使用Scala实现ID3决策树算法

ID3算法scalaa语言实现
源代码

import scala.io.Source

object ID3 extends App{
  def log2(x: Double) = scala.math.log(x) / scala.math.log(2)
  val car=Source.fromFile("/usr/shujuceshi/car.data").getLines().toList.map(_.split(","))
 def entropy(l:List[Array[String]]):Double={
    val num=l.length
    val ent=l.map(x=>x(6)).distinct.map(x=>
      -(l.count(_(6)==x).toDouble/num)*log2(l.count(_(6)==x).toDouble/num)
    ).sum
   ent
 }
 def entropybyattri(l:List[Array[String]],attri:Int)= {
   entropy(l) - l.map(x => x(attri)).distinct.map(x =>
     entropy(l.filter(_(attri) == x)) * l.count(_(attri) == x) / l.length
   ).sum
 }
 def maxentropyattri(l:List[Array[String]],leftattri:List[Int])={
   (leftattri zip leftattri.map(x=>entropybyattri(l,x))).sortBy(_._2).last
 }
 def isleaf(l:List[Array[String]],maxentropy:Double,leftattri:List[Int])=l.length<=10||l.map(x=>x(6)).distinct.length==1||maxentropy<=0.0000001||leftattri.length==0
 def classbelonged(l:List[Array[String]]) :String=l.map(x=>x(6)).distinct.map(x=>(x,l.count(_(6)==x))).head._1
  sealed trait tree
  case class node(Dattri:Int,Aattri:String,child:List[tree]) extends tree
  case class leaf(Aattri:String,Belong:String) extends tree
  val leftattri=List(0,1,2,3,4,5)
  def buidtree(l:List[Array[String]],Aattri:String="root",leftattri:List[Int]):tree={