Book Image

Python Web Scraping

By : Richard Penman
Book Image

Python Web Scraping

By: Richard Penman

Overview of this book

The Internet contains the most useful set of data ever assembled, largely publicly accessible for free. However, this data is not easily reusable. It is embedded within the structure and style of websites and needs to be carefully extracted to be useful. Web scraping is becoming increasingly useful as a means to easily gather and make sense of the plethora of information available online. Using a simple language like Python, you can crawl the information out of complex websites using simple programming. This book is the ultimate guide to using Python to scrape data from websites. In the early chapters it covers how to extract data from static web pages and how to use caching to manage the load on servers. After the basics we'll get our hands dirty with building a more sophisticated crawler with threads and more advanced topics. Learn step-by-step how to use Ajax URLs, employ the Firebug extension for monitoring, and indirectly scrape data. Discover more scraping nitty-gritties such as using the browser renderer, managing cookies, how to submit forms to extract data from complex websites protected by CAPTCHA, and so on. The book wraps up with how to create high-level scrapers with Scrapy libraries and implement what has been learned to real websites.
Table of Contents (11 chapters)

Analyzing a web page

To understand how a web page is structured, we can try examining the source code. In most web browsers, the source code of a web page can be viewed by right-clicking on the page and selecting the View page source option:

Analyzing a web page

The data we are interested in is found in this part of the HTML:

<table>
<tr id="places_national_flag__row"><td class="w2p_fl"><label for="places_national_flag" id="places_national_flag__label">National Flag: </label></td><td class="w2p_fw"><img src="/places/static/images/flags/gb.png" /></td><td class="w2p_fc"></td></tr>
...
<tr id="places_neighbours__row"><td class="w2p_fl"><label for="places_neighbours" id="places_neighbours__label">Neighbours: </label></td><td class="w2p_fw"><div><a href="/iso/IE">IE...