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Re: st: merging dataset


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: merging dataset
Date   Fri, 31 Aug 2007 14:30:12 +0100 (BST)

--- Rima Chakravarty <Rima.Chakravarty@dornc.com> wrote:

> Wondering if anybody can help me with this. I want to merge two
> dataset (AA and BB) based on ID. 
> 
> Dataset AA
> ID    Var 1   Var 2   Var 3 
> 12     785     .         748
> 45     74       2        63
> 74     789     0        7485
> 
> 
> Dataset BB
> ID    Var 1   Var 2    Var 3
> 12      .         45        748
> 94      41       78        74
> 74      789     0          7485
> 
> I have used the merge command but the problem with that is that the
> dataset BB has missing value for ID =12 (Var 1). I want to replace
> the non-missing value in the merged dataset with the missing value
> and I think the merge command do not do that. Everything else did
> correctly.

*--------------- begin example ------------------
drop _all
input id    aavar1   aavar2   aavar3 
12     785     .         748
45     74       2        63
74     789     0        7485
end

sort id
tempfile aa
save `aa'

drop _all
input id    bbvar1   bbvar2    bbvar3
12      .         45        748
94      41       78        74
74      789     0          7485
end

sort id
merge id using `aa'

drop _merge
forvalues i = 1/3 {
	replace bbvar`i' = aavar`i' if bbvar`i' == .
	rename bbvar`i' var`i'
	drop aavar`i'
}

list
*--------------- end example ---------------
(For more on how to use examples I sent to the Statalist, see
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )

Hope this helps,
Maarten


-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


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