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st: RE: Making symmetry


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Making symmetry
Date   Fri, 11 Apr 2003 10:41:26 +0100

Alexander
> 
> I have 2 ID-variables:
> 
> Id1	Id2
> 1	1
> 2	3
> 3	5
> 4	.
> 5	.
> 
> And I want the variabels to be symmetric in relation to ID1
> 
> Like this:
> 
> Id1	Id2
> 1	1
> 2	.
> 3	3
> 4	.
> 5	5

This will work if the number of distinct 
levels in -Id2- is modest: 

ssc inst levels 
levels Id2 
replace Id2 = . 
foreach l of local levels { 
	qui replace Id2 = `l' if Id1 == `l' 
} 

Slow but sure with arbitrarily large data sets: 

gen draft = . 
forval i = 1 / `=_N' { 
	qui replace draft = Id2[`i'] if Id1 == Id2[`i'] 
} 
replace Id2 = draft 

Nick 
n.j.cox@durham.ac.uk 
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