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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: identifying variables |

Date |
Mon, 9 Apr 2012 11:07:54 +0100 |

You can do it this way foreach v of var * { capture if strpos(`v'[1], "real") { local vars `vars' `v' } } The { } are best called braces or curly brackets. Parentheses are strictly (). See e.g. http://www.catb.org/jargon/html/A/ASCII.html for a useful glossary. (The entire site is superb.) Nick On Mon, Apr 9, 2012 at 10:56 AM, Abhimanyu Arora <abhimanyu.arora1987@gmail.com> wrote: > Very useful to know, Nick. Just to confirm, in general stata goes > further into the command only if the _if_ condition returns 1. There > is no need for parenthesis or a separate line for -local-. Thanks for > this detail. > Cheers > Abhimanyu > > > On Mon, Apr 9, 2012 at 11:33 AM, Nick Cox <njcoxstata@gmail.com> wrote: >> Note also that a solution from first principles is also possible: >> >> foreach v of var * { >> capture if strpos(`v'[1], "real") local vars `vars' `v' >> } >> >> di "`vars'" >> >> You need the -capture- unless all the variables are string. >> >> Nick >> >> On Mon, Apr 9, 2012 at 8:57 AM, Nick Cox <njcoxstata@gmail.com> wrote: >>> You have provided yet another example of a problem in which -strpos()- >>> offers a simple alternative to -regexm()-. >>> >>> That aside, your syntax is looking for the string "real" in the >>> _variable names_ themselves, for which >>> >>> . findname *real* >>> >>> would be a more obvious syntax, and indeed -describe *real*- would >>> work fine. Stata has a similar distinction in all string and regular >>> expression functions between looking in a string variable strvar and >>> looking in a variable name "varname". >>> >>> . l in 1 >>> >>> +-------------------------------------------+ >>> | foo bar bazz y x | >>> |-------------------------------------------| >>> 1. | reality surreal unreal 42 3.14159 | >>> +-------------------------------------------+ >>> >>> . findname in 1, all(strpos(@, "real")) >>> foo bar bazz >>> >>> . findname in 1, all(regexm(@, "[real]")) >>> foo bar bazz >>> >>> . findname in 1, all(regexm(@, "real")) >>> foo bar bazz >>> >>> @ is the default generic varname. -placeholder()- lets you specify an >>> alternative. You only need to specify "@" for searching the variable >>> names, but as above there are easier ways to do that. >>> >>> Nick >>> >>> On Mon, Apr 9, 2012 at 3:50 AM, Abhimanyu Arora >>> <abhimanyu.arora1987@gmail.com> wrote: >>> >>>> I need to identify the variables for which the first observation >>>> contains the string "real". >>>> I used Nick Cox's -findname- from the SSC (updated 27 February 2012) >>>> in the following command. >>>> >>>> findname var1-var56 in 1,all(regexm("@","real+")) loc (varnames) >>>> >>>> But since -return list- comes up empty, something is amiss, perhaps in >>>> the use of the regular expression. May I also request some clarity in >>>> understanding of the role played by a "placeholder" in -findname-? As >>>> I see it, a generally character designated as a "placeholder" is >>>> supposed to take on supplied values—string or numerals. Or in other >>>> words, how would stata read the "@" in the above command? >>>> >> >> * >> * 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/ > > * > * 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/ * * 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: identifying variables***From:*Abhimanyu Arora <abhimanyu.arora1987@gmail.com>

**References**:**st: identifying variables***From:*Abhimanyu Arora <abhimanyu.arora1987@gmail.com>

**Re: st: identifying variables***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: identifying variables***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: identifying variables***From:*Abhimanyu Arora <abhimanyu.arora1987@gmail.com>

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