Add kdoc for Split.match and test for Split.inplace

Author: koperagen

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

@@ -126,10 +126,18 @@ internal inline fun <T, C, R> Split<T, C>.by(
 
 // region match
 
+/**
+ * Creates new String columns according to MatchResult [capturing groups](https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.text/-match-result/group-values.html)
+ * Created columns will be nullable if [regex] doesn't match some rows or there are nulls in original column
+ * Check [Split.by] overload with regex parameter if you're looking to split String value by [Regex] delimiter
+ */
 public fun <T, C : String?> Split<T, C>.match(
     @Language("RegExp") regex: String,
 ): SplitWithTransform<T, C, String?> = match(regex.toRegex())
 
+/**
+ * @include [match]
+ */
 public fun <T, C : String?> Split<T, C>.match(regex: Regex): SplitWithTransform<T, C, String?> =
     by {
         it?.let {

core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/testSets/person/DataFrameTests.kt

@@ -2184,6 +2184,14 @@ class DataFrameTests : BaseTest() {
         split["name"] shouldBe typed.name.map { it.toCharArray().toList() }
     }
 
+    @Test
+    fun `split iterable inplace`() {
+        val df = dataFrameOf("a" to listOf(listOf(1), null)).split { "a"<List<Int>?>() }.inplace()
+
+        df["a"].type() shouldBe typeOf<List<Int>>()
+        df["a"].values() shouldBe listOf(listOf(1), emptyList())
+    }
+
     @Test
     fun `split into rows with transform`() {
         val split = typed.split { city }.by { it.toCharArray().toList() }.intoRows()