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st: RE: RE: unique value count in several variables


From   "Scott Merryman" <smerryman@kc.rr.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: RE: unique value count in several variables
Date   Sun, 19 Jun 2005 06:30:02 -0500

In addition to Nick's suggestion of using -reshape-, another possibility is
to use -levelsof- and the macro extended functions (assuming your cross
sections are not too large):


. l, noobs

  +------------------------------------+
  | gvkey   psic   ssic   year   subno |
  |------------------------------------|
  |  1223   4767   4743   1999       1 |
  |  1223   4767   4763   1999       2 |
  |  1223   4757   4767   1999       3 |
  |  1223   4767   4753   1999       4 |
  |  1223   4777   4787   1999       5 |
  |------------------------------------|
  |  1223   4767   4743   1999       6 |
  +------------------------------------+

. levelsof psic, local(p) 
4757 4767 4777

. levelsof ssic, local(s)
4743 4753 4763 4767 4787

. local total: list s | p

. local total:list uniq total

. local count:list sizeof total

. gen nvals = `count'

. l, noobs

  +--------------------------------------------+
  | gvkey   psic   ssic   year   subno   nvals |
  |--------------------------------------------|
  |  1223   4767   4743   1999       1       7 |
  |  1223   4767   4763   1999       2       7 |
  |  1223   4757   4767   1999       3       7 |
  |  1223   4767   4753   1999       4       7 |
  |  1223   4777   4787   1999       5       7 |
  |--------------------------------------------|
  |  1223   4767   4743   1999       6       7 |
  +--------------------------------------------+


Scott


> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-
> statalist@hsphsun2.harvard.edu] On Behalf Of Wanli Zhao
> Sent: Saturday, June 18, 2005 3:17 PM
> To: statalist@hsphsun2.harvard.edu
> Subject: st: RE: unique value count in several variables
> 
> Thanks, Nick. I looked into the suggestions and I think I might have
> confused you on my problem. My panel data is like this:
> Gvkey  psic  ssic  year  subno
> 1223   4767  4743  1999  1
> 1223   4767  4763  1999  2
> 1223   4757  4767  1999  3
> 1223   4767  4753  1999  4
> 1223   4777  4787  1999  5
> 1223   4767  4743  1999  6
> 
> Using command unique, I can count the distinct values of psic and ssic by
> gvkey by year. So for psic it's 3 and for ssic it's 5. what I want is to
> count the distinct values of both psic and ssic by gvkey by year. In this
> case, it's 7 (4767, 4757, 4777, 4743, 4763, 4753, 4787). How to generate a
> new variable for my purpose? Hope I'm clear now. Pls help.
> 
> Thanks.
> Wanli Zhao
> 


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