implement copeland

Author: jbytecode

src/main/scala/copeland.scala

@@ -0,0 +1,40 @@
+package org.expr.mcdm
+
+import org.expr.mcdm.Direction.{Maximize, Minimize}
+
+case class CopelandResult(
+    ranks: Vec,
+)
+
+
+def level_of_dominance(v1: Array[Int], v2: Array[Int]): Int = 
+    var lod = 0
+    val n = v1.length
+    for (i <- 0 until n) 
+        if (v1(i) < v2(i)) 
+            lod += 1
+
+    lod
+
+
+def dominance_scores(ordering_mat: Array[Array[Int]]): Array[Array[Int]] = 
+    val n = ordering_mat.length
+    Array.tabulate(n, n)((i, j) => level_of_dominance(ordering_mat(i), ordering_mat(j)))
+
+
+def winloss_scores(dommat: Array[Array[Int]]): Array[Array[Int]] = 
+    val n = dommat.length
+    Array.tabulate(n, n)((i, j) => (dommat(i)(j) - dommat(j)(i)).sign.toInt)
+
+def copeland(rankmatrix: Array[Array[Int]]): CopelandResult = 
+
+    /* 
+    winlosses = ordering_mat |> dominance_scores |> winloss_scores
+    n, _ = size(winlosses)
+    scores = map(i -> Int(sum(winlosses[i, :])), 1:n)
+    return scores
+     */
+    val winloses = winloss_scores(dominance_scores(rankmatrix))
+    val scores = Array.tabulate(winloses.length)(i => winloses(i).sum)
+    val ranks = ranksfromscores(scores.map(_.toDouble))
+    CopelandResult(ranks)

src/main/scala/matrix.scala

@@ -1,6 +1,7 @@
 package org.expr.mcdm
 
 import scala.math as math
+import scala.collection.AbstractSeq
 
 object Matrix:
 

src/test/scala/testcopeland.scala

@@ -0,0 +1,28 @@
+import munit.Assertions as A
+
+import org.expr.mcdm.copeland
+import org.expr.mcdm.Direction.{Maximize, Minimize}
+import org.expr.mcdm.Matrix
+import org.expr.mcdm.rov
+
+class TestCopeland extends munit.FunSuite {
+  test("Copeland Example - 1") {
+    
+    val mopa_rank = Array(1, 4, 2, 3).reverse
+    val moosra_rank = Array(1, 2, 3, 4).reverse
+    val copras_rank = Array(1, 3, 2, 4).reverse
+    val saw_rank = Array(1, 3, 2, 4).reverse
+    val wpm_rank = Array(1, 3, 2, 4).reverse
+    val rov_rank = Array(4, 1, 2, 3).reverse
+
+
+    val mat = Array(mopa_rank, moosra_rank, copras_rank, saw_rank, wpm_rank, rov_rank).transpose
+
+    val result = copeland(mat) 
+
+    val expected = Array(4.0, 2, 3, 1)
+
+    A.assert(Matrix.elementwise_equal(result.ranks, expected), s"Expected ${expected.mkString(",")} but got ${result.ranks.mkString(",")}")
+
+  }
+}