| Package | Description | 
|---|---|
| org.apache.hadoop.mapred | |
| org.apache.hadoop.mapred.lib | |
| org.apache.hadoop.mapred.lib.aggregate | 
| Modifier and Type | Interface and Description | 
|---|---|
interface  | 
Mapper<K1,V1,K2,V2>
Maps input key/value pairs to a set of intermediate key/value pairs. 
 | 
interface  | 
Reducer<K2,V2,K3,V3>
Reduces a set of intermediate values which share a key to a smaller set of
 values. 
 | 
| Modifier and Type | Class and Description | 
|---|---|
class  | 
ChainMapper
The ChainMapper class allows to use multiple Mapper classes within a single
 Map task. 
 | 
class  | 
ChainReducer
The ChainReducer class allows to chain multiple Mapper classes after a
 Reducer within the Reducer task. 
 | 
class  | 
FieldSelectionMapReduce<K,V>
This class implements a mapper/reducer class that can be used to perform
 field selections in a manner similar to unix cut. 
 | 
class  | 
IdentityMapper<K,V>
Implements the identity function, mapping inputs directly to outputs. 
 | 
class  | 
IdentityReducer<K,V>
Performs no reduction, writing all input values directly to the output. 
 | 
class  | 
InverseMapper<K,V>
A  
Mapper that swaps keys and values. | 
class  | 
LongSumReducer<K>
A  
Reducer that sums long values. | 
class  | 
RegexMapper<K>
A  
Mapper that extracts text matching a regular expression. | 
class  | 
TokenCountMapper<K>
A  
Mapper that maps text values into  | 
| Modifier and Type | Class and Description | 
|---|---|
class  | 
ValueAggregatorCombiner<K1 extends WritableComparable,V1 extends Writable>
This class implements the generic combiner of Aggregate. 
 | 
class  | 
ValueAggregatorJobBase<K1 extends WritableComparable,V1 extends Writable>
This abstract class implements some common functionalities of the
 the generic mapper, reducer and combiner classes of Aggregate. 
 | 
class  | 
ValueAggregatorMapper<K1 extends WritableComparable,V1 extends Writable>
This class implements the generic mapper of Aggregate. 
 | 
class  | 
ValueAggregatorReducer<K1 extends WritableComparable,V1 extends Writable>
This class implements the generic reducer of Aggregate. 
 | 
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