fun DataFrame.unite(colName: String, which: List<String>, sep: String = "_", remove: Boolean = true): DataFrame
Convenience function to paste together multiple columns into one.
colName - Name of the column to add
sep - Separator to use between values.
remove - If TRUE, remove input columns from output data frame.
fun DataFrame.unite(colName: String, vararg which: ColNames.() -> List<Boolean?>, sep: String = "_", remove: Boolean = true): DataFrame