examples/src/main/kotlin/space/kscience/kmath/series/DTWTest.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2018-2023 KMath contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package space.kscience.kmath.series
+
+import space.kscience.kmath.nd.*
+import space.kscience.kmath.operations.algebra
+import space.kscience.kmath.operations.bufferAlgebra
+import space.kscience.kmath.structures.asBuffer
+
+fun main() = with(Double.algebra.bufferAlgebra.seriesAlgebra()) {
+    val firstSequence: DoubleArray = doubleArrayOf(0.0, 2.0, 3.0, 1.0, 3.0, 0.1, 0.0, 1.0)
+    val secondSequence: DoubleArray = doubleArrayOf(1.0, 0.0, 3.0, 0.0, 0.0, 3.0, 2.0, 0.0, 2.0)
+
+    val seriesOne = firstSequence.asBuffer()
+    val seriesTwo = secondSequence.asBuffer()
+
+    val result = DoubleFieldOpsND.dynamicTimeWarping(seriesOne, seriesTwo)
+    println("Total penalty coefficient: ${result.totalCost}")
+    print("Alignment: ")
+    println(result.alignMatrix)
+    for ((i , j) in result.alignMatrix.indices) {
+        if (result.alignMatrix[i, j] > 0.0) {
+            print("[$i, $j] ")
+        }
+    }
+}

kmath-stat/src/commonTest/kotlin/space/kscience/kmath/series/DTWTest.kt

@@ -6,30 +6,52 @@
 package space.kscience.kmath.series
 
 import space.kscience.kmath.nd.*
+import space.kscience.kmath.operations.DoubleField
 import space.kscience.kmath.operations.algebra
 import space.kscience.kmath.operations.bufferAlgebra
 import space.kscience.kmath.structures.asBuffer
+import space.kscience.kmath.structures.toDoubleBuffer
+import kotlin.math.PI
 import kotlin.test.Test
+import kotlin.test.assertEquals
 
 
 class DTWTest {
 
     @Test
     fun someData() {
-        val firstSequence: DoubleArray = doubleArrayOf(0.0, 2.0, 3.0, 1.0, 3.0, 0.1, 0.0, 1.0)
-        val secondSequence: DoubleArray = doubleArrayOf(1.0, 0.0, 3.0, 0.0, 0.0, 3.0, 2.0, 0.0, 2.0)
+        val firstSequence: DoubleArray = doubleArrayOf(0.0, 2.0, 3.0, 1.0, 2.0, 3.0, 1.0, 1.0)
+        val secondSequence: DoubleArray = doubleArrayOf(0.0, 2.0, 3.0, 1.0, 2.0, 3.0, 1.0, 1.0)
 
         val seriesOne = firstSequence.asBuffer()
         val seriesTwo = secondSequence.asBuffer()
 
         val result = DoubleFieldOpsND.dynamicTimeWarping(seriesOne, seriesTwo)
-        println("Total penalty coefficient: ${result.totalCost}")
-        print("Alignment: ")
-        println(result.alignMatrix)
-        for ((i , j) in result.alignMatrix.indices) {
-            if (result.alignMatrix[i, j] > 0.0) {
-                print("[$i, $j] ")
+        assertEquals(result.totalCost, 0.0)
+    }
+
+    @Test
+    fun pathTest() = with(Double.algebra.bufferAlgebra.seriesAlgebra()) {
+        val s1 = series(10) { DoubleField.sin(2 * PI * it / 100)}.toDoubleBuffer()
+        val s2 = series(20) {sin(PI * it / 100)}.toDoubleBuffer()
+        val s3 = series(20) {sin(PI * it / 100  + 2 * PI)}.toDoubleBuffer()
+
+        val resS1S2 = DoubleFieldOpsND.dynamicTimeWarping(s1, s2).alignMatrix
+        var pathLengthS1S2 = 0
+        for ((i,j) in resS1S2.indices) {
+            if (resS1S2[i, j] > 0.0) {
+                ++pathLengthS1S2
             }
         }
+
+        val resS1S3 = DoubleFieldOpsND.dynamicTimeWarping(s1, s3).alignMatrix
+        var pathLengthS1S3 = 0
+        for ((i,j) in resS1S3.indices) {
+            if (resS1S2[i, j] > 0.0) {
+                ++pathLengthS1S3
             }
         }
+        assertEquals(pathLengthS1S3, pathLengthS1S2)
+    }
+
+}