Read HTML or XML.

Usage

read_xml(x, encoding = "", ..., as_html = FALSE, options = "NOBLANKS")

read_html(x, encoding = "", ..., options = c("RECOVER", "NOERROR", "NOBLANKS"))

# S3 method for character
read_xml(x, encoding = "", ..., as_html = FALSE, options = "NOBLANKS")

# S3 method for raw
read_xml(
  x,
  encoding = "",
  base_url = "",
  ...,
  as_html = FALSE,
  options = "NOBLANKS"
)

# S3 method for connection
read_xml(
  x,
  encoding = "",
  n = 64 * 1024,
  verbose = FALSE,
  ...,
  base_url = "",
  as_html = FALSE,
  options = "NOBLANKS"
)

Arguments

x

A string, a connection, or a raw vector.

A string can be either a path, a url or literal xml. Urls will be converted into connections either using base::url or, if installed, curl::curl. Local paths ending in .gz, .bz2, .xz, .zip will be automatically uncompressed.

If a connection, the complete connection is read into a raw vector before being parsed.

encoding

Specify a default encoding for the document. Unless otherwise specified XML documents are assumed to be in UTF-8 or UTF-16. If the document is not UTF-8/16, and lacks an explicit encoding directive, this allows you to supply a default.

...

Additional arguments passed on to methods.

as_html

Optionally parse an xml file as if it's html.

options

Set parsing options for the libxml2 parser. Zero or more of

RECOVER: recover on errors
NOENT: substitute entities
DTDLOAD: load the external subset
DTDATTR: default DTD attributes
DTDVALID: validate with the DTD
NOERROR: suppress error reports
NOWARNING: suppress warning reports
PEDANTIC: pedantic error reporting
NOBLANKS: remove blank nodes
SAX1: use the SAX1 interface internally
XINCLUDE: Implement XInclude substitition
NONET: Forbid network access
NODICT: Do not reuse the context dictionary
NSCLEAN: remove redundant namespaces declarations
NOCDATA: merge CDATA as text nodes
NOXINCNODE: do not generate XINCLUDE START/END nodes
COMPACT: compact small text nodes; no modification of the tree allowed afterwards (will possibly crash if you try to modify the tree)
OLD10: parse using XML-1.0 before update 5
NOBASEFIX: do not fixup XINCLUDE xml:base uris
HUGE: relax any hardcoded limit from the parser
OLDSAX: parse using SAX2 interface before 2.7.0
IGNORE_ENC: ignore internal document encoding hint
BIG_LINES: Store big lines numbers in text PSVI field

base_url

When loading from a connection, raw vector or literal html/xml, this allows you to specify a base url for the document. Base urls are used to turn relative urls into absolute urls.

n

If file is a connection, the number of bytes to read per iteration. Defaults to 64kb.

verbose

When reading from a slow connection, this prints some output on every iteration so you know its working.

Value

An XML document. HTML is normalised to valid XML - this may not be exactly the same transformation performed by the browser, but it's a reasonable approximation.

Setting the "user agent" header

When performing web scraping tasks it is both good practice --- and often required --- to set the user agent request header to a specific value. Sometimes this value is assigned to emulate a browser in order to have content render in a certain way (e.g. Mozilla/5.0 (Windows NT 5.1; rv:52.0) Gecko/20100101 Firefox/52.0 to emulate more recent Windows browsers). Most often, this value should be set to provide the web resource owner information on who you are and the intent of your actions like this Google scraping bot user agent identifier: Googlebot/2.1 (+http://www.google.com/bot.html).

You can set the HTTP user agent for URL-based requests using httr::set_config() and httr::user_agent():

httr::set_config(httr::user_agent("me@example.com; +https://example.com/info.html"))

httr::set_config() changes the configuration globally, httr::with_config() can be used to change configuration temporarily.

Examples

# Literal xml/html is useful for small examples
read_xml("<foo><bar /></foo>")
#> {xml_document}
#> <foo>
#> [1] <bar/>
read_html("<html><title>Hi<title></html>")
#> {html_document}
#> <html>
#> [1] <head>\n<meta http-equiv="Content-Type" content="text/html; charset ...
read_html("<html><title>Hi")
#> {html_document}
#> <html>
#> [1] <head>\n<meta http-equiv="Content-Type" content="text/html; charset ...

# From a local path
read_html(system.file("extdata", "r-project.html", package = "xml2"))
#> {html_document}
#> <html lang="en">
#> [1] <head>\n<meta http-equiv="Content-Type" content="text/html; charset ...
#> [2] <body>\n    <div class="container page">\n      <div class="row">\n ...

if (FALSE) {
# From a url
cd <- read_xml(xml2_example("cd_catalog.xml"))
me <- read_html("http://had.co.nz")
}