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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: forvalues and _N |

Date |
Fri, 10 Oct 2008 19:11:13 +0100 |

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 n.j.cox@durham.ac.uk 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' { >> >> .... >> >> } >> * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: forvalues and _N***From:*"Michael I. Lichter" <mlichter@buffalo.edu>

**References**:**st: forvalues and _N***From:*"Bastian Steingros" <Steingros@gmx.de>

**Re: st: forvalues and _N***From:*Philip Ryan <philip.ryan@adelaide.edu.au>

**Re: st: forvalues and _N***From:*"Michael I. Lichter" <mlichter@buffalo.edu>

**Re: st: forvalues and _N***From:*"Martin Weiss" <martin.weiss1@gmx.de>

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