Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.

# Re: st: Identify combinations without respect to the order of the elements

 From Oliver Jones To statalist@hsphsun2.harvard.edu Subject Re: st: Identify combinations without respect to the order of the elements Date Wed, 13 Jul 2011 20:28:11 +0200

```Hi everybody,

someone just sent me an solution to my private email:
------------------------------------------------------------------------------------------
```
One way to solve the problem would be to create two new variables which have a standard order for the cities. Then you can use egen group to identify the pairs.
```
That is:

gen first = var1 if var1 <= var2
replace first = var2 if first == ""

gen second = var2 if var1 <= var2
replace second = var1 if second == ""

egen paired = group(first second)
------------------------------------------------------------------------------------------

To my example with the cities var1 would be the variable from and var2 would be the
variable to.

Best
Oliver
--
Universität Bielefeld
Fakultät für Wirtschaftswissenschaften
Lehrstuhl für Ökonometrie und Statistik
- -
Bielefeld University
Chair of Econometrics and Statistics
- -
Raum / room:  V9-110
Tel / phone:  +49 (0)521 106 4871
---
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```