init research

dataframe/plugins/kotlin-dataframe/testData/box/convertAsColumn.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.*
+
+fun box(): String {
+    val res = dataFrameOf("a")(1, 2, 3).convert { a }.asColumn { it.convertToString() }
+    val str: DataColumn<String> = res.a
+
+    val res1 = dataFrameOf("a")(1).convert { a }.asColumn { dataFrameOf("b", "c")(2, 3.0).asColumnGroup() }
+    val i: DataColumn<Int> = res1.a.b
+    val d: DataColumn<Double> = res1.a.c
+    return "OK"
+}