Github user jkbradley commented on a diff in the pull request:
https://github.com/apache/spark/pull/19433#discussion_r150154413
--- Diff:
mllib/src/main/scala/org/apache/spark/ml/tree/impl/AggUpdateUtils.scala ---
@@ -0,0 +1,86 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.ml.tree.impl
+
+import org.apache.spark.ml.tree.Split
+
+/**
+ * Helpers for updating DTStatsAggregators during collection of sufficient
stats for tree training.
+ */
+private[impl] object AggUpdateUtils {
+
+ /**
+ * Updates the parent node stats of the passed-in impurity aggregator
with the labels
+ * corresponding to the feature values at indices [from, to).
+ * @param indices Array of row indices for feature values; indices(i) =
row index of the ith
+ * feature value
+ */
+ private[impl] def updateParentImpurity(
+ statsAggregator: DTStatsAggregator,
+ indices: Array[Int],
+ from: Int,
+ to: Int,
+ instanceWeights: Array[Double],
+ labels: Array[Double]): Unit = {
+ from.until(to).foreach { idx =>
+ val rowIndex = indices(idx)
+ val label = labels(rowIndex)
+ statsAggregator.updateParent(label, instanceWeights(rowIndex))
+ }
+ }
+
+ /**
+ * Update aggregator for an (unordered feature, label) pair
+ * @param featureSplits Array of splits for the current feature
+ */
+ private[impl] def updateUnorderedFeature(
+ agg: DTStatsAggregator,
+ featureValue: Int,
+ label: Double,
+ featureIndex: Int,
+ featureIndexIdx: Int,
+ featureSplits: Array[Split],
+ instanceWeight: Double): Unit = {
+ val leftNodeFeatureOffset = agg.getFeatureOffset(featureIndexIdx)
+ // Each unordered split has a corresponding bin for impurity stats of
data points that fall
+ // onto the left side of the split. For each unordered split, update
left-side bin if applicable
+ // for the current data point.
+ val numSplits = agg.metadata.numSplits(featureIndex)
+ var splitIndex = 0
+ while (splitIndex < numSplits) {
+ if (featureSplits(splitIndex).shouldGoLeft(featureValue,
featureSplits)) {
+ agg.featureUpdate(leftNodeFeatureOffset, splitIndex, label,
instanceWeight)
+ }
+ splitIndex += 1
+ }
+ }
+
+ /** Update aggregator for an (ordered feature, label) pair */
+ private[impl] def updateOrderedFeature(
+ agg: DTStatsAggregator,
+ featureValue: Int,
+ label: Double,
+ featureIndex: Int,
--- End diff --
featureIndex is not used
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