core/org.jetbrains.kotlinx.dataframe.impl.aggregation.aggregators/AggregatorMultipleColumnsHandler

AggregatorMultipleColumnsHandler

interface AggregatorMultipleColumnsHandler<in Value : Any, out Return> : AggregatorHandler<Value, Return>

The multiple columns handler, which specifies how to aggregate multiple columns into a single value by using the supplied AggregatorAggregationHandler. It can also calculate the return type of the aggregation given all input column types.

Inheritors

Aggregator

FlatteningMultipleColumnsHandler

NoMultipleColumnsHandler

TwoStepMultipleColumnsHandler

Properties

aggregator

abstract var aggregator: Aggregator<Value, Return>?

Reference to the aggregator instance.

Functions

aggregateMultipleColumns

abstract fun aggregateMultipleColumns(columns: Sequence<DataColumn<Value?>>): Return

Aggregates the data in the multiple given columns and computes a single resulting value. Calls Aggregator.aggregateSequence or Aggregator.aggregateSingleColumn.

calculateReturnTypeMultipleColumns

abstract fun calculateReturnTypeMultipleColumns(colTypes: Set<KType>, colsEmpty: Boolean): KType

Function that can give the return type of aggregateMultipleColumns, given types of the columns. This allows aggregators to avoid runtime type calculations.

init

open fun init(aggregator: Aggregator<Value, Return>)