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)

Controlling the depth of a crawl

The depth of a crawl can be controlled using Scrapy DepthMiddleware middleware. The depth middleware limits the number of follows that Scrapy will take from any given link. This option can be useful for controlling how deep you go into a particular crawl. This is also used to keep a crawl from going on too long, and useful if you know that the content you are crawling for is located within a certain number of degrees of separation from the pages at the start of your crawl.

How to do it

The depth control middleware is installed in the middleware pipeline by default. An example of depth limiting is contained in the 06/06_limit_depth.py script. This script crawls the static site provided with...