[GitHub] spark pull request: [SPARK-2756] [mllib] Decision tree bug fixes

[jkbradley <gi...@git.apache.org>]

Github user jkbradley commented on a diff in the pull request:

    https://github.com/apache/spark/pull/1673#discussion_r15676566
  
    --- Diff: examples/src/main/scala/org/apache/spark/examples/mllib/DecisionTreeRunner.scala ---
    @@ -100,16 +109,57 @@ object DecisionTreeRunner {
       }
     
       def run(params: Params) {
    +
         val conf = new SparkConf().setAppName("DecisionTreeRunner")
         val sc = new SparkContext(conf)
     
         // Load training data and cache it.
    -    val examples = MLUtils.loadLabeledPoints(sc, params.input).cache()
    +    val origExamples = params.dataFormat match {
    +      case "dense" => MLUtils.loadLabeledPoints(sc, params.input).cache()
    +      case "libsvm" => MLUtils.loadLibSVMFile(sc, params.input).cache()
    +    }
    +    // For classification, re-index classes if needed.
    +    val (examples, numClasses) = params.algo match {
    +      case Classification => {
    +        // classCounts: class --> # examples in class
    +        val classCounts = origExamples.map(_.label).countByValue()
    +        val sortedClasses = classCounts.keys.toList.sorted
    +        val numClasses = classCounts.size
    +        // classIndexMap: class --> index in 0,...,numClasses-1
    +        val classIndexMap = {
    +          if (classCounts.keySet != Set(0.0, 1.0)) {
    +            sortedClasses.zipWithIndex.toMap
    +          } else {
    +            Map[Double, Int]()
    +          }
    +        }
    +        val examples = {
    +          if (classIndexMap.isEmpty) {
    +            origExamples
    +          } else {
    +            origExamples.map(lp => LabeledPoint(classIndexMap(lp.label), lp.features))
    +          }
    +        }
    +        val numExamples = examples.count()
    +        println(s"numClasses = $numClasses.")
    --- End diff --
    
    @mengxr  Your thoughts?


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