Hi Knut,

Try

sum(subset(df, row1 == 3 & row2 == 2)[,1])

and

nrow(subset( df, row1 == 3 & row2 == 2) )

HTH,
Jorge


On Fri, Nov 13, 2009 at 1:59 PM, Knut Krueger <> wrote:

> Hi to all
> is there any construct to sum
> data=data.frame(row1=c(1,1,3,1,2,3,2,2,1,3,4,5,2,3,2,1) ,
>                         row2=c(2,2,1,1,1,2,1,2,1,1,1,1,2,2,2,1) )
> Means I would like to get all y of row1 if in row2 of the data.frame is an
> x
> f.e row1=3 and row2=2
> so I would like to get 6
>
> And is there another construct to get the count of pairs where
> row1=3 and row2=2
> means the result should be 2
> I could do this with loop but I am wondering whether there is any better
> way.
>
> Regards Knut
>
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