srowen commented on a change in pull request #26413: [SPARK-16872][ML][PYSPARK]
Impl Gaussian Naive Bayes Classifier
URL: https://github.com/apache/spark/pull/26413#discussion_r344247755
##########
File path:
mllib/src/main/scala/org/apache/spark/ml/classification/NaiveBayes.scala
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@@ -280,15 +381,35 @@ class NaiveBayesModel private[ml] (
* This precomputes log(1.0 - exp(theta)) and its sum which are used for the
linear algebra
* application of this condition (in predict function).
*/
- private lazy val (thetaMinusNegTheta, negThetaSum) = $(modelType) match {
- case Multinomial => (None, None)
+ @transient private lazy val (thetaMinusNegTheta, negThetaSum) = $(modelType)
match {
case Bernoulli =>
val negTheta = theta.map(value => math.log1p(-math.exp(value)))
val ones = new DenseVector(Array.fill(theta.numCols) {1.0})
val thetaMinusNegTheta = theta.map { value =>
value - math.log1p(-math.exp(value))
}
- (Option(thetaMinusNegTheta), Option(negTheta.multiply(ones)))
+ (thetaMinusNegTheta, negTheta.multiply(ones))
+ case Multinomial => (null, null)
+ case Gaussian => (null, null)
+ case _ =>
+ // This should never happen.
+ throw new IllegalArgumentException(s"Invalid modelType:
${$(modelType)}.")
+ }
+
+ /**
+ * Gaussian scoring requires sum of log(Variance).
+ * This precomputes sum of log(Variance) which are used for the linear
algebra
+ * application of this condition (in predict function).
+ */
+ @transient private lazy val logVarSum = $(modelType) match {
+ case Gaussian =>
+ Array.tabulate(numClasses) { i =>
+ Iterator.range(0, numFeatures).map { j =>
+ math.log(sigma(i, j))
+ }.sum
+ }
+ case Multinomial => null
Review comment:
Same as previous comment
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