Web Scrapping with Python
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Introduction on how to crawl for sites and content from the unstructured data on the web. using the Python programming language and some existing python modules.
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Web Scrapping with Python
- 1. Web Scrapping with Python Miguel Miranda de Mattos :@mmmattos - mmmattos.net Porto Alegre, Brazil. 2012
- 2. Web Scrapping with Python ● Tools: ○ BeautifulSoup ○ Mechanize
- 3. BeautifulSoup An HTML/XML parser for Python that can turn even invalid markup into a parse tree. It provides simple, idiomatic ways of navigating, searching, and modifying the parse tree. It commonly saves programmers hours or days of work. ● In Summary: ○ Navigate the "soup" of HTML/XML tags, programatically ○ Access tag´s properties and values ○ Search for tags and their attributes.
- 4. BeautifulSoup ○ Example: from BeautifulSoup import BeautifulSoup doc = "<html><h1>Heading</h1><p>Text" soup = BeautifulSoup(doc) print soup.prettify() # <html> # <h1> # Heading # </h1> # <p> # Text # </p> # </html> ○
- 5. BeautifulSoup ○ Searching / Looking for things ■ 'find', 'findAll', 'findAllNext', 'findAllPrevious', 'findChild', 'findChildren', 'findNext', 'findNextSibling', 'findNextSiblings', 'findParent', 'findParents', 'findPrevious', 'findPreviousSibling', 'findPreviousSiblings' ■ findAll ● findAll(self, name=None, attrs={}, recursive=True, text=None, limit=None, **kwargs) ● Extracts a list of Tag objects that match the given ● criteria. You can specify the name of the Tag and any ● attributes you want the Tag to have.
- 6. BeautifulSoup ● Example: >>> from BeautifulSoup import BeautifulSoup >>> doc = "<table><tr><td>one</td><td>two</td></tr></table>" >>> docSoup = BeautifulSoup(doc) >>> print docSoup.findAll('tr') [<tr><td>one</td><td>two</td></tr>] >>> print docSoup.findAll('td') [<td>one</td>, <td>two</td>]
- 7. BeautifulSoup ● findAll (cont´d.): >>> for t in docSoup.findAll('td'): >>> print t <td>one</td> <td>two</td> >>> for t in docSoup.findAll('td'): >>> print t.getText() one two
- 8. BeautifulSoup ● findAll using attributes to qualify: >>> soup.findAll('div',attrs = {'class': 'Menus'}) [<div>musicMenu</div>,<div>videoMenu</div>] ● For more options: ○ dir (BeautifulSoup) ○ help (yourSoup.<command>) ● Use BeautifulSoup rather than regexp patterns: patFinderTitle = re.compile(r'<a[^>]*stitle="(.*?)"') re.findAll(patFinderTitle, html) ○ by soup = BeautifulSoup(html) for tag in brand_row_soup.findAll('a'): print tag['title']
- 9. Mechanize ● Stateful programmatic web browsing in Python, after Andy Lester’s Perl module. ● mechanize.Browser and mechanize.UserAgentBase, so: ○ any URL can be opened, not just http: ○ mechanize.UserAgentBase offers easy dynamic configuration of user-agent features like protocol, cookie, redirection and robots. txt handling, without having to make a new OpenerDirector each time, e.g. by callingbuild_opener(). ● Easy HTML form filling. ● Convenient link parsing and following. ● Browser history (.back() and .reload() methods). ● The Referer HTTP header is added properly (optional). ● Automatic observance of robots.txt. ● Automatic handling of HTTP-Equiv and Refresh.
- 10. Mechanize ● Navigation commands: ○ open(url) ○ follow_link(link) ○ back() ○ submit() ○ reload() ● Examples br = mechanize.Browser() br.open("python.org") gothtml = br.response().read() for link in br.links(url_regex="python.org"): print link br.follow_link(link) # takes EITHER Link instance OR keyword args br.back()
- 11. Mechanize ● Example: import re import mechanize br = mechanize.Browser() br.open("http://www.example.com/") # follow second link with element text matching # regular expression response1 = br.follow_link(text_regex=r"cheeses*shop") assert br.viewing_html() print br.title() print response1.geturl() print response1.info() # headers print response1.read() # body
- 12. Mechanize ● Example: Combining Mechanize and BeautifulSoup import re import mechanize from BeautifulSoup import BeutifulSoup url = "http://www.hp.com" br = mechanize.Browser() br..open(url) assert br.viewing_html() html = br.response().read() result_soup = BeautifulSoup(html) found_divs = soup.findAll('div') print "Found " + str(len(found_divs)) for d in found_divs: print d
- 13. Mechanize ● Example: Combining Mechanize and BeautifulSoup import re import mechanize url = "http://www.hp.com" br = mechanize.Browser() br..open(url) assert br.viewing_html() html = br.response().read() result_soup = BeautifulSoup(html) found_divs = soup.findAll('div') print "Found " + str(len(found_divs)) for d in found_divs: if d.has_key('class'): print d['class']