Dataframe 0.14 Help

KProperties API

DataFrame can be used as an intermediate structure for data transformation between two data formats. If either source or destination is a Kotlin object, e.g. data class, it is convenient to use its properties for typed data access in DataFrame. This can be done using :: expression that provides property references

data class Passenger( val survived: Boolean, val home: String, val age: Int, val lastName: String ) val passengers = DataFrame.read("titanic.csv") .add(Passenger::lastName) { "name"<String>().split(",").last() } .dropNulls(Passenger::age) .filter { it[Passenger::survived] && it[Passenger::home].endsWith("NY") && it[Passenger::age] in 10..20 } .toListOf<Passenger>()

By default, DataFrame uses name and returnType of KProperty for typed access to data. When column name differs from property name, use @ColumnName annotation:

data class Passenger( @ColumnName("survived") val isAlive: Boolean, @ColumnName("home") val city: String, val name: String ) val passengers = DataFrame.read("titanic.csv") .filter { it[Passenger::city].endsWith("NY") } .toListOf<Passenger>()

The titanic.csv file could be found here.

Last modified: 27 September 2024