Creates List, DataFrame or DataColumn with values computed from rows of original DataFrame.
Related operations: Add / map / remove columns
Map into List:
map { rowExpression }: List<T> rowExpression: DataRow.(DataRow) -> Value
df.map { 2021 - it.age }
Map into DataColumn:
mapToColumn(columnName) { rowExpression }: DataColumn rowExpression: DataRow.(DataRow) -> Value
df.mapToColumn("year of birth") { 2021 - age }
df.mapToColumn("year of birth") { 2021 - "age"<Int>() }
See row expressions
Map into DataFrame:
mapToFrame { columnMapping columnMapping ... } : DataFrame columnMapping = column into columnName | columnName from column | columnName from { rowExpression } | +column
df.mapToFrame { "year of birth" from { 2021 - age } expr { age > 18 } into "is adult" name.lastName.map { it.length } into "last name length" "full name" from { name.firstName + " " + name.lastName } +city }
df.mapToFrame { "year of birth" from { 2021 - "age"<Int>() } expr { "age"<Int>() > 18 } into "is adult" "name"["lastName"]<String>().map { it.length } into "last name length" "full name" from { "name"["firstName"]<String>() + " " + "name"["lastName"]<String>() } +"city" }
10 March 2026