datafu.pig.bags

Class Enumerate

java.lang.Object

org.apache.pig.EvalFunc<T>

org.apache.pig.AccumulatorEvalFunc<org.apache.pig.data.DataBag>

datafu.pig.bags.Enumerate

All Implemented Interfaces:

org.apache.pig.Accumulator<org.apache.pig.data.DataBag>

public class Enumerate
extends org.apache.pig.AccumulatorEvalFunc<org.apache.pig.data.DataBag>

Enumerate a bag, appending to each tuple its index within the bag. For example:

   {(A),(B),(C),(D)} => {(A,0),(B,1),(C,2),(D,3)}
 

The first constructor parameter (optional) dictates the starting index of the counting. This UDF implements the accumulator interface, reducing DataBag materialization costs.

Example:

 
 define Enumerate datafu.pig.bags.Enumerate('1');

 -- input:
 -- ({(100),(200),(300),(400)})
 input = LOAD 'input' as (B: bag{T: tuple(v2:INT)});

 -- output:
 -- ({(100,1),(200,2),(300,3),(400,4)})
 output = FOREACH input GENERATE Enumerate(B);
 
 

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.pig.EvalFunc

org.apache.pig.EvalFunc.SchemaType

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Constructors

Constructor and Description
Enumerate()
Enumerate(java.lang.String start)

Method Summary

Modifier and Type	Method and Description
void	accumulate(org.apache.pig.data.Tuple arg0)
void	cleanup()
org.apache.pig.data.DataBag	getValue()
org.apache.pig.impl.logicalLayer.schema.Schema	outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input)

Methods inherited from class org.apache.pig.AccumulatorEvalFunc

exec

Methods inherited from class org.apache.pig.EvalFunc

allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, getShipFiles, isAsynchronous, progress, setInputSchema, setPigLogger, setReporter, setUDFContextSignature, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

Enumerate

public Enumerate()

Enumerate

public Enumerate(java.lang.String start)

Method Detail

accumulate

public void accumulate(org.apache.pig.data.Tuple arg0)
                throws java.io.IOException

Specified by:

accumulate in interface org.apache.pig.Accumulator<org.apache.pig.data.DataBag>

Specified by:

accumulate in class org.apache.pig.AccumulatorEvalFunc<org.apache.pig.data.DataBag>

Throws:

java.io.IOException

cleanup

public void cleanup()

Specified by:

cleanup in interface org.apache.pig.Accumulator<org.apache.pig.data.DataBag>

Specified by:

cleanup in class org.apache.pig.AccumulatorEvalFunc<org.apache.pig.data.DataBag>

getValue

public org.apache.pig.data.DataBag getValue()

Specified by:

getValue in interface org.apache.pig.Accumulator<org.apache.pig.data.DataBag>

Specified by:

getValue in class org.apache.pig.AccumulatorEvalFunc<org.apache.pig.data.DataBag>

outputSchema

public org.apache.pig.impl.logicalLayer.schema.Schema outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input)

Overrides:

outputSchema in class org.apache.pig.EvalFunc<org.apache.pig.data.DataBag>