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xml2vscssselect

MIT 63 3 216
624.5 thousand (month) Apr 20 2015 1.3.6(9 months ago)
281 8 21 BSD
1.2.0(1 year, 5 months ago) Apr 14 2012 8.3 million (month)

The xml2 package is a binding to libxml2, making it easy to work with HTML and XML from R. The API is somewhat inspired by jQuery.

xml2 can be used to parse HTML documents using XPath selectors and is a successor to R's XML package with a few improvements:

  • xml2 takes care of memory management for you. It will automatically free the memory used by an XML document as soon as the last reference to it goes away.
  • xml2 has a very simple class hierarchy so don't need to think about exactly what type of object you have, xml2 will just do the right thing.
  • More convenient handling of namespaces in Xpath expressions - see xml_ns() and xml_ns_strip() to get started.

cssselect is a BSD-licensed Python library to parse CSS3 selectors and translate them to XPath 1.0 expressions.

XPath 1.0 expressions can be used in lxml or another XPath engine to find the matching elements in an XML or HTML document.

cssselect is used by other popular Python packages like parsel and scrapy but can also be used on it's own to generate valid XPath 1.0 expressions for parsing HTML and XML documents in other tools.

Note that because XPath selectors are more powerful than CSS selectors this translation is only possible one way. Converting XPath to CSS selectors is impractical and not supported by cssselect.

Example Use


library("xml2")
x <- read_xml("<foo> <bar> text <baz/> </bar> </foo>")
x

xml_name(x)
xml_children(x)
xml_text(x)
xml_find_all(x, ".//baz")

h <- read_html("<html><p>Hi <b>!")
h
xml_name(h)
from cssselect import GenericTranslator, SelectorError

translator = GenericTranslator()
try:
    expression = translator.css_to_xpath('div.content')
    print(expression)
    'descendant-or-self::div[@class and contains(concat(' ', normalize-space(@class), ' '), ' content ')]'
except SelectorError as e:
    print(f'Invalid selector {e}')

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