regex - 根据特定元素的位置在字符串向量中插入连字符或破折号

Question

给定的是 string vector vecA:

vecA <- c("Population 1222",
          "Population 90over",
          "population under78",
          "population 99101",
          "Population 1254", 
          "Population 78 92")

问题

我想到达对应于以下内容的 vecB:

vecB <- c("Population 12 - 22",
          "Population 90 over",
          "population under 78",
          "population 99 - 101",
          "Population 12 - 54", 
          "Population 78 - 92")

主要特征

vecB 具有以下特征:

• 在前两位数字后插入空格、破折号和空格 (-)
• 如果存在空格，则仅插入破折号 (-)
• 对于 underDigitDigit 之类的组合，仅插入空格:underDigitDigit

---

尝试

我正在考虑利用 gsub 中的组，在线:

gsub("^([[:alpha:]]*[[:blank:]])(\\d{2})(.*)$", "\\2", vecA)

但这并不适用于所有情况:

> t(t(gsub("^([[:alpha:]]*[[:blank:]])(\\d{2})(.*)$", "\\2", vecA)))
     [,1]                
[1,] "12"                
[2,] "90"                
[3,] "population under78"
[4,] "99"                
[5,] "12"                
[6,] "78" 

t() 仅用于演示目的； regex101 link .

Answer 1

这是我的建议 - 分两步进行:1)首先在数字之间添加连字符，然后 2)在单词“over”/“under”和数字之间添加空格:

vecA <- c("Population 1222",
           "Population 90over",
           "population under78",
           "population 99101",
           "Population 1254", 
           "Population 78 92")
v <- gsub("^([[:alpha:]]+[[:blank:]]+)([[:digit:]]{2})\\s*([[:digit:]])", "\\1\\2 - \\3", vecA)
gsub("^([[:alpha:]]+[[:blank:]]+)(?|(over|under)(\\d+)|(\\d+)(over|under))", "\\1\\2 \\3", v, perl=T)

code demo 的输出:

[1] "Population 12 - 22"  "Population 90 over"  "population under 78"
[4] "population 99 - 101" "Population 12 - 54"  "Population 78 - 92"

第二个正则表达式包含分支重置模式 (?|...|...) 以在替代子模式中保留相同的组 ID，因此需要 perl=T。