Counting Frequencies

Count how often each value appears.

FrequencyCount.scala

object Main {
  def main(args: Array[String]): Unit = {
    val target = 
    val items = List(1, 2, 2, 3, 2, 1)
    var counts = Map[Int, Int]()
    for (n <- items) {
      val current = counts.getOrElse(n, 0)
      counts = counts + (n -> (current + 1))
    }
    val targetCount = counts.getOrElse(target, 0)

    println("distinct=" + counts.size)
    println("targetCount=" + targetCount)
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    val target = 
    val items = List(1, 2, 2, 3, 2, 1)
    var counts = Map[Int, Int]()
    for (n <- items) {
      val current = counts.getOrElse(n, 0)
      counts = counts + (n -> (current + 1))
    }
    val targetCount = counts.getOrElse(target, 0)

    println("distinct=" + counts.size)
    println("targetCount=" + targetCount)
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    val target = 
    val items = List(1, 2, 2, 3, 2, 1)
    var counts = Map[Int, Int]()
    for (n <- items) {
      val current = counts.getOrElse(n, 0)
      counts = counts + (n -> (current + 1))
    }
    val targetCount = counts.getOrElse(target, 0)

    println("distinct=" + counts.size)
    println("targetCount=" + targetCount)
  }
}

frequency-count A frequency count builds a map from each value to its running tally. Each step reads the current count and stores one more.