使用正则表达式删除父括号

Question

希望就我认为简单的正则表达式问题获得一些帮助。我想从字符串中删除父括号集，但保留子括号。例如:

gsub(some regex ,"LOG((X))")  

会返回

(X)

我已经接近了

 gsub("LOG\\(|\\)","","LOG((X))")

但是这会返回

 (X

有什么建议吗？

Answer 1

也许有点太强大了，但如果你想要一个具有所有级别嵌套的向量，你可以这样做:

v <- c("LOG(EXP(X))", "A", "EXP(LOG(2*SIN(X)))")


unnest_parentheses <- function(x) {
  
  lapply(x, \(x) {
    
    start <- gregexpr("\\(", x)[[1]]
    end <- rev(gregexpr("\\)", x)[[1]])
    
    if (length(start) != length(end)) {
      
      stop("We either miss a starting or ending parentheses")
      
    } else {
      
      tree <- unlist(Map(f = \(start, end) {
        str_sub(x, start+1, end-1)
      }, start, end))
      tree <- c(x, tree) # comment out if you not want the parent
      tree[tree != ""]
      
    }
    
  })
  
}

unnest_parentheses(v)

输出

[[1]]
[1] "LOG(EXP(X))" "EXP(X)"      "X"          

[[2]]
[1] "A"

[[3]]
[1] "EXP(LOG(2*SIN(X)))" "LOG(2*SIN(X))"      "2*SIN(X)"           "X"