datafu.pig.bags
Class BagGroup

java.lang.Object
  org.apache.pig.EvalFunc<T>
      datafu.pig.util.ContextualEvalFunc<T>
          datafu.pig.util.AliasableEvalFunc<org.apache.pig.data.DataBag>
              datafu.pig.bags.BagGroup

public class BagGroup
extends AliasableEvalFunc<org.apache.pig.data.DataBag>

Performs an in-memory group operation on a bag. The first argument is the bag. The second argument is a projection of that bag to the group keys.

Example: define BagGroup datafu.pig.bags.BagGroup(); data = LOAD 'input' AS (input_bag: bag {T: tuple(k: int, v: chararray)}); -- ({(1,A),(1,B),(2,A),(2,B),(2,C),(3,A)}) data2 = FOREACH data GENERATE BagGroup(input_bag, input_bag.(k)) as grouped; -- data2: {grouped: {(group: int,input_bag: {T: (k: int,v: chararray)})}} -- ({(1,{(1,A),(1,B)}),(2,{(2,A),(2,B),(2,C)}),(3,{(3,A)})})

Author:

wvaughan

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

BagGroup()

Method Summary

org.apache.pig.data.DataBag	exec(org.apache.pig.data.Tuple input)
org.apache.pig.impl.logicalLayer.schema.Schema	getOutputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input) Specify the output schema as in {link EvalFunc#outputSchema(Schema)}.

Methods inherited from class datafu.pig.util.AliasableEvalFunc

getBag, getBoolean, getDouble, getDouble, getFieldAliases, getFloat, getFloat, getInteger, getInteger, getLong, getLong, getObject, getPosition, getPosition, getPrefixedAliasName, getString, getString, outputSchema

Methods inherited from class datafu.pig.util.ContextualEvalFunc

getContextProperties, getInstanceName, getInstanceProperties, setUDFContextSignature

Methods inherited from class org.apache.pig.EvalFunc

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

Methods inherited from class java.lang.Object

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

Constructor Detail

BagGroup

public BagGroup()

Method Detail

getOutputSchema

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

Description copied from class: AliasableEvalFunc

Specify the output schema as in {link EvalFunc#outputSchema(Schema)}.

Specified by:

getOutputSchema in class AliasableEvalFunc<org.apache.pig.data.DataBag>

Returns:

outputSchema

exec

public org.apache.pig.data.DataBag exec(org.apache.pig.data.Tuple input)
                                 throws java.io.IOException

Specified by:

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

Throws:

java.io.IOException