In this tutorial, we shall explore the exciting world of web crawling using Python. Web crawlers, also known as spiders, are internet bots that systematically crawl through the web for the purpose of indexing (web search engines), data scraping, and much more. So, grab your gear, and let’s get started!
Set up the Environment
To perform web crawling in Python, we first need to install two crucial packages – BeautifulSoup and requests. BeautifulSoup is a Python library that is used for web scraping purposes to pull the data out of HTML and XML files. The requests library is used for making HTTP requests in Python.
You can install these packages using pip:
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pip install beautifulsoup4 requests |
Choose the Webpage for Crawling
Next, you need to decide which webpage you want to crawl. For example, let’s take some articles’ links from the Wikipedia homepage. Please be mindful and respectful of the website’s robots.txt file and policies.
Send an HTTP Request
The very first step in web-crawling is to send an HTTP request to the website server. This can be done using the requests package:
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import requests URL = "https://your-website-url" page = requests.get(URL) |
Parse the Page Content
Now that we’ve got the content of the webpage, it’s time to parse it so that we can extract useful information from it. This is where BeautifulSoup comes in:
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from bs4 import BeautifulSoup soup = BeautifulSoup(page.content, "html.parser") |
This will create a BeautifulSoup object, and parse the page content in HTML.
Extract Data
After parsing the contents of the page, we can extract the data we need using BeautifulSoup’s functions:
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data = soup.find_all('your-tag') |
This code will find all HTML tags with the specified name and return them as a list.
Conclusion
All set! You have just made a simple web crawler in Python. It retrieves a webpage’s HTML content, parses it, and extracts the necessary information. Although this is a basic example, it provides a solid foundation upon which you can build more complex web crawlers in the future.
The Full Code:
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import requests from bs4 import BeautifulSoup URL = "https://your-website-url" page = requests.get(URL) soup = BeautifulSoup(page.content, "html.parser") data = soup.find_all('your-tag') print(data) |