R正則表達式可替換除句子標記，撇號和連字符以外的所有標點符號

Question

我正在尋找一種在R中標記句子開頭和結尾的方法。為此，我想消除所有句子標點符號，例如句號，感嘆號，詢問符和連字符，這是我想用標記***代替。 同時，我還想保留包含撇號的單詞。 給一個具體的例子，給出以下字符串：

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?"

理想的結果是

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***"

我還沒有出來一個正則表達式來做到這一點。 任何提示，不勝感激。

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***"

除了句末標記，例如句號，感嘆號，審問標記和連字符以外，我想消除所有標點符號。

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

我想用標記***代替。 同時，我還想保留包含撇號的單詞。

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

Answer 2

您可以通過使用兩個正則表達式來做到這一點。 首先，您可以使用字符類來刪除不需要的字符：

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

並使用空的替換字符串。

然后，您可以使用第二個正則表達式，如下所示：

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

用替換字符串：

<S>

工作演示