How can I extract data from HTML tables in Perl?

问题:

Possible duplicate:
Can you provide an example of parsing HTML with your favorite parser?
How can I extract content from HTML files using Perl?

---

I'm trying to use regular expressions in Perl to parse a table with the following structure. The first line is as follows:

<tr class="Highlight"><td>Time Played</a></td><td></td><td>Artist</td><td width="1%"></td><td>Title</td><td>Label</td></tr>

Here I wish to take out "Time Played", "Artist", "Title", and "Label", and print them to an output file.

Any help would be greatly apreciated!

Ok sorry... I've tried many regular expressions such as:

$lines =~ / (<td>) /
       OR
$lines =~ / <td>(.*)< /
       OR
$lines =~ / >(.*)< /

My current program looks like so:

#!perl -w

open INPUT_FILE, "<", "FIRST_LINE_OF_OUTPUT.txt" or die $!;

open OUTPUT_FILE, ">>", "PLAYLIST_TABLE.txt" or die $!;

my $lines = join '', <INPUT_FILE>;

print "Hello 2\n";

if ($lines =~ / (\S.*\S) /) {
print "this is 1: \n";
print $1;
    if ($lines =~ / <td>(.*)< / ) {
    print "this is the 2nd 1: \n";
    print $1;
    print "the word was: $1.\n";
    $Time = $1;
    print $Time;
    print OUTPUT_FILE $Time;
    } else {
    print "2ND IF FAILED\n";
    }
} else { 
print "THIS FAILED\n";
}

close(INPUT_FILE);
close(OUTPUT_FILE);

回答1:

Do NOT use regexps to parse HTML. There are a very large number of CPAN modules which do this for you much more effectively.

• Can you provide some examples of why it is hard to parse XML and HTML with a regex?
• Can you provide an example of parsing HTML with your favorite parser?
• HTML::Parser
• HTML::TreeBuilder
• HTML::TableExtract

回答2:

Use HTML::TableExtract. Really.

#!/usr/bin/perl

use strict;
use warnings;

use HTML::TableExtract;
use LWP::Simple;

my $file = 'Table3.htm';
unless ( -e $file ) {
    my $rc = getstore(
        'http://www.ntsb.gov/aviation/Table3.htm',
        $file);
    die "Failed to download document\n" unless $rc == 200;
}

my @headers = qw( Year Fatalities );

my $te = HTML::TableExtract->new(
    headers => \@headers,
    attribs => { id => 'myTable' },
);

$te->parse_file($file);

my ($table) = $te->tables;

print join("\t", @headers), "\n";

for my $row ($te->rows ) {
    print join("\t", @$row), "\n";
}

This is what I meant in another post by "task-specific" HTML parsers.

You could have saved a lot of time by directing your energy to reading some documentation rather than throwing regexes at the wall and seeing if any stuck.

回答3:

That's an easy one:

my $html = '<tr class="Highlight"><td>Time Played</a></td><td></td><td>Artist</td><td width="1%"></td><td>Title</td><td>Label</td></tr>';
my @stuff = $html =~ />([^<]+)</g;
print join (", ", @stuff), "\n";

See http://codepad.org/qz9d5Bro if you want to try running it.