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RE: st: RE: Creating repeated index
From
Nick Cox <[email protected]>
To
"'[email protected]'" <[email protected]>
Subject
RE: st: RE: Creating repeated index
Date
Wed, 20 Oct 2010 17:04:40 +0100
Try
bysort studentid visitdate : gen first = _n == 1
by studentid : replace first = sum(first)
Nick
[email protected]
Pete
It doesn't work. The index should start with "1" for every student.
On Wed, Oct 20, 2010 at 10:36 PM, Nick Cox <[email protected]> wrote:
> egen index = group(studentid visitdate)
>
> Nick
> [email protected]
>
> Pete
>
> I am trying to create an index/running number based upon same value of
> one variable, i.e., visit date. Different visit date will have
> different index/running number. I can do it by finding duplicates and
> drop them, then create an index and save as a new file, then merge a
> new file with the original one. However, I want to know whether there
> is a short cut to do this. My data will looks like this.
>
> StudentID Visit Date Item Index
> 1 1/1/2010 A 1
> 1 1/1/2010 B 1
> 1 2/4/2010 A 2
> 1 2/4/2010 B 2
> 1 2/4/2010 C 2
> 2 4/1/2010 A 1
> 2 4/1/2010 B 1
> 2 4/1/2010 C 1
> 2 3/3/2010 A 2
> 2 3/3/2010 E 2
>
>
> *
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>
*
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*
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* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/