In addition to other answers, please see
http://www.stata.com/support/faqs/data/pairs.html
In this case, the problem appears simpler
than that discussed in the FAQ. In addition,
no loops appear needed.
local nobs = _N
expand `nobs'
bysort country1 : gen temp = _n
gen country2 = country1[`nobs' * temp]
drop if country2 >= country1
Nick
[email protected]
Mark Manger
> I'm struggling with a data manipulation problem: I have a
> dataset with list
> of observations on a string variable and want to create pairwise
> combinations. My dataset looks like this:
>
> country1
> A
> B
> C
>
> I need the possible combinations so that the new dataset looks like
>
> country1 country2
> A B
> A C
> C B
>
> I could take the same list in two different datasets and then use the
> command "cross", but that gives me 3! combinations:
>
> AB AC BA BC CA CB
>
> For my purposes, AB and BA are identical. How do I create the list?
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