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

AggregatorAggregationHandler

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

The base functionality of the aggregator, which defines how the aggregation of a single Sequence or column is done. It also provides information on which return type will be given, as KType, given a value type. It can also provide the index of the result in the input values if it is a selecting aggregator.

Inheritors

Aggregator

HybridAggregationHandler

ReducingAggregationHandler

SelectingAggregationHandler

Properties

aggregator

abstract var aggregator: Aggregator<Value, Return>?

Reference to the aggregator instance.

Functions

aggregateSequence

abstract fun aggregateSequence(values: Sequence<Value?>, valueType: ValueType): Return

Base function of Aggregator.

aggregateSingleColumn

open fun aggregateSingleColumn(column: DataColumn<Value?>): Return

Aggregates the data in the given column and computes a single resulting value. Calls aggregateSequence. It tries to exploit a cache for statistics which can be accessed by ValueColumnInternal

calculateReturnType

abstract fun calculateReturnType(valueType: KType, emptyInput: Boolean): KType

Function that can give the return type of aggregateSequence as KType, given the type of the input. This allows aggregators to avoid runtime type calculations.

indexOfAggregationResultSingleSequence

abstract fun indexOfAggregationResultSingleSequence(values: Sequence<Value?>, valueType: ValueType): Int

Function that can give the index of the aggregation result in the input values, if it applies. This is used for AggregatorAggregationHandlers where Value== Return, and where the result exists in the input.

init

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