Please remove the "gen" from the last line of the loop.
Nick
[email protected]
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Nick Cox
> Sent: 19 June 2005 12:37
> To: [email protected]
> Subject: st: RE: RE: RE: unique value count in several variables
>
>
> 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
> [email protected]
>
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]]On Behalf Of
> > Scott Merryman
> > Sent: 19 June 2005 12:30
> > To: [email protected]
> > 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: [email protected] [mailto:owner-
> > > [email protected]] On Behalf Of Wanli Zhao
> > > Sent: Saturday, June 18, 2005 3:17 PM
> > > To: [email protected]
> > > 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
> > >
> >
> >
> > *
> > * For searches and help try:
> > * http://www.stata.com/support/faqs/res/findit.html
> > * http://www.stata.com/support/statalist/faq
> > * http://www.ats.ucla.edu/stat/stata/
> >
>
> *
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>
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