st: Use foreach or forvalues to create the long form data

["Supnithadnaporn, Anupit" <gtg065t@mail.gatech.edu>]

Dear all,

Would you please suggest me how to create data in the long form
by *not* using reshape? I would like to avoid reshape because reshape
takes very very long time. In fact, the final & total number of records 
that I have to create would be around 12,000,000.

I think foreach and forvalues can do this work. 
But, I am a novice in Stata programming and could not figure out so far.

In the beginning, I have only Obsid which is created by

gen Obsid = _n

The desired data would look like this:

Obsid   Vid     Imp
1       1       1
2       1       2
3       1       3
4       1       4
5       2       1
6       2       2
7       2       3
8       2       4

...


100     25      4

Would anybody please help?

Thank you,

Anupit


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