| [.XMLNode {XML} | R Documentation |
These provide a simplified syntax for extracting the children of an XML node.
obj[[i]] "[.XMLNode"(obj, ..., all = FALSE) "[[.XMLNode"(obj, ...) "[[.XMLDocumentContent"(obj, ...)
obj |
the XML node or the top-level document content in which the children are to be accessed.
The XMLDocumentContent is the container for the top-level node that also contains information
such as the URI/filename and XML version. This accessor method is merely a convenience to get
access to children of the top-level node. |
i |
index of the child of interest or the name of an XML element of interest. In this latter case, only the first matching element is returned, if any. |
... |
the identifiers for the children to be retrieved,
given as integer indices, names, etc. in the usual format for the
generic link{[} and link{[[} operators |
all |
logical value. When ... is a character vector, a value
of TRUE for all means to retrieve all of the
nodes with those names rather than just the first one.
FALSE gives the usual result of subsetting a list by name
which gives just the first element.
This allows us to avoid the idiom
node[ names(node) == "bob" ]
which is complicated when node is the result of an inline
computation
and instead we use
node["bob", all = TRUE].
|
A list or single element containing the
children of the XML node given by obj
and identified by ....
Duncan Temple Lang
http://www.w3.org/XML, http://www.omegahat.org/RSXML
xmlAttrs
[<-.XMLNode
[[<-.XMLNode
f = system.file("exampleData", "gnumeric.xml", package = "XML")
top = xmlRoot(xmlTreeParse(f))
# Get the first RowInfo element.
top[["Sheets"]][[1]][["Rows"]][["RowInfo"]]
# Get a list containing only the first row element
top[["Sheets"]][[1]][["Rows"]]["RowInfo"]
top[["Sheets"]][[1]][["Rows"]][1]
# Get all of the RowInfo elements by position
top[["Sheets"]][[1]][["Rows"]][1:xmlSize(top[["Sheets"]][[1]][["Rows"]])]
# But more succinctly and accurately, get all of the RowInfo elements
top[["Sheets"]][[1]][["Rows"]]["RowInfo", all = TRUE]