What is "Web Scraping"?
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Created 9 months ago (Last Update: 13 minutes ago)
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web scraping
Web scraping is the process of extracting large amounts of data from websites. It involves fetching web pages, parsing the HTML or XML code, and then extracting specific data elements, such as text, images, links, or structured information like product details, from these web pages. It is also known as web harvesting or web data extraction.
Web scraping typically follows these steps:
- Sending an HTTP request to the target website's server to retrieve the web page's HTML content.
- Parsing the HTML content to identify and locate the desired data elements using techniques like XPath, CSS selectors, or regular expressions.
- Extracting the data and saving it in a structured format, such as CSV, JSON, or a database.
- Repeating the process for multiple pages or websites, if necessary.
There are four common approaches to web scraping:
- Commercially available web scrapers (Off-the-shelf web scrapers): Software tools like Octoparse, ParseHub, or Import.io that allow users to extract data from websites without the need for extensive coding or customization.
- Custom-built web scrapers (In-house web scrapers): An organization creates its own web scraping script using programming languages like Python and libraries like Beautiful Soup or Scrapy to collect specific data from websites tailored to its unique requirements.
- Web scraping services (Web scraping APIs): A third-party service like ScrapingHub or Apify that provides APIs or platforms for web scraping. Users can send requests to these APIs, and the service handles the scraping and data extraction for them.
- Pre-existing datasets (Ready-made datasets): Datasets available on platforms like Kaggle, data.gov, or academic research repositories that are already collected, cleaned, and ready for analysis. These datasets often cover various topics, from climate data to social media sentiment analysis.
There are a few techniques that are very commonly used for web scraping. These techniques can be mapped to one or more of the web scraping approaches discussed earlier. The techniques are as follows:
- HTML Parsing: Uses JavaScript to target either a linear or nested HTML page. This method is powerful and swift in extracting text, links such as a nested link or email address, scraping screens, and pulling resources.
- DOM Parsing: The Document Object Model (DOM) defines the organization of an XML file, basically its structure, style, and content. Typically, scrapers employ DOM parsers to thoroughly inspect the structure of web pages, access nodes containing information, and perform web scraping using tools like XPath. When dealing with dynamically generated content, scrapers have the option to integrate web browsers such as Firefox and Internet Explorer for extracting entire web pages or specific portions.
- Vertical Aggregation: Refers to the process of collecting data from multiple sources or web pages that share a common theme or category. This approach involves scraping data that is within the same category or the same type of information. Usually, companies with extensive computing capabilities employ this technique to create data harvesting platforms to target particular verticals.
- XML Path Language: XPath is a query language used in web scraping to navigate and extract specific data from XML and HTML documents. It allows users to locate and select elements or attributes within the document's hierarchical structure
- Google Sheets: The importXML function of Google Sheets is used to extract specific patterns or data from a website.
- Image Processing: Using Machine learning and image processing to analyze web pages by visually interpreting information on web pages as a human being would. Not very common but a substantially used technique.
- Market Research and Competitive Analysis: Web scraping enables businesses to gather market intelligence, track competitors' pricing strategies, and analyze customer reviews and sentiment. This information aids in making informed decisions and staying competitive.
- Data for Business Intelligence: By scraping data from various sources, companies can generate valuable insights for business intelligence, such as tracking customer behavior, monitoring product performance, and identifying emerging trends.
- Price Monitoring and E-commerce: E-commerce businesses can use web scraping to monitor competitors' prices, update their own pricing strategies in real-time, and ensure they remain competitive in the market.
- News and Content Aggregation: Media outlets and content aggregators can automate the process of collecting news articles, blog posts, and other content from across the web, providing readers with up-to-date information.
- Website Structure Changes: Websites may change their structure or layout, necessitating updates to scraping scripts to adapt to these changes.
- IP Blocking and Security Measures: Some websites implement IP blocking or employ security measures to detect and block scrapers. This can pose challenges for web scrapers.
- Handling Large Volumes of Data: Scraping large volumes of data can strain computing resources and require efficient data storage and processing solutions.
Web scraping is a powerful tool for extracting valuable data from the vast expanse of the internet. When used ethically and responsibly, it can provide businesses with crucial insights and information. However, it's essential to be aware of legal and ethical considerations, respect website terms of service, and employ best practices to ensure that web scraping remains valuable and ethical.
