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lxmlvschopper

BSD-3-Clause 19 12 2,562
85.1 million (month) Dec 13 2022 5.2.1(3 days ago)
22 3 1 MIT
0.6.0(11 months ago) Jul 24 2014 820 (month)

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

Chopper is a tool to extract elements from HTML by preserving ancestors and CSS rules.

Compared to other HTML parsers Chopper is designed to retain original HTML tree but eliminate elements that do not match parsing rules. Meaning, we can parse HTML elements and keep thei structure for machine learning or other tasks where data structure is needed as well as the data value.

Highlights


low-levelfast

Example Use


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"
HTML = """
<html>
  <head>
    <title>Test</title>
  </head>
  <body>
    <div id="header"></div>
    <div id="main">
      <div class="iwantthis">
        HELLO WORLD
        <a href="/nope">Do not want</a>
      </div>
    </div>
    <div id="footer"></div>
  </body>
</html>
"""

CSS = """
div { border: 1px solid black; }
div#main { color: blue; }
div.iwantthis { background-color: red; }
a { color: green; }
div#footer { border-top: 2px solid red; }
"""

extractor = Extractor.keep('//div[@class="iwantthis"]').discard('//a')
html, css = extractor.extract(HTML, CSS)

# will result in:
html
"""
<html>
  <body>
    <div id="main">
      <div class="iwantthis">
        HELLO WORLD
      </div>
    </div>
  </body>
</html>"""

css
"""
div{border:1px solid black;}
div#main{color:blue;}
div.iwantthis{background-color:red;}
"""

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