Github user derrickburns commented on a diff in the pull request:
https://github.com/apache/spark/pull/2419#discussion_r17640379
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/clustering/package.scala ---
@@ -0,0 +1,140 @@
+/*
+ * 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
+
+import org.apache.spark.mllib.linalg.Vector
+import breeze.linalg.{Vector => BV}
+import org.apache.spark.rdd.RDD
+
+package object base {
+
+ val Zero = 0.0
+ val One = 1.0
+ val Infinity = Double.MaxValue
+ val Unknown = -1.0
+
+ private[mllib] trait FP extends Serializable {
+ val weight: Double
+ val raw: BV[Double]
+ }
+
+ private[mllib] class FPoint(val raw: BV[Double], val weight: Double)
extends FP {
+ override def toString: String = weight + "," + (raw.toArray mkString
",")
+ lazy val inh = (raw :* (1.0 / weight)).toArray
+ }
+
+ /**
+ * A mutable point in homogeneous coordinates
+ */
+ private[mllib] class Centroid extends Serializable {
+ override def toString: String = weight + "," + (raw.toArray mkString
",")
+
+ def isEmpty = weight == Zero
+
+ var raw: BV[Double] = null
+
+ var weight: Double = Zero
+
+ def add(p: Centroid): this.type = add(p.raw, p.weight)
+
+ def add(p: FP): this.type = add(p.raw, p.weight)
+
+ def sub(p: Centroid): this.type = sub(p.raw, p.weight)
+
+ def sub(p: FP): this.type = sub(p.raw, p.weight)
+
+ def sub(r: BV[Double], w: Double): this.type = {
+ if (r != null) {
+ if (raw == null) {
+ raw = r.toVector :*= -1.0
+ weight = w * -1
+ } else {
+ raw -= r
+ weight = weight - w
+ }
+ }
+ this
+ }
+
+ def add(r: BV[Double], w: Double) : this.type = {
+ if (r != null) {
+ if (raw == null) {
+ raw = r.toVector
+ weight = w
+ } else {
+ raw += r
+ weight = weight + w
+ }
+ }
+ this
+ }
+ }
+
+ private[mllib] trait PointOps[P <: FP, C <: FP] {
--- End diff --
This is the distance function trait. For now, only two implementations are
provided. A future pull request will provide others. I have implemented the
Kullback-Leibler distance function successfully with this interface. I see no
reason why any other distance function cannot be implemented efficiently with
this interface, since it provides the opportunity to cache data per point and
center.
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