Thanks for the sharp-eyed corrections.
Nick
[email protected]
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: [email protected]
> > [mailto:[email protected]]On Behalf Of Nick Cox
> > Sent: Friday, September 17, 2004 4:52 AM
> > To: [email protected]
> > 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>
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