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 containing dataframepath: ColumnPath
— path to the column; depends on the way column was retrieved from dataframetype: KType
— type of elements in the columnhasNulls: Boolean
— flag indicating whether column containsnull
valuesvalues: Iterable<T>
— column datasize: Int
— number of elements in the column
Column kinds
DataColumn
instances can be one of three subtypes: ValueColumn
, ColumnGroup
or FrameColumn
ValueColumn
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.
ColumnGroup
Container for nested columns. Is used to create column hierarchy.
FrameColumn
Special case of ValueColumn
that stores another 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.