在忽略 URL 字符串末尾的一些标点符号的 R 正则表达式中

Question

是否可以使用 Regex 函数忽略 URL 字符串末尾的一些标点符号（不是“/'s”）（即 url 字符串后跟 space) 提取时？提取 URLs 时，我在提取的字符串末尾得到句号、括号、问号和感叹号，例如：

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!

和

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.

有没有办法修改这些函数，以便 . ) ? ! 或 , 或（如果可能）). )? )! 或 ),在字符串的末尾找到后跟 space（即如果标点符号：句点、括号、问号、感叹号或逗号在 URL 字符串的末尾后跟 space) 不提取它们？

Answer 1

使用积极的前瞻性，您也可以将两者结合起来...

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"

在忽略 URL 字符串末尾的一些标点符号的 R 正则表达式中

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