R: Manipulate sibling XML nodes

getSibling {XML}

R Documentation

Manipulate sibling XML nodes

Description

These functions allow us to both access the sibling node to the left or right of a given node and so walk the chain of siblings, and also to insert a new sibling

Usage

getSibling(node, after = TRUE, ...)
addSibling(node, ..., kids = list(...), after = NA)

Arguments

`node`	the internal XML node (XMLInternalNode) whose siblings are of interest
`...`	the XML nodes to add as siblings or children to node.
`kids`	a list containing the XML nodes to add as siblings. This is equivalent to ... but used when we already have the nodes in a list rather than as individual objects. This is used in programmatic calls to `addSibling` rather interactive use where we more commonly have the individual node objects.
`after`	a logical value indicating whether to retrieve or add the nodes to the right (`TRUE`) or to the left (`FALSE`) of this sibling.

Value

getSibling returns an object of class XMLInternalNode (or some derived S3 class, e.g. XMLInternalTextNode)

addSibling returns a list whose elements are the newly added XML (internal) nodes.

Examples

  
          # Reading Apple's iTunes files
     # 
     #           Here we read  a "censored" "database" of songs from Apple's  iTune application
     #           which is stored in a property list.  The format is quite generic and 
     #            the fields for each song are given in the form
     #           
     #             <key>Artist</key><string>Person's name</string>
     # 	  
     #           So to find the names of the artists for all the songs, we want to 
     #           find all the <key>Artist<key> nodes and then get their next sibling
     #           which has the actual value.
     #         
     #           More information can be found in .
     # 	
           fileName = system.file("exampleData", "iTunes.plist", package = "XML")

           doc = xmlParse(fileName)
           nodes = getNodeSet(doc, "//key[text() = 'Artist']")
           sapply(nodes, function(x)  xmlValue(getSibling(x)))
	

      f = system.file("exampleData", "simple.xml", package = "XML")
      tt = as(xmlParse(f), "XMLHashTree") 

       tt

      e = getSibling(xmlRoot(tt)[[1]])
        # and back to the first one again by going backwards along the sibling list.
      getSibling(e, after = FALSE)


         # This also works for multiple top-level "root" nodes
      f = system.file("exampleData", "job.xml", package = "XML")
      tt = as(xmlParse(f), "XMLHashTree")
       x = xmlRoot(tt, skip = FALSE)
       getSibling(x)
       getSibling(getSibling(x), after = FALSE)