package my.bigdata.scala08 import scala.collection.mutable import scala.collection.mutable.ArrayBuffer import scala.io.Source /** scala word count   * Created by lq on 2017/8/7.   */ object Task2 {
     /**     * basic 核心是外部变量 + map.getOrElse     */   def scalaWC0(): Unit ={
       val in = new java.util.Scanner(new java.io.File("myfile.txt"))     //var tt = null;     val words = new ArrayBuffer[String]     while(in.hasNext())     {
         words ++= in.next().split("\\s+")     }     var map = Map[String,Int]()     for(key <- words) {
         map +=(key -> (map.getOrElse(key, 0)+1))       println((key -> (map.getOrElse(key, 0)+1)))       //     }     print(map)   }   /**     * basic 核心是外部变量 + map.getOrElse     */   def scalaWC1(): Unit ={
       val lines = Source.fromFile("myfile.txt").getLines();     val resMap = new mutable.HashMap[String,Long]()     //lines.map(line=>{line.split("\\s+")}).     for(line <- lines){
         val fields = line.split("\\s+")       for(f <- fields){
           val v =  resMap.getOrElse(f,0L);         resMap.put(f,v+1L)       }     }     resMap.foreach(println(_))   }   /**     * 利用遍历+外部变量map实现     */   def scalaWC5(): Unit = {
       val lines = Source.fromFile("myfile.txt").getLines();     val resMap = new mutable.HashMap[String, Long]()     val res = lines.flatMap(_.split("\\s+")).map(t=>{resMap+=((t,resMap.getOrElse(t,0L)+1L))})     println(resMap)   }   /**     * 利用遍历+外部变量map实现     */   def scalaWC4(): Unit = {
       val lines = Source.fromFile("myfile.txt").getLines();     val resMap = new mutable.HashMap[String, Long]()     val res = lines.flatMap(line => {
         line.split("\\s+")}).foldLeft(resMap)((x,y:String)=>{
         resMap+=((y,resMap.getOrElse(y,0L)+1L))     })     println(resMap)   }   /**     * advance 没有用到外部变量, foldLeft 传入一个map,然后传入一个偏函数,偏函数结合遍历的数据处理map返回一个map,最后整个函数返回一个map     */   def scalaWC41(): Unit = {
       val lines = Source.fromFile("myfile.txt").getLines();     val res = lines.flatMap(_.split("\\s+")).foldLeft(mutable.Map[String,Long]())((m,y:String)=>{
         m += ((y,m.getOrElse(y,0L)+1L))     })     println(res)   }   /**     * advance 没有用到外部变量, foldLeft的遍历所有的功能     */   def scalaWC2(): Unit ={
       val lines = Source.fromFile("myfile.txt").getLines();     //val resMap = new mutable.HashMap[String,Long]()     val res = lines.map(line=>{line.split("\\s+").toBuffer})       .toList.flatMap(x=>x).map((_,1)).groupBy(_._1)       .map(x=>(x._1,x._2.foldLeft(0)((sum,t) =>{sum + t._2})))     println(res)   }   /**     * advance 没有用到外部变量, reduceLeft的遍历所有的功能     */   def scalaWC3(): Unit ={
       val lines = Source.fromFile("myfile.txt").getLines();     val res = lines.map(line=>{line.split("\\s+").toBuffer})       .toList.flatMap(x=>x).map((_,1)).groupBy(_._1)       .map(x=>(x._2.reduceLeft((x,y)=>{
           (x._1,x._2+y._2)       })))     //出现     println(res)   }   /**     * 主函数     *     * @param args     */   def main(args: Array[String]): Unit = {
       // arrFun2()     // printJavaProp()     //customMap()     scalaWC41()   }   /*   总结:wc的实现思路   1.循环+外部map变量+map特性   2.利用集合的方法,通过各种变换,的到结果   3.集合具有遍历的方法有map,filter,foreach,reduceLeft,foldLeft,这些加上外部map变量+map特性都能实现WordCount    */ }