Introduction to the scrapy Selector

Web Scraping in Python

Thomas Laetsch

Data Scientist, NYU

Setting up a Selector

from scrapy import Selector

html = '''
<html>
  <body>
    <div class="hello datacamp">
      <p>Hello World!</p>
    </div>
    <p>Enjoy DataCamp!</p>
  </body>
</html>
'''

sel = Selector( text = html )

Created a scrapy Selector object using a string with the html code
The selector sel has selected the entire html document

Selecting Selectors

We can use the xpath call within a Selector to create new Selectors of specific pieces of the html code
The return is a SelectorList of Selector objects

sel.xpath("//p")

# outputs the SelectorList:
[<Selector xpath='//p' data='<p>Hello World!</p>'>, 
 <Selector xpath='//p' data='<p>Enjoy DataCamp!</p>'>]

Extracting Data from a SelectorList

Use the extract() method

>>> sel.xpath("//p")

out: [<Selector xpath='//p' data='<p>Hello World!</p>'>,
      <Selector xpath='//p' data='<p>Enjoy DataCamp!</p>'>]

>>> sel.xpath("//p").extract()

out: [ '<p>Hello World!</p>', 
       '<p>Enjoy DataCamp!</p>' ]

We can use extract_first() to get the first element of the list

>>> sel.xpath("//p").extract_first()

out: '<p>Hello World!</p>'

Extracting Data from a Selector

ps = sel.xpath('//p')

second_p = ps[1]

second_p.extract()

out: '<p>Enjoy DataCamp!</p>'

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Web Scraping in Python