R正则表达式可替换除句子标记，撇号和连字符以外的所有标点符号

Question

我正在寻找一种在R中标记句子开头和结尾的方法。为此，我想消除所有句子标点符号，例如句号，感叹号，询问符和连字符，这是我想用标记***代替。 同时，我还想保留包含撇号的单词。 给一个具体的例子，给出以下字符串：

txt <- "We have examined all the possibilities, however we have not reached a solid conclusion - however we keep and open mind! Have you considered any other approach? Haven't you?"

理想的结果是

txt <- "We have examined all the possibilities however he have not reached a solid conclusion *** however we keep and open mind*** Have you considered any other approach*** Haven't you***"

我还没有出来一个正则表达式来做到这一点。 任何提示，不胜感激。

Answer 1

您可以使用gsub。

> txt <- "We have examined all the possibilities, however he have not reached a solid conclusion - however we keep and open mind! Have you considered any other approach? Haven't you?"
> gsub("[-.?!]", "<S>", gsub("(?![-.?!'])[[:punct:]]", "", txt, perl=T))
[1] "We have examined all the possibilities however he have not reached a solid conclusion <S> however we keep and open mind<S> Have you considered any other approach<S> Haven't you<S>"
> gsub("[-.?!]", "***", gsub("(?![-.?!'])[[:punct:]]", "", txt, perl=T))
[1] "We have examined all the possibilities however he have not reached a solid conclusion *** however we keep and open mind*** Have you considered any other approach*** Haven't you***"

除了句末标记，例如句号，感叹号，审问标记和连字符以外，我想消除所有标点符号。

gsub("(?![-.?!'])[[:punct:]]", "", txt, perl=T)

我想用标记***代替。 同时，我还想保留包含撇号的单词。

gsub("[-.?!]", "***", gsub("(?![-.?!'])[[:punct:]]", "", txt, perl=T))

Answer 2

您可以通过使用两个正则表达式来做到这一点。 首先，您可以使用字符类来删除不需要的字符：

[,.]
  ^--- Whatever you want to remove, put it here

并使用空的替换字符串。

然后，您可以使用第二个正则表达式，如下所示：

[?!-]
  ^--- Add characters you want to replace here

用替换字符串：

<S>

工作演示