[R] paired samples, matching rows, merge()

[Gabor Grothendieck]

On Fri, Aug 20, 2010 at 9:59 AM, Cecilia Carmo <cecilia.carmo at ua.pt> wrote:
> The last one worked! The other one, not.
> Thank you very much!
>
> Another question about merge(): sometimes I'm merging two dataframes and the
> merged dataframe has much more rows than the two merged? I think this should
> not happen,does it?
>

That is normal behavior.  If there are m rows of with a key in x and n
rows of that key in y then there will be mn rows generated.  Every
such row in x will be matched to every such row in  y.