Hi JR,

Try also

with(DF, tapply(Acres, Bldgid, sum) )

HTH,
Jorge


On Thu, Oct 29, 2009 at 3:03 PM, PDXRugger <> wrote:

>
> Hello All,
>   I would like to select records with identical IDs then sum an attribute
> then and return them to the data frame as a single record.  Please consider
>
>
> Acres<-c(100,101,100,130,156,.5,293,300,.09)
> Bldgid<-c(1,2,3,4,5,5,6,7,7)
>
> DF=cbind(Acres,Bldgid)
> DF<-as.data.frame(DF)
>
> So that:
>
>  Acres Bldgid
> 1 100.00      1
> 2 101.00      2
> 3 100.00      3
> 4 130.00      4
> 5 156.00      5
> 6   0.50      5
> 7 293.00      6
> 8 300.00      7
> 9   0.09      7
>
> Becomes
>
>  Acres Bldgid
> 1 100.00      1
> 2 101.00      2
> 3 100.00      3
> 4 130.00      4
> 5 156.50      5
> 7 293.00      6
> 8 300.09      7
>
> dup<-unique(DF$Bldgid[duplicated(Bldgid)])
> dupbuild<-DF[DF$Bldgid %in% dup,]
> dupbuild..dupareasum<-sum(dupbuild$Acres[duplicated(dupbuild$Bldgid)])
>
> This sums the unique Ids of the duplicated records, not whati want.  Thanks
> ahead of time
>
> JR
>
>
> --
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>
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