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Re: Re: text extract

by shu (Initiate)
on Feb 03, 2004 at 08:41 UTC ( #326149=note: print w/ replies, xml ) Need Help??


in reply to Re: text extract
in thread text extract

As far as my project goes, I have been able to make a flowchart of what I need to do and started development. But for the reasons of dynamic and ever changing formats of HTML, I have narrowed my focus on around 10 educational web pages and extracting info from there. However being new to perl, I am confused as to how to use the modules effectively. I have read and understood the functionality and can perform the basic functions but the combination of regular expressions and the HTML::parse etc to extract only CERTAIN parts of tect from a page is where i keep getting stuck. Please help or advise what I should do. The code you gave works fine with the page i mentioned. 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. These small hiccups are what are avoiding me from moving on fast. In the end i need GUI also which i think i can manage as Ive worked on it. Thanx...


Comment on Re: Re: text extract
Re: Re: Re: text extract
by Roger (Parson) on Feb 03, 2004 at 13:10 UTC
    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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