init research

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

@@ -0,0 +1,15 @@
+import org.jetbrains.kotlinx.dataframe.*
+import org.jetbrains.kotlinx.dataframe.annotations.*
+import org.jetbrains.kotlinx.dataframe.api.*
+import org.jetbrains.kotlinx.dataframe.io.*
+
+fun box(): String {
+    val df = dataFrameOf("i", "group")(1, dataFrameOf("a", "b")(111, 222))
+    val aggregated1 = df.asGroupBy { group }.aggregate { maxOf { a } into "max" }
+    val aggregated2 = df.asGroupBy().aggregate { maxOf { a } into "max" }
+
+    val i: Int = aggregated1.max[0]
+
+    compareSchemas(aggregated1, aggregated2)
+    return "OK"
+}