Nick
[email protected]
Jeremy Miles
> Thanks for that - it makes sense, when you put it like that, although
> it's a pretty subtle distinction in the manuals [-gen- uses =exp ;
> -egen- uses =fcn(arguments)].
>
> When there's a Wiki, I'll write that in it. :)
> On 07/01/07, n j cox <[email protected]> wrote:
> > There is no need for guessing on this. If you
> > look directly at the help you can see that the
> > syntax of -egen- is
> >
> > egen [type] newvar = fcn(arguments) [if] [in] [, options]
> >
> > and so there is no scope for anything on the right-hand
> > side other than -if- or -in- stuff or options.
> >
> > There is really is a world of difference between functions
> > (strict sense) and -egen- functions: in several ways use
> > of the same term is unfortunate, although a different
> > term would also not have been desirable.
> >
> > In many contexts functions can be combined pretty well
> > arbitrarily with all kinds of other stuff in complicated
> > expressions, but with -egen- functions there is no
> > hidden flexibility -- except, as Scott Merrymsn indicated,
> > the flexibility you provide yourself as programmer
> > through options. Otherwise what you want requires two
> > lines.
> >
> > Nick
> > [email protected]
> >
> > Sergio Correia
> >
> > I don't think you can't do it in one line. Even if you
> could, I think
> > that it would be a bad idea for more advanced uses of
> -egen-. Imagine
> > trying to understand (or even program!) something like:
> >
> > egen x = 2+5*log(seq(), from(1) to(10) by(region))
> >
> > On the other hand, with -generate- you can mix all the functions you
> > want, like in:
> > generate x = 3 * (price + mpg) / 2
> >
> > Which is similar to what you did, except for the treatment
> of missing
> > values.
> >
> > Jeremy Miles
> >
> > Am I missing something obvious here, when I try to combine two steps
> > into one line:
> > . sysuse auto
> > . egen x = rowmean(price mpg) * 3
> >
> > Stata says:
> > varlist not allowed
> > r(101);
> >
> > For:
> > . egen x = 3 * rowmean(price mpg)
> >
> > Stata says:
> > r(198);
> > (Invalid syntax)
> >
> > I can do it in two steps, but that seems inelegant. Have I missed
> > something obvious?
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