如果“引用”，我该如何拆分字符串并忽略分隔符

时间：2018-04-11 12:50:38

标签： r regex strsplit

说我有以下字符串：

params <- "var1 /* first, variable */, var2, var3 /* third, variable */"

我想使用,作为分隔符将其拆分，然后提取“引用的子串”，所以我得到2个向量如下：

params_clean <- c("var1","var2","var3")
params_def   <- c("first, variable","","third, variable") # note the empty string as a second element.

我在广义上使用术语“引用”，其中包含/*和*/的任意字符串，可保护子字符串不被分割。

我找到了一个基于read.table的解决方法，以及它允许​​引用元素的事实：

library(magrittr)
params %>%
  gsub("/\\*","_temp_sep_ '",.) %>%
  gsub("\\*/","'",.) %>%
  read.table(text=.,strin=F,sep=",") %>%
  unlist %>%
  unname %>%
  strsplit("_temp_sep_") %>%
  lapply(trimws) %>%
  lapply(`length<-`,2) %>%
  do.call(rbind,.) %>%
  inset(is.na(.),value="")

但是它非常丑陋和hackish，有什么更简单的方法？我认为在这种情况下必须有regex提供给strsplit。

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3 个答案:

答案 0 :(得分：2)

您可以使用

library(stringr)
cmnt_rx <- "(\\w+)\\s*(/\\*[^*]*\\*+(?:[^/*][^*]*\\*+)*/)?"
res <- str_match_all(params, cmnt_rx)
params_clean <- res[[1]][,2]
params_clean
## => [1] "var1" "var2" "var3"
params_def <- gsub("^/[*]\\s*|\\s*[*]/$", "", res[[1]][,3])
params_def[is.na(params_def)] <- ""
params_def
## => [1] "first, variable" ""                "third, variable"

主要的正则表达式详细信息（实际上是(\w+)\s*)(COMMENTS_REGEX)?）：

  • (\w+) - 捕获第1组：一个或多个单词字符
  • \s* - 0+空白字符
  • ( - 捕获第2组开始
  • /\* - 匹配评论开始/*
  • [^*]*\*+ - 匹配*以外的0 +个字符，后跟1 +字面*
  • (?:[^/*][^*]*\*+)* - 0+序列：
    • [^/*][^*]*\*+ - 不是/或*（与[^/*]匹配），后跟0 +非星号字符（[^*]*），后跟1 +星号（\*+）
  • / - 关闭/
  • )? - 捕获第2组结束，重复1次或0次（这意味着它是可选的）。

请参阅regex demo。

"^/[*]\\s*|\\s*[*]/$"中的gsub模式会删除/*和*/相邻的空格。

params_def[is.na(params_def)] <- ""部分用空字符串替换NA。

答案 1 :(得分：1)

你在这里

<!DOCTYPE html>
<html lang="en">

<head>
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  <script defer src="https://use.fontawesome.com/releases/v5.0.9/js/all.js" integrity="sha384-8iPTk2s/jMVj81dnzb/iFR2sdA7u06vHJyyLlAd4snFpCl/SnyUjRrbdJsw1pGIl" crossorigin="anonymous"></script>
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  <style>
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    ul.nav-pills {
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      position: fixed;
    }
    
    div.col-sm-9 div {
      height: 250px;
      font-size: 28px;
    }
    
    .bg-1 {
      background-color: black;
    }
    
    .bg-1 ul li {
      color: #ecf0f1;
      font-family: 'Gugi', cursive;
      font-size: 15px;
    }
    
    .bg-2 {
      width: 86%;
      background-color: #d1d8e0;
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    .col-sm-3 {
      width: 14% !important;
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    @media screen and (max-width: 810px) {
      #about,
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      #interest {
        margin-left: 150px;
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    }
    
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      font-family: 'Black Han Sans', sans-serif;
      font-size: 65px;
      margin-left: 150px;
      margin-top: 200px;
    }
    
    #name {
      font-family: 'Montserrat', sans-serif;
      font-size: 55px;
      font-weight: 600;
      margin-left: 150px;
      margin-top: 30px;
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    #self {
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      margin-left: 150px;
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    }
    
    #engineer {
      font-family: 'Montserrat', sans-serif;
      font-size: 30px;
      font-weight: 500;
      margin-left: 150px;
      margin-top: 30px;
    }
    
    #intro {
      font-family: 'Lora', serif;
      font-size: 20px;
      color: #d1d8e0;
      margin-left: 150px;
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    }
    
    hr {
      width: 400px;
      border-top: 1px solid #4b6584;
      border-bottom: 1px solid #4b6584;
    }
    
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      margin-top: 0px;
    }
    
    #email {
      font-size: 10px;
    }
    
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      font-family: 'Saira Extra Condensed', sans-serif;
      color: #343a40;
      font-weight: 700;
      font-size: 50px;
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      margin-left: 20px;
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    .subheadings {
      font-family: 'Saira Extra Condensed', sans-serif;
      color: #20bf6b;
      font-weight: 500;
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    }
    
    #certifications {
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      color: #fff;
      /* background-color: #337ab7; */
      background-color: unset !important;
    }
  </style>
</head>

<body data-spy="scroll" data-target="#myScrollspy" data-offset="20">

  <div class="container-fluid">
    <div class="row bg-1">
      <!--  Left Side Navigation Bar -->
      <div class="col-sm-3 text-center" id="backg">
        <nav id="myScrollspy">

          <ul class="nav nav-pills nav-stacked ">
            <img class="img-rounded img-responsive center-block image" src="naqqash.png" height="150" width="150 ">
            <li class="active"><a href="#about">ABOUT</a></li>
            <li><a href="#education">EDUCATION</a></li>
            <li><a href="#certifications">CERTIFICATIONS</a></li>
            <li><a href="#skills">SKILLS</a></li>
            <li><a href="#projects">PROJECTS</a></li>
            <li><a href="#experience">EXPERIENCE</a></li>
            <li><a href="#interest">INTEREST</a></li>
          </ul>
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      </div>
      <!--  Right Side  -->
      <div class="col-sm-9 bg-2">
        <!-- About -->
        <div id="about">
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          <h3 id="name">I'm Muhammad Naqqash,</h3>
          <h3 id="self">a self taught developer.</h3>
          <h3 id="engineer">I'm a Computer Engineer. </h3>
          <p id="intro">I'm a positive and friendly person. Also, I love to set goals and achieve them.<br> My important qualities: self-motivated, ability overcome difficulties and the <br> ability to learn.</p>

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          <br>
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          <h1 id="headings">EDUCATION</h1>
          <h3 class="subheadings"><i class="fas fa-graduation-cap fa-sm"></i><span style="display:inline-block; width: 20px;"></span>BS Computer Engineering</h3>
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          <p>Try to scroll this section and look at the navigation list while scrolling!</p>
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        <div id="experience">
          <h1 id="headings">Section 6</h1>
          <p>Try to scroll this section and look at the navigation list while scrolling!</p>
        </div>
        <div id="interest">
          <h1 id="headings">Section 7</h1>
          <p>Try to scroll this section and look at the navigation list while scrolling!</p>
        </div>
        <div>
          <h1>Section 7</h1>
          <p>Try to scroll this section and look at the navigation list while scrolling!</p>
        </div>
      </div>
    </div>
  </div>

</body>

</html>

答案 2 :(得分：1)

您可以将其包装在一个函数中并使用普通(*SKIP)(*FAIL)中的（没有详细记录的）R机制：

getparams <- function(params) {
  tmp <- unlist(strsplit(params, "/\\*.*?\\*/(*SKIP)(*FAIL)|,", perl = TRUE))

  params_clean <- vector(length = length(tmp))
  params_def <- vector(length = length(tmp))

  for (i in seq_along(tmp)) {
    # get params_def if available
    match <- regmatches(tmp[i], regexec("/\\*(.*?)\\*/", tmp[i]))
    params_def[i] <- ifelse(identical(match[[1]], character(0)), "", trimws(match[[1]][2]))

    # params_clean
    params_clean[i] <- trimws(gsub("/(.*)\\*.*?\\*/", "\\1", tmp[i]))
  }

  return(list(params_clean = params_clean, params_def = params_def))
}

params <- "var1 /* first, variable */, var2, var3 /* third, variable */"
getparams(params)

这会使用(*SKIP)(*FAIL)（请参阅a demo on regex101.com）拆分初始字符串，然后分析这些部分。

<小时/> 这会产生一个列表：

$params_clean
[1] "var1" "var2" "var3"

$params_def
[1] "first, variable" ""                "third, variable"

<小时/> 或者，sapply：

缩短 
getparams <- function(params) {
  tmp <- unlist(strsplit(params, "/\\*.*?\\*/(*SKIP)(*FAIL)|,", perl = TRUE))
  (p <- sapply(tmp, function(x) {
    match <- regmatches(x, regexec("/\\*(.*?)\\*/", x))
    def <- ifelse(identical(match[[1]], character(0)), "", trimws(match[[1]][2]))
    clean <- trimws(gsub("/(.*)\\*.*?\\*/", "\\1", x))
    c(clean, def)
  }, USE.NAMES = F))
}

这将产生一个矩阵：

     [,1]              [,2]   [,3]             
[1,] "var1"            "var2" "var3"           
[2,] "first, variable" ""     "third, variable"

使用后者，您可以获得变量名称，例如： result[1,]。

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