Shulou(Shulou.com)06/03 Report--

This article is to share with you about the working principle of Python crawler, the editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

With the rapid development of computer, Internet, Internet of things, cloud computing and other network technology, network information is growing explosively. The information of the Internet covers almost all topics such as society, culture, politics, economy, entertainment and so on. With the improvement of people's living standards, the requirements of quality of life are getting higher and higher. People have a smartphone anytime, anywhere, whether it is the presentation or running speed of the mobile phone interface, the requirement of experience convenience is also getting higher and higher. The rise of Python and the rise of Python crawler can more efficiently return the data content concerned by users directly to users, so that users can quickly find the content they need in the massive data content.

Many friends are also learning Python crawlers, but do you really understand how crawlers work?

How the Python crawler works

The web crawler finds the target web page through the unified resource locator URL, and returns the data content concerned by the user directly to the user, and does not need the user to obtain information in the form of browsing the web page, which saves the user time and energy, and improves the accuracy of data collection, so that the user can quickly find the content he needs in the massive data. The ultimate goal of web crawlers is to get the information they need from the web page. Although you can develop a crawler program and get the required content by using some crawler basic libraries such as urllib, urllib2, re, etc., all crawler programs are written in this way, which is a bit too much work, so there is a crawler framework. The use of crawler framework can greatly improve efficiency and shorten development time.

Web crawler (web crawler) is also known as web spider (web spider) or web robot (web robot). Other infrequently used names include ants, automatic indexing, simulators, or worms, and it is also one of the core concepts of the "Internet of things". Web crawler is essentially a computer program or script, which automatically crawls and downloads web pages of the World wide Web according to certain logic and algorithm rules, which is an important part of search engines.

Generally speaking, a web crawler starts with a predetermined URL of one or more initial web pages, and then crawls the web page according to certain rules to obtain the URL list on the initial web page. Then every time a web page is crawled, the crawler will extract the new URL of the web page and put it into the uncrawled queue, and then take out a URL from the uncrawled queue for a new round of crawling, repeating the above process again and again. The crawler will not end until the URL in the queue has been fetched or other established conditions have been reached. The specific process is shown in the following figure.

With the increasing of Internet information, there must be opportunities to use web crawler tools to obtain the required information. Using web crawlers to collect information can not only achieve efficient, accurate and automatic acquisition of information on web, but also facilitate companies or researchers to carry out follow-up mining and analysis of the collected data.

This is how the Python crawler works. The editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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