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Re: st: Re: question about ids in a group
From
Nick Cox <[email protected]>
To
[email protected]
Subject
Re: st: Re: question about ids in a group
Date
Sun, 20 Mar 2011 10:22:44 +0000
I wonder if you missed the -unique- option within -egen, rank()-.
Nick
On Sun, Mar 20, 2011 at 3:41 AM, Pat R <[email protected]> wrote:
> Thank you Joseph, this is exactly what I wanted! Now to figure out how
> exactly it works :)
> On Sat, Mar 19, 2011 at 11:33 PM, Joseph Coveney <[email protected]> wrote:
>>
>> Pat R wrote:
>>
>> I have a panel dataset from which I'm trying to make a smaller dataset
>> with new identifiers. My (new) dataset is organised this way right
>> now:
>>
>> QID | Year | PersonID
>>
>> 1 | 2009 | 3
>> 1 | 2009 | 4
>> 2 | 2009 | 9
>> 2 | 2009 | 10
>> 2 | 2010 | 9
>> 2 | 2010 | 10
>> 2 | 2009 | 11
>>
>> I want to create new identifiers for each person (consistent across
>> years), starting from 1, within each QID. I tried using the -egen
>> group- function, but since I cannot combine that with -by-, it creates
>> unique values which ignore the QID. I tried using -egen rank-, but
>> that of course skips a rank if two IDs are the same. I'm sure there's
>> a terribly easy way to do this, but I just can't see it. Can anyone
>> help? (It's my first time asking a question, so I apologize if I've
>> left out important information)
>>
>> --------------------------------------------------------------------------------
>>
>> If I understand you correctly, then it would be something like that illustrated
>> below. If that's not what you want, then write back to the list with a fourth
>> column in you example that shows just what you want as the result.
>>
>> Joseph Coveney
>>
>> . version 11.1
>>
>> .
>> . clear *
>>
>> . set more off
>>
>> .
>> . input long (QID Year PersonID)
>>
>> QID Year PersonID
>> 1. 1 2009 3
>> 2. 1 2009 4
>> 3. 2 2009 9
>> 4. 2 2009 10
>> 5. 2 2010 9
>> 6. 2 2010 10
>> 7. 2 2009 11
>> 8. end
>>
>> .
>> . *
>> . * Begin Here
>> . *
>> . bysort QID PersonID: generate long new_id = _n == 1
>>
>> . quietly by QID: replace new_id = sum(new_id)
>>
>> . list, noobs sepby(QID)
>>
>> +--------------------------------+
>> | QID Year PersonID new_id |
>> |--------------------------------|
>> | 1 2009 3 1 |
>> | 1 2009 4 2 |
>> |--------------------------------|
>> | 2 2010 9 1 |
>> | 2 2009 9 1 |
>> | 2 2009 10 2 |
>> | 2 2010 10 2 |
>> | 2 2009 11 3 |
>> +--------------------------------+
>>
>> . exit
>>
>> end of do-file
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