Github user yanboliang commented on a diff in the pull request: https://github.com/apache/spark/pull/12819#discussion_r81105501 --- Diff: mllib/src/main/scala/org/apache/spark/mllib/classification/NaiveBayes.scala --- @@ -355,79 +356,33 @@ class NaiveBayes private ( */ @Since("0.9.0") def run(data: RDD[LabeledPoint]): NaiveBayesModel = { - val requireNonnegativeValues: Vector => Unit = (v: Vector) => { - val values = v match { - case sv: SparseVector => sv.values - case dv: DenseVector => dv.values - } - if (!values.forall(_ >= 0.0)) { - throw new SparkException(s"Naive Bayes requires nonnegative feature values but found $v.") - } - } + val spark = SparkSession + .builder() + .sparkContext(data.context) + .getOrCreate() - val requireZeroOneBernoulliValues: Vector => Unit = (v: Vector) => { - val values = v match { - case sv: SparseVector => sv.values - case dv: DenseVector => dv.values - } - if (!values.forall(v => v == 0.0 || v == 1.0)) { - throw new SparkException( - s"Bernoulli naive Bayes requires 0 or 1 feature values but found $v.") - } - } + import spark.implicits._ - // Aggregates term frequencies per label. - // TODO: Calling combineByKey and collect creates two stages, we can implement something - // TODO: similar to reduceByKeyLocally to save one stage. - val aggregated = data.map(p => (p.label, p.features)).combineByKey[(Long, DenseVector)]( - createCombiner = (v: Vector) => { - if (modelType == Bernoulli) { - requireZeroOneBernoulliValues(v) - } else { - requireNonnegativeValues(v) - } - (1L, v.copy.toDense) - }, - mergeValue = (c: (Long, DenseVector), v: Vector) => { - requireNonnegativeValues(v) - BLAS.axpy(1.0, v, c._2) - (c._1 + 1L, c._2) - }, - mergeCombiners = (c1: (Long, DenseVector), c2: (Long, DenseVector)) => { - BLAS.axpy(1.0, c2._2, c1._2) - (c1._1 + c2._1, c1._2) - } - ).collect().sortBy(_._1) + val nb = new NewNaiveBayes() + .setModelType(modelType) + .setSmoothing(lambda) - val numLabels = aggregated.length - var numDocuments = 0L - aggregated.foreach { case (_, (n, _)) => - numDocuments += n - } - val numFeatures = aggregated.head match { case (_, (_, v)) => v.size } - - val labels = new Array[Double](numLabels) - val pi = new Array[Double](numLabels) - val theta = Array.fill(numLabels)(new Array[Double](numFeatures)) - - val piLogDenom = math.log(numDocuments + numLabels * lambda) - var i = 0 - aggregated.foreach { case (label, (n, sumTermFreqs)) => - labels(i) = label - pi(i) = math.log(n + lambda) - piLogDenom - val thetaLogDenom = modelType match { - case Multinomial => math.log(sumTermFreqs.values.sum + numFeatures * lambda) - case Bernoulli => math.log(n + 2.0 * lambda) - case _ => - // This should never happen. - throw new UnknownError(s"Invalid modelType: $modelType.") - } - var j = 0 - while (j < numFeatures) { - theta(i)(j) = math.log(sumTermFreqs(j) + lambda) - thetaLogDenom - j += 1 - } - i += 1 + val labels = data.map(_.label).distinct().collect().sorted --- End diff -- It's not necessary to get labels by RDD operation which is expensive. Since we sort the labels and guarantee it in range [0, numClass), we can use ```val labels = pi.indices.map(_.toDouble).toArray``` directly.
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