marcg wrote:
> Hello R
>
> For expierienced user, the following problem will be easy to solve:
>
> a<-c(0,1,0,1,0,2,3,4,3,2)
> b<-c(3,3,3,4,4,4,7,7,7,10)
> c<-data.frame(a,b)
>
> Data Frame c contains tow colums. I would like to sum up all values in a as
> long as b stays the same:
>
> sum(a[which(b==1)])
>
> does this, but i have to manually put in b
>
> then i tryied st like this, but i canno't save it properly
>
> for (i in 0:max(b)){
> i<-sum(a[which(b==i)])
> }
>
> i tried to figure out, how tapply works, but neither
> with(c, tapply(a, list(b), sum))
3 4 7 10
1 3 10 2
> thanks alot
>
> marc
> --
>
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