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# RE: st: Generating unique values from unique and duplicate cases

 From Nick Cox To "'statalist@hsphsun2.harvard.edu'" Subject RE: st: Generating unique values from unique and duplicate cases Date Mon, 17 Oct 2011 17:15:54 +0100

```I can see why Sergio and Richard answered as they did, but their answers are different. That is, your question remains ambiguous.

Did you check out -duplicates-.

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

Sergio Alvarez
==============

I don't know if this is what you need, but I know this will give you
unique values for each value of 'dup':

sort dup id
by dup: gen new_id = _n

then if you sort by id I think you'll get the observation in the order
you want.

Richard Goldstein
=================

if I understand what you want, use the -egen- command with the group function; e.g.,

egen id=group(var1 var2 var3)

Tim Morris
==========

> I have created syntax to check for and label potential duplicate
> cases across 3 variables (two text and one numeric). the syntax is as
> follows:
>
> sort var1 var2 var3
> quietly by  var1 var2 var3:  gen dup = cond(_N==1,0,_n) if var1!=. |
> var2!="" | var3!=""
>
> this results in a new variable (dup) which may read as follows
> through the cases: 0, 0, 0, 1, 2, 0, 0 (1 and 2 being duplicate cases
> the rest being unique). What i want to do is create a new variable
> (id) that assigns a unique id to each unique case and groups together
> the corresponding duplicates into the same id, so based upon the
> example above the results will be along the lines of:
>
> dup	id
> 0 	1
> 0 	2
> 0 	3
> 1 	4
> 2 	4
> 0 	5
> 0 	6
>
> I have played around with various code, searched online and spoken to
> other Stata users for help but cannot find a way to make Stata assign
> unique values for each 'group' of duplicates.

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```