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


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: RE: RE: unique value count in several variables
Date   Sun, 19 Jun 2005 12:37:05 +0100

I too am fond of -levelsof-. For the problem mentioned, 
this would need to be embedded in a loop over groups, 
somewhat as follows: 

gen nvals = . 
egen group = group(Gvkey year)
su group, meanonly 
qui forval i = 1/`r(max)' { 
	levelsof psic if group == `i', local(p) 
	levelsof ssic if group == `i', local(s)
	local total: list s | p
	local total:list uniq total
	local count:list sizeof total
	replace gen nvals = `count' if group == `i' 
}

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

> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of 
> Scott Merryman
> Sent: 19 June 2005 12:30
> To: statalist@hsphsun2.harvard.edu
> Subject: st: RE: RE: unique value count in several variables
> 
> 
> 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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