[R] count id by id

[Bert Gunter]

Homework exercise ??

-- Bert

On Tue, Jan 18, 2011 at 2:03 PM, Denis Kazakiewicz
<d.kazakiewicz at gmail.com> wrote:
>
> Hi
>
> Trying to work out that:
> Each person can take from 1 to 9 drugs. And data frame looks like
>
>
> id      drug
> 1       d
> 2       g
> 2       d
> 2       r
> 3       e
> 3       a
> ...........
>
> Q: How many drugs one person takes on average?
>
> Thank you
>
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>



-- 
Bert Gunter
Genentech Nonclinical Biostatistics