smile.math.distance.MeanMahanttan.scala Maven / Gradle / Ivy

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/*
 * Copyright (c) 2010-2021 Haifeng Li. All rights reserved.
 *
 * Smile 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.
 *
 * Smile 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 Smile.  If not, see .
 */
 
package smile.math.distance

/** Mean Mahantan distance. Compared to regular Manhattan distance, it normalizes
	* the distance by the sum of contingency table values.
	*
	* References
	*  - Seung-Seok Choi, et al. A Survey of Binary Similarity and Distance Measures.
	*    http://www.iiisci.org/journal/CV$/sci/pdfs/GS315JG.pdf
	*
	* @author Beck Gaël
  */
class MeanMahanttan extends Distance[Array[Int]] {
	override def d(x: Array[Int], y: Array[Int]): Double = {
		val (a, b, c, d) = contingency(x, y)
		(b + c).toDouble / (a + b + c + d)
	}
}