二重引用符付きCSVを処理するとして、str.split(",")した後のクォーテーション除去を map(_.replace("¥"")) と map(_.init.tail) で速度比較したら後者の方が速かった (20回ずつ動かして比較) #scala

gistfile1.scala

object Hoge {

  def main(args: Array[String]) {
    for (i <- (1 to 20)) mainRecur(args(0).toInt)
  }

  private def mainRecur(ver: Int) {
    var start = System.nanoTime

    val s = "\"1\",\"22\",\"333\",\"4444\",\"55555\""
    val ss = s.split(",")
    val l = if (ver == 1) verReplace(ss) else verInitTail(ss)

    var end = System.nanoTime
    var sec = (end - start)
    println("Done. Total nano sec: %d".format(sec))
  }

  private def verReplace(ss: Array[String]) = {
    ss map { _.replace("\"", "") }
  }

  private def verInitTail(ss: Array[String]) = {
    ss map { _.init.tail }
  }

}

replace版

Done. Total nano sec: 614000
Done. Total nano sec: 35000
Done. Total nano sec: 34000
Done. Total nano sec: 31000
Done. Total nano sec: 31000
Done. Total nano sec: 30000
Done. Total nano sec: 30000
Done. Total nano sec: 29000
Done. Total nano sec: 30000
Done. Total nano sec: 30000
Done. Total nano sec: 30000
Done. Total nano sec: 29000
Done. Total nano sec: 29000
Done. Total nano sec: 30000
Done. Total nano sec: 32000
Done. Total nano sec: 29000
Done. Total nano sec: 29000
Done. Total nano sec: 28000
Done. Total nano sec: 29000
Done. Total nano sec: 32000

init.tail版

Done. Total nano sec: 579000
Done. Total nano sec: 14000
Done. Total nano sec: 13000
Done. Total nano sec: 15000
Done. Total nano sec: 12000
Done. Total nano sec: 12000
Done. Total nano sec: 15000
Done. Total nano sec: 11000
Done. Total nano sec: 11000
Done. Total nano sec: 12000
Done. Total nano sec: 15000
Done. Total nano sec: 11000
Done. Total nano sec: 11000
Done. Total nano sec: 11000
Done. Total nano sec: 14000
Done. Total nano sec: 11000
Done. Total nano sec: 11000
Done. Total nano sec: 15000
Done. Total nano sec: 11000
Done. Total nano sec: 11000