Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: RE: RE: RE: RE: RE: Re: How to speed up loop


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: RE: RE: RE: RE: Re: How to speed up loop
Date   Mon, 20 Sep 2004 19:30:08 +0100

Thanks for the sharp-eyed corrections. 

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

David E Moore
 
> While it is doubtless clear from the example what was meant, there is
> nonetheless a typo that might throw off a newcomer to the 
> wonderful world of
> variable indexing.  In the nicely worked example presented by 
> Nick he translates
> the expression "age[mlineno]" as "age[3]" when, in fact, it 
> should have been
> "age[2]."  I mention this because it's really a tricky 
> concept for someone not
> accustomed to using variables as indexes.  If you didn't 
> already grasp the
> principles involved, taking the values literally might leave 
> you hopelessly
> confused.  So, in the excerpt quoted below, substitute 
> "age[2]" for "age[3]" and
> "second" for "third" to see the correct connections.
> 
> > -----Original Message-----
> > From: owner-statalist@hsphsun2.harvard.edu
> > [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Nick Cox
> > Sent: Friday, September 17, 2004 4:52 AM
> > To: statalist@hsphsun2.harvard.edu
> > Subject: st: RE: RE: RE: Re: How to speed up loop
> >
>        <snip>
> > Take
> >
> > hhid    lineno       age   mlineno      mage
> >   1         1        32         .         .
> >   1         2        30         .         .
> >   1         3         5         2        30
> >
> > Each expression within [ ] is evaluated
> > separately for each observation. For
> > the first and second
> >
> > 	age[mlineno] becomes age[.]
> >
> > which is taken as missing. For the third,
> >
> > 	age[mlineno] becomes age[3]
> >
> > which by the wrinkle rule above is 30.
> > It is the third observation _within that group_.
> 
>       <snip>

*
*   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/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index