Scala为每个列表项填充一个case类

我有一个国家的csv文件和一个CountryData案例类

文件中的示例数据：

丹麦、欧洲、1.23、7.89

澳大利亚，澳大利亚，8.88，9.99

巴西、南美洲、7.77、3.33

我可以在文件中读取和拆分等来获取

（名单（丹麦、欧洲，1.23、7.89） （名单（澳大利亚、澳大利亚，8.88、9.99） （名单（巴西、南美洲，7.77,3.33）

现在如何为每个列表项填充CountryData案例类？ 我试过：

for (line <- Source.getLines.drop(1)) {  
val splitInput = line.split(",", -1).map(_.trim).toList
val country = splitInput(0)
val region = splitInput(1)
val population = splitInput(2)
val economy = splitInput(3)

val dataList: List[CountryData]=List(CountryData(country,region,population,economy))

---

for（line不清楚您的问题具体在哪里。是关于
Double
vs
String
还是关于
List
在循环中。类似的方法可能仍然有效

case class CountryData(country: String, region: String, population: Double, economy: Double)


object CountryDataMain extends App {
  val src = "\nDenmark, Europe, 1.23, 7.89\nAustralia, Australia, 8.88, 9.99\nBrazil, South America, 7.77,3.33"

  val list = Source.fromString(src).getLines.drop(1).map(line => {
    val splitInput = line.split(",", -1).map(_.trim).toList
    val country = splitInput(0)
    val region = splitInput(1)
    val population = splitInput(2)
    val economy = splitInput(3)

    CountryData(country, region, population.toDouble, economy.toDouble)
  }).toList

  println(list)
}

我会使用scala大小写匹配：即

def doubleOrNone(str: Double): Option[Double] = {
   Try {
      Some(str.toDouble) //Not sure of exact name of method, should be quick to find
   } catch {
      case t: Throwable => None
  }
}    

def parseCountryLine(line: String): Vector[CountryData] = {
   lines.split(",").toVector match {
      case Vector(countryName, region, population, economy) => CountryData(countryName, region, doubleOrNone(population), doubleOrNone(economy))//I would suggest having them as options because you may not have data for all countries
      case s => println(s"Error parsing line:\n$s"); 
   }
}

一般建议：尝试分解问题并隔离问题。例如，
splitInput
的值是多少？为什么它是问题的一部分？确保您正确读取和分析了文件，然后通过将
splitInput
设置为其所包含的任何值并删除文件读取部分来更新您的问题。My我猜你的CSV的第一行的某个地方有标题/列名，这就是你正在阅读的内容。我可以看到你想删除它，但之前可能有一个空行。无论是哪种方式，案例类填充都应该按照你的预期工作。
填充
和
经济
需要是
双倍
def doubleOrNone(str: Double): Option[Double] = {
   Try {
      Some(str.toDouble) //Not sure of exact name of method, should be quick to find
   } catch {
      case t: Throwable => None
  }
}    

def parseCountryLine(line: String): Vector[CountryData] = {
   lines.split(",").toVector match {
      case Vector(countryName, region, population, economy) => CountryData(countryName, region, doubleOrNone(population), doubleOrNone(economy))//I would suggest having them as options because you may not have data for all countries
      case s => println(s"Error parsing line:\n$s"); 
   }
}