gsub 仅捕获组的最后一个字符

Question

我有这个字符向量

vec <- c("(0,13.2]", "(13.2,28.3]", "(28.3,39.3]", "(39.3,49.4]", "(49.4,59.4]",
     "(59.4,69.3]", "(69.3,78.9]", "(78.9,87.8]", "(87.8,95.5]", "(95.5,100]")

我想将条目更改为

expected <- c("0 to 13.2",  "13.2 to 28.3",  "28.3 to 39.3",  "39.3 to 49.4",  "49.4 to 59.4", 
     "59.4 to 69.3",  "69.3 to 78.9",  "78.9 to 87.8",  "87.8 to 95.5",  "95.5 to 100")

我所做的是

vec %>%
  strsplit(., ",") %>%
  lapply(., function(level_i){
    from <- gsub("^\\(([0-9])+(\\.)*([0-9])*$", "\\1\\2\\3", level_i[1])
    to <- gsub("^([0-9])+(\\.)*([0-9])*]$", "\\1\\2\\3", level_i[2])
    paste0(from, " to ", to)
  }) %>%
  unlist()
# This gives:
# "0 to 3.2" "3.2 to 8.3" "8.3 to 9.3" "9.3 to 9.4" "9.4 to 9.4" "9.4 to 9.3" "9.3 to 8.9"
# "8.9 to 7.8" "7.8 to 5.5" "5.5 to 0"

我的代码仅捕获组的最后一个元素，即

"(0,13.2]"

变为

"0 to 3.2"

而不是

"0 to 13.2"

。如何捕获一组中的所有角色？

Answer 1

使用

gsub

，您可以使用

()

捕获组：

gsub('\\((.*),(.*)\\]', "\\1 to \\2", vec)
#[1] "0 to 13.2"    "13.2 to 28.3" "28.3 to 39.3" "39.3 to 49.4" "49.4 to 59.4"
#[6] "59.4 to 69.3" "69.3 to 78.9" "78.9 to 87.8" "87.8 to 95.5" "95.5 to 100" 

要准确捕获数字而不是

.*

，您可以这样做。这包括整数和小数格式：

gsub('\\((\\d+[\\.]*\\d*),(\\d+[\\.]*\\d*)\\]', "\\1 to \\2", vec)

有了所有这些反冲，您可以使用原始字符串简化正则表达式：

r"{\((\d+[\.]*\d*),(\d+[\.]*\d*)\]}"

Answer 2

你可以尝试这个技巧

read.table

+

trimws

do.call(paste, c(
    read.table(text = trimws(vec, whitespace = "[\\(\\]]"), sep = ","),
    sep = " to "
))

这给出了

 [1] "0 to 13.2"    "13.2 to 28.3" "28.3 to 39.3" "39.3 to 49.4" "49.4 to 59.4"
 [6] "59.4 to 69.3" "69.3 to 78.9" "78.9 to 87.8" "87.8 to 95.5" "95.5 to 100"

---

另一个技巧是

sub

+

trimws

+

chartr

> sub(",", " to ", trimws(chartr("(]", "  ", vec)))
 [1] "0 to 13.2"    "13.2 to 28.3" "28.3 to 39.3" "39.3 to 49.4" "49.4 to 59.4"
 [6] "59.4 to 69.3" "69.3 to 78.9" "78.9 to 87.8" "87.8 to 95.5" "95.5 to 100"