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Re: st: Generating unique values from unique and duplicate cases


From   Richard Goldstein <richgold@ix.netcom.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Generating unique values from unique and duplicate cases
Date   Mon, 17 Oct 2011 11:26:48 -0400

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

egen id=group(var1 var2 var3)

Rich

On 10/17/11 10:49 AM, Tim Morris wrote:
> Hello,
> 
> 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. Thanks in advance for any
> help.
> 
> regards,
> tim morris
> 
> ----------------------
> Tim Morris, ALSPAC
> Tim.Morris@bristol.ac.uk
> 0117 331 0022
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