init research

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

@@ -0,0 +1,14 @@
+import org.jetbrains.kotlinx.dataframe.*
+import org.jetbrains.kotlinx.dataframe.annotations.*
+import org.jetbrains.kotlinx.dataframe.api.*
+import org.jetbrains.kotlinx.dataframe.io.*
+
+@DataSchema
+data class Record(val a: String, val b: Int)
+
+fun box(): String {
+    val df = List(10) { Record(it.toString(), it) }.let { dataFrameOf(*it.toTypedArray()) }
+    val df1 = df.groupBy { b }.aggregate { sumFor { b } into "sum" }
+    df1.sum.b
+    return "OK"
+}