add

Create a new column and add it to DataFrame

add(columnName: String) { rowExpression }

rowExpression: DataRow.(DataRow) -> Value

df.add("year of birth") { 2021 - age }

val age by column<Int>()
val yearOfBirth by column<Int>("year of birth")

df.add(yearOfBirth) { 2021 - age }

df.add("year of birth") { 2021 - "age"<Int>() }

You can use the newValue() function to access value that was already calculated for the preceding row. It is helpful for recurrent computations:

df.add("fibonacci") {
    if (index() < 2) 1
    else prev()!!.newValue<Int>() + prev()!!.prev()!!.newValue<Int>()
}

Create and add several columns to DataFrame

add {
    columnMapping
    columnMapping
    ...
}

columnMapping = column into columnName
    | columnName from column
    | columnName from { rowExpression }
    | columnGroupName {
        columnMapping
        columnMapping
        ...
    }

df.add {
    "year of birth" from 2021 - age
    age gt 18 into "is adult"
    "details" {
        name.lastName.length() into "last name length"
        "full name" from { name.firstName + " " + name.lastName }
    }
}

val yob = column<Int>("year of birth")
val lastNameLength = column<Int>("last name length")
val age by column<Int>()
val isAdult = column<Boolean>("is adult")
val fullName = column<String>("full name")
val name by columnGroup()
val details by columnGroup()
val firstName by name.column<String>()
val lastName by name.column<String>()

df.add {
    yob from 2021 - age
    age gt 18 into isAdult
    details from {
        lastName.length() into lastNameLength
        fullName from { firstName() + " " + lastName() }
    }
}

df.add {
    "year of birth" from 2021 - "age"<Int>()
    "age"<Int>() gt 18 into "is adult"
    "details" {
        "name"["lastName"]<String>().length() into "last name length"
        "full name" from { "name"["firstName"]<String>() + " " + "name"["lastName"]<String>() }
    }
}

Create columns using intermediate result

class CityInfo(val city: String?, val population: Int, val location: String)

fun queryCityInfo(city: String?): CityInfo = CityInfo(city, city?.length ?: 0, "35.5 32.2")

val personWithCityInfo = df.add {
    val cityInfo = city.map { queryCityInfo(it) }
    "cityInfo" {
        cityInfo.map { it.location } into CityInfo::location
        cityInfo.map { it.population } into "population"
    }
}

val city by column<String?>()
val personWithCityInfo = df.add {
    val cityInfo = city().map { queryCityInfo(it) }
    "cityInfo" {
        cityInfo.map { it.location } into CityInfo::location
        cityInfo.map { it.population } into "population"
    }
}

val personWithCityInfo = df.add {
    val cityInfo = "city"<String?>().map { queryCityInfo(it) }
    "cityInfo" {
        cityInfo.map { it.location } into CityInfo::location
        cityInfo.map { it.population } into "population"
    }
}

Add existing column to DataFrame

val score by columnOf(4, 3, 5, 2, 1, 3, 5)

df.add(score)
df + score

Add all columns from another DataFrame

df.add(df1, df2)

addId

addId(name: String = "id")

add﻿

Create a new column and add it to DataFrame﻿

Create and add several columns to DataFrame﻿

Create columns using intermediate result﻿

Add existing column to DataFrame﻿

Add all columns from another DataFrame﻿

addId﻿

Create a new column and add it to DataFrame

Create and add several columns to DataFrame

Create columns using intermediate result

Add existing column to DataFrame

Add all columns from another DataFrame

addId