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beautifulsoupvslxml

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beautifulsoup is a Python library for pulling data out of HTML and XML files. It creates parse trees from the source code that can be used to extract data from HTML, which is useful for web scraping. With beautifulsoup, you can search, navigate, and modify the parse tree. It sits atop popular Python parsers like lxml and html5lib, allowing users to try out different parsing strategies or trade speed for flexibility.

beautifulsoup has a number of useful methods and attributes that can be used to extract and manipulate data from an HTML or XML document. Some of the key features include:

  • Searching the parse tree
    You can search the parse tree using the various search methods that beautifulsoup provides, such as find(), find_all(), and select(). These methods take various arguments to search for specific tags, attributes, and text, and return a list of matching elements.
  • Navigating the parse tree
    You can navigate the parse tree using the various navigation methods that beautifulsoup provides, such as next_sibling, previous_sibling, next_element, previous_element, parent, and children. These methods allow you to move up, down, and around the parse tree.
  • Modifying the parse tree
    You can modify the parse tree using the various modification methods that beautifulsoup provides, such as append(), extend(), insert(), insert_before(), and insert_after(). These methods allow you to add new elements to the parse tree, or to change the position of existing elements.
  • Accessing tag attributes
    You can access the attributes of a tag using the attrs property. This property returns a dictionary of the tag's attributes and their values.
  • Accessing tag text
    You can access the text within a tag using the string property. This property returns the text as a string, with any leading or trailing whitespace removed.

With the above feature one can easily extract data out of HTML or XML files. It is widely used in web scraping and other data extraction projects.

It also has features for parsing XML files, special methods for dealing with HTML forms, pretty printing HTML and a few other functionalities.

lxml is a low-level XML and HTML tree processor. It's used by many other libraries such as parsel or beautifulsoup for higher level HTML parsing.

One of the main features of lxml is its speed and efficiency.
It is built on top of the libxml2 and libxslt C libraries, which are known for their high performance and low memory footprint. This makes lxml well-suited for processing large and complex XML and HTML documents.

One of the key components of lxml is the ElementTree API, which is modeled after the ElementTree API from the Python standard library's xml module. This API provides a simple and intuitive way to access and manipulate the elements and attributes of an XML or HTML document. It also provides a powerful and flexible Xpath engine that allows you to select elements based on their names, attributes, and contents.

Another feature of lxml is its support for parsing and creating XML documents using the XSLT standard. The lxml library provides a powerful and easy-to-use interface for applying XSLT stylesheets to XML documents, which can be used to transform and convert XML documents into other formats, such as HTML, PDF, or even other XML formats.

For web scraping it's best to use other higher level libraries that use lxml like parsel or beautifulsoup

Highlights


css-selectorsdsl-selectorshttp2
low-levelfast

Example Use


from bs4 import BeautifulSoup

# this is our HTML page:
html = """
<head>
  <title>Hello World!</title>
</head>
<body>
  <div id="product">
    <h1>Product Title</h1>
    <p>paragraph 1</p>
    <p>paragraph2</p>
    <span class="price">$10</span>
  </div>
</body>
"""

soup = BeautifulSoup(html)

# we can iterate using dot notation:
soup.head.title
"Hello World"

# or use find method to recursively find matching elements:
soup.find(class_="price").text
"$10"

# the selected elements can be modified in place:
soup.find(class_="price").string = "$20"

# beautifulsoup also supports CSS selectors:
soup.select_one("#product .price").text
"$20"

# bs4 also contains various utility functions like HTML formatting
print(soup.prettify())
"""
<html>
 <head>
  <title>
   Hello World!
  </title>
 </head>
 <body>
  <div id="product">
   <h1>
    Product Title
   </h1>
   <p>
    paragraph 1
   </p>
   <p>
    paragraph2
   </p>
   <span class="price">
    $20
   </span>
  </div>
 </body>
</html>
"""
from lxml import etree

# this is our HTML page:
html = """
<head>
  <title>Hello World!</title>
</head>
<body>
  <div id="product">
    <h1>Product Title</h1>
    <p>paragraph 1</p>
    <p>paragraph2</p>
    <span class="price">$10</span>
  </div>
</body>
"""

tree = tree.fromstring(html)

# for parsing, LXML only supports XPath selectors:
tree.xpath('//span[@class="price"]')[0].text
"$10"

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