Ruby Regex Help

Question

I know a little bit of regex, but not mutch. What is the best way to get just the number out of the following html. (I want to have 32 returned). the values of width,row span, and size are all different in this horrible html page. Any help?

<td width=14 rowspan=2 align=right><font size=2 face="helvetica">32</font></td>

The best way is to use a parser not regular expressions. :-) — Erik
– Erik, Commented Mar 14, 2010 at 1:52
@Erik: In principle yes, but for quick and dirty screenscraping regex are usually a viable tool. — Joey
– Joey, Commented Mar 14, 2010 at 1:55
Well, your example certainly is valid, though :-). And HTML parsers usually are designed to deal with erroneous markup. — Joey
– Joey, Commented Mar 14, 2010 at 2:06

Joey · Accepted Answer · 2010-03-14 02:00:11Z

2

How about

>(\d+)<

Or, if you desperately want to avoid using capturing groups at all:

(?<=>)\d+(?=<)

edited Mar 14, 2010 at 2:00

answered Mar 14, 2010 at 1:54

Joey

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2 Comments

bunnyBEARZ Over a year ago

This returns >32< but I guess I could just do string.match(/>(\d+)</).match(/\d+/)

Joey Over a year ago

@bun: Well, you'll find the 32 in the first capturing group ... I edited the answer to include an example which doesn't need the group, though.

Jörg W Mittag · Accepted Answer · 2010-05-23 16:04:41Z

2

Please, do yourself a favor:

#!/usr/bin/env ruby
require 'nokogiri'

require 'test/unit'
class TestExtraction < Test::Unit::TestCase
  def test_that_it_extracts_the_number_correctly
    doc = Nokogiri::HTML('<td width=14 rowspan=2 align=right><font size=2 face="helvetica">32</font></td>')
    assert_equal [32], (doc / '//td/font').map {|el| el.text.to_i }
  end
end

edited May 23, 2010 at 16:04

answered Mar 14, 2010 at 2:19

Jörg W Mittag

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1 Comment

the Tin Man Over a year ago

I agree. Going after HTML content with regex is a lot more error prone over the long term compared to using a parser.

user3458 · Accepted Answer · 2010-03-14 01:58:51Z

0

May be

<td[^>]*><font[^>]*>\d+</font></td>

answered Mar 14, 2010 at 1:58

user3458

2 Comments

Joey Over a year ago

This will certainly match the string above, but won't do anything to extract the 32.

user3458 Over a year ago

Well, if Ruby's regexp synatx is borrowed from Perl, then you need to put \d+ in parentheses. And then use match()[1]

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