XML (version 0.99-4)

getNodeSet: Find matching nodes in an internal XML tree/DOM

Description

This function provides a way to find XML nodes that match a particular criterion. It uses the XPath syntax and allows quite powerful expressions for identifying nodes. The XPath language requires some knowledge, but tutorials are available.

Usage

getNodeSet(doc, path, namespaces = character())

Arguments

doc

an object of class XMLInternalDocument

path

a string (character vector of length 1) giving the XPath expression to evaluate.

namespaces

a named character vector giving the name-URI pairs for the namespaces of interest in the XPath query.

Value

• The results can currently be different based on the returned value from the XPath expression evaluation:
• list
  a node set
• numeric
  a number
• logical
  a boolean
• character
  a string, i.e. a single character element.

Details

This calls the libxml routine xmlXPathEval.

References

http://xmlsoft.org, http://www.w3.org/xml http://www.w3.org/TR/xpath http://www.omegahat.org/RSXML

See Also

xmlTreeParse with useInternalNodes as TRUE.

Examples

doc = xmlTreeParse(system.file("exampleData", "tagnames.xml", package = "XML"), useInternalNodes = TRUE)
 getNodeSet(doc, "/doc//b[@status]")
 getNodeSet(doc, "/doc//b[@status='foo']")

 
 els = getNodeSet(doc, "/doc//a[@status]")
 sapply(els, function(el) xmlGetAttr(el, "status"))