add

Returns DataFrame which contains all columns from original DataFrame followed by newly added columns. Original DataFrame is not modified.

add appends columns to the end of the dataframe by default. If you want to add a single column to a specific position in the dataframe, use insert.

Create a new column and add it to `DataFrame`

add(columnName: String) { rowExpression }

rowExpression: DataRow.(DataRow) -> Value

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

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

See row expressions

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 }
    }
}

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

Consider this API:

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")

Use the following approach to add multiple columns by calling the given API only once per row:

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

Adds a column with sequential values 0, 1, 2,... The new column will be added in the beginning of the column list and will become the first column in DataFrame.

addId(name: String = "id")

Parameters:

name: String = "id" - name of the new column.

20 May 2025

add

Create a new column and add it to DataFrame

Create and add several columns to DataFrame