[R] Count Code

[Peter Dalgaard]

David Winsemius wrote:
> 
> On Apr 22, 2009, at 3:42 PM, Bronagh Grimes wrote:
> 
>> Hi there,
>> I am interested in converting SAS code to R & I wondered if anyone had
>> any quick R code/tips for the following piece of test SAS code?
>>
>> Any feedback greatly appreciated.
>>
>> data A1;
>>   set A1;
>>  count + 1;
>>  by subject_id;
>>  if first.subject_id then count = 1;
>> run;
> 
> There were several solution offered a couple of months back to the 
> challenge of replicating the features of the SAS _N_ construct. At least 
> that is my memory of how it looks in SAS. You probably have the right 
> books to consult for that question to construct a proper search:

I think this one could be

count <- ave(a1$subject_id, a1$subject_id, FUN = seq_along)

(assuming that "count+1;" increases the value from the previous record.)

-- 
    O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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