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From |
Abhimanyu Arora <abhimanyu.arora1987@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: identifying variables |

Date |
Mon, 9 Apr 2012 12:12:58 +0200 |

Thank you for this "squiggly" tidbit, Nick! On Mon, Apr 9, 2012 at 12:07 PM, Nick Cox <njcoxstata@gmail.com> wrote: > 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/ * * 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/

**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>

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

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