DoubleValueSum (Hadoop 1.2.1 API) (original) (raw)

org.apache.hadoop.mapred.lib.aggregate

Class DoubleValueSum

java.lang.Object extended by org.apache.hadoop.mapred.lib.aggregate.DoubleValueSum

All Implemented Interfaces:

ValueAggregator

public class DoubleValueSum

extends Object

implements ValueAggregator

This class implements a value aggregator that sums up a sequence of double values.

Constructor Summary
DoubleValueSum() The default constructor

Method Summary
void	addNextValue(double val) add a value to the aggregator
void	addNextValue(Object val) add a value to the aggregator
ArrayList<String>	getCombinerOutput()
String	getReport()
double	getSum()
void	reset() reset the aggregator

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DoubleValueSum

public DoubleValueSum()

The default constructor

Method Detail

addNextValue

public void addNextValue(Object val)

add a value to the aggregator

Specified by:

[addNextValue](../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregator.html#addNextValue%28java.lang.Object%29) in interface [ValueAggregator](../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregator.html "interface in org.apache.hadoop.mapred.lib.aggregate")

Parameters:

val - an object whose string representation represents a double value.

addNextValue

public void addNextValue(double val)

add a value to the aggregator

Parameters:

val - a double value.

getReport

public String getReport()

Specified by:

[getReport](../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregator.html#getReport%28%29) in interface [ValueAggregator](../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregator.html "interface in org.apache.hadoop.mapred.lib.aggregate")

Returns:

the string representation of the aggregated value

getSum

public double getSum()

Returns:

the aggregated value

reset

public void reset()

reset the aggregator

Specified by:

[reset](../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregator.html#reset%28%29) in interface [ValueAggregator](../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregator.html "interface in org.apache.hadoop.mapred.lib.aggregate")

getCombinerOutput

public ArrayList<String> getCombinerOutput()

Specified by:

[getCombinerOutput](../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregator.html#getCombinerOutput%28%29) in interface [ValueAggregator](../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregator.html "interface in org.apache.hadoop.mapred.lib.aggregate")

Returns:

return an array of one element. The element is a string representation of the aggregated value. The return value is expected to be used by the a combiner.