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Re: st: Generating all possible combinations of pairs


From   "Svend Juul" <SJ@SOCI.AU.DK>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: Generating all possible combinations of pairs
Date   Wed, 27 Sep 2006 13:10:31 +0200

Karin wrote:

I have some repeated paired observations and would like to generate
all possible combinations of pairs.

The data looks like this :-
Pair  Subject  Var
101        1  134
101        2  563
101        2  455
102        1  345
102        1  363
102        1  299
102        2  647
102        2  352

I wish to generate data that looks like this :-
Pair  Var1  Var2
101   134   563
101   134   455
102   345   647
102   345   352
102   363   647
102   363   352
102   299   647
102   299   352
----------------------------------------------------------------

This is a case for -joinby-:

clear
input pair subject var
101  1  134
101  2  563
101  2  455
102  1  345
102  1  363
102  1  299
102  2  647
102  2  352
end

sort pair
preserve
keep if subject==2
rename var var2
save x2.dta , replace
restore
keep if subject==1
rename var var1
joinby pair using x2.dta
drop subject
sort pair var1 var2
list

Hope this helps
Svend

__________________________________________

Svend Juul
Institut for Folkesundhed, Afdeling for Epidemiologi
(Institute of Public Health, Department of Epidemiology)
Vennelyst Boulevard 6
DK-8000  Aarhus C, Denmark
Phone: +45 8942 6090
Home:  +45 8693 7796
Email: sj@soci.au.dk
__________________________________________ 

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