 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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?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))
>
>
>
> _________________________________________________________________
>
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Dear Daren,

Try this:

tapply(t[,"value"],t[,"id"],mean)

HTH,

Jorge



On Tue, Jun 10, 2008 at 11:37 AM, Daren Tan <daren76@hotmail.com> wrote:
>
> 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))
>
>
>
> _________________________________________________________________
>
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
	[[alternative HTML version deleted]]