Options for HTML scraping? [closed]

StackOverflow https://stackoverflow.com/questions/2861

Question

I'm thinking of trying Beautiful Soup, a Python package for HTML scraping. Are there any other HTML scraping packages I should be looking at? Python is not a requirement, I'm actually interested in hearing about other languages as well.

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Solution

The Ruby world's equivalent to Beautiful Soup is why_the_lucky_stiff's Hpricot.

OTHER TIPS

In the .NET world, I recommend the HTML Agility Pack. Not near as simple as some of the above options (like HTMLSQL), but it's very flexible. It lets you maniuplate poorly formed HTML as if it were well formed XML, so you can use XPATH or just itereate over nodes.

http://www.codeplex.com/htmlagilitypack

BeautifulSoup is a great way to go for HTML scraping. My previous job had me doing a lot of scraping and I wish I knew about BeautifulSoup when I started. It's like the DOM with a lot more useful options and is a lot more pythonic. If you want to try Ruby they ported BeautifulSoup calling it RubyfulSoup but it hasn't been updated in a while.

Other useful tools are HTMLParser or sgmllib.SGMLParser which are part of the standard Python library. These work by calling methods every time you enter/exit a tag and encounter html text. They're like Expat if you're familiar with that. These libraries are especially useful if you are going to parse very large files and creating a DOM tree would be long and expensive.

Regular expressions aren't very necessary. BeautifulSoup handles regular expressions so if you need their power you can utilize it there. I say go with BeautifulSoup unless you need speed and a smaller memory footprint. If you find a better HTML parser on Python, let me know.

I found HTMLSQL to be a ridiculously simple way to screenscrape. It takes literally minutes to get results with it.

The queries are super-intuitive - like:

SELECT title from img WHERE $class == 'userpic'

There are now some other alternatives that take the same approach.

The Python lxml library acts as a Pythonic binding for the libxml2 and libxslt libraries. I like particularly its XPath support and pretty-printing of the in-memory XML structure. It also supports parsing broken HTML. And I don't think you can find other Python libraries/bindings that parse XML faster than lxml.

For Perl, there's WWW::Mechanize.

Python has several options for HTML scraping in addition to Beatiful Soup. Here are some others:

  • mechanize: similar to perl WWW:Mechanize. Gives you a browser like object to ineract with web pages
  • lxml: Python binding to libwww. Supports various options to traverse and select elements (e.g. XPath and CSS selection)
  • scrapemark: high level library using templates to extract informations from HTML.
  • pyquery: allows you to make jQuery like queries on XML documents.
  • scrapy: an high level scraping and web crawling framework. It can be used to write spiders, for data mining and for monitoring and automated testing

'Simple HTML DOM Parser' is a good option for PHP, if your familiar with jQuery or JavaScript selectors then you will find yourself at home.

Find it here

There is also a blog post about it here.

Why has no one mentioned JSOUP yet for Java? http://jsoup.org/

The templatemaker utility from Adrian Holovaty (of Django fame) uses a very interesting approach: You feed it variations of the same page and it "learns" where the "holes" for variable data are. It's not HTML specific, so it would be good for scraping any other plaintext content as well. I've used it also for PDFs and HTML converted to plaintext (with pdftotext and lynx, respectively).

I would first find out if the site(s) in question provide an API server or RSS Feeds for access the data you require.

I know and love Screen-Scraper.

Screen-Scraper is a tool for extracting data from websites. Screen-Scraper automates:

* Clicking links on websites
* Entering data into forms and submitting
* Iterating through search result pages
* Downloading files (PDF, MS Word, images, etc.)

Common uses:

* Download all products, records from a website
* Build a shopping comparison site
* Perform market research
* Integrate or migrate data

Technical:

* Graphical interface--easy automation
* Cross platform (Linux, Mac, Windows, etc.)
* Integrates with most programming languages (Java, PHP, .NET, ASP, Ruby, etc.)
* Runs on workstations or servers

Three editions of screen-scraper:

* Enterprise: The most feature-rich edition of screen-scraper. All capabilities are enabled.
* Professional: Designed to be capable of handling most common scraping projects.
* Basic: Works great for simple projects, but not nearly as many features as its two older brothers.

Another option for Perl would be Web::Scraper which is based on Ruby's Scrapi. In a nutshell, with nice and concise syntax, you can get a robust scraper directly into data structures.

Scraping Stack Overflow is especially easy with Shoes and Hpricot.

require 'hpricot'

Shoes.app :title => "Ask Stack Overflow", :width => 370 do
  SO_URL = "http://stackoverflow.com"
  stack do
    stack do
      caption "What is your question?"
      flow do
        @lookup = edit_line "stackoverflow", :width => "-115px"
        button "Ask", :width => "90px" do
          download SO_URL + "/search?s=" + @lookup.text do |s|
            doc = Hpricot(s.response.body)
            @rez.clear()
            (doc/:a).each do |l|
              href = l["href"]
              if href.to_s =~ /\/questions\/[0-9]+/ then
                @rez.append do
                  para(link(l.inner_text) { visit(SO_URL + href) })
                end
              end
            end
            @rez.show()
          end
        end
      end
    end
    stack :margin => 25 do
      background white, :radius => 20
      @rez = stack do
      end
    end
    @rez.hide()
  end
end

I've had some success with HtmlUnit, in Java. It's a simple framework for writing unit tests on web UI's, but equally useful for HTML scraping.

Another tool for .NET is MhtBuilder

There is this solution too: netty HttpClient

I use Hpricot on Ruby. As an example this is a snippet of code that I use to retrieve all book titles from the six pages of my HireThings account (as they don't seem to provide a single page with this information):

pagerange = 1..6
proxy = Net::HTTP::Proxy(proxy, port, user, pwd)
proxy.start('www.hirethings.co.nz') do |http|
  pagerange.each do |page|
    resp, data = http.get "/perth_dotnet?page=#{page}" 
    if resp.class == Net::HTTPOK
      (Hpricot(data)/"h3 a").each { |a| puts a.innerText }
    end
  end
end

It's pretty much complete. All that comes before this are library imports and the settings for my proxy.

I've used Beautiful Soup a lot with Python. It is much better than regular expression checking, because it works like using the DOM, even if the HTML is poorly formatted. You can quickly find HTML tags and text with simpler syntax than regular expressions. Once you find an element, you can iterate over it and its children, which is more useful for understanding the contents in code than it is with regular expressions. I wish Beautiful Soup existed years ago when I had to do a lot of screenscraping -- it would have saved me a lot of time and headache since HTML structure was so poor before people started validating it.

Although it was designed for .NET web-testing, I've been using the WatiN framework for this purpose. Since it is DOM-based, it is pretty easy to capture HTML, text, or images. Recentely, I used it to dump a list of links from a MediaWiki All Pages namespace query into an Excel spreadsheet. The following VB.NET code fragement is pretty crude, but it works.

Sub GetLinks(ByVal PagesIE As IE, ByVal MyWorkSheet As Excel.Worksheet)

    Dim PagesLink As Link
    For Each PagesLink In PagesIE.TableBodies(2).Links
        With MyWorkSheet
            .Cells(XLRowCounterInt, 1) = PagesLink.Text
            .Cells(XLRowCounterInt, 2) = PagesLink.Url
        End With
        XLRowCounterInt = XLRowCounterInt + 1
    Next
End Sub

Implementations of the HTML5 parsing algorithm: html5lib (Python, Ruby), Validator.nu HTML Parser (Java, JavaScript; C++ in development), Hubbub (C), Twintsam (C#; upcoming).

You would be a fool not to use Perl.. Here come the flames..

Bone up on the following modules and ginsu any scrape around.

use LWP
use HTML::TableExtract
use HTML::TreeBuilder
use HTML::Form
use Data::Dumper

I have used LWP and HTML::TreeBuilder with Perl and have found them very useful.

LWP (short for libwww-perl) lets you connect to websites and scrape the HTML, you can get the module here and the O'Reilly book seems to be online here.

TreeBuilder allows you to construct a tree from the HTML, and documentation and source are available in HTML::TreeBuilder - Parser that builds a HTML syntax tree.

There might be too much heavy-lifting still to do with something like this approach though. I have not looked at the Mechanize module suggested by another answer, so I may well do that.

In Java, you can use TagSoup.

Well, if you want it done from the client side using only a browser you have jcrawl.com. After having designed your scrapping service from the web application (http://www.jcrawl.com/app.html), you only need to add the generated script to an HTML page to start using/presenting your data.

All the scrapping logic happens on the the browser via JavaScript. I hope you find it useful. Click this link for a live example that extracts the latest news from Yahoo tennis.

You probably have as much already, but I think this is what you are trying to do:

from __future__ import with_statement
import re, os

profile = ""

os.system('wget --no-cookies --header "Cookie: soba=(SeCreTCODe)" http://stackoverflow.com/users/30/myProfile.html')
with open("myProfile.html") as f:
    for line in f:
        profile = profile + line
f.close()
p = re.compile('summarycount">(\d+)</div>') #Rep is found here
print p
m = p.search(profile)
print m
print m.group(1)
os.system("espeak \"Rep is at " + m.group(1) + " points\""
os.remove("myProfile.html")

I've had mixed results in .NET using SgmlReader which was originally started by Chris Lovett and appears to have been updated by MindTouch.

I like Google Spreadsheets' ImportXML(URL, XPath) function.

It will repeat cells down the column if your XPath expression returns more than one value.

You can have up to 50 importxml() functions on one spreadsheet.

RapidMiner's Web Plugin is also pretty easy to use. It can do posts, accepts cookies, and can set the user-agent.

I've also had great success using Aptana's Jaxer + jQuery to parse pages. It's not as fast or 'script-like' in nature, but jQuery selectors + real JavaScript/DOM is a lifesaver on more complicated (or malformed) pages.

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