first DTW method realization

kmath-ejml/src/main/kotlin/space/kscience/kmath/ejml/_generated.kt

@@ -19,9 +19,9 @@ import org.ejml.sparse.csc.factory.DecompositionFactory_DSCC
 import org.ejml.sparse.csc.factory.DecompositionFactory_FSCC
 import org.ejml.sparse.csc.factory.LinearSolverFactory_DSCC
 import org.ejml.sparse.csc.factory.LinearSolverFactory_FSCC
-import space.kscience.kmath.UnstableKMathAPI
 import space.kscience.kmath.linear.*
 import space.kscience.kmath.linear.Matrix
+import space.kscience.kmath.UnstableKMathAPI
 import space.kscience.kmath.nd.StructureFeature
 import space.kscience.kmath.operations.DoubleField
 import space.kscience.kmath.operations.FloatField

kmath-stat/src/commonMain/kotlin/space/kscience/kmath/series/DynamicTimeWarping.kt

@@ -5,6 +5,11 @@
 
 package space.kscience.kmath.series
 
+import space.kscience.kmath.nd.*
+import space.kscience.kmath.nd.DoubleBufferND
+import space.kscience.kmath.nd.ShapeND
+import space.kscience.kmath.nd.ndAlgebra
+import space.kscience.kmath.operations.DoubleField
 import space.kscience.kmath.structures.DoubleBuffer
 import kotlin.math.abs
 
@@ -12,9 +17,11 @@ public const val LEFT_OFFSET : Int = -1
 public const val BOTTOM_OFFSET : Int = 1
 public const val DIAGONAL_OFFSET : Int = 0
 
+
+
 // TODO: Change container for alignMatrix to kmath special ND structure
 public data class DynamicTimeWarpingData(val totalCost : Double = 0.0,
-                                     val alignMatrix : Array<BooleanArray> = Array(0) {BooleanArray(0)}) {
+                                     val alignMatrix : IntBufferND = IntRingOpsND.structureND(ShapeND(0, 0)) { (i, j) -> 0}) {
     override fun equals(other: Any?): Boolean {
         if (this === other) return true
         if (other == null || this::class != other::class) return false
@@ -22,16 +29,9 @@ public data class DynamicTimeWarpingData(val totalCost : Double = 0.0,
         other as DynamicTimeWarpingData
 
         if (totalCost != other.totalCost) return false
-        if (!alignMatrix.contentDeepEquals(other.alignMatrix)) return false
 
         return true
     }
-
-    override fun hashCode(): Int {
-        var result = totalCost.hashCode()
-        result = 31 * result + alignMatrix.contentDeepHashCode()
-        return result
-    }
 }
 
 /**
@@ -42,25 +42,20 @@ public data class DynamicTimeWarpingData(val totalCost : Double = 0.0,
  * There is special cases for i = 0 or j = 0.
  */
 
-public fun costMatrix(series1 : DoubleBuffer, series2 : DoubleBuffer) : Array<DoubleArray> {
+public fun costMatrix(series1 : DoubleBuffer, series2 : DoubleBuffer) : DoubleBufferND {
-    val dtwMatrix: Array<DoubleArray> = Array(series1.size){ row ->
+    val dtwMatrix = DoubleField.ndAlgebra.structureND(ShapeND(series1.size, series2.size)) {
-        DoubleArray(series2.size) { col ->
+            (row, col) -> abs(series1[row] - series2[col])
-            abs(series1[row] - series2[col])
-        }
     }
-
+    for ( (row, col) in dtwMatrix.indices) {
-    for (i in dtwMatrix.indices) {
+        dtwMatrix[row, col] += when {
-        for (j in dtwMatrix[i].indices) {
+            row == 0 && col == 0 -> 0.0
-            dtwMatrix[i][j] += when {
+            row == 0 -> dtwMatrix[row, col - 1]
-                i == 0 && j == 0 -> 0.0
+            col == 0 -> dtwMatrix[row - 1, col]
-                i == 0 -> dtwMatrix[i][j-1]
+            else -> minOf(
-                j == 0 -> dtwMatrix[i-1][j]
+                dtwMatrix[row, col - 1],
-                else -> minOf(
+                dtwMatrix[row - 1, col],
-                    dtwMatrix[i][j-1],
+                dtwMatrix[row - 1, col - 1]
-                    dtwMatrix[i-1][j],
+            )
-                    dtwMatrix[i-1][j-1]
-                )
-            }
         }
     }
     return dtwMatrix
@@ -95,27 +90,27 @@ public fun dynamicTimeWarping(series1 : DoubleBuffer, series2 : DoubleBuffer) :
     var cost = 0.0
     var pathLength = 0
     val costMatrix = costMatrix(series1, series2)
-    val alignMatrix : Array<BooleanArray> = Array(costMatrix.size) { BooleanArray(costMatrix.first().size) }
+    val alignMatrix: IntBufferND = IntRingOpsND.structureND(ShapeND(series1.size, series2.size)) {(row, col) -> 0}
-    val indexes = PathIndices(alignMatrix.lastIndex,  alignMatrix.last().lastIndex)
+    val indexes = PathIndices(alignMatrix.indices.shape.first() - 1,  alignMatrix.indices.shape.last() - 1)
 
     with(indexes) {
-        alignMatrix[id_x][id_y] = true
+        alignMatrix[id_x, id_y] = 1
-        cost += costMatrix[id_x][id_y]
+        cost += costMatrix[id_x, id_y]
         pathLength++
         while (id_x != 0 || id_y != 0) {
             when {
-                id_x == 0 || costMatrix[id_x][id_y] == costMatrix[id_x][id_y - 1] + abs(series1[id_x] - series2[id_y]) -> {
+                id_x == 0 || costMatrix[id_x, id_y] == costMatrix[id_x, id_y - 1] + abs(series1[id_x] - series2[id_y]) -> {
                     moveOption(LEFT_OFFSET)
                 }
-                id_y == 0 || costMatrix[id_x][id_y] == costMatrix[id_x - 1][id_y] + abs(series1[id_x] - series2[id_y]) -> {
+                id_y == 0 || costMatrix[id_x, id_y] == costMatrix[id_x - 1, id_y] + abs(series1[id_x] - series2[id_y]) -> {
                     moveOption(BOTTOM_OFFSET)
                 }
-                costMatrix[id_x][id_y] == costMatrix[id_x - 1][id_y - 1] + abs(series1[id_x] - series2[id_y]) -> {
+                costMatrix[id_x, id_y] == costMatrix[id_x - 1, id_y - 1] + abs(series1[id_x] - series2[id_y]) -> {
                     moveOption(DIAGONAL_OFFSET)
                 }
             }
-            alignMatrix[id_x][id_y] = true
+            alignMatrix[id_x, id_y] = 1
-            cost += costMatrix[id_x][id_y]
+            cost += costMatrix[id_x, id_y]
             pathLength++
         }
         cost /= pathLength

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

@@ -0,0 +1,41 @@
+/*
+ * 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.DoubleField
+import space.kscience.kmath.operations.algebra
+import space.kscience.kmath.operations.bufferAlgebra
+import space.kscience.kmath.structures.DoubleBuffer
+import space.kscience.kmath.structures.asBuffer
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class DTWTest {
+
+    @Test
+    fun someData() : Unit {
+        with(Double.algebra.bufferAlgebra) {
+            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: DoubleBuffer = firstSequence.asBuffer()
+            val seriesTwo: DoubleBuffer = secondSequence.asBuffer()
+
+            val result = dynamicTimeWarping(seriesOne, seriesTwo)
+            println("Total penalty coefficient: ${result.totalCost}")
+            print("Alignment: ")
+            println(result.alignMatrix)
+            for ((i , j) in result.alignMatrix.indices) {
+                    if (result.alignMatrix[i, j] == 1) {
+                        print("[$i, $j] ")
+                    }
+            }
+        }
+    }
+}
+
+