lxml.etree and lxml.html are both part of the lxml library in Python, which is a powerful and feature-rich library for parsing XML and HTML documents. Despite being part of the same library, these two modules are designed for different use cases.
lxml.etree
lxml.etree is primarily designed for parsing and working with XML documents. It follows the ElementTree API, which is a simple and lightweight XML processor. The etree module is highly optimized for XML parsing, and it is often used in situations where namespaces, XSLT transformations, schema validation, and XPath expressions are needed. It is extremely fast and suitable for processing large XML files.
Here's how you might parse and work with an XML document using lxml.etree:
from lxml import etree
xml_data = """<root>
<child1>Content of child 1</child1>
<child2>Content of child 2</child2>
</root>"""
tree = etree.fromstring(xml_data)
print(tree.tag) # Output: root
for child in tree:
print(child.tag, child.text) # Output: child1 Content of child 1
# child2 Content of child 2
lxml.html
lxml.html is specifically tailored for HTML parsing and manipulation. HTML is more lenient than XML in terms of structure and syntax, and lxml.html is designed to handle the quirks of real-world HTML, which might not be well-formed. This module provides methods for handling HTML documents, such as parsing HTML from strings or files, handling broken HTML, and cleaning up HTML to remove unwanted tags and attributes.
Here's an example of parsing an HTML document using lxml.html:
from lxml import html
html_data = """
<!DOCTYPE html>
<html>
<body>
<h1>Welcome to my website</h1>
<p>This is a paragraph.</p>
</body>
</html>
"""
document = html.fromstring(html_data)
h1_tag = document.xpath('//h1')[0]
print(h1_tag.text) # Output: Welcome to my website
Key Differences
- Intended Use:
lxml.etreeis for XML processing, which requires strict adherence to XML standards, whilelxml.htmlis for parsing and interacting with HTML content, which can be more flexible and forgiving of non-standard constructs. - Tolerance for Errors:
lxml.htmlis designed to handle poorly formed HTML and can clean up the HTML to some extent, making it more reliable for web scraping where HTML might not be well-formed.lxml.etree, on the other hand, expects well-formed XML and may raise errors if the XML is not correctly structured. - API and Features: Although both modules share many similarities in their API (such as the use of XPath for querying elements),
lxml.etreeincludes additional XML-specific features like namespace handling, DTD validation, and XSLT transformations, which are not typically necessary or applicable for HTML processing.
In summary, you should use lxml.etree for strict XML parsing and processing, especially in cases where you need to work with XML-specific features. Use lxml.html when dealing with HTML content, particularly when scraping data from websites where the HTML might not conform to XML standards.
