
mgo.tools.metric.KNearestNeighboursAverageDistance.scala Maven / Gradle / Ivy
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/*
* Copyright (C) 09/05/2014 Guillaume Chérel
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*/
package mgo.tools.metric
import cats._
import mgo.tools.KDTree
/**
* Distance to the K Nearest Neighbours using the KD-Tree algorithm
*
*/
object KNearestNeighboursAverageDistance {
def apply(values: Vector[Seq[Double]], k: Int): Vector[Later[Double]] = {
val tree = KDTree(values)
values.map {
v =>
Later {
val neighbours = tree.knearest(k, v)
neighbours.foldLeft(0: Double) { case (sum, cur) => sum + tree.distance(cur.toSeq, v) } / neighbours.size
}
}
}
}
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