org.apache.flink.api.java.summarize.aggregation

Class NumericSummaryAggregator<T extends Number>

java.lang.Object

org.apache.flink.api.java.summarize.aggregation.NumericSummaryAggregator<T>

Type Parameters:

T - numeric type to aggregrate and create a summary, e.g. Integer, DoubleValue

All Implemented Interfaces:

Serializable, Aggregator<T,NumericColumnSummary<T>>

Direct Known Subclasses:

DoubleSummaryAggregator, FloatSummaryAggregator, IntegerSummaryAggregator, LongSummaryAggregator, ShortSummaryAggregator

@Internal
public abstract class NumericSummaryAggregator<T extends Number>
extends Object
implements Aggregator<T,NumericColumnSummary<T>>

Generic aggregator for all numeric types creates a summary of a column of numbers.

Uses the Kahan summation algorithm to avoid numeric instability when computing variance. The algorithm is described in: "Scalable and Numerically Stable Descriptive Statistics in SystemML", Tian et al, International Conference on Data Engineering 2012

Implementation that couldn't be generic for all numbers was pushed to subclasses. For example, there isn't a generic way to calculate min, max, sum, isNan, isInfinite for all numeric types so subclasses must implement these.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
NumericSummaryAggregator()

Method Summary

Modifier and Type	Method and Description
void	aggregate(T value) Add a value to the current aggregation.
void	combine(Aggregator<T,NumericColumnSummary<T>> otherSameType) combine two aggregations.
protected abstract Aggregator<T,T>	initMax()
protected abstract Aggregator<T,T>	initMin()
protected abstract Aggregator<T,T>	initSum()
protected abstract boolean	isInfinite(T number)
protected abstract boolean	isNan(T number)
NumericColumnSummary<T>	result() Provide the final result of the aggregation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NumericSummaryAggregator

public NumericSummaryAggregator()

Method Detail

aggregate

public void aggregate(T value)

Add a value to the current aggregation.

Specified by:

aggregate in interface Aggregator<T extends Number,NumericColumnSummary<T extends Number>>

combine

public void combine(Aggregator<T,NumericColumnSummary<T>> otherSameType)

combine two aggregations.

Specified by:

combine in interface Aggregator<T extends Number,NumericColumnSummary<T extends Number>>

result

public NumericColumnSummary<T> result()

Description copied from interface: Aggregator

Provide the final result of the aggregation.

Specified by:

result in interface Aggregator<T extends Number,NumericColumnSummary<T extends Number>>

initMin

protected abstract Aggregator<T,T> initMin()

initMax

protected abstract Aggregator<T,T> initMax()

initSum

protected abstract Aggregator<T,T> initSum()

isNan

protected abstract boolean isNan(T number)

isInfinite

protected abstract boolean isInfinite(T number)