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Re: Re: Re: text extract

by Roger (Parson)
on Feb 03, 2004 at 13:10 UTC ( #326186=note: print w/ replies, xml ) Need Help??


in reply to Re: Re: text extract
in thread text extract

Now suppose i need to make a generic code that just searched for the keywords "publications" and "interests" within a given page, how do i reform the code.

That's no moon, that's a space station -- Obiwan Kenobi.

To do text extraction based on known pattern is easy if you know what the section start and finish look like in general. However you are looking for a generic algorithm on logical text extraction, you need to build a text-classification/pattern-recognition engine, and that's going to be very very difficult. Difficult, but not impossible. But that's way beyond me, besides I don't want to lose too many brain cells over this. ;-)

I will only cover the easy way, ie, (deterministic) text extraction based on a set of known patterns...

use strict; use warnings; use Data::Dumper; # build a hash of known patterns for each known web site my %patterns = ( 'www.foo.com' => { start => "<h3><font[^>]*><b><!--KEY--></b>", finish => "(?<!</font>\n)<br>", }, 'www.bar.com' => { start => "...", finish => "...", }, ); my $html = do { local $/; <DATA> }; print ExtractSection($html, 'www.foo.com', 'Section 2'), "\n\n"; print ExtractSection($html, 'www.foo.com', 'Section 1'), "\n\n"; print ExtractSection($html, 'www.foo.com', 'Section 3'), "\n\n"; # ----------------------------------------------------- sub ExtractSection { my ($html, $site, $section) = @_; my $ps = $patterns{$site}->{start}; my $pf = $patterns{$site}->{finish}; $ps =~ s/<!--KEY-->/$section/; $pf =~ s/<!--KEY-->/$section/; my ($text) = $html =~ /($ps.*?$pf)/sm; return $text; } __DATA__ <HTML> <h3><font size=+1><b>Section 1</b></font> <br> <li>Item 1 <li>Item 2 <li>Item 3 <br> <h3><font size=+1><b>Section 2</b></font> <br> <li>Item 4 <li>Item 5 <li>Item 6 <br> <h3><font size=+1><b>Section 3</b></font> <br> <li>Item 7 <li>Item 8 <li>Item 9 <br> </HTML>

And the output -
<h3><font size=+1><b>Section 2</b></font> <br> <li>Item 4 <li>Item 5 <li>Item 6 <br> <h3><font size=+1><b>Section 1</b></font> <br> <li>Item 1 <li>Item 2 <li>Item 3 <br> <h3><font size=+1><b>Section 3</b></font> <br> <li>Item 7 <li>Item 8 <li>Item 9 <br>


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