r - 向量中的 substring() 和 ()

Question

我想将此列分成 2 个，使用第一个括号作为分隔符。我使用了 word(x,2, sep = "(") 但我得到了一个错误。我知道 R 不喜欢括号作为 sep 。我想使用 "(" 作为 sep 因为数据是没有一致记录，在某些行上，我们在国家和州之间有一个空格，在其他一些行上我们没有。
我该如何解决这个问题？谢谢你。

x <- c("United States (Alabama) ", "United States (California) ", 
"United States (California) ", "United States (California) ", 
"United States (California) ", "United States (Colorado) ", 
"United States (Colorado) ", "United States (Colorado) ", 
"United States(Connecticut) ", "United States(Connecticut) "
)
word(x,2,sep = "("). 

Error in stri_locate_all_regex(string, pattern, omit_no_match = TRUE, : Incorrectly nested parentheses in regexp pattern. (U_REGEX_MISMATCHED_PAREN, context=()

Answer 1

我想你可以试试 strsplit + gsub像下面

trimws(
  gsub(
    "\\(|\\)",
    "",
    do.call(
      rbind,
      strsplit(x,
        "((?<=\\s)\\()|(?=)\\(",
        perl = TRUE
      )
    )
  )
)

这使

      [,1]            [,2]
 [1,] "United States" "Alabama"
 [2,] "United States" "California"
 [3,] "United States" "California"
 [4,] "United States" "California" 
 [5,] "United States" "California"
 [6,] "United States" "Colorado"
 [7,] "United States" "Colorado"
 [8,] "United States" "Colorado"
 [9,] "United States" "Connecticut"
[10,] "United States" "Connecticut"