Tools for Working with XML Files as R Dataframes.
flatXML - Tools for Working with XML Files as R Dataframes
Overview
flatxml
provides functions to easily deal with XML files. When parsing an XML document with fxml_importXMLFlat
, flatxml
produces a special dataframe that is 'flat' by its very nature but contains all necessary information about the hierarchical structure of the underlying XML document (for details on the dataframe see the reference for the fxml_importXMLFlat
function).
flatxml
offers a set of functions to work with this dataframe.
Apart from representing the XML document in a dataframe structure, there is yet another way in which flatxml
relates to dataframes: the fxml_toDataFrame
and fxml_toXML
functions can be used convert XML data to dataframes and vice versa.
Each XML element, for example <tag attribute="some value">Here is some text</tag>
has certain characteristics that can be accessed via the flatxml
interface functions, after an XML document has been imported with fxml_importXMLFlat
. These characteristics are:
value
: The (text) value of the element,"Here is some text"
in the example aboveattributes
: The XML attributes of the element,attribute
with its value"some value"
in the example abovechildren
: The elements on the next lower hierarchical levelparent
: The element of the next higher hierarchical level, i.e. the element to which the current element is a childsiblings
: The elements on the same hierarchical level as the current element
Structure of the flatxml interface
The flatxml
interface to access these characteristics follows a simple logic: For each of the characteristics there are typically three functions available:
fxml_has...()
: Determines if the current XML element has (at least one instance of) the characteristicfxml_num...()
: Returns the number of the characteristics of the current XML (e.g. the number of children elements)fxml_get...()
: Returns (the IDs of) the respective characteristics of the current XML element (e.g. the children of the current element)
Functions to access the characteristics of an XML element
For values:
fxml_hasValue
fxml_getValue
For attributes:
fxml_hasAttributes
fxml_numAttributes
fxml_getAttribute
(note: no plural 's'!)fxml_getAttributesAll
(get all attributes instead of a specific one)
For children:
fxml_hasChildren
fxml_numChildren
fxml_getChildren
For parents:
fxml_hasParent
fxml_getParent
For siblings:
fxml_hasSiblings
fxml_numSiblings
fxml_getSiblings
Functions for searching in the XML document
fxml_findPath
(search anywhere in the path to an XML element)fxml_findPathFull
(find an element based on its complete path)fxml_findPathRoot
(search in the path to an XML element starting at the top element [root node])fxml_findPathBottom
(search in the path to an XML element starting at the lowest hierarchical level)
Functions for converting between XML and dataframe
fxml_toDataFrame
(converts a (flattened) XML document to a dataframe)fxml_toXML
(converts a dataframe to an XML document)
Other functions
fxml_getElement
(name on an XML element (thetag
in<tag>…</tag>
)fxml_getUniqueElements
(unique XML elements in the document)fxml_getElementInfo
(all relevant information on an XML element (children, siblings, etc.)fxml_getDepthLevel
(level of an element in the hierarchy of the XML document)