DataColumn

DataColumn represents a column of values. It can store objects of primitive or reference types, or other DataFrame objects.

Properties

name: String — name of the column; should be unique within the containing dataframe
path: ColumnPath — path to the column; depends on the way the column was retrieved from the dataframe
type: KType — type of elements in the column
hasNulls: Boolean — flag indicating whether the column contains null values
values: Iterable<T> — column data
size: Int — number of elements in the column

DataColumn instances can be one of three subtypes: ValueColumn, ColumnGroup or FrameColumn

Represents a sequence of values.

It can store values of primitive (integers, strings, decimals, etc.) or reference types. Currently, it uses List as underlying data storage.

Container for nested columns. Used to create column hierarchy.

You can create column groups using the group operation or by splitting inward — see group and split for details.

Special case of ValueColumn that stores other DataFrame objects as elements.

DataFrame stored in FrameColumn may have different schemas.

FrameColumn may appear after reading from JSON or other hierarchical data structures, or after grouping operations such as groupBy or pivot.

30 October 2026