R 正则表达式替换除句子标记、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，我想消除除句末标记（如句号、感叹号、问号和连字符）之外的所有标点符号。我想用标记 *** 代替。同时，我也想保留包含撇号的单词。举一个具体的例子，给定这个字符串：

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?"

期望的结果是

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***"

我还没能拿出一个正则表达式来做到这一点。非常感谢任何提示。

Answer 1

你可以使用 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***"

我想删除除句末标记之外的所有标点符号，例如句号、感叹号、问号和连字符。

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

我想用标记 *** 替换它。同时，我也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，您可以使用字符类删除不需要的字符：

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

并使用一个空的替换字符串。

然后，您可以像这样使用第二个正则表达式：

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

使用替换字符串：

<S>

Working demo