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Re: st: forvalues and _N

From   "Michael I. Lichter" <>
Subject   Re: st: forvalues and _N
Date   Fri, 10 Oct 2008 15:02:26 -0400

Thanks Nick and Martin, although I don't see this in either -help macro- or -help variables- ... unless it's the uninterpretable (to me)

	"[...] `expansion_optr' [...]"

in -help macro- (FYI: Stata 9.2). I'm guessing that it IS in [P] Macro, but I frankly can't afford the manuals and wish Stata would make them available free online like SAS or on the install DVD like SPSS or at a reasonable price in PDF form online which I know is one of those things you're not supposed to talk about on Statalist. Grrr.


Nick Cox wrote:
I think what Michael wants to know is documented better at -help macro-.

`=exp' where exp is an expression lets you evaluate an expression on the
fly and use its result.
`=2 + 2' would be in these terms: the expression is 2 + 2; Stata would
evaluate that; and the command would see 4. As the example implies, the expression can be a single item such as _N.
This has been in Stata since (I think) sometime during Stata 7 but was
not documented until Stata 8. There is a discussion within
SJ-3-2  pr0009  . . . . . . . . . . . . . Speaking Stata:  Problems with
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N.
J. Cox
        Q2/03   SJ 3(2):185--202                                 (no
        discusses ways of working through lists held in macros

which is visible under the 3-year rule.
P.S. The help and the manuals are, as always, the first documentation to
think of. Typically, the FAQs fill in some odd gaps or fill out some
tricky topics.
Martin Weiss

see -help _variables-. The equal sign evaluates this -expression- so no
need for any -macro-...

Michael I. Lichter

Whoa! This works even though `=_N' is clearly not a macro. Is this an undocumented feature, or is it a "real" part of Stata that will stick around? I'm sorry if this is discussed somewhere in the FAQ -- I have
idea how to search for it.

Philip Ryan wrote:

forvalues i = 1/`=_N'  {



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