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.
Michael
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
lists
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N.
J. Cox
Q2/03 SJ 3(2):185--202 (no
commands)
discusses ways of working through lists held in macros
which is visible under the 3-year rule. Nick
[email protected] 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
no
idea how to search for it.
Philip Ryan wrote:
Try:
forvalues i = 1/`=_N' {
....
}
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--
Michael I. Lichter, Ph.D.
Research Assistant Professor & NRSA Fellow
UB Department of Family Medicine / Primary Care Research Institute
UB Clinical Center, 462 Grider Street, Buffalo, NY 14215
Office: CC 125 / Phone: 716-898-4751 / E-Mail: [email protected]
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