Re: How do I extract a text between some delimiters

[jkahn]

in reply to How do I extract a text between some delimiters

I'm sure there's a CPAN module that does generic tag extraction, but it might not conform to the form you're using here (I assume you're testing/building a part-of-speech tagger).

Barring a CPAN module (untested code follows, please tell me if this doesn't work -- it may be missing some whitespace in the substitution, for example):

sub stripPOS {
  my $words = shift;
  # rip out any / plus following characters, up to the 
  # first space
  $words =~ s!/\S*!!g;
  return $words;
}
  $sentence =~
    s! \s \<NP\d*\> (.*?) \</NP\> \s ! stripPOS($1). '/NP' !egx;

Let's break that out:

• s!

  begins the substitution.

• \s \<NP\d*\> \s

  looks for an <NP#> tag between spaces

• (.*?)

  looks for the shortest possible string until...

• \</NP\> \s

  you can find the closing tag

• ! stripPOS($1) . '/NP' !e

  replace it with the POS-stripped version of the stuff in the middle, followed by an /NP "pseudo-POS"

• gx;

  do it everywhere, and make it easier to read

Hope that helps, -- jkahn

Update (ca. 9p GMT-8): I've just realized that this code won't work if there are nested tags, e.g.:

<NP1> <NP2> The/D best/A one/N </NP>
  of/P <NP2> the/D Perl/N Monks/N </NP> </NP>

Anonymous Monk, does this happen in your input data? I will look at this and see if I can come up with a good answer if it does, or if I feel like it.....

[adrianh]

AM might want to consider extract_tagged() in Text::Balanced if s/he needs to cope with recursive NP tags.

Of course - they could always go the whole hog and write a proper parser with Parse::RecDescent... or wait for perl6 rules to arrive :-)

[Anonymous Monk]

Hello Monk
It does not happen in my input data. There are not nested tags in my sentences. I already run your code, and it works for some of the examples I tried so far.
Thanks