<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<!--NewPage-->
<HTML>
<HEAD>
<!-- Generated by javadoc (build 1.6.0_26) on Sat Feb 18 07:05:45 UTC 2012 -->
<META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<TITLE>
ValueAggregatorReducer (Apache Hadoop Main 0.23.1 API)
</TITLE>

<META NAME="date" CONTENT="2012-02-18">

<LINK REL ="stylesheet" TYPE="text/css" HREF="../../../../../../stylesheet.css" TITLE="Style">

<SCRIPT type="text/javascript">
function windowTitle()
{
    if (location.href.indexOf('is-external=true') == -1) {
        parent.document.title="ValueAggregatorReducer (Apache Hadoop Main 0.23.1 API)";
    }
}
</SCRIPT>
<NOSCRIPT>
</NOSCRIPT>

</HEAD>

<BODY BGCOLOR="white" onload="windowTitle();">
<HR>


<!-- ========= START OF TOP NAVBAR ======= -->
<A NAME="navbar_top"><!-- --></A>
<A HREF="#skip-navbar_top" title="Skip navigation links"></A>
<TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY="">
<TR>
<TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1">
<A NAME="navbar_top_firstrow"><!-- --></A>
<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY="">
  <TR ALIGN="center" VALIGN="top">
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> &nbsp;<FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="class-use/ValueAggregatorReducer.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A>&nbsp;</TD>
  </TR>
</TABLE>
</TD>
<TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM>
</EM>
</TD>
</TR>

<TR>
<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
&nbsp;<A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorMapper.html" title="class in org.apache.hadoop.mapred.lib.aggregate"><B>PREV CLASS</B></A>&nbsp;
&nbsp;<A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueHistogram.html" title="class in org.apache.hadoop.mapred.lib.aggregate"><B>NEXT CLASS</B></A></FONT></TD>
<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
  <A HREF="../../../../../../index.html?org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html" target="_top"><B>FRAMES</B></A>  &nbsp;
&nbsp;<A HREF="ValueAggregatorReducer.html" target="_top"><B>NO FRAMES</B></A>  &nbsp;
&nbsp;<SCRIPT type="text/javascript">
  <!--
  if(window==top) {
    document.writeln('<A HREF="../../../../../../allclasses-noframe.html"><B>All Classes</B></A>');
  }
  //-->
</SCRIPT>
<NOSCRIPT>
  <A HREF="../../../../../../allclasses-noframe.html"><B>All Classes</B></A>
</NOSCRIPT>


</FONT></TD>
</TR>
<TR>
<TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">
  SUMMARY:&nbsp;NESTED&nbsp;|&nbsp;<A HREF="#fields_inherited_from_class_org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase">FIELD</A>&nbsp;|&nbsp;<A HREF="#constructor_summary">CONSTR</A>&nbsp;|&nbsp;<A HREF="#method_summary">METHOD</A></FONT></TD>
<TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">
DETAIL:&nbsp;FIELD&nbsp;|&nbsp;<A HREF="#constructor_detail">CONSTR</A>&nbsp;|&nbsp;<A HREF="#method_detail">METHOD</A></FONT></TD>
</TR>
</TABLE>
<A NAME="skip-navbar_top"></A>
<!-- ========= END OF TOP NAVBAR ========= -->

<HR>
<!-- ======== START OF CLASS DATA ======== -->
<H2>
<FONT SIZE="-1">
org.apache.hadoop.mapred.lib.aggregate</FONT>
<BR>
Class ValueAggregatorReducer&lt;K1 extends <A HREF="../../../../../../org/apache/hadoop/io/WritableComparable.html" title="interface in org.apache.hadoop.io">WritableComparable</A>,V1 extends <A HREF="../../../../../../org/apache/hadoop/io/Writable.html" title="interface in org.apache.hadoop.io">Writable</A>&gt;</H2>
<PRE>
<A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">java.lang.Object</A>
  <IMG SRC="../../../../../../resources/inherit.gif" ALT="extended by "><A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorJobBase.html" title="class in org.apache.hadoop.mapred.lib.aggregate">org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase</A>&lt;K1,V1&gt;
      <IMG SRC="../../../../../../resources/inherit.gif" ALT="extended by "><B>org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorReducer&lt;K1,V1&gt;</B>
</PRE>
<DL>
<DT><B>All Implemented Interfaces:</B> <DD><A HREF="http://download.oracle.com/javase/6/docs/api/java/io/Closeable.html?is-external=true" title="class or interface in java.io">Closeable</A>, <A HREF="../../../../../../org/apache/hadoop/mapred/JobConfigurable.html" title="interface in org.apache.hadoop.mapred">JobConfigurable</A>, <A HREF="../../../../../../org/apache/hadoop/mapred/Mapper.html" title="interface in org.apache.hadoop.mapred">Mapper</A>&lt;K1,V1,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;, <A HREF="../../../../../../org/apache/hadoop/mapred/Reducer.html" title="interface in org.apache.hadoop.mapred">Reducer</A>&lt;<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;</DD>
</DL>
<HR>
<DL>
<DT><PRE><FONT SIZE="-1">@InterfaceAudience.Public
@InterfaceStability.Stable
</FONT>public class <A HREF="../../../../../../src-html/org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html#line.37"><B>ValueAggregatorReducer&lt;K1 extends <A HREF="../../../../../../org/apache/hadoop/io/WritableComparable.html" title="interface in org.apache.hadoop.io">WritableComparable</A>,V1 extends <A HREF="../../../../../../org/apache/hadoop/io/Writable.html" title="interface in org.apache.hadoop.io">Writable</A>&gt;</B></A><DT>extends <A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorJobBase.html" title="class in org.apache.hadoop.mapred.lib.aggregate">ValueAggregatorJobBase</A>&lt;K1,V1&gt;</DL>
</PRE>

<P>
This class implements the generic reducer of Aggregate.
<P>

<P>
<HR>

<P>
<!-- =========== FIELD SUMMARY =========== -->

<A NAME="field_summary"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2">
<B>Field Summary</B></FONT></TH>
</TR>
</TABLE>
&nbsp;<A NAME="fields_inherited_from_class_org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor">
<TH ALIGN="left"><B>Fields inherited from class org.apache.hadoop.mapred.lib.aggregate.<A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorJobBase.html" title="class in org.apache.hadoop.mapred.lib.aggregate">ValueAggregatorJobBase</A></B></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorJobBase.html#aggregatorDescriptorList">aggregatorDescriptorList</A></CODE></TD>
</TR>
</TABLE>
&nbsp;
<!-- ======== CONSTRUCTOR SUMMARY ======== -->

<A NAME="constructor_summary"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2">
<B>Constructor Summary</B></FONT></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><B><A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html#ValueAggregatorReducer()">ValueAggregatorReducer</A></B>()</CODE>

<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</TD>
</TR>
</TABLE>
&nbsp;
<!-- ========== METHOD SUMMARY =========== -->

<A NAME="method_summary"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2">
<B>Method Summary</B></FONT></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>&nbsp;void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html#map(K1, V1, org.apache.hadoop.mapred.OutputCollector, org.apache.hadoop.mapred.Reporter)">map</A></B>(<A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html" title="type parameter in ValueAggregatorReducer">K1</A>&nbsp;arg0,
       <A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html" title="type parameter in ValueAggregatorReducer">V1</A>&nbsp;arg1,
       <A HREF="../../../../../../org/apache/hadoop/mapred/OutputCollector.html" title="interface in org.apache.hadoop.mapred">OutputCollector</A>&lt;<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;&nbsp;arg2,
       <A HREF="../../../../../../org/apache/hadoop/mapred/Reporter.html" title="interface in org.apache.hadoop.mapred">Reporter</A>&nbsp;arg3)</CODE>

<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Do nothing.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>&nbsp;void</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html#reduce(org.apache.hadoop.io.Text, java.util.Iterator, org.apache.hadoop.mapred.OutputCollector, org.apache.hadoop.mapred.Reporter)">reduce</A></B>(<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&nbsp;key,
             <A HREF="http://download.oracle.com/javase/6/docs/api/java/util/Iterator.html?is-external=true" title="class or interface in java.util">Iterator</A>&lt;<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;&nbsp;values,
             <A HREF="../../../../../../org/apache/hadoop/mapred/OutputCollector.html" title="interface in org.apache.hadoop.mapred">OutputCollector</A>&lt;<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;&nbsp;output,
             <A HREF="../../../../../../org/apache/hadoop/mapred/Reporter.html" title="interface in org.apache.hadoop.mapred">Reporter</A>&nbsp;reporter)</CODE>

<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<i>Reduces</i> values for a given key.</TD>
</TR>
</TABLE>
&nbsp;<A NAME="methods_inherited_from_class_org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor">
<TH ALIGN="left"><B>Methods inherited from class org.apache.hadoop.mapred.lib.aggregate.<A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorJobBase.html" title="class in org.apache.hadoop.mapred.lib.aggregate">ValueAggregatorJobBase</A></B></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorJobBase.html#close()">close</A>, <A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorJobBase.html#configure(org.apache.hadoop.mapred.JobConf)">configure</A>, <A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorJobBase.html#logSpec()">logSpec</A></CODE></TD>
</TR>
</TABLE>
&nbsp;<A NAME="methods_inherited_from_class_java.lang.Object"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor">
<TH ALIGN="left"><B>Methods inherited from class java.lang.<A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</A></B></TH>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD><CODE><A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#clone()" title="class or interface in java.lang">clone</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#equals(java.lang.Object)" title="class or interface in java.lang">equals</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#finalize()" title="class or interface in java.lang">finalize</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#getClass()" title="class or interface in java.lang">getClass</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#hashCode()" title="class or interface in java.lang">hashCode</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#notify()" title="class or interface in java.lang">notify</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#notifyAll()" title="class or interface in java.lang">notifyAll</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#toString()" title="class or interface in java.lang">toString</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait()" title="class or interface in java.lang">wait</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait(long)" title="class or interface in java.lang">wait</A>, <A HREF="http://download.oracle.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait(long, int)" title="class or interface in java.lang">wait</A></CODE></TD>
</TR>
</TABLE>
&nbsp;
<P>

<!-- ========= CONSTRUCTOR DETAIL ======== -->

<A NAME="constructor_detail"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2">
<B>Constructor Detail</B></FONT></TH>
</TR>
</TABLE>

<A NAME="ValueAggregatorReducer()"><!-- --></A><H3>
ValueAggregatorReducer</H3>
<PRE>
public <A HREF="../../../../../../src-html/org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html#line.37"><B>ValueAggregatorReducer</B></A>()</PRE>
<DL>
</DL>

<!-- ============ METHOD DETAIL ========== -->

<A NAME="method_detail"><!-- --></A>
<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
<TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2">
<B>Method Detail</B></FONT></TH>
</TR>
</TABLE>

<A NAME="reduce(org.apache.hadoop.io.Text, java.util.Iterator, org.apache.hadoop.mapred.OutputCollector, org.apache.hadoop.mapred.Reporter)"><!-- --></A><H3>
reduce</H3>
<PRE>
public void <A HREF="../../../../../../src-html/org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html#line.50"><B>reduce</B></A>(<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&nbsp;key,
                   <A HREF="http://download.oracle.com/javase/6/docs/api/java/util/Iterator.html?is-external=true" title="class or interface in java.util">Iterator</A>&lt;<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;&nbsp;values,
                   <A HREF="../../../../../../org/apache/hadoop/mapred/OutputCollector.html" title="interface in org.apache.hadoop.mapred">OutputCollector</A>&lt;<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;&nbsp;output,
                   <A HREF="../../../../../../org/apache/hadoop/mapred/Reporter.html" title="interface in org.apache.hadoop.mapred">Reporter</A>&nbsp;reporter)
            throws <A HREF="http://download.oracle.com/javase/6/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</A></PRE>
<DL>
<DD><B>Description copied from interface: <CODE><A HREF="../../../../../../org/apache/hadoop/mapred/Reducer.html#reduce(K2, java.util.Iterator, org.apache.hadoop.mapred.OutputCollector, org.apache.hadoop.mapred.Reporter)">Reducer</A></CODE></B></DD>
<DD><i>Reduces</i> values for a given key.  
 
 <p>The framework calls this method for each 
 <code>&lt;key, (list of values)></code> pair in the grouped inputs.
 Output values must be of the same type as input values.  Input keys must 
 not be altered. The framework will <b>reuse</b> the key and value objects
 that are passed into the reduce, therefore the application should clone
 the objects they want to keep a copy of. In many cases, all values are 
 combined into zero or one value.
 </p>
   
 <p>Output pairs are collected with calls to  
 <A HREF="../../../../../../org/apache/hadoop/mapred/OutputCollector.html#collect(K, V)"><CODE>OutputCollector.collect(Object,Object)</CODE></A>.</p>

 <p>Applications can use the <A HREF="../../../../../../org/apache/hadoop/mapred/Reporter.html" title="interface in org.apache.hadoop.mapred"><CODE>Reporter</CODE></A> provided to report progress 
 or just indicate that they are alive. In scenarios where the application 
 takes a significant amount of time to process individual key/value 
 pairs, this is crucial since the framework might assume that the task has 
 timed-out and kill that task. The other way of avoiding this is to set 
 <a href="../../../../../../../mapred-default.html#mapreduce.task.timeout">
 mapreduce.task.timeout</a> to a high-enough value (or even zero for no 
 time-outs).</p>
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>key</CODE> - the key is expected to be a Text object, whose prefix indicates
          the type of aggregation to aggregate the values. In effect, data
          driven computing is achieved. It is assumed that each aggregator's
          getReport method emits appropriate output for the aggregator. This
          may be further customiized.<DD><CODE>values</CODE> - the list of values to reduce.<DD><CODE>output</CODE> - to collect keys and combined values.<DD><CODE>reporter</CODE> - facility to report progress.
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://download.oracle.com/javase/6/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</A></CODE></DL>
</DD>
</DL>
<HR>

<A NAME="map(org.apache.hadoop.io.WritableComparable,org.apache.hadoop.io.Writable,org.apache.hadoop.mapred.OutputCollector,org.apache.hadoop.mapred.Reporter)"><!-- --></A><A NAME="map(K1, V1, org.apache.hadoop.mapred.OutputCollector, org.apache.hadoop.mapred.Reporter)"><!-- --></A><H3>
map</H3>
<PRE>
public void <A HREF="../../../../../../src-html/org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html#line.72"><B>map</B></A>(<A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html" title="type parameter in ValueAggregatorReducer">K1</A>&nbsp;arg0,
                <A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html" title="type parameter in ValueAggregatorReducer">V1</A>&nbsp;arg1,
                <A HREF="../../../../../../org/apache/hadoop/mapred/OutputCollector.html" title="interface in org.apache.hadoop.mapred">OutputCollector</A>&lt;<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;&nbsp;arg2,
                <A HREF="../../../../../../org/apache/hadoop/mapred/Reporter.html" title="interface in org.apache.hadoop.mapred">Reporter</A>&nbsp;arg3)
         throws <A HREF="http://download.oracle.com/javase/6/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</A></PRE>
<DL>
<DD>Do nothing. Should not be called
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>arg0</CODE> - the input key.<DD><CODE>arg1</CODE> - the input value.<DD><CODE>arg2</CODE> - collects mapped keys and values.<DD><CODE>arg3</CODE> - facility to report progress.
<DT><B>Throws:</B>
<DD><CODE><A HREF="http://download.oracle.com/javase/6/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</A></CODE></DL>
</DD>
</DL>
<!-- ========= END OF CLASS DATA ========= -->
<HR>


<!-- ======= START OF BOTTOM NAVBAR ====== -->
<A NAME="navbar_bottom"><!-- --></A>
<A HREF="#skip-navbar_bottom" title="Skip navigation links"></A>
<TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY="">
<TR>
<TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1">
<A NAME="navbar_bottom_firstrow"><!-- --></A>
<TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY="">
  <TR ALIGN="center" VALIGN="top">
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> &nbsp;<FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="class-use/ValueAggregatorReducer.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A>&nbsp;</TD>
  <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1">    <A HREF="../../../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A>&nbsp;</TD>
  </TR>
</TABLE>
</TD>
<TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM>
</EM>
</TD>
</TR>

<TR>
<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
&nbsp;<A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorMapper.html" title="class in org.apache.hadoop.mapred.lib.aggregate"><B>PREV CLASS</B></A>&nbsp;
&nbsp;<A HREF="../../../../../../org/apache/hadoop/mapred/lib/aggregate/ValueHistogram.html" title="class in org.apache.hadoop.mapred.lib.aggregate"><B>NEXT CLASS</B></A></FONT></TD>
<TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2">
  <A HREF="../../../../../../index.html?org/apache/hadoop/mapred/lib/aggregate/ValueAggregatorReducer.html" target="_top"><B>FRAMES</B></A>  &nbsp;
&nbsp;<A HREF="ValueAggregatorReducer.html" target="_top"><B>NO FRAMES</B></A>  &nbsp;
&nbsp;<SCRIPT type="text/javascript">
  <!--
  if(window==top) {
    document.writeln('<A HREF="../../../../../../allclasses-noframe.html"><B>All Classes</B></A>');
  }
  //-->
</SCRIPT>
<NOSCRIPT>
  <A HREF="../../../../../../allclasses-noframe.html"><B>All Classes</B></A>
</NOSCRIPT>


</FONT></TD>
</TR>
<TR>
<TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">
  SUMMARY:&nbsp;NESTED&nbsp;|&nbsp;<A HREF="#fields_inherited_from_class_org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase">FIELD</A>&nbsp;|&nbsp;<A HREF="#constructor_summary">CONSTR</A>&nbsp;|&nbsp;<A HREF="#method_summary">METHOD</A></FONT></TD>
<TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">
DETAIL:&nbsp;FIELD&nbsp;|&nbsp;<A HREF="#constructor_detail">CONSTR</A>&nbsp;|&nbsp;<A HREF="#method_detail">METHOD</A></FONT></TD>
</TR>
</TABLE>
<A NAME="skip-navbar_bottom"></A>
<!-- ======== END OF BOTTOM NAVBAR ======= -->

<HR>
Copyright &#169; 2012 <a href="http://www.apache.org">Apache Software Foundation</a>. All Rights Reserved.
</BODY>
</HTML>
