rollback of changes to mean

Author: Jolanrensen

core/api/core.api

@@ -25,7 +25,7 @@ public interface ColumnDescription {
     public val nulls: Int
     public val top: Any
     public val freq: Int
-    public val mean: Number?
+    public val mean: Double
     public val std: Double
     public val min: Any
     public val p25: Any

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/describe.kt

@@ -1,22 +1,7 @@
 package org.jetbrains.kotlinx.dataframe.impl
 
-import java.math.BigDecimal
-import java.math.BigInteger
-
 internal fun <T> T?.throwIfNull(message: String): T = this ?: throw NoSuchElementException(message)
 
 @PublishedApi
 internal fun <T> T?.suggestIfNull(operation: String): T =
     throwIfNull("No elements for `$operation` operation. Use `${operation}OrNull` instead.")
-
-@PublishedApi
-internal fun BigInteger?.suggestIfNull(operation: String): BigInteger =
-    throwIfNull(
-        "The `$operation` operation either had no elements, or the result is NaN. Use `${operation}OrNull` instead.",
-    )
-
-@PublishedApi
-internal fun BigDecimal?.suggestIfNull(operation: String): BigDecimal =
-    throwIfNull(
-        "The `$operation` operation either had no elements, or the result is NaN. Use `${operation}OrNull` instead.",
-    )

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/api/mean.kt

@@ -643,13 +643,3 @@ internal fun Iterable<Any>.classes(): Set<KClass<*>> = mapTo(mutableSetOf()) { i
  * @return A set of [KType] objects corresponding to the star-projected runtime types of elements in the iterable.
  */
 internal fun Iterable<Any>.types(): Set<KType> = classes().mapTo(mutableSetOf()) { it.createStarProjectedType(false) }
-
-/**
- * Casts [this]: [Number] to a [Double]. If [this] is `null`, returns [Double.NaN].
- */
-internal fun Number?.asDoubleOrNaN(): Double = this as Double? ?: Double.NaN
-
-/**
- * Casts [this]: [Number] to a [Float]. If [this] is `null`, returns [Float.NaN].
- */
-internal fun Number?.asFloatOrNaN(): Float = this as Float? ?: Float.NaN

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/ExceptionUtils.kt

@@ -19,7 +19,7 @@ import kotlin.reflect.full.withNullability
  *   will always return a [Return]`?`.
  */
 @PublishedApi
-internal interface Aggregator<Value, Return> {
+internal interface Aggregator<in Value, out Return> {
 
     /** The name of this aggregator. */
     val name: String

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/TypeUtils.kt

@@ -16,7 +16,7 @@ import kotlin.reflect.full.withNullability
  * @param name The name of this aggregator.
  * @param aggregator Functional argument for the [aggregate] function.
  */
-internal abstract class AggregatorBase<Value, Return>(
+internal abstract class AggregatorBase<in Value, out Return>(
     override val name: String,
     protected val getReturnTypeOrNull: (type: KType, emptyInput: Boolean) -> KType?,
     protected val aggregator: (values: Iterable<Value>, type: KType) -> Return?,

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/aggregation/aggregators/Aggregator.kt

@@ -7,7 +7,7 @@ package org.jetbrains.kotlinx.dataframe.impl.aggregation.aggregators
  * @see AggregatorOptionSwitch2
  */
 @PublishedApi
-internal class AggregatorOptionSwitch1<Param1, AggregatorType : Aggregator<*, *>>(
+internal class AggregatorOptionSwitch1<in Param1, out AggregatorType : Aggregator<*, *>>(
     val name: String,
     val getAggregator: (param1: Param1) -> AggregatorProvider<AggregatorType>,
 ) {
@@ -28,7 +28,7 @@ internal class AggregatorOptionSwitch1<Param1, AggregatorType : Aggregator<*, *>
      *   MyAggregator.Factory(param1)
      * }
      */
-    class Factory<Param1, AggregatorType : Aggregator<*, *>>(
+    class Factory<in Param1, out AggregatorType : Aggregator<*, *>>(
         val getAggregator: (Param1) -> AggregatorProvider<AggregatorType>,
     ) : Provider<AggregatorOptionSwitch1<Param1, AggregatorType>> by Provider({ name ->
             AggregatorOptionSwitch1(name, getAggregator)
@@ -42,7 +42,7 @@ internal class AggregatorOptionSwitch1<Param1, AggregatorType : Aggregator<*, *>
  * @see AggregatorOptionSwitch1
  */
 @PublishedApi
-internal class AggregatorOptionSwitch2<Param1, Param2, AggregatorType : Aggregator<*, *>>(
+internal class AggregatorOptionSwitch2<in Param1, in Param2, out AggregatorType : Aggregator<*, *>>(
     val name: String,
     val getAggregator: (param1: Param1, param2: Param2) -> AggregatorProvider<AggregatorType>,
 ) {
@@ -64,7 +64,7 @@ internal class AggregatorOptionSwitch2<Param1, Param2, AggregatorType : Aggregat
      * }
      * ```
      */
-    class Factory<Param1, Param2, AggregatorType : Aggregator<*, *>>(
+    class Factory<in Param1, in Param2, out AggregatorType : Aggregator<*, *>>(
         val getAggregator: (Param1, Param2) -> AggregatorProvider<AggregatorType>,
     ) : Provider<AggregatorOptionSwitch2<Param1, Param2, AggregatorType>> by Provider({ name ->
             AggregatorOptionSwitch2(name, getAggregator)

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/aggregation/aggregators/AggregatorBase.kt

@@ -10,7 +10,7 @@ import kotlin.reflect.KProperty
  * val myNamedValue by MyFactory
  * ```
  */
-internal fun interface Provider<T> {
+internal fun interface Provider<out T> {
 
     fun create(name: String): T
 }
@@ -25,4 +25,4 @@ internal operator fun <T> Provider<T>.getValue(obj: Any?, property: KProperty<*>
  * val myAggregator by MyAggregator.Factory
  * ```
  */
-internal fun interface AggregatorProvider<AggregatorType : Aggregator<*, *>> : Provider<AggregatorType>
+internal fun interface AggregatorProvider<out AggregatorType : Aggregator<*, *>> : Provider<AggregatorType>

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/aggregation/aggregators/AggregatorOptionSwitch.kt

@@ -1,12 +1,10 @@
 package org.jetbrains.kotlinx.dataframe.impl.aggregation.aggregators
 
-import org.jetbrains.kotlinx.dataframe.math.meanOrNull
-import org.jetbrains.kotlinx.dataframe.math.meanTypeResultOrNull
+import org.jetbrains.kotlinx.dataframe.math.mean
 import org.jetbrains.kotlinx.dataframe.math.median
 import org.jetbrains.kotlinx.dataframe.math.percentile
 import org.jetbrains.kotlinx.dataframe.math.std
 import org.jetbrains.kotlinx.dataframe.math.sum
-import java.math.BigDecimal
 import kotlin.reflect.KType
 import kotlin.reflect.full.withNullability
 import kotlin.reflect.typeOf
@@ -92,43 +90,51 @@ internal object Aggregators {
         getAggregator: (Param1, Param2) -> AggregatorProvider<AggregatorType>,
     ) = AggregatorOptionSwitch2.Factory(getAggregator)
 
-    val min by twoStepPreservingType<Comparable<Any?>> { minOrNull() }
+    // T: Comparable<T> -> T?
+    val min by twoStepPreservingType<Comparable<Any?>> {
+        minOrNull()
+    }
 
-    val max by twoStepPreservingType<Comparable<Any?>> { maxOrNull() }
+    // T: Comparable<T> -> T?
+    val max by twoStepPreservingType<Comparable<Any?>> {
+        maxOrNull()
+    }
 
+    // T: Number? -> Double
     val std by withTwoOptions { skipNA: Boolean, ddof: Int ->
         flatteningChangingTypes<Number, Double>(
-            getReturnTypeOrNull = { type, emptyInput -> typeOf<Double>().withNullability(emptyInput) },
-        ) { std(it, skipNA, ddof) }
+            getReturnTypeOrNull = { _, emptyInput -> typeOf<Double>().withNullability(emptyInput) },
+        ) { type ->
+            std(type, skipNA, ddof)
+        }
     }
 
-    @Suppress("ClassName")
-    object mean {
-        val toNumber = withOneOption { skipNA: Boolean ->
-            twoStepForNumbers(::meanTypeResultOrNull) { meanOrNull(it, skipNA) }
-        }.create(mean::class.simpleName!!)
-
-        val toDouble = withOneOption { skipNA: Boolean ->
-            twoStepForNumbers(::meanTypeResultOrNull) { meanOrNull(it, skipNA) as Double? }
-        }.create(mean::class.simpleName!!)
-
-        val toBigDecimal =
-            twoStepForNumbers(::meanTypeResultOrNull) {
-                meanOrNull(it) as BigDecimal?
-            }.create(mean::class.simpleName!!)
+    // step one: T: Number? -> Double
+    // step two: Double -> Double
+    val mean by withOneOption { skipNA: Boolean ->
+        twoStepChangingType(
+            getReturnTypeOrNull = { _, _ -> typeOf<Double>() },
+            stepOneAggregator = { type -> mean(type, skipNA) },
+            stepTwoAggregator = { mean(skipNA) },
+        )
     }
 
+    // T: Comparable<T>? -> T
     val percentile by withOneOption { percentile: Double ->
-        flatteningChangingTypes<Comparable<Any?>, Comparable<Any?>>(preserveReturnTypeNullIfEmpty) { type ->
+        flatteningPreservingTypes<Comparable<Any?>> { type ->
             percentile(percentile, type)
         }
     }
 
-    val median by flatteningPreservingTypes<Comparable<Any?>> {
-        median(it)
+    // T: Comparable<T>? -> T
+    val median by flatteningPreservingTypes<Comparable<Any?>> { type ->
+        median(type)
     }
 
+    // T: Number -> T
     val sum by twoStepForNumbers(
         getReturnTypeOrNull = { type, _ -> type.withNullability(false) },
-    ) { sum(it) }
+    ) { type ->
+        sum(type)
+    }
 }