May 2017
Beginner to intermediate
220 pages
5h 2m
English
Content preview from Python Web Scraping - Second Edition
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Parsing robots.txt
First, we need to interpret robots.txt to avoid downloading blocked URLs. Python urllib comes with the robotparser module, which makes this straightforward, as follows:
>>> from urllib import robotparser>>> rp = robotparser.RobotFileParser()>>> rp.set_url('http://example.webscraping.com/robots.txt')>>> rp.read()>>> url = 'http://example.webscraping.com'>>> user_agent = 'BadCrawler'>>> rp.can_fetch(user_agent, url)False>>> user_agent = 'GoodCrawler'>>> rp.can_fetch(user_agent, url)True
The robotparser module loads a robots.txt file and then provides a can_fetch()function, which tells you whether a particular user agent is allowed to access a web page or not. Here, when the user agent is set to 'BadCrawler', the robotparser ...
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