XML: xmlSubset – R documentation

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XML

xmlSubset

Convenience accessors for the children of XMLNode objects.

Description

These provide a simplified syntax for extracting the children of an XML node.

Usage

## S3 method for class 'XMLNode'
x[..., all = FALSE]
## S3 method for class 'XMLNode'
x[[...]]
## S3 method for class 'XMLDocumentContent'
x[[...]]

Arguments

x

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.

...

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].

Value

A list or single element containing the children of the XML node given by obj and identified by ....

Author(s)

Duncan Temple Lang

References

http://www.w3.org/XML/, http://www.omegahat.net/RSXML/

Examples

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]

XML

Tools for Parsing and Generating XML Within R and S-Plus

v3.99-0.10

BSD_3_clause + file LICENSE

Authors

CRAN Team [ctb, cre] (de facto maintainer since 2013), Duncan Temple Lang [aut] (<https://orcid.org/0000-0003-0159-1546>), Tomas Kalibera [ctb]

Initial release