Re: st: ST: delete duplicate observations

[Jeph Herrin <junk@spandrel.net>]

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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