st: Unique dyads

[emanuele mazzini <madsoenistata@gmail.com>]

Dear all Stata users,
I am using an unbalanced dyadic panel dataset for which I need to
generate an unique dyad id. I looked at this help:
http://www.ats.ucla.edu/stat/stata/faq/dyad_ids.htm but the
suggestions I found here do not seem to work in my dataset. In
particular, the example shows that there is a certain symmetry, so
that the couple for which a=1 and b=5 is the same couple for which a=5
and b=1. Hence the couple considered gets the same value for the
variable dyad. But this does not work in my dataset because the couple
that gets a given value for the variables a and b is not the same
couple that gets the same values for b and a.
I can be more clear with the following example, which will be in terms
of countries, as in my dataset. Suppose I consider the couple USA and
GBR and I apply the suggested procedure. Then when the couple is:
USA-GBR i got a=1 and b=75

but when I consider the reverted couple, i.e GBR-USA, i got a=46 and
b=90, which are absolutely not the same values, as the help i read
suggest.

Anyone can please help me to understand why this is happening or has
an alternative way to proceed to get an unique dyad-id identifier?

Thanks to all of you in advance,
Regards,
Emanuele.
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