kmath-core/src/commonMain/kotlin/space/kscience/kmath/structures/BufferView.kt

@@ -148,4 +148,45 @@ public class PermutedBuffer<T>(
 /**
  * Created a permuted view of given buffer using provided [indices]
  */
-public fun <T> Buffer<T>.permute(indices: IntArray): PermutedBuffer<T> = PermutedBuffer(this, indices)
+public fun <T> Buffer<T>.permute(indices: IntArray): PermutedBuffer<T> =
+    PermutedBuffer(this, indices)
+
+/**
+ * A [BufferView] that overrides indexing of the original buffer
+ */
+public class PermutedMutableBuffer<T>(
+    override val origin: MutableBuffer<T>,
+    private val permutations: IntArray,
+) : BufferView<T>, MutableBuffer<T> {
+    init {
+        permutations.forEach { index ->
+            if (index !in origin.indices) {
+                throw IndexOutOfBoundsException("Index $index is not in ${origin.indices}")
+            }
+        }
+    }
+
+    override val size: Int get() = permutations.size
+
+    override fun get(index: Int): T = origin[permutations[index]]
+
+    override fun set(index: Int, value: T) {
+        origin[permutations[index]] = value
+    }
+
+    override fun copy(): MutableBuffer<T> = PermutedMutableBuffer(origin.copy(), permutations)
+    //TODO Probably could be optimized
+
+    override fun iterator(): Iterator<T> = permutations.asSequence().map { origin[it] }.iterator()
+
+    @UnstableKMathAPI
+    override fun originIndex(index: Int): Int = if (index in permutations.indices) permutations[index] else -1
+
+    override fun toString(): String = Buffer.toString(this)
+}
+
+/**
+ * Created a permuted mutable view of given buffer using provided [indices]
+ */
+public fun <T> MutableBuffer<T>.permute(indices: IntArray): PermutedMutableBuffer<T> =
+    PermutedMutableBuffer(this, indices)

kmath-tensors/src/commonMain/kotlin/space/kscience/kmath/tensors/core/DoubleTensor.kt

@@ -10,6 +10,7 @@ import space.kscience.kmath.misc.UnstableKMathAPI
 import space.kscience.kmath.nd.MutableStructure2D
 import space.kscience.kmath.nd.MutableStructureND
 import space.kscience.kmath.nd.Shape
+import space.kscience.kmath.nd.Strides
 import space.kscience.kmath.structures.*
 import space.kscience.kmath.tensors.core.internal.toPrettyString
 import kotlin.jvm.JvmInline
@@ -81,7 +82,9 @@ public inline fun OffsetDoubleBuffer.mapInPlace(operation: (Double) -> Double) {
 }
 
 /**
- * Default [BufferedTensor] implementation for [Double] values
+ * Default [BufferedTensor] implementation for [Double] values.
+ *
+ * [DoubleTensor] always uses row-based strides
  */
 public class DoubleTensor(
     shape: IntArray,
@@ -128,34 +131,37 @@ public value class DoubleTensor2D(public val tensor: DoubleTensor) : MutableStru
         }
 
 
-//    @OptIn(PerformancePitfall::class)
+    @OptIn(PerformancePitfall::class)
-//    override val columns: List<MutableBuffer<Double>> get() = List(colNum) { j ->
+    override val columns: List<PermutedMutableBuffer<Double>>
-//        object : MutableBuffer<Double>{
+        get() = List(colNum) { j ->
-//
+            val indices = IntArray(rowNum) { i -> j + i * colNum }
-//            override fun get(index: Int): Double {
+            tensor.source.permute(indices)
-//                tensor.source.get()
+        }
-//            }
-//
-//            override fun set(index: Int, value: Double) {
-//                TODO("Not yet implemented")
-//            }
-//
-//            override fun copy(): MutableBuffer<Double> {
-//                TODO("Not yet implemented")
-//            }
-//
-//            override val size: Int
-//                get() = TODO("Not yet implemented")
-//
-//            override fun toString(): String {
-//                TODO("Not yet implemented")
-//            }
-//
-//        }
-//    }
 
     @PerformancePitfall
     override fun elements(): Sequence<Pair<IntArray, Double>> = tensor.elements()
     override fun get(index: IntArray): Double = tensor[index]
     override val shape: Shape get() = tensor.shape
 }
+
+public fun DoubleTensor.asDoubleTensor2D(): DoubleTensor2D = DoubleTensor2D(this)
+
+public fun DoubleTensor.asDoubleBuffer(): OffsetDoubleBuffer = if(shape.size == 1){
+    source
+} else {
+    error("Only 1D tensors could be cast to 1D" )
+}
+
+public inline fun DoubleTensor.forEachMatrix(block: (index: IntArray, matrix: DoubleTensor2D) -> Unit) {
+    val n = shape.size
+    check(n >= 2) { "Expected tensor with 2 or more dimensions, got size $n" }
+    val matrixOffset = shape[n - 1] * shape[n - 2]
+    val matrixShape = intArrayOf(shape[n - 2], shape[n - 1])
+
+    val size = Strides.linearSizeOf(matrixShape)
+    for (i in 0 until linearSize / matrixOffset) {
+        val offset = i * matrixOffset
+        val index = indices.index(offset).sliceArray(0 until (shape.size - 2))
+        block(index, DoubleTensor(matrixShape, source.view(offset, size)).asDoubleTensor2D())
+    }
+}

kmath-tensors/src/commonMain/kotlin/space/kscience/kmath/tensors/core/DoubleTensorAlgebra.kt

@@ -496,7 +496,7 @@ public open class DoubleTensorAlgebra :
      * with `0.0` mean and `1.0` standard deviation.
      */
     public fun randomNormal(shape: IntArray, seed: Long = 0): DoubleTensor =
-        DoubleTensor(shape, getRandomNormals(shape.reduce(Int::times), seed))
+        DoubleTensor(shape, DoubleBuffer.randomNormals(shape.reduce(Int::times), seed))
 
     /**
      * Returns a tensor with the same shape as `input` of random numbers drawn from normal distributions
@@ -508,7 +508,7 @@ public open class DoubleTensorAlgebra :
      * with `0.0` mean and `1.0` standard deviation.
      */
     public fun Tensor<Double>.randomNormalLike(seed: Long = 0): DoubleTensor =
-        DoubleTensor(shape, getRandomNormals(shape.reduce(Int::times), seed))
+        DoubleTensor(shape, DoubleBuffer.randomNormals(shape.reduce(Int::times), seed))
 
     /**
      * Concatenates a sequence of tensors with equal shapes along the first dimension.
@@ -781,7 +781,7 @@ public open class DoubleTensorAlgebra :
         pTensor
             .matrixSequence()
             .zip(pivotsTensor.asIntTensor().vectorSequence())
-            .forEach { (p, pivot) -> pivInit(p.as2D(), pivot.as1D(), n) }
+            .forEach { (p, pivot) -> pivInit(p.asDoubleTensor2D(), pivot.as1D(), n) }
 
         val lTensor = zeroesLike(luTensor)
         val uTensor = zeroesLike(luTensor)
@@ -791,7 +791,7 @@ public open class DoubleTensorAlgebra :
             .zip(luTensor.asDoubleTensor().matrixSequence())
             .forEach { (pairLU, lu) ->
                 val (l, u) = pairLU
-                luPivotHelper(l.as2D(), u.as2D(), lu.as2D(), n)
+                luPivotHelper(l.asDoubleTensor2D(), u.asDoubleTensor2D(), lu.asDoubleTensor2D(), n)
             }
 
         return Triple(pTensor, lTensor, uTensor)
@@ -818,7 +818,7 @@ public open class DoubleTensorAlgebra :
         val lTensor = zeroesLike(this)
 
         for ((a, l) in asDoubleTensor().matrixSequence().zip(lTensor.matrixSequence()))
-            for (i in 0 until n) choleskyHelper(a.as2D(), l.as2D(), n)
+            for (i in 0 until n) choleskyHelper(a.asDoubleTensor2D(), l.asDoubleTensor2D(), n)
 
         return lTensor
     }
@@ -837,7 +837,7 @@ public open class DoubleTensorAlgebra :
                     .zip(rTensor.matrixSequence()))
             ).forEach { (matrix, qr) ->
                 val (q, r) = qr
-                qrHelper(matrix, q, r.as2D())
+                qrHelper(matrix, q, r.asDoubleTensor2D())
             }
 
         return qTensor to rTensor
@@ -867,7 +867,7 @@ public open class DoubleTensorAlgebra :
         val sTensor = zeros(commonShape + intArrayOf(min(n, m)))
         val vTensor = zeros(commonShape + intArrayOf(min(n, m), m))
 
-        val matrices: VirtualBuffer<DoubleTensor> = asDoubleTensor().matrices
+        val matrices = asDoubleTensor().matrices
         val uTensors = uTensor.matrices
         val sTensorVectors = sTensor.vectors
         val vTensors = vTensor.matrices
@@ -922,7 +922,7 @@ public open class DoubleTensorAlgebra :
         val utv = u.transposed() matmul v
         val n = s.shape.last()
         for (matrix in utv.matrixSequence()) {
-            matrix.as2D().cleanSym(n)
+            matrix.asDoubleTensor2D().cleanSym(n)
         }
 
         val eig = (utv dot s.view(shp)).view(s.shape)
@@ -940,7 +940,7 @@ public open class DoubleTensorAlgebra :
         var eigenvalueStart = 0
         var eigenvectorStart = 0
         for (matrix in asDoubleTensor().matrixSequence()) {
-            val matrix2D = matrix.as2D()
+            val matrix2D = matrix.asDoubleTensor2D()
             val (d, v) = matrix2D.jacobiHelper(maxIteration, epsilon)
 
             for (i in 0 until matrix2D.rowNum) {
@@ -986,8 +986,8 @@ public open class DoubleTensorAlgebra :
         )
 
         luTensor.matrixSequence().zip(pivotsTensor.vectorSequence()).forEachIndexed { index, (lu, pivots) ->
-            resBuffer[index] = if (luHelper(lu.as2D(), pivots.as1D(), epsilon))
+            resBuffer[index] = if (luHelper(lu.asDoubleTensor2D(), pivots.as1D(), epsilon))
-                0.0 else luMatrixDet(lu.as2D(), pivots.as1D())
+                0.0 else luMatrixDet(lu.asDoubleTensor2D(), pivots.as1D())
         }
 
         return detTensor
@@ -1010,7 +1010,7 @@ public open class DoubleTensorAlgebra :
         val seq = luTensor.matrixSequence().zip(pivotsTensor.vectorSequence()).zip(invTensor.matrixSequence())
         for ((luP, invMatrix) in seq) {
             val (lu, pivots) = luP
-            luMatrixInv(lu.as2D(), pivots.as1D(), invMatrix.as2D())
+            luMatrixInv(lu.asDoubleTensor2D(), pivots.as1D(), invMatrix.asDoubleTensor2D())
         }
 
         return invTensor

kmath-tensors/src/commonMain/kotlin/space/kscience/kmath/tensors/core/internal/doubleTensorHelpers.kt

@@ -7,9 +7,7 @@ package space.kscience.kmath.tensors.core.internal
 
 import space.kscience.kmath.nd.*
 import space.kscience.kmath.nd.Strides.Companion.linearSizeOf
-import space.kscience.kmath.operations.asSequence
 import space.kscience.kmath.structures.DoubleBuffer
-import space.kscience.kmath.structures.VirtualBuffer
 import space.kscience.kmath.structures.asBuffer
 import space.kscience.kmath.structures.indices
 import space.kscience.kmath.tensors.core.BroadcastDoubleTensorAlgebra.eye
@@ -155,13 +153,13 @@ internal fun List<OffsetDoubleBuffer>.concat(): DoubleBuffer {
     return array.asBuffer()
 }
 
-internal val DoubleTensor.vectors: VirtualBuffer<DoubleTensor>
+internal val DoubleTensor.vectors: List<DoubleTensor>
     get() {
         val n = shape.size
         val vectorOffset = shape[n - 1]
         val vectorShape = intArrayOf(shape.last())
 
-        return VirtualBuffer(linearSize / vectorOffset) { index ->
+        return List(linearSize / vectorOffset) { index ->
             val offset = index * vectorOffset
             DoubleTensor(vectorShape, source.view(offset, vectorShape.first()))
         }
@@ -171,7 +169,7 @@ internal val DoubleTensor.vectors: VirtualBuffer<DoubleTensor>
 internal fun DoubleTensor.vectorSequence(): Sequence<DoubleTensor> = vectors.asSequence()
 
 
-internal val DoubleTensor.matrices: VirtualBuffer<DoubleTensor>
+internal val DoubleTensor.matrices: List<DoubleTensor>
     get() {
         val n = shape.size
         check(n >= 2) { "Expected tensor with 2 or more dimensions, got size $n" }
@@ -180,7 +178,7 @@ internal val DoubleTensor.matrices: VirtualBuffer<DoubleTensor>
 
         val size = linearSizeOf(matrixShape)
 
-        return VirtualBuffer(linearSize / matrixOffset) { index ->
+        return List(linearSize / matrixOffset) { index ->
             val offset = index * matrixOffset
             DoubleTensor(matrixShape, source.view(offset, size))
         }

kmath-tensors/src/commonMain/kotlin/space/kscience/kmath/tensors/core/internal/linUtils.kt

@@ -5,8 +5,12 @@
 
 package space.kscience.kmath.tensors.core.internal
 
-import space.kscience.kmath.nd.*
+import space.kscience.kmath.nd.MutableStructure1D
+import space.kscience.kmath.nd.MutableStructure2D
+import space.kscience.kmath.nd.StructureND
+import space.kscience.kmath.nd.as1D
 import space.kscience.kmath.operations.invoke
+import space.kscience.kmath.structures.DoubleBuffer
 import space.kscience.kmath.structures.IntBuffer
 import space.kscience.kmath.structures.asBuffer
 import space.kscience.kmath.structures.indices
@@ -109,7 +113,7 @@ internal fun DoubleTensorAlgebra.computeLU(
     val pivotsTensor = tensor.setUpPivots()
 
     for ((lu, pivots) in luTensor.matrixSequence().zip(pivotsTensor.vectorSequence()))
-        if (luHelper(lu.as2D(), pivots.as1D(), epsilon))
+        if (luHelper(lu.asDoubleTensor2D(), pivots.as1D(), epsilon))
             return null
 
     return Pair(luTensor, pivotsTensor)
@@ -210,18 +214,18 @@ internal fun DoubleTensorAlgebra.qrHelper(
 ) {
     checkSquareMatrix(matrix.shape)
     val n = matrix.shape[0]
-    val qM = q.as2D()
+    val qM = q.asDoubleTensor2D()
     val matrixT = matrix.transposed(0, 1)
     val qT = q.transposed(0, 1)
 
     for (j in 0 until n) {
         val v = matrixT.getTensor(j)
-        val vv = v.as1D()
+        val vv = v.asDoubleBuffer()
         if (j > 0) {
             for (i in 0 until j) {
                 r[i, j] = (qT.getTensor(i) dot matrixT.getTensor(j)).value()
                 for (k in 0 until n) {
-                    val qTi = qT.getTensor(i).as1D()
+                    val qTi = qT.getTensor(i).asDoubleBuffer()
                     vv[k] = vv[k] - r[i, j] * qTi[k]
                 }
             }
@@ -239,10 +243,10 @@ internal fun DoubleTensorAlgebra.svd1d(a: DoubleTensor, epsilon: Double = 1e-10)
     val b: DoubleTensor
     if (n > m) {
         b = a.transposed(0, 1).dot(a)
-        v = DoubleTensor(intArrayOf(m), getRandomUnitVector(m, 0))
+        v = DoubleTensor(intArrayOf(m), DoubleBuffer.randomUnitVector(m, 0))
     } else {
         b = a.dot(a.transposed(0, 1))
-        v = DoubleTensor(intArrayOf(n), getRandomUnitVector(n, 0))
+        v = DoubleTensor(intArrayOf(n), DoubleBuffer.randomUnitVector(n, 0))
     }
 
     var lastV: DoubleTensor

kmath-tensors/src/commonMain/kotlin/space/kscience/kmath/tensors/core/internal/utils.kt

@@ -14,14 +14,14 @@ import space.kscience.kmath.tensors.core.BufferedTensor
 import space.kscience.kmath.tensors.core.DoubleTensor
 import kotlin.math.*
 
-internal fun getRandomNormals(n: Int, seed: Long): DoubleBuffer {
+internal fun DoubleBuffer.Companion.randomNormals(n: Int, seed: Long): DoubleBuffer {
     val distribution = GaussianSampler(0.0, 1.0)
     val generator = RandomGenerator.default(seed)
     return distribution.sample(generator).nextBufferBlocking(n)
 }
 
-internal fun getRandomUnitVector(n: Int, seed: Long): DoubleBuffer {
+internal fun DoubleBuffer.Companion.randomUnitVector(n: Int, seed: Long): DoubleBuffer {
-    val unnorm: DoubleBuffer = getRandomNormals(n, seed)
+    val unnorm: DoubleBuffer = randomNormals(n, seed)
     val norm = sqrt(unnorm.array.sumOf { it * it })
     return unnorm.map { it / norm }
 }
@@ -67,7 +67,7 @@ internal fun format(value: Double, digits: Int = 4): String = buildString {
 }
 
 @OptIn(PerformancePitfall::class)
-internal fun DoubleTensor.toPrettyString(): String = buildString {
+public fun DoubleTensor.toPrettyString(): String = buildString {
     var offset = 0
     val shape = this@toPrettyString.shape
     val linearStructure = this@toPrettyString.indices

kmath-tensors/src/commonTest/kotlin/space/kscience/kmath/tensors/core/TestDoubleTensor.kt

@@ -11,6 +11,7 @@ import space.kscience.kmath.operations.invoke
 import space.kscience.kmath.structures.DoubleBuffer
 import space.kscience.kmath.structures.toDoubleArray
 import space.kscience.kmath.tensors.core.internal.matrixSequence
+import space.kscience.kmath.testutils.assertBufferEquals
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertTrue
@@ -38,7 +39,7 @@ internal class TestDoubleTensor {
     @Test
     fun testGet() = DoubleTensorAlgebra {
         val tensor = fromArray(intArrayOf(1, 2, 2), doubleArrayOf(3.5, 5.8, 58.4, 2.4))
-        val matrix = tensor.getTensor(0).as2D()
+        val matrix = tensor.getTensor(0).asDoubleTensor2D()
         assertEquals(matrix[0, 1], 5.8)
 
         val vector = tensor.getTensor(0, 1).as1D()
@@ -52,8 +53,8 @@ internal class TestDoubleTensor {
 
         tensor.matrixSequence().forEach {
             val a = it.asDoubleTensor()
-            val secondRow = a.getTensor(1).as1D()
+            val secondRow = a.getTensor(1).asDoubleBuffer()
-            val secondColumn = a.transposed(0, 1).getTensor(1).as1D()
+            val secondColumn = a.transposed(0, 1).getTensor(1).asDoubleBuffer()
             assertEquals(secondColumn[0], 77.89)
             assertEquals(secondRow[1], secondColumn[1])
         }
@@ -86,6 +87,23 @@ internal class TestDoubleTensor {
 
         tensorArray[intArrayOf(0)] = 55.9
         assertEquals(ndArray[intArrayOf(0)], 1.0)
+    }
 
+    @Test
+    fun test2D() = with(DoubleTensorAlgebra) {
+        val tensor: DoubleTensor = structureND(intArrayOf(3, 3)) { (i, j) -> (i - j).toDouble() }
+        //println(tensor.toPrettyString())
+        val tensor2d = tensor.asDoubleTensor2D()
+        assertBufferEquals(DoubleBuffer(1.0, 0.0, -1.0), tensor2d.rows[1])
+        assertBufferEquals(DoubleBuffer(-2.0, -1.0, 0.0), tensor2d.columns[2])
+    }
+
+    @Test
+    fun testMatrixIteration() = with(DoubleTensorAlgebra) {
+        val tensor = structureND(intArrayOf(3, 3, 3, 3)) { index -> index.sum().toDouble() }
+        tensor.forEachMatrix { index, matrix ->
+            println(index.joinToString { it.toString() })
+            println(matrix)
+        }
     }
 }