r - 按句子拆分文本，但不按特殊模式拆分

Question

这是我的示例文本:

text = "First sentence. This is a second sentence. I like pets e.g. cats or birds."

我有一个按句子拆分文本的功能

library(stringi)
split_by_sentence <- function (text) {

  # split based on periods, exclams or question marks
  result <- unlist(strsplit(text, "\\.\\s|\\?|!") )

  result <- stri_trim_both(result)
  result <- result [nchar (result) > 0]

  if (length (result) == 0)
    result <- ""

  return (result)
}

它实际上是由标点符号分割的。这是输出:

> split_by_sentence(text)
[1] "First sentence"            "This is a second sentence" "I like pets e.g"           "cats or birds." 

是否有可能排除诸如“例如”之类的特殊模式？

Answer 1

在您的模式中，您可以指定要在任何后跟空格的标点符号处进行拆分，前提是它之前至少有 2 个字母数字字符(使用环视)。这将导致:

unlist(strsplit(text, "(?<=[[:alnum:]]{3})[?!.]\\s", perl=TRUE))
#[1] "First sentence"                  "This is a second sentence"       "I like pets e.g. cats or birds."

如果你想保留标点符号，那么你可以在后视中添加模式并且只在空间上分割:

unlist(strsplit(text, "(?<=[[:alnum:]]{3}[[?!.]])\\s", perl=TRUE))
# [1] "First sentence."                 "This is a second sentence."      "I like pets e.g. cats or birds."

text2 <- "I like pets (cats and birds) and horses. I have 1.8 bn. horses."

unlist(strsplit(text2, "(?<=[[:alnum:]]{3}[?!.])\\s", perl=TRUE))
#[1] "I like pets (cats and birds) and horses." "I have 1.8 bn. horses."

注意:如果标点符号后可能有多个空格，可以输入 \\s+而不是 \\s在模式中