org.apache.hadoop.mapred.lib.aggregate

类 ValueHistogram

java.lang.Object

org.apache.hadoop.mapred.lib.aggregate.ValueHistogram

所有已实现的接口:

ValueAggregator

public class ValueHistogram
extends Object
implements ValueAggregator

This class implements a value aggregator that computes the histogram of a sequence of strings.

构造器概要

构造器

构造器和说明
ValueHistogram()

方法概要

方法

限定符和类型	方法和说明
void	addNextValue(Object val) add the given val to the aggregator.
ArrayList	getCombinerOutput()
String	getReport()
String	getReportDetails()
TreeMap	getReportItems()
void	reset() reset the aggregator

从类继承的方法 java.lang.Object

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

构造器详细资料

ValueHistogram

public ValueHistogram()

方法详细资料

addNextValue

public void addNextValue(Object val)

add the given val to the aggregator.

指定者:

addNextValue 在接口中 ValueAggregator

参数:

val - the value to be added. It is expected to be a string in the form of xxxx\tnum, meaning xxxx has num occurrences.

getReport

public String getReport()

指定者:

getReport 在接口中 ValueAggregator

返回:

the string representation of this aggregator. It includes the following basic statistics of the histogram: the number of unique values the minimum value the media value the maximum value the average value the standard deviation

getReportDetails

public String getReportDetails()

返回:

a string representation of the list of value/frequence pairs of the histogram

getCombinerOutput

public ArrayList getCombinerOutput()

指定者:

getCombinerOutput 在接口中 ValueAggregator

返回:

a list value/frequence pairs. The return value is expected to be used by the reducer.

getReportItems

public TreeMap getReportItems()

返回:

a TreeMap representation of the histogram

reset

public void reset()

reset the aggregator

指定者:

reset 在接口中 ValueAggregator