Anatoly Nikitin

Actually, there is non-documented API for that. I haven't found a good name for that, so it's currently called `read`: ``` data class City(val name:String, val code:Int) data class Person(val...

And also `List` -> `DataFrame` conversion is called `toDataFrame` instead of `asDataFrame`, because in Kotlin Stdlib `as` means wrapping and `to` means copying: `asSequence`, but `toList`.

Currently column selectors in all `DataFrame` operations don't allow to select columns of a particular `DataFrame` stored in `FrameColumn`. Only `ColumnGroup`s can be traversed. For some operations (e.g. `select` or...