org.apache.hadoop.mapred.lib.aggregate
Class UniqValueCount

java.lang.Object
  org.apache.hadoop.mapred.lib.aggregate.UniqValueCount

All Implemented Interfaces:

ValueAggregator

public class UniqValueCount
extends Object
implements ValueAggregator

This class implements a value aggregator that dedupes a sequence of objects.

Constructor Summary

UniqValueCount()
the default constructor

UniqValueCount(long maxNum)
constructor

Method Summary

void	addNextValue(Object val) add a value to the aggregator
ArrayList	getCombinerOutput()
String	getReport()
Set	getUniqueItems()
void	reset() reset the aggregator
long	setMaxItems(long n) Set the limit on the number of unique values

Methods inherited from class java.lang.Object

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

Constructor Detail

UniqValueCount

public UniqValueCount()

the default constructor

UniqValueCount

public UniqValueCount(long maxNum)

constructor

Parameters:

maxNum - the limit in the number of unique values to keep.

Method Detail

setMaxItems

public long setMaxItems(long n)

Set the limit on the number of unique values

Parameters:

n - the desired limit on the number of unique values

Returns:

the new limit on the number of unique values

addNextValue

public void addNextValue(Object val)

add a value to the aggregator

Specified by:

addNextValue in interface ValueAggregator

Parameters:

val - an object.

getReport

public String getReport()

Specified by:

getReport in interface ValueAggregator

Returns:

return the number of unique objects aggregated

getUniqueItems

public Set getUniqueItems()

Returns:

the set of the unique objects

reset

public void reset()

reset the aggregator

Specified by:

reset in interface ValueAggregator

getCombinerOutput

public ArrayList getCombinerOutput()

Specified by:

getCombinerOutput in interface ValueAggregator

Returns:

return an array of the unique objects. The return value is expected to be used by the a combiner.