init research

dataframe/plugins/kotlin-dataframe/testData/box/selectionDsl.kt

@@ -0,0 +1,17 @@
+import org.jetbrains.kotlinx.dataframe.*
+import org.jetbrains.kotlinx.dataframe.annotations.*
+import org.jetbrains.kotlinx.dataframe.api.*
+import org.jetbrains.kotlinx.dataframe.io.*
+
+data class Nested(val d: List<Double>)
+
+data class Record(val a: String, val b: Int, val nested: List<Nested>)
+
+fun box(): String {
+    val df = listOf(Record("112", 42, listOf(Nested(listOf(3.0))))).toDataFrame(maxDepth = 1)
+
+    df.group { nested }.into("group").convert { colsAtAnyDepth().frameCols() }.with { 1 }.compareSchemas()
+    df.group { b }.into("group").convert { colsAtAnyDepth().colsOf<Int>() }.with { "" }.compareSchemas()
+    df.convert { all().frameCols() }.with { 1 }.compareSchemas()
+    return "OK"
+}