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Get URL hosts

Source: R/accessors.R
get_host.Rd

Extracts the host component of a URL.

Usage

get_host(
  url,
  protocol_handling = "keep",
  www_handling = "none",
  source = c("all", "private", "icann"),
  subdomain_levels_to_keep = NULL,
  case_handling = c("lower", "keep", "upper", "lower_host"),
  host_encoding = c("keep", "idna", "unicode")
)

Arguments

url

A character vector of URLs.

protocol_handling

A character string specifying how to handle protocols. Defaults to "keep".

  • "keep": If a scheme exists (http, https, ftp, ftps), it's used. If no scheme, "http://" is added.

  • "none": If a scheme exists, it's used. If no scheme, then no scheme is used (scheme component will be NA).

  • "strip": Any existing scheme is removed (scheme component will be NA).

  • "http": The scheme is forced to be "http".

  • "https": The scheme is forced to be "https".

www_handling

A character string specifying how to handle "www" and "www[number]" prefixes in the host. Defaults to "none".

  • "none": (Default) Leaves the host's www prefix (or lack thereof) untouched.

  • "strip": Removes any "www." or "www[number]." prefix.

  • "keep": Ensures the host starts with "www.". If it has "www[number].", it's normalized to "www.". If no www prefix, "www." is added. An empty input host remains empty.

  • "if_no_subdomain": If the host is a bare registered domain (e.g., "example.com"), "www." is added. If the host already has a "www." or "www[number]." prefix, it is normalized to "www." (e.g., "www1.example.com" becomes "www.example.com"; "www1.sub.example.com" becomes "www.sub.example.com"). If a non-www subdomain exists (e.g., "sub.example.com" or the normalized "www.sub.example.com"), the host is not further altered. An empty input host remains empty.

source

Which PSL source to use: "all", "private", or "icann". Subdomain trimming depends on which section is consulted, so pass source = "icann" to exclude private suffixes (e.g. github.io).

subdomain_levels_to_keep

An integer or NULL. Determines how many levels of subdomains are kept, in addition to any 'www.' prefix handled by `www_handling`.

  • `NULL`: (Default) No specific subdomain stripping is performed beyond `www_handling`.

  • `0`: All subdomains are stripped. If `www_handling` preserved or added 'www.', it remains (e.g., 'www.sub.example.com' becomes 'www.example.com'; 'sub.example.com' becomes 'example.com').

  • `N > 0`: Keeps up to N levels of subdomains, counted from right-to-left (closest to the registered domain), in addition to any 'www.' prefix. E.g., if N=1, 'three.two.one.example.com' becomes 'one.example.com'; 'www.three.two.one.example.com' (post www_handling) becomes 'www.one.example.com'.

case_handling

How to handle casing of the returned host. Defaults to "lower".

host_encoding

How to present the host in `clean_url`. Defaults to "keep".

  • "keep": Leave host as parsed by curl (may preserve original case).

  • "idna": Convert Unicode host labels to Punycode (IDNA) for the cleaned URL.

  • "unicode": Decode Punycode labels to Unicode for the cleaned URL.

Value

A character vector of URL hosts.

Examples

get_host("http://sub.example.com:8080")
#> http://sub.example.com:8080 
#>           "sub.example.com" 
get_host(
  "http://www.two.one.example.com",
  subdomain_levels_to_keep = 1
) # Result: "www.one.example.com"
#> http://www.two.one.example.com 
#>          "www.one.example.com" 
get_host(
  "http://www.two.one.example.com",
  www_handling = "strip",
  subdomain_levels_to_keep = 1
) # Result: "one.example.com"
#> http://www.two.one.example.com 
#>              "one.example.com" 
get_host(
  "http://www.two.one.example.com",
  www_handling = "keep",
  subdomain_levels_to_keep = 1
) # Result: "www.one.example.com"
#> http://www.two.one.example.com 
#>          "www.one.example.com" 
get_host(
  "http://three.two.one.example.com",
  subdomain_levels_to_keep = 0
) # Result: "example.com"
#> http://three.two.one.example.com 
#>                    "example.com" 
get_host(
  "http://www.three.two.one.example.com",
  subdomain_levels_to_keep = 0
) # Result: "www.example.com"
#> http://www.three.two.one.example.com 
#>                    "www.example.com"