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Re: st: ST: delete duplicate observations


From   Jeph Herrin <junk@spandrel.net>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: ST: delete duplicate observations
Date   Mon, 14 Sep 2009 14:46:34 -0400

If by "first" you mean "smallest value of Z" then

 bys ID (Z) : keep if _n==1

will do it.

hth,
Jeph

Laura Platchkov wrote:
Dear all, I have a dataset with 200'000 observations, and a lot of observation have the same ID. I want to keep only 1 observation of each ID, lets say the first one that have this particular ID. My dataset is like this:
ID  variable Z

1     45.6
1     46.7
1     47.8
1     .
2      .
2
2
3
4
5
5
5
5


An I want to transform the dataset like this: 1 45.6
2
3
4

Does anyone has the magic command for that???

Laura
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