Re: st: macro problem

[Jeph Herrin <stata@spandrel.net>]

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?
>
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