[R] frequency

Bert Gunter gunter.berton at gene.com
Tue Oct 23 22:17:02 CEST 2012

Are the data in a data frame?  Is it the first letter of the id that
defines unique ID's or something else?

Depending on your answers:


may be useful, as in with(yourdata,table(substring(ID,1,1)))

... or not, if you meant something else.

-- Bert

On Tue, Oct 23, 2012 at 12:14 PM, farnoosh sheikhi
<farnoosh_81 at yahoo.com> wrote:
> Hello,
> I have a data as follow:
> ID    Visit
> xa1
> xa2
> yb1
> yc23
> yb33
> I want to look at frequency of visit for ID and create a new column as response .
> For example my response would be 2 for x and 3 for y.
> I think I need to write a loop, but I don't know how.
> I really appreciate your help.
> Thanks a lot.
> Best,Farnoosh Sheikhi
>         [[alternative HTML version deleted]]
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Bert Gunter
Genentech Nonclinical Biostatistics

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