UniqValueCount (Hadoop 1.2.1 API) (original) (raw)

org.apache.hadoop.mapred.lib.aggregate

Class UniqValueCount

java.lang.Object extended by 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](../../../../../../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.

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:

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](../../../../../../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 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 the unique objects. The return value is expected to be used by the a combiner.