Github user mengxr commented on a diff in the pull request:
https://github.com/apache/spark/pull/2634#discussion_r22693139
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/clustering/metrics/FastEuclideanOps.scala
---
@@ -0,0 +1,77 @@
+/*
+ * 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.mllib.clustering.metrics
+
+import breeze.linalg.{ DenseVector => BDV, SparseVector => BSV, Vector =>
BV }
+
+import org.apache.spark.mllib.base._
+import org.apache.spark.mllib.linalg.{ SparseVector, DenseVector, Vector }
+import org.apache.spark.mllib.base.{ Centroid, FPoint, PointOps, Infinity,
Zero }
+
+class FastEUPoint(raw: BV[Double], weight: Double) extends FPoint(raw,
weight) {
+ val norm = if (weight == Zero) Zero else raw.dot(raw) / (weight * weight)
+}
+
+/**
+ * Euclidean distance measure, expedited by pre-computing vector norms
+ */
+class FastEuclideanOps extends PointOps[FastEUPoint, FastEUPoint] with
Serializable {
+
+ type C = FastEUPoint
+ type P = FastEUPoint
+
+ val epsilon = 1e-4
+
+ /* compute a lower bound on the euclidean distance distance */
+
+ def distance(p: P, c: C, upperBound: Double): Double = {
+ val d = if (p.weight == Zero || c.weight == Zero) {
+ p.norm + c.norm
+ } else {
+ val x = p.raw.dot(c.raw) / (p.weight * c.weight)
--- End diff --
same question about using `weight` in `distance`
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