[WIP] Another histogram refactor

CHANGELOG.md

@@ -48,6 +48,7 @@
 - Operations -> Ops
 - Default Buffer and ND algebras are now Ops and lack neutral elements (0, 1) as well as algebra-level shapes.
 - Tensor algebra takes read-only structures as input and inherits AlgebraND
+- `UnivariateDistribution` renamed to `Distribution1D`
 
 ### Deprecated
 - Specialized `DoubleBufferAlgebra`

kmath-core/src/commonMain/kotlin/space/kscience/kmath/domains/Domain1D.kt

@@ -35,6 +35,23 @@ public class DoubleDomain1D(
     }
 
     override fun volume(): Double = range.endInclusive - range.start
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (other == null || this::class != other::class) return false
+
+        other as DoubleDomain1D
+
+        if (doubleRange != other.doubleRange) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int = doubleRange.hashCode()
+
+    override fun toString(): String = doubleRange.toString()
+
+
 }
 
 @UnstableKMathAPI

kmath-core/src/commonMain/kotlin/space/kscience/kmath/misc/sorting.kt

@@ -3,43 +3,71 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
  */
 
+
 package space.kscience.kmath.misc
 
-import kotlin.comparisons.*
 import space.kscience.kmath.structures.Buffer
+import space.kscience.kmath.structures.VirtualBuffer
 
 /**
- * Return a new list filled with buffer indices. Indice order is defined by sorting associated buffer value.
+ * Return a new array filled with buffer indices. Indices order is defined by sorting associated buffer value.
- * This feature allows to sort buffer values without reordering its content.
+ * This feature allows sorting buffer values without reordering its content.
  *
- * @return List of buffer indices, sorted by associated value.
+ * @return Buffer indices, sorted by associated value.
  */
-@PerformancePitfall
 @UnstableKMathAPI
-public fun <V: Comparable<V>> Buffer<V>.permSort() : IntArray = _permSortWith(compareBy<Int> { get(it) })
+public fun <V : Comparable<V>> Buffer<V>.indicesSorted(): IntArray = permSortIndicesWith(compareBy { get(it) })
+
+/**
+ * Create a zero-copy virtual buffer that contains the same elements but in ascending order
+ */
+@OptIn(UnstableKMathAPI::class)
+public fun <V : Comparable<V>> Buffer<V>.sorted(): Buffer<V> {
+    val permutations = indicesSorted()
+    return VirtualBuffer(size) { this[permutations[it]] }
+}
 
-@PerformancePitfall
 @UnstableKMathAPI
-public fun <V: Comparable<V>> Buffer<V>.permSortDescending() : IntArray = _permSortWith(compareByDescending<Int> { get(it) })
+public fun <V : Comparable<V>> Buffer<V>.indicesSortedDescending(): IntArray =
+    permSortIndicesWith(compareByDescending { get(it) })
+
+/**
+ * Create a zero-copy virtual buffer that contains the same elements but in descending order
+ */
+@OptIn(UnstableKMathAPI::class)
+public fun <V : Comparable<V>> Buffer<V>.sortedDescending(): Buffer<V> {
+    val permutations = indicesSortedDescending()
+    return VirtualBuffer(size) { this[permutations[it]] }
+}
 
-@PerformancePitfall
 @UnstableKMathAPI
-public fun <V, C: Comparable<C>> Buffer<V>.permSortBy(selector: (V) -> C) : IntArray = _permSortWith(compareBy<Int> { selector(get(it)) })
+public fun <V, C : Comparable<C>> Buffer<V>.indicesSortedBy(selector: (V) -> C): IntArray =
+    permSortIndicesWith(compareBy { selector(get(it)) })
+
+@OptIn(UnstableKMathAPI::class)
+public fun <V, C : Comparable<C>> Buffer<V>.sortedBy(selector: (V) -> C): Buffer<V> {
+    val permutations = indicesSortedBy(selector)
+    return VirtualBuffer(size) { this[permutations[it]] }
+}
 
-@PerformancePitfall
 @UnstableKMathAPI
-public fun <V, C: Comparable<C>> Buffer<V>.permSortByDescending(selector: (V) -> C) : IntArray = _permSortWith(compareByDescending<Int> { selector(get(it)) })
+public fun <V, C : Comparable<C>> Buffer<V>.indicesSortedByDescending(selector: (V) -> C): IntArray =
+    permSortIndicesWith(compareByDescending { selector(get(it)) })
+
+@OptIn(UnstableKMathAPI::class)
+public fun <V, C : Comparable<C>> Buffer<V>.sortedByDescending(selector: (V) -> C): Buffer<V> {
+    val permutations = indicesSortedByDescending(selector)
+    return VirtualBuffer(size) { this[permutations[it]] }
+}
 
-@PerformancePitfall
 @UnstableKMathAPI
-public fun <V> Buffer<V>.permSortWith(comparator : Comparator<V>) : IntArray = _permSortWith { i1, i2 -> comparator.compare(get(i1), get(i2)) }
+public fun <V> Buffer<V>.indicesSortedWith(comparator: Comparator<V>): IntArray =
+    permSortIndicesWith { i1, i2 -> comparator.compare(get(i1), get(i2)) }
 
-@PerformancePitfall
+private fun <V> Buffer<V>.permSortIndicesWith(comparator: Comparator<Int>): IntArray {
-@UnstableKMathAPI
+    if (size < 2) return IntArray(size) { 0 }
-private fun <V> Buffer<V>._permSortWith(comparator : Comparator<Int>) : IntArray {
-    if (size < 2) return IntArray(size)
 
-    /* TODO: optimisation : keep a constant big array of indices (Ex: from 0 to 4096), then create indice
+    /* TODO: optimisation : keep a constant big array of indices (Ex: from 0 to 4096), then create indices
      * arrays more efficiently by copying subpart of cached one. For bigger needs, we could copy entire
      * cached array, then fill remaining indices manually. Not done for now, because:
      *  1. doing it right would require some statistics about common used buffer sizes.
@@ -53,3 +81,12 @@ private fun <V> Buffer<V>._permSortWith(comparator : Comparator<Int>) : IntArray
      */
     return packedIndices.sortedWith(comparator).toIntArray()
 }
+
+/**
+ * Checks that the [Buffer] is sorted (ascending) and throws [IllegalArgumentException] if it is not.
+ */
+public fun <T : Comparable<T>> Buffer<T>.requireSorted() {
+    for (i in 0..(size - 2)) {
+        require(get(i + 1) >= get(i)) { "The buffer is not sorted at index $i" }
+    }
+}

kmath-core/src/commonTest/kotlin/space/kscience/kmath/misc/PermSortTest.kt

@@ -6,14 +6,13 @@
 package space.kscience.kmath.misc
 
 import space.kscience.kmath.misc.PermSortTest.Platform.*
-import kotlin.random.Random
-import kotlin.test.Test
-import kotlin.test.assertEquals
-import kotlin.test.assertTrue
-
 import space.kscience.kmath.structures.IntBuffer
 import space.kscience.kmath.structures.asBuffer
+import kotlin.random.Random
+import kotlin.test.Test
 import kotlin.test.assertContentEquals
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
 
 class PermSortTest {
 
@@ -29,9 +28,9 @@ class PermSortTest {
     @Test
     fun testOnEmptyBuffer() {
         val emptyBuffer = IntBuffer(0) {it}
-        var permutations = emptyBuffer.permSort()
+        var permutations = emptyBuffer.indicesSorted()
         assertTrue(permutations.isEmpty(), "permutation on an empty buffer should return an empty result")
-        permutations = emptyBuffer.permSortDescending()
+        permutations = emptyBuffer.indicesSortedDescending()
         assertTrue(permutations.isEmpty(), "permutation on an empty buffer should return an empty result")
     }
 
@@ -47,25 +46,25 @@ class PermSortTest {
 
     @Test
     fun testPermSortBy() {
-        val permutations = platforms.permSortBy { it.name }
+        val permutations = platforms.indicesSortedBy { it.name }
         val expected = listOf(ANDROID, JS, JVM, NATIVE, WASM)
         assertContentEquals(expected, permutations.map { platforms[it] }, "Ascending PermSort by name")
     }
 
     @Test
     fun testPermSortByDescending() {
-        val permutations = platforms.permSortByDescending { it.name }
+        val permutations = platforms.indicesSortedByDescending { it.name }
         val expected = listOf(WASM, NATIVE, JVM, JS, ANDROID)
         assertContentEquals(expected, permutations.map { platforms[it] }, "Descending PermSort by name")
     }
 
     @Test
     fun testPermSortWith() {
-        var permutations = platforms.permSortWith { p1, p2 -> p1.name.length.compareTo(p2.name.length) }
+        var permutations = platforms.indicesSortedWith { p1, p2 -> p1.name.length.compareTo(p2.name.length) }
         val expected = listOf(JS, JVM, WASM, NATIVE, ANDROID)
         assertContentEquals(expected, permutations.map { platforms[it] }, "PermSort using custom ascending comparator")
 
-        permutations = platforms.permSortWith(compareByDescending { it.name.length })
+        permutations = platforms.indicesSortedWith(compareByDescending { it.name.length })
         assertContentEquals(expected.reversed(), permutations.map { platforms[it] }, "PermSort using custom descending comparator")
     }
 
@@ -75,7 +74,7 @@ class PermSortTest {
         println("Test randomization seed: $seed")
 
         val buffer = Random(seed).buffer(bufferSize)
-        val indices = buffer.permSort()
+        val indices = buffer.indicesSorted()
 
         assertEquals(bufferSize, indices.size)
         // Ensure no doublon is present in indices
@@ -87,7 +86,7 @@ class PermSortTest {
             assertTrue(current <= next, "Permutation indices not properly sorted")
         }
 
-        val descIndices = buffer.permSortDescending()
+        val descIndices = buffer.indicesSortedDescending()
         assertEquals(bufferSize, descIndices.size) 
         // Ensure no doublon is present in indices
         assertEquals(descIndices.toSet().size, descIndices.size)

kmath-for-real/build.gradle.kts

@@ -21,19 +21,22 @@ readme {
 
     feature(
         id = "DoubleVector",
-        description = "Numpy-like operations for Buffers/Points",
         ref = "src/commonMain/kotlin/space/kscience/kmath/real/DoubleVector.kt"
-    )
+    ){
+        "Numpy-like operations for Buffers/Points"
+    }
 
     feature(
         id = "DoubleMatrix",
-        description = "Numpy-like operations for 2d real structures",
         ref = "src/commonMain/kotlin/space/kscience/kmath/real/DoubleMatrix.kt"
-    )
+    ){
+        "Numpy-like operations for 2d real structures"
+    }
 
     feature(
         id = "grids",
-        description = "Uniform grid generators",
         ref = "src/commonMain/kotlin/space/kscience/kmath/structures/grids.kt"
-    )
+    ){
+        "Uniform grid generators"
+    }
 }

kmath-histograms/build.gradle.kts

@@ -17,6 +17,8 @@ kotlin.sourceSets {
     commonTest {
         dependencies {
             implementation(project(":kmath-for-real"))
+            implementation(projects.kmath.kmathStat)
+            implementation("org.jetbrains.kotlinx:kotlinx-coroutines-test:1.6.0")
         }
     }
 }

kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/DoubleHistogramGroup.kt

@@ -16,11 +16,11 @@ import kotlin.math.floor
 /**
  * Multivariate histogram space for hyper-square real-field bins.
  */
-public class DoubleHistogramSpace(
+public class DoubleHistogramGroup(
     private val lower: Buffer<Double>,
     private val upper: Buffer<Double>,
     private val binNums: IntArray = IntArray(lower.size) { 20 },
-) : IndexedHistogramSpace<Double, Double> {
+) : IndexedHistogramGroup<Double, Double> {
 
     init {
         // argument checks
@@ -105,7 +105,7 @@ public class DoubleHistogramSpace(
          */
         public fun fromRanges(
             vararg ranges: ClosedFloatingPointRange<Double>,
-        ): DoubleHistogramSpace = DoubleHistogramSpace(
+        ): DoubleHistogramGroup = DoubleHistogramGroup(
             ranges.map(ClosedFloatingPointRange<Double>::start).asBuffer(),
             ranges.map(ClosedFloatingPointRange<Double>::endInclusive).asBuffer()
         )
@@ -121,7 +121,7 @@ public class DoubleHistogramSpace(
          */
         public fun fromRanges(
             vararg ranges: Pair<ClosedFloatingPointRange<Double>, Int>,
-        ): DoubleHistogramSpace = DoubleHistogramSpace(
+        ): DoubleHistogramGroup = DoubleHistogramGroup(
             ListBuffer(
                 ranges
                     .map(Pair<ClosedFloatingPointRange<Double>, Int>::first)

kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/Histogram1D.kt

@@ -6,6 +6,7 @@
 package space.kscience.kmath.histogram
 
 import space.kscience.kmath.domains.Domain1D
+import space.kscience.kmath.linear.Point
 import space.kscience.kmath.misc.UnstableKMathAPI
 import space.kscience.kmath.operations.asSequence
 import space.kscience.kmath.structures.Buffer
@@ -18,7 +19,7 @@ import space.kscience.kmath.structures.Buffer
  * @property standardDeviation Standard deviation of the bin value. Zero or negative if not applicable
  */
 @UnstableKMathAPI
-public class Bin1D<T : Comparable<T>, out V>(
+public data class Bin1D<T : Comparable<T>, out V>(
     public val domain: Domain1D<T>,
     override val binValue: V,
 ) : Bin<T, V>, ClosedRange<T> by domain.range {
@@ -35,12 +36,15 @@ public interface Histogram1D<T : Comparable<T>, V> : Histogram<T, V, Bin1D<T, V>
     override operator fun get(point: Buffer<T>): Bin1D<T, V>? = get(point[0])
 }
 
-@UnstableKMathAPI
 public interface Histogram1DBuilder<in T : Any, V : Any> : HistogramBuilder<T, V> {
     /**
      * Thread safe put operation
      */
     public fun putValue(at: T, value: V = defaultValue)
+
+    override fun putValue(point: Point<out T>, value: V) {
+        putValue(point[0], value)
+    }
 }
 
 @UnstableKMathAPI
@@ -52,5 +56,5 @@ public fun Histogram1DBuilder<Double, *>.fill(array: DoubleArray): Unit =
     array.forEach(this::putValue)
 
 @UnstableKMathAPI
-public fun Histogram1DBuilder<Double, *>.fill(buffer: Buffer<Double>): Unit =
+public fun <T: Any> Histogram1DBuilder<T, *>.fill(buffer: Buffer<T>): Unit =
     buffer.asSequence().forEach(this::putValue)

kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/IndexedHistogramGroup.kt

@@ -28,7 +28,7 @@ public data class DomainBin<in T : Comparable<T>, out V>(
  * @param V the type of bin value
  */
 public class IndexedHistogram<T : Comparable<T>, V : Any>(
-    public val histogramSpace: IndexedHistogramSpace<T, V>,
+    public val histogramSpace: IndexedHistogramGroup<T, V>,
     public val values: StructureND<V>,
 ) : Histogram<T, V, DomainBin<T, V>> {
 
@@ -48,8 +48,8 @@ public class IndexedHistogram<T : Comparable<T>, V : Any>(
 /**
  * A space for producing histograms with values in a NDStructure
  */
-public interface IndexedHistogramSpace<T : Comparable<T>, V : Any>
+public interface IndexedHistogramGroup<T : Comparable<T>, V : Any> : Group<IndexedHistogram<T, V>>,
-    : Group<IndexedHistogram<T, V>>, ScaleOperations<IndexedHistogram<T, V>> {
+    ScaleOperations<IndexedHistogram<T, V>> {
     public val shape: Shape
     public val histogramValueAlgebra: FieldND<V, *> //= NDAlgebra.space(valueSpace, Buffer.Companion::boxing, *shape),
 

kmath-histograms/src/commonMain/kotlin/space/kscience/kmath/histogram/UniformHistogram1D.kt

@@ -5,8 +5,92 @@
 
 package space.kscience.kmath.histogram
 
-//class UniformHistogram1D(
+import space.kscience.kmath.domains.DoubleDomain1D
-//    public val borders: Buffer<Double>,
+import space.kscience.kmath.misc.UnstableKMathAPI
-//    public val values: Buffer<Long>,
+import space.kscience.kmath.operations.Group
-//) : Histogram1D<Double, Long> {
+import space.kscience.kmath.operations.Ring
-//}
+import space.kscience.kmath.operations.ScaleOperations
+import space.kscience.kmath.operations.invoke
+import space.kscience.kmath.structures.Buffer
+import kotlin.math.floor
+
+@OptIn(UnstableKMathAPI::class)
+public class UniformHistogram1D<V : Any>(
+    public val group: UniformHistogram1DGroup<V, *>,
+    public val values: Map<Int, V>,
+) : Histogram1D<Double, V> {
+
+    private val startPoint get() = group.startPoint
+    private val binSize get() = group.binSize
+
+    private fun produceBin(index: Int, value: V): Bin1D<Double, V> {
+        val domain = DoubleDomain1D((startPoint + index * binSize)..(startPoint + (index + 1) * binSize))
+        return Bin1D(domain, value)
+    }
+
+    override val bins: Iterable<Bin1D<Double, V>> get() = values.map { produceBin(it.key, it.value) }
+
+    override fun get(value: Double): Bin1D<Double, V>? {
+        val index: Int = group.getIndex(value)
+        val v = values[index]
+        return v?.let { produceBin(index, it) }
+    }
+}
+
+public class UniformHistogram1DGroup<V : Any, A>(
+    public val valueAlgebra: A,
+    public val binSize: Double,
+    public val startPoint: Double = 0.0,
+) : Group<UniformHistogram1D<V>>, ScaleOperations<UniformHistogram1D<V>> where A : Ring<V>, A : ScaleOperations<V> {
+    override val zero: UniformHistogram1D<V> by lazy { UniformHistogram1D(this, emptyMap()) }
+
+    public fun getIndex(at: Double): Int = floor((at - startPoint) / binSize).toInt()
+
+    override fun add(left: UniformHistogram1D<V>, right: UniformHistogram1D<V>): UniformHistogram1D<V> = valueAlgebra {
+        require(left.group == this@UniformHistogram1DGroup)
+        require(right.group == this@UniformHistogram1DGroup)
+        val keys = left.values.keys + right.values.keys
+        UniformHistogram1D(
+            this@UniformHistogram1DGroup,
+            keys.associateWith { (left.values[it] ?: valueAlgebra.zero) + (right.values[it] ?: valueAlgebra.zero) }
+        )
+    }
+
+    override fun UniformHistogram1D<V>.unaryMinus(): UniformHistogram1D<V> = valueAlgebra {
+        UniformHistogram1D(this@UniformHistogram1DGroup, values.mapValues { -it.value })
+    }
+
+    override fun scale(
+        a: UniformHistogram1D<V>,
+        value: Double,
+    ): UniformHistogram1D<V> = UniformHistogram1D(
+        this@UniformHistogram1DGroup,
+        a.values.mapValues { valueAlgebra.scale(it.value, value) }
+    )
+
+    public inline fun produce(block: Histogram1DBuilder<Double, V>.() -> Unit): UniformHistogram1D<V> {
+        val map = HashMap<Int, V>()
+        val builder = object : Histogram1DBuilder<Double, V> {
+            override val defaultValue: V get() = valueAlgebra.zero
+
+            override fun putValue(at: Double, value: V) {
+                val index = getIndex(at)
+                map[index] = with(valueAlgebra) { (map[index] ?: zero) + one }
+            }
+        }
+        builder.block()
+        return UniformHistogram1D(this, map)
+    }
+}
+
+public fun <V : Any, A> Histogram.Companion.uniform1D(
+    algebra: A,
+    binSize: Double,
+    startPoint: Double = 0.0,
+): UniformHistogram1DGroup<V, A> where A : Ring<V>, A : ScaleOperations<V> =
+    UniformHistogram1DGroup(algebra, binSize, startPoint)
+
+@UnstableKMathAPI
+public fun <V : Any> UniformHistogram1DGroup<V, *>.produce(
+    buffer: Buffer<Double>,
+): UniformHistogram1D<V> = produce { fill(buffer) }

kmath-histograms/src/commonTest/kotlin/space/kscience/kmath/histogram/MultivariateHistogramTest.kt

@@ -14,7 +14,7 @@ import kotlin.test.*
 internal class MultivariateHistogramTest {
     @Test
     fun testSinglePutHistogram() {
-        val hSpace = DoubleHistogramSpace.fromRanges(
+        val hSpace = DoubleHistogramGroup.fromRanges(
             (-1.0..1.0),
             (-1.0..1.0)
         )
@@ -29,7 +29,7 @@ internal class MultivariateHistogramTest {
 
     @Test
     fun testSequentialPut() {
-        val hSpace = DoubleHistogramSpace.fromRanges(
+        val hSpace = DoubleHistogramGroup.fromRanges(
             (-1.0..1.0),
             (-1.0..1.0),
             (-1.0..1.0)
@@ -49,7 +49,7 @@ internal class MultivariateHistogramTest {
 
     @Test
     fun testHistogramAlgebra() {
-        DoubleHistogramSpace.fromRanges(
+        DoubleHistogramGroup.fromRanges(
             (-1.0..1.0),
             (-1.0..1.0),
             (-1.0..1.0)

kmath-histograms/src/commonTest/kotlin/space/kscience/kmath/histogram/UniformHistogram1DTest.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2018-2021 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.histogram
+
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.test.runTest
+import space.kscience.kmath.distributions.NormalDistribution
+import space.kscience.kmath.misc.UnstableKMathAPI
+import space.kscience.kmath.operations.DoubleField
+import space.kscience.kmath.stat.RandomGenerator
+import space.kscience.kmath.stat.nextBuffer
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+@OptIn(ExperimentalCoroutinesApi::class, UnstableKMathAPI::class)
+internal class UniformHistogram1DTest {
+    @Test
+    fun normal() = runTest {
+        val generator = RandomGenerator.default(123)
+        val distribution = NormalDistribution(0.0, 1.0)
+        with(Histogram.uniform1D(DoubleField, 0.1)) {
+            val h1 = produce(distribution.nextBuffer(generator, 10000))
+
+            val h2 = produce(distribution.nextBuffer(generator, 50000))
+
+            val h3 = h1 + h2
+
+            assertEquals(60000, h3.bins.sumOf { it.binValue }.toInt())
+        }
+    }
+}

kmath-stat/src/commonMain/kotlin/space/kscience/kmath/distributions/Distribution.kt

@@ -27,7 +27,7 @@ public interface Distribution<T : Any> : Sampler<T> {
     public companion object
 }
 
-public interface UnivariateDistribution<T : Comparable<T>> : Distribution<T> {
+public interface Distribution1D<T : Comparable<T>> : Distribution<T> {
     /**
      * Cumulative distribution for ordered parameter (CDF)
      */
@@ -37,7 +37,7 @@ public interface UnivariateDistribution<T : Comparable<T>> : Distribution<T> {
 /**
  * Compute probability integral in an interval
  */
-public fun <T : Comparable<T>> UnivariateDistribution<T>.integral(from: T, to: T): Double {
+public fun <T : Comparable<T>> Distribution1D<T>.integral(from: T, to: T): Double {
     require(to > from)
     return cumulative(to) - cumulative(from)
 }

kmath-stat/src/commonMain/kotlin/space/kscience/kmath/distributions/NormalDistribution.kt

@@ -14,14 +14,9 @@ import space.kscience.kmath.stat.RandomGenerator
 import kotlin.math.*
 
 /**
- * Implements [UnivariateDistribution] for the normal (gaussian) distribution.
+ * Implements [Distribution1D] for the normal (gaussian) distribution.
  */
-public class NormalDistribution(public val sampler: GaussianSampler) : UnivariateDistribution<Double> {
+public class NormalDistribution(public val sampler: GaussianSampler) : Distribution1D<Double> {
-    public constructor(
-        mean: Double,
-        standardDeviation: Double,
-        normalized: NormalizedGaussianSampler = ZigguratNormalizedGaussianSampler,
-    ) : this(GaussianSampler(mean, standardDeviation, normalized))
 
     override fun probability(arg: Double): Double {
         val x1 = (arg - sampler.mean) / sampler.standardDeviation
@@ -43,3 +38,9 @@ public class NormalDistribution(public val sampler: GaussianSampler) : Univariat
         private val SQRT2 = sqrt(2.0)
     }
 }
+
+public fun NormalDistribution(
+    mean: Double,
+    standardDeviation: Double,
+    normalized: NormalizedGaussianSampler = ZigguratNormalizedGaussianSampler,
+): NormalDistribution = NormalDistribution(GaussianSampler(mean, standardDeviation, normalized))

kmath-stat/src/commonMain/kotlin/space/kscience/kmath/stat/Sampler.kt

@@ -67,3 +67,12 @@ public fun Sampler<Double>.sampleBuffer(generator: RandomGenerator, size: Int):
 @JvmName("sampleIntBuffer")
 public fun Sampler<Int>.sampleBuffer(generator: RandomGenerator, size: Int): Chain<Buffer<Int>> =
     sampleBuffer(generator, size, ::IntBuffer)
+
+
+/**
+ * Samples a [Buffer] of values from this [Sampler].
+ */
+public suspend fun Sampler<Double>.nextBuffer(generator: RandomGenerator, size: Int): Buffer<Double> =
+    sampleBuffer(generator, size).first()
+
+//TODO add `context(RandomGenerator) Sampler.nextBuffer

kmath-stat/src/commonMain/kotlin/space/kscience/kmath/stat/UniformDistribution.kt

@@ -8,9 +8,9 @@ package space.kscience.kmath.stat
 import space.kscience.kmath.chains.Chain
 import space.kscience.kmath.chains.SimpleChain
 import space.kscience.kmath.distributions.Distribution
-import space.kscience.kmath.distributions.UnivariateDistribution
+import space.kscience.kmath.distributions.Distribution1D
 
-public class UniformDistribution(public val range: ClosedFloatingPointRange<Double>) : UnivariateDistribution<Double> {
+public class UniformDistribution(public val range: ClosedFloatingPointRange<Double>) : Distribution1D<Double> {
     private val length: Double = range.endInclusive - range.start
 
     override fun probability(arg: Double): Double = if (arg in range) 1.0 / length else 0.0