reducebykey.scala

import scala.collection.mutable.Map

object reduce {

    def reduceByKey(func: (Int, Int) => Int, pairs: List[(String, Int)]): Map[String, Int] = {
        val ret = Map[String, Int]()

        for (tup <- pairs) {
            val k = tup._1
            val v = tup._2
            val nv = ret.getOrElse(k, 0)
            ret(k) = func(nv, v)
        }
        ret
    }


    def main(args :Array[String]) {
        val l = List("the quick brown fox", "jumps over the lazy dog", "how mumbo jumbo", "took over the world", "the world is flat")
        val fm = l.flatMap(line => line.split(" ")).map(w => (w, 1))
        val fin = reduceByKey((a, b) => (a + b), fm)
        println(fin)
    }
}