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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: macro problem |

Date |
Mon, 11 Jun 2012 22:19:52 +0100 |

Note first that I didn't recommend either of your examples; and second -- and much more importantly -- that they make more sense when you follow the principles I outlined. When you define local list "a b" "b c" "c d" Stata strips the outermost " " as delimiters so (for example) "a b" is no longer a single word (Stata sense), but two words a and b". Stata evidently has rules that differ for single " on the left and the right, but the overarching principle remains that the way to insist that " " remain as such is to wrap them in further delimiters. Nick On Mon, Jun 11, 2012 at 8:04 PM, Jeph Herrin <stata@spandrel.net> wrote: > Thanks. In both cases I should have clarified that I want the list of match > strings to be part of a macro (as in my example) because the list will > change from time to time (and I prefer to isolate code changes to macros). > In that case, your example and others produce surprising results: > > . local list "a b" "b c" "c d" > > . foreach s in `list' { > > 2. di "`s'" > 3. } > a > b > b c > c d > > . local list "a" "b" > > . foreach s in `list' { > > 2. di `"`s'"' > 3. } > a" > b > > (note the trailing " on the -a-) and so on. > > cheers, > Jeph > > > > > > > On 6/11/2012 12:29 PM, Nick Cox wrote: >> >> " " have two roles in Stata; they act as string delimiters (which by >> default are stripped) and they act as literal characters which you want to >> preserve as part of a string (in which you often need `" "' as delimiters). >> >> However, this works >> >> . foreach s in "a b" "b c" "c d" { >> 2. di "`s'" >> 3. } >> a b >> b c >> c d >> >> so maybe something simpler would also work for you. >> >> Nick >> n.j.cox@durham.ac.uk >> >> Jeph Herrin >> >> There is no problem with -strpos-, which never returns missing and which >> is zero exactly when I want it to be. The problem was in creating the >> original macro and then referencing the elements so that they appear in >> -strpos- with the correct number of quotations marks; I was achieving >> either too many or too few of the latter. >> >> The solution (or at least, a solution) is for local -matchlist- needed >> to be enclosed in compound quotes, and then ditto the reference: >> >> local matchlist `""string 1" "string 2" "string 3" .... "string 55""' >> >> gen byte match=0 >> foreach S of local matchlist { >> replace match = 1 if strpos(strvar,`"`S'"') >> } >> >> >> The reference in -strpos- looks wrong to me - I would anticipate that >> `S' would include the necessary "'s for -strpos-, but it does not. >> Without the extra quotes on the original local, however, `"`S'"' >> resolves to include too many "'s. >> >> On 6/11/2012 11:58 AM, Richard Goldstein wrote: >> >>> you don't make it clear about what doesn't work >>> >>> but here is a guess: you are getting match=1 in all cases (or at least >>> all where strvar is not missing); remember, however, that strpos=0 if >>> "S" is not found; so, in addition to the quotes, etc., I guess you want >>> to ensure that strpos is>0 (and maybe<.) >> >> >> On 6/11/12 11:50 AM, Jeph Herrin wrote: >> >>>> This should be trivial, but for some reason I cannot get it. >>>> >>>> I have a string variable, and I have a list of string values I need to >>>> match against it. There are occasional trailing or leading characters in >>>> the variable, so I am using -strpos- to find matches. Thus >>>> >>>> local matchlist "string 1" "string 2" "string 3" .... "string 55" >>>> >>>> gen byte match=0 >>>> foreach S in `matchlist' { >>>> replace match = 1 if strpos(strvar,`S') >>>> } >>>> >>>> Now, I know I have got the quotes and macro evaluations wrong, but that >>>> is the problem: I've tried this many different ways, and yet cannot seem >>>> to find a combination that works. Any thoughts? >> * * 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: macro problem***From:*Jeph Herrin <stata@spandrel.net>

**Re: st: macro problem***From:*Richard Goldstein <richgold@ix.netcom.com>

**Re: st: macro problem***From:*Jeph Herrin <stata@spandrel.net>

**RE: st: macro problem***From:*Nick Cox <n.j.cox@durham.ac.uk>

**Re: st: macro problem***From:*Jeph Herrin <stata@spandrel.net>

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