CODEWITHSUNDEEP
regexrstringtext-extraction
Robert
Robert

Reputation: 530

In R Regex that ignores some punctuation at the end of a URL string

Is it possible to use a Regex function that ignores SOME punctuation (not "/'s") at the end of URL strings (i.e. punctuation at the end of a url string followed by a space) when extracted? When extracting URLs, I'm getting periods, parenthesizes, question marks and exclamation points at the end of the strings I extract so for example:

findURL <- function(x){
  m <- gregexpr("http[^[:space:]]+", x, perl=TRUE)
  w <- unlist(regmatches(x,m))
  op <- paste(w,collapse=" ")
  return(op)
}

x <- "find out more at http://bit.ly/SS/VUEr). check it out here http://bit.ly/14pwinr)? http://bit.ly/108vJOM! Now!" 

findURL(x)

[1] http://bit.ly/SS/VUEr).http://bit.ly/14pwinr)? http://bit.ly/108vJOM!

And

findURL2 <- function(x){
  m <- gregexpr("www[^[:space:]]+", x, perl=TRUE)
  w <- unlist(regmatches(x,m))
  op <- paste(w,collapse=" ")
  return(op)
}


y <-  "This is an www.example.com/store/locator. of the type of www.example.com/Google/Voice. data I'd like to extract www.example.com/network. get it?"  

findURL2(y)     

[1] www.example.com/store/locator. www.example.com/Google/Voice. www.example.com/network.

Is there a way to modify these functions so that if a . ) ? ! or , OR (IF POSSIBLE) a ). )? )! or ),is found at the end of the string followed by a space (i.e. if punctuation: periods, parenthesizes, question marks, exclamation points, or comma's at the end of a URL string followed by a space) to NOT extract them?

Upvotes: 0

Views: 71

Answers (1)

Avinash Raj
Avinash Raj

Reputation: 174706

Use a positive lookahead and also you may combine the both...

findURL <- function(x){
  m <- gregexpr("\\b(?:www|http)[^[:space:]]+?(?=[^\\s\\w]*(?:\\s|$))", x, perl=TRUE)
  w <- unlist(regmatches(x,m))
  op <- paste(w,collapse=" ")
  return(op)
}

x <- "find out more at http://bit.ly/SS/VUEr). check it out here http://bit.ly/14pwinr)? http://bit.ly/108vJOM! Now!" 
y <-  "This is an www.example.com/store/locator. of the type of www.example.com/Google/Voice. data I'd like to extract www.example.com/network. get it?"

findURL(x)
findURL(y)

# [1] "http://bit.ly/SS/VUEr http://bit.ly/14pwinr http://bit.ly/108vJOM"

# [1] "www.example.com/store/locator www.example.com/Google/Voice www.example.com/network"

Upvotes: 2

Related Questions