Regex extract domain from web page

[john.smith]

Hi,

I have been scratching my head all day on this as im not a regex expert.

If i have a web address like:

"https://www.facebook.com/foo/"

"https://www.facebook.is/foo/"

"https://www.facebook.lw/foo/"

"https://www.facebook.de/foo/"

"https://www.instagram.de/foo/"

"https://www.twitter.de/foo/"

"https://www.amazon.de/foo/"

These are all made up addresses

I wish to be able to just extract the middle part so the first four web addresses would produce facebook, the second instagram, the third twitter and the fourth amazon

Below is the closest I have gotten to it

test <- "https://www.facebook.com/foo/"

stringr::str_extract(test, '(?<=www.)(.*)(?=.)')

# "facebook.com/foo"

Thank you for your time

[john.smith]

Hi All,

I think the below should do it

extract_website <- function(website){

  my <- str_split(website, '\\.', simplify = TRUE)
  parts <- ncol(my)
  
  if(website == 'missing'){
    result='missing'; 
  }
  else if(my[parts-1] %in% c('co','com','gov','net', 'org', 'edu')) {
    result=my[parts-2]; 
  } else{
    result=my[parts-1]; 
  }
  result
}