In data mining, web crawling and web scraping are two important techniques used to gather data from the internet. Web crawling and web scraping are often used interchangeably, but they are actually different techniques. In this article, we will discuss the differences between web crawling and web scraping and explore some popular open source web crawlers for data mining.
Web Crawling:
Web crawling, also known as spidering, is a technique used to systematically browse and index web pages. Web crawlers, or spiders, use automated scripts to browse through websites and follow links to other pages, creating a map of the web. Web crawlers are used by search engines like Google to index web pages for search results.
Examples of Open Source Web Crawlers:
Scrapy:
Scrapy is a popular open source web crawling framework written in Python. It allows developers to easily create and manage web crawlers, and provides features such as automatic throttling and parallelism.
Apache Nutch:
Web scraping, on the other hand, is the process of extracting data from websites. Unlike web crawling, web scraping does not involve indexing or browsing through websites. Instead, it involves extracting data from specific web pages or sites.
Examples of Open Source Web Scrapper:
Beautiful Soup:
Beautiful Soup is a popular Python library used for web scraping. It allows developers to parse HTML and XML documents, and provides features such as automatic encoding detection and HTML formatting.
Scrapy:
Scrapy, which was mentioned earlier as a web crawling framework, can also be used for web scraping. Its flexible architecture allows developers to easily extract data from websites and export it in various formats.
Difference Between Web Crawling and Web Scraping:
- Web crawling is used to systematically browse and index web pages, while web scraping is used to extract data from specific web pages or sites.
- Web crawling involves indexing and mapping of websites, while web scraping involves extracting data from HTML pages.
- Web crawlers follow links to other pages, while web scrapers target specific pages for data extraction.
Conclusion:
Web crawling and web scraping are important techniques used in data mining. While they are often used interchangeably, they are actually different techniques. Open source web crawling frameworks like Scrapy and Apache Nutch are used to create and manage web crawlers, while open source web scraping libraries like Beautiful Soup and Scrapy can be used to extract data from websites. By understanding the differences between these techniques and using the appropriate tools, developers can efficiently gather and extract data from the internet for various applications.
