st: Creation of family id

[Juan Baron <juan.baron@anu.edu.au>]

Dear Stata Users:

Suppose I have the following data

id         p_id1      p_id2      pid3
1            .               .            .
2            6              7           9
3            8              .            .
4            5              1           .
5            .               .            .
6            .               .            .
7            .               .            .
8            .               .            .
9            .               .            .
10         5               .            .   

where id is a unique id for each indiviidual and p_id#'s the id of the 
parent  (in the real data I have more than 3 pid variables)

I want to create a family id in the most efficient way.   My solution to 
this problem involves looping over observations, and because of that
it takes  a long time.  That wouldn't be a problem if my data contained 
only a few observations, but that is not the case.

Can anybody suggest more efficient ways to do this task?  I was 
wondering also, how about using MATA?

Thanks,

Juan

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