## org.apache.hadoop.examples
Class AggregateWordCount.WordCountPlugInClass

    java.lang.Object
      org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorBaseDescriptor
          org.apache.hadoop.examples.AggregateWordCount.WordCountPlugInClass

All Implemented Interfaces:
  ValueAggregatorDescriptor

Enclosing class:
  AggregateWordCount

    public static class AggregateWordCount.WordCountPlugInClass

extends ValueAggregatorBaseDescriptor

Field Summary

Fields inherited from class org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorBaseDescriptor
`DOUBLE_VALUE_SUM, inputFile, LONG_VALUE_MAX, LONG_VALUE_MIN, LONG_VALUE_SUM, STRING_VALUE_MAX, STRING_VALUE_MIN, UNIQ_VALUE_COUNT, VALUE_HISTOGRAM`

Fields inherited from interface org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorDescriptor
`ONE, TYPE_SEPARATOR`

Constructor Summary
`AggregateWordCount.WordCountPlugInClass()`

Method Summary
`ArrayList<Map.Entry<Text,Text>>` `generateKeyValPairs(Object key, Object val)` Generate 1 or 2 aggregation-id/value pairs for the given key/value pair.

Methods inherited from class org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorBaseDescriptor
`configure, generateEntry, generateValueAggregator`

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

Constructor Detail

### AggregateWordCount.WordCountPlugInClass

    public AggregateWordCount.WordCountPlugInClass()

Method Detail

### generateKeyValPairs

    public ArrayList<Map.Entry<Text,Text>> generateKeyValPairs(Object key,
                                                               Object val)

  Description copied from class: `ValueAggregatorBaseDescriptor`
  Generate 1 or 2 aggregation-id/value pairs for the given key/value pair. The first id will be of type LONG_VALUE_SUM, with "record_count" as its aggregation id. If the input is a file split, the second id of the same type will be generated too, with the file name as its aggregation id. This achieves the behavior of counting the total number of records in the input data, and the number of records in each input file.

  Specified by:
    `generateKeyValPairs` in interface `ValueAggregatorDescriptor`
  Overrides:
    `generateKeyValPairs` in class `ValueAggregatorBaseDescriptor`
  Parameters:
    `key` - input key
    `val` - input value
  Returns:
    a list of aggregation id/value pairs. An aggregation id encodes an aggregation type which is used to guide the way to aggregate the value in the reduce/combiner phrase of an Aggregate based job.

Copyright © 2009 The Apache Software Foundation