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Re^5: Breaking The Rules II

by BrowserUk (Pope)
on Jul 03, 2007 at 21:18 UTC ( #624792=note: print w/ replies, xml ) Need Help??


in reply to Re^4: Breaking The Rules II
in thread Breaking The Rules II

Some monks do indeed argue that "you can parse HTML with a regex" (e.g. tye) but I've never seen any argue against using a parser.

You didn't read what I wrote. I never said "use regex to parse html". If i wanted to parse html, I would use HTML::Parser (which I mentioned above as a fine pragmatic module). But if I want to extract some strings from amongst some other strings, I use regex.

To bring the linked example above up to date as the page it used went away many moons ago. One of the web pages I visit frequently is the BBC Weather forecast.

Here is a script to extract and print a selection of the data that page contains:

#! perl -slw use strict; use LWP::Simple; our $area ||= 1040; my $url = "http://www.bbc.co.uk/weather/5day.shtml?id=$area"; my $html = get $url or die "Failed to get html: $!, $^E"; my $reTag = qr[< [^>]+ > \s*? ]x; my( $state, $temp, $wDir, $wSpeed, $humid, $press, $updown, $vis ) = $ +html =~ m[ Current\s+Nearest\s+Observations $reTag : $reTag+ ( \S+ ) $reTag \s+ ( \d+ ) .+? ( [NSEW]+ ) \s+ \( ( \d+ ) .+? Relative\s+Humidity .+? : \s+ ( \d+ ) .+? Pressure .+? : \s+ ( \d+ ), \s+ ( \S+ ) , .+? Visibility .+? : \s+ ( [^<]+ ) ]smx or warn 'Regex failed!' and getstore $url, 'weather.failed'; print <<EOP; Sky: $state Temp: $temp Wind Direction: $wDir Speed: $wSpeed Humidity: $humid% Pressure: $press $updown Visibility: $vis EOP

When run it produces output like this:

C:\test>getWeather.pl Sky: cloudy Temp: 16 Wind Direction: S Speed: 5 Humidity: 77% Pressure: 999 Rising Visibility: Very good C:\test>getWeather.pl -area=3200 Sky: cloudy Temp: 17 Wind Direction: SW Speed: 17 Humidity: 67% Pressure: 999 Rising Visibility: Very good

Your mission, should you choose to accept it, is to reproduce that script using HTML::TokeParser::Simple and post it here.

If you took the time to learn perl well you'll not need to. And I say that with no limitations or caveats. :-)

That's simply not true. For one, I couldn't replace HTML::Parser with Perl code, because it's a Perl wrapper around an XS wrapper around 41k of intensely involved C code. Nor GD for similar reasons. Nor Time::HiRes. Nor... about 60 more modules, but that would just belabour the point.


Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.


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Re^6: Breaking The Rules II
by wfsp (Abbot) on Jul 04, 2007 at 08:43 UTC
    #! perl use strict; use warnings; use LWP::Simple; use HTML::TokeParser::Simple; our $area ||= 1040; my $url = "http://www.bbc.co.uk/weather/5day.shtml?id=$area"; my $html = get $url or die "Failed to get html: $!, $^E"; my $p = HTML::TokeParser::Simple->new(\$html); while (my $t = $p->get_tag('div')){ last if $t->get_attr('class') and $t->get_attr('class') eq 'display'; } my @data; while (my $t = $p->get_token){ last if $t->is_end_tag('div'); push @data, $t->as_is if $t->is_text; } # raw data #for (0..$#data){ # print "$_: $data[$_]\n"; #} my ($dir, $speed) = split(/\(/, $data[5]); print <<EOP; Sky: $data[2] Temp: $data[3] Wind Direction: $dir Speed: $speed Humidity$data[11] Pressure$data[15] Visibility$data[17] EOP __DATA__ Sky: cloudy Temp: 14 Wind Direction: SW Speed: 10 Humidity: 80, Pressure: 1004, Rising, Visibility: Very good ## raw data ## 0: Current Nearest Observations 1: : 2: cloudy 3: 14 4: C 5: SW (10 6: mph 7: ) 8: Relative Humidity ( 9: &#37; 10: ) 11: : 80, 12: Pressure ( 13: mB 14: ) 15: : 1004, Rising, 16: Visibility 17: : Very good

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