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Re: st: Reshape related


From   Phil Schumm <pschumm@uchicago.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Reshape related
Date   Sat, 22 Nov 2008 16:57:59 -0600

On Nov 22, 2008, at 4:12 PM, Kir1 wrote:
Perhaps the subject line is not the best one to address my problem, but here it is:

My original data set is of the 'long' format like this

gvkey    year      revenue
1000     1999    111
1000     2000    222
.
.
1001   1999       888

From this I want to retrieve only one value of revenue per 'gvkey' which corresponds to a year value that i lookup in a different database. So if in the other data base my gvkey is 1000 and lookupyear is 2000, then only 222 should be in the revenue cell of the final database.


The simplest way to handle this is to merge the two datasets by gvkey and year, and then just keep those observations for which _merge==3. For example, assuming that the variables in your other dataset are named gvkey and lookupyear, you would do


gen lookupyear = year
merge gvkey lookupyear using <other dataset name>, sort
keep if _merge==3


This will leave you with what you want.


-- Phil

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