R 把句子简化成单词

我在寻找一种有效的方法，将一个大句缩短到一个特定的长度，并以一个完整的单词结尾

例如，将每个句子减少到最多24个字符，并以整个单词结尾

fruits <- c(
  "apples and oranges and pears and bananas",
  "pineapples and mangos and guavas"
)

---

fruits多取一个字符，然后删除最后一个空格后的所有内容（包括空格）

fruits <- c(
  "apples and oranges and pears and bananas",
  "pineapples and mangos and guavas"
)

n <- 24

sub(
  " [^ ]*$",
  "",
  substr(fruits, 1, n + 1)
)
#> [1] "apples and oranges and" "pineapples and mangos" 

水果