Book Image

Python Web Scraping Cookbook

By : Michael Heydt
Book Image

Python Web Scraping Cookbook

By: Michael Heydt

Overview of this book

Python Web Scraping Cookbook is a solution-focused book that will teach you techniques to develop high-performance scrapers and deal with crawlers, sitemaps, forms automation, Ajax-based sites, caches, and more. You'll explore a number of real-world scenarios where every part of the development/product life cycle will be fully covered. You will not only develop the skills needed to design and develop reliable performance data flows, but also deploy your codebase to AWS. If you are involved in software engineering, product development, or data mining (or are interested in building data-driven products), you will find this book useful as each recipe has a clear purpose and objective. Right from extracting data from the websites to writing a sophisticated web crawler, the book's independent recipes will be a godsend. This book covers Python libraries, requests, and BeautifulSoup. You will learn about crawling, web spidering, working with Ajax websites, paginated items, and more. You will also learn to tackle problems such as 403 errors, working with proxy, scraping images, and LXML. By the end of this book, you will be able to scrape websites more efficiently and able to deploy and operate your scraper in the cloud.
Table of Contents (13 chapters)

Querying the DOM with XPath and lxml

XPath is a query language for selecting nodes from an XML document and is a must-learn query language for anyone performing web scraping. XPath offers a number of benefits to its user over other model-based tools:

  • Can easily navigate through the DOM tree
  • More sophisticated and powerful than other selectors like CSS selectors and regular expressions
  • It has a great set (200+) of built-in functions and is extensible with custom functions
  • It is widely supported by parsing libraries and scraping platforms

XPath contains seven data models (we have seen some of them previously):

  • root node (top level parent node)
  • element nodes (<a>..</a>)
  • attribute nodes (href="example.html")
  • text nodes ("this is a text")
  • comment nodes (<!-- a comment -->)
  • namespace nodes
  • processing instruction nodes

XPath expressions can...