Extract the public suffix from a vector of domains or hostnames
Examples
public_suffix("http://example.com")
#> [1] "com"
# doesn't work for general URLs
public_suffix("http://example.com/path/to/file")
#> [1] NA
# extracting hostname first does the trick
public_suffix(ada_get_hostname("http://example.com/path/to/file"))
#> [1] "com"