Optimized mapping functions for NDElements

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDAlgebra.kt

@@ -14,7 +14,7 @@ class ShapeMismatchException(val expected: IntArray, val actual: IntArray) : Run
 /**
  * The base interface for all nd-algebra implementations
  * @param T the type of nd-structure element
- * @param C the type of the context
+ * @param C the type of the element context
  * @param N the type of the structure
  */
 interface NDAlgebra<T, C, N : NDStructure<T>> {
@@ -112,10 +112,13 @@ interface NDField<T, F : Field<T>, N : NDStructure<T>> : Field<N>, NDRing<T, F,
     operator fun T.div(arg: N) = map(arg) { divide(it, this@div) }
 
     companion object {
+
+        private val realNDFieldCache = HashMap<IntArray, RealNDField>()
+
         /**
-         * Create a nd-field for [Double] values
+         * Create a nd-field for [Double] values or pull it from cache if it was created previously
          */
-        fun real(shape: IntArray) = RealNDField(shape)
+        fun real(shape: IntArray) = realNDFieldCache.getOrPut(shape){RealNDField(shape)}
 
         /**
          * Create a nd-field with boxing generic buffer

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDElement.kt

@@ -7,6 +7,9 @@ import scientifik.kmath.operations.Space
 
 /**
  * The root for all [NDStructure] based algebra elements. Does not implement algebra element root because of problems with recursive self-types
+ * @param T  the type of the element of the structure
+ * @param C the type of the context for the element
+ * @param N the type of the underlying [NDStructure]
  */
 interface NDElement<T, C, N : NDStructure<T>> : NDStructure<T> {
 
@@ -16,9 +19,6 @@ interface NDElement<T, C, N : NDStructure<T>> : NDStructure<T> {
 
     fun N.wrap(): NDElement<T, C, N>
 
-    fun mapIndexed(transform: C.(index: IntArray, T) -> T) = context.mapIndexed(unwrap(), transform).wrap()
-    fun map(transform: C.(T) -> T) = context.map(unwrap(), transform).wrap()
-
     companion object {
         /**
          * Create a optimized NDArray of doubles
@@ -61,10 +61,17 @@ interface NDElement<T, C, N : NDStructure<T>> : NDStructure<T> {
     }
 }
 
+
+fun <T, C, N : NDStructure<T>> NDElement<T, C, N>.mapIndexed(transform: C.(index: IntArray, T) -> T) =
+    context.mapIndexed(unwrap(), transform).wrap()
+
+fun <T, C, N : NDStructure<T>> NDElement<T, C, N>.map(transform: C.(T) -> T) = context.map(unwrap(), transform).wrap()
+
+
 /**
  * Element by element application of any operation on elements to the whole [NDElement]
  */
-operator fun <T, C> Function1<T, T>.invoke(ndElement: NDElement<T, C, *>) =
+operator fun <T, C, N : NDStructure<T>> Function1<T, T>.invoke(ndElement: NDElement<T, C, N>) =
     ndElement.map { value -> this@invoke(value) }
 
 /* plus and minus */
@@ -72,13 +79,13 @@ operator fun <T, C> Function1<T, T>.invoke(ndElement: NDElement<T, C, *>) =
 /**
  * Summation operation for [NDElement] and single element
  */
-operator fun <T, S : Space<T>> NDElement<T, S, *>.plus(arg: T) =
+operator fun <T, S : Space<T>, N : NDStructure<T>> NDElement<T, S, N>.plus(arg: T) =
     map { value -> arg + value }
 
 /**
  * Subtraction operation between [NDElement] and single element
  */
-operator fun <T, S : Space<T>> NDElement<T, S, *>.minus(arg: T) =
+operator fun <T, S : Space<T>, N : NDStructure<T>> NDElement<T, S, N>.minus(arg: T) =
     map { value -> arg - value }
 
 /* prod and div */
@@ -86,13 +93,13 @@ operator fun <T, S : Space<T>> NDElement<T, S, *>.minus(arg: T) =
 /**
  * Product operation for [NDElement] and single element
  */
-operator fun <T, R : Ring<T>> NDElement<T, R, *>.times(arg: T) =
+operator fun <T, R : Ring<T>, N : NDStructure<T>> NDElement<T, R, N>.times(arg: T) =
     map { value -> arg * value }
 
 /**
  * Division operation between [NDElement] and single element
  */
-operator fun <T, F : Field<T>> NDElement<T, F, *>.div(arg: T) =
+operator fun <T, F : Field<T>, N : NDStructure<T>> NDElement<T, F, N>.div(arg: T) =
     map { value -> arg / value }
 
 

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/RealNDField.kt

@@ -86,11 +86,25 @@ inline fun BufferedNDField<Double, RealField>.produceInline(crossinline initiali
     return BufferedNDFieldElement(this, DoubleBuffer(array))
 }
 
+/**
+ * Map one [RealNDElement] using function with indexes
+ */
+inline fun RealNDElement.mapIndexed(crossinline transform: RealField.(index: IntArray, Double) -> Double) =
+    context.produceInline { offset -> transform(strides.index(offset), buffer[offset]) }
+
+/**
+ * Map one [RealNDElement] using function without indexes
+ */
+inline fun RealNDElement.map(crossinline transform: RealField.(Double) -> Double): RealNDElement {
+    val array = DoubleArray(strides.linearSize) { offset -> RealField.transform(buffer[offset]) }
+    return BufferedNDFieldElement(context, DoubleBuffer(array))
+}
+
 /**
  * Element by element application of any operation on elements to the whole array. Just like in numpy
  */
 operator fun Function1<Double, Double>.invoke(ndElement: RealNDElement) =
-    ndElement.context.produceInline { i -> invoke(ndElement.buffer[i]) }
+    ndElement.map { this@invoke(it) }
 
 
 /* plus and minus */
@@ -99,10 +113,10 @@ operator fun Function1<Double, Double>.invoke(ndElement: RealNDElement) =
  * Summation operation for [BufferedNDElement] and single element
  */
 operator fun RealNDElement.plus(arg: Double) =
-    context.produceInline { i -> buffer[i] + arg }
+    map { it + arg }
 
 /**
  * Subtraction operation between [BufferedNDElement] and single element
  */
 operator fun RealNDElement.minus(arg: Double) =
-    context.produceInline { i -> buffer[i] - arg }
+    map { it - arg }

settings.gradle.kts

@@ -2,8 +2,7 @@ pluginManagement {
     repositories {
         mavenCentral()
         maven("https://plugins.gradle.org/m2/")
-        maven { setUrl("https://dl.bintray.com/kotlin/kotlin-eap") }
-        maven { setUrl("https://plugins.gradle.org/m2/") }
+        maven ("https://dl.bintray.com/kotlin/kotlin-eap")
     }
 }