Navigate around the family tree.

xml_children returns only elements, xml_contents returns all nodes. xml_length returns the number of children. xml_parent returns the parent node, xml_parents returns all parents up to the root. xml_siblings returns all nodes at the same level. xml_child makes it easy to specify a specific child to return.

Usage

xml_children(x)

xml_child(x, search = 1, ns = xml_ns(x))

xml_contents(x)

xml_parents(x)

xml_siblings(x)

xml_parent(x)

xml_length(x, only_elements = TRUE)

xml_root(x)

Arguments

x

A document, node, or node set.

search

For xml_child, either the child number to return (by position), or the name of the child node to return. If there are multiple child nodes with the same name, the first will be returned

ns

Optionally, a named vector giving prefix-url pairs, as produced by xml_ns(). If provided, all names will be explicitly qualified with the ns prefix, i.e. if the element bar is defined in namespace foo, it will be called foo:bar. (And similarly for attributes). Default namespaces must be given an explicit name. The ns is ignored when using xml_name<-() and xml_set_name().

only_elements

For xml_length, should it count all children, or just children that are elements (the default)?

Value

A node or nodeset (possibly empty). Results are always de-duplicated.

Examples

x <- read_xml("<foo> <bar><boo /></bar> <baz/> </foo>")
xml_children(x)
#> {xml_nodeset (2)}
#> [1] <bar>\n  <boo/>\n</bar>
#> [2] <baz/>
xml_children(xml_children(x))
#> {xml_nodeset (1)}
#> [1] <boo/>
xml_siblings(xml_children(x)[[1]])
#> {xml_nodeset (1)}
#> [1] <baz/>

# Note the each unique node only appears once in the output
xml_parent(xml_children(x))
#> {xml_nodeset (1)}
#> [1] <foo>\n  <bar>\n    <boo/>\n  </bar>\n  <baz/>\n</foo>

# Mixed content
x <- read_xml("<foo> a <b/> c <d>e</d> f</foo>")
# Childen gets the elements, contents gets all node types
xml_children(x)
#> {xml_nodeset (2)}
#> [1] <b/>
#> [2] <d>e</d>
xml_contents(x)
#> {xml_nodeset (5)}
#> [1]  a 
#> [2] <b/>
#> [3]  c 
#> [4] <d>e</d>
#> [5]  f

xml_length(x)
#> [1] 2
xml_length(x, only_elements = FALSE)
#> [1] 5

# xml_child makes it easier to select specific children
xml_child(x)
#> {xml_node}
#> <b>
xml_child(x, 2)
#> {xml_node}
#> <d>
xml_child(x, "baz")
#> {xml_missing}
#> <NA>