One possibility is:

library(doBy)
summaryBy(Rate~Source+Bin, data=Df, FUN=sum)


On 5/17/2011 12:48 PM, LCOG1 wrote:
> Okay everyone heres a likely softball for someone.
>
> Consider the following data frame:
>
> #Create data
> x<-rep(c(1,15),10)
> y<-rnorm(20)
> z<-c(rep("auto",10),rep("bus",10))
> a<-rep(c(1,1,2,2,3,3,4,4,5,5),2)
> #Create Data frame
> Df<-data.frame(Source=x,Rate=y,Bin=a,Type=z)
>
>
> I want to create a new column the equals the sum of the Rates for each type
> (1,15) by Bin.
>
> A related question:  I have been using R for a while now and usually
> manipulate my data in data frames but i know lists are better for R so
> perhaps the above should be done using lists.  Feel free to offer
> suggestions coming from that angle.
>
> Thanks guys
>
> JR-
>
>
>
> --
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