explode fixes

Author: AndreiKingsley

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

@@ -25,13 +25,13 @@ private val defaultExplodeColumns: ColumnsSelector<*, *> = {
 
 /**
  * Splits list-like values in the specified [\columns] and spreads them vertically —
- * that is, adds a separate row for each element (one value per row).
+ * that is, it adds a separate row for each element (one value per row).
  * Values in all other columns are duplicated to preserve row context.
  *
  * If no [\columns] are specified, all columns (at any depth) containing
  * [List] or [DataFrame] values will be exploded.
  *
- * If [dropEmpty] is `true`, rows with empty lists or DataFrames will be removed.
+ * If [dropEmpty] is `true`, rows with empty lists or [DataFrame]s will be removed.
  * If `false`, such rows will be exploded into `null` values.
  *
  * Returns a new [DataFrame] with exploded columns.
@@ -117,7 +117,7 @@ public fun <T, C> DataFrame<T>.explode(vararg columns: KProperty<C>, dropEmpty:
 
 /**
  * Splits list-like values in the specified [\columns] of this [DataRow] and spreads them vertically —
- * that is, adds a separate row for each element (one value per row)
+ * that is, it adds a separate row for each element (one value per row)
  * and combine them into new [DataFrame].
  * Values in all other columns are duplicated to preserve row context.
  *
@@ -201,7 +201,7 @@ public fun <T, C> DataRow<T>.explode(vararg columns: KProperty<C>, dropEmpty: Bo
 
 /**
  * Splits list-like values in this [DataColumn] and spreads them vertically —
- * that is, adds a separate row for each element (one value per row).
+ * that is, it adds a separate row for each element (one value per row).
  *
  * Returns a new [DataColumn] with the exploded values.
  * The resulting column will have a new type (`List<T>` → `T`).

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

@@ -259,6 +259,8 @@ public fun <T, C, K, R> Gather<T, C?, K, R>.notNull(): Gather<T, C, K, R> = wher
  *   .mapValues { (it + 0.5).toFloat() }
  *   .into("series", "value")
  * ```
+ *
+ * @see [explode]
  * @return A new [Gather] instance with exploded list values.
  */
 @Interpretable("GatherExplodeLists")
@@ -296,6 +298,8 @@ public fun <T, C, K, R> Gather<T, C, K, R>.explodeLists(): Gather<T, C, K, R> =
  *   .mapValues { (it + 0.5).toFloat() }
  *   .into("series", "value")
  * ```
+ *
+ * @see [explode]
  * @return A new [Gather] instance with exploded list values.
  */
 @JvmName("explodeListsTyped")

plugins/kotlin-dataframe/src/org/jetbrains/kotlinx/dataframe/plugin/impl/api/explode.kt

@@ -16,11 +16,11 @@ import org.jetbrains.kotlinx.dataframe.plugin.impl.simpleColumnOf
 internal class Explode0 : AbstractInterpreter<PluginDataFrameSchema>() {
     val Arguments.dropEmpty: Boolean by arg(defaultValue = Present(true))
     val Arguments.receiver: PluginDataFrameSchema by dataFrame()
-    val Arguments.selector: ColumnsResolver? by arg(defaultValue = Present(null))
+    val Arguments.columns: ColumnsResolver? by arg(defaultValue = Present(null))
     override val Arguments.startingSchema get() = receiver
 
     override fun Arguments.interpret(): PluginDataFrameSchema {
-        val columns = selector ?: object : ColumnsResolver {
+        val columns = columns ?: object : ColumnsResolver {
             override fun resolve(df: PluginDataFrameSchema): List<ColumnWithPathApproximation> {
                 return df.flatten(includeFrames = false).filter {
                     val column = it.column