minixml

minixml is a package for building xml documents in R.

minixml vs xml2

xml2 is a fantastic package for parsing a pre-existing XML file and navigating through it, slicing it etc.

minixml is focussed on creating XML documents by assembling nodes with attributes in a programmatic fashion.

Overview

Need to build R6 object alternate initialisation
XML elements XMLElement$new() xml_elem()
XML document XMLDocument$new() xml_doc()

Quick Examples

XML Entity code result
XML elements XMLElement$new('info', "Hello there") <info>Hello there</info>
XML elements xml_elem('info', 'Hello')$update(date = '2019') <info date="2019">Hello</info>
XML document this_xml <- XMLDocument$new('core'); this_xml$add('info', 'hello') <core><info>hello</info></core>

Installation

You can install minixml from GitHub with:

Interface

  • Individual elements can be created in a number of ways.
    • As a stand-alone element
      • new_elem <- XMLElement$new('info', type = 'meta')
      • new_elem <- xml_elem('info', type = 'meta')
    • As a sub-element of an existing document or element - the element is created, added to the parent document (or element) and returned.
      • doc <- XMLDocument$new('xx'); new_elem <- doc$add('info', type = 'meta')
      • elem <- XMLElement$new('xxx'); new_elem <- elem$add('info', type = 'meta')
  • $add() creates an element and adds it to the parent (and returns it)
    • new_elem <- doc$add('info', type = 'meta')
  • $append() appends the given elements as children
    • new_elem <- xml_elem('info', type = 'meta'); doc$append(new_elem, ...)
  • $new(name, ...), $update(...) and $add(name, ...) all accept ... where
    • named arguments are added as attributes of this node
    • unnamed argument are added as children of this node

Simple example

   <thing>
     <node style="color: blue;">
       <mytag>
         Some example text.
       </mytag>
     </node>
   </thing>

Parsing XML into a minixml document

minixml uses xml2 to parse XML text (or file) into a minixml document.

   <eg x="1" y="2">
     Node contents
     <inner>
       inner contents
     </inner>
   </eg>

More complex example: Creating an XML X3D 3d object

X3D is an XML-based 3D object format that is the successor to VRML.

In this example, we’ll build a simple 3D cube to view in the browser.

   <x3d width="300px" height="200px">
     <scene>
       <shape>
         <appearance>
           <material diffuseColor="0 0 1" />
         </appearance>
         <box />
       </shape>
     </scene>
   </x3d>

View the object

To view the X3D object, include it in an HTML document with the x3dom.js javascript.

The following code will run in an R session as an interactive 3d object browser. On github you’ll just see a short gif.