org.apache.pig.builtin
Class AlgebraicDoubleMathBase

java.lang.Object
  org.apache.pig.EvalFunc<T>
      org.apache.pig.builtin.AlgebraicDoubleMathBase

All Implemented Interfaces:

Accumulator<Double>, Algebraic

Direct Known Subclasses:

DoubleMax, DoubleMin, DoubleSum

public abstract class AlgebraicDoubleMathBase
extends EvalFunc<T>
implements Accumulator<Double>

Core logic for applying an accumulative/algebraic math function to a bag of doubles.

Nested Class Summary

static class	AlgebraicDoubleMathBase.Final
static class	AlgebraicDoubleMathBase.Intermediate
static class	AlgebraicMathBase.Initial
protected static class	AlgebraicMathBase.KNOWN_OP
protected static interface	AlgebraicMathBase.KnownOpProvider

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

EvalFunc.SchemaType

Field Summary

protected AlgebraicMathBase.KnownOpProvider

opProvider

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

AlgebraicDoubleMathBase()

Method Summary

void	accumulate(Tuple b) Pass tuples to the UDF.
void	cleanup() Called after getValue() to prepare processing for next key.
protected static Double	doTupleWork(Tuple input, AlgebraicMathBase.KnownOpProvider opProvider)
Double	exec(Tuple input) This callback method must be implemented by all subclasses.
String	getFinal() Get the final function.
String	getInitial() Get the initial function.
String	getIntermed() Get the intermediate function.
protected static Double	getSeed(AlgebraicMathBase.KNOWN_OP op)
Double	getValue() Called when all tuples from current key have been passed to accumulate.
Schema	outputSchema(Schema input) Report the schema of the output of this UDF.
protected void	setOp(AlgebraicMathBase.KNOWN_OP op)

Methods inherited from class org.apache.pig.EvalFunc

finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, 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

Field Detail

opProvider

protected AlgebraicMathBase.KnownOpProvider opProvider

Constructor Detail

AlgebraicDoubleMathBase

public AlgebraicDoubleMathBase()

Method Detail

getSeed

protected static Double getSeed(AlgebraicMathBase.KNOWN_OP op)

doTupleWork

protected static Double doTupleWork(Tuple input,
                                    AlgebraicMathBase.KnownOpProvider opProvider)
                             throws ExecException

Throws:

ExecException

exec

public Double exec(Tuple input)
            throws IOException

Description copied from class: EvalFunc

This callback method must be implemented by all subclasses. This is the method that will be invoked on every Tuple of a given dataset. Since the dataset may be divided up in a variety of ways the programmer should not make assumptions about state that is maintained between invocations of this method.

Specified by:

exec in class EvalFunc<Double>

Parameters:

input - the Tuple to be processed.

Returns:

result, of type T.

Throws:

IOException

outputSchema

public Schema outputSchema(Schema input)

Description copied from class: EvalFunc

Report the schema of the output of this UDF. Pig will make use of this in error checking, optimization, and planning. The schema of input data to this UDF is provided.

The default implementation interprets the OutputSchema annotation, if one is present. Otherwise, it returns null (no known output schema).

Overrides:

outputSchema in class EvalFunc<Double>

Parameters:

input - Schema of the input

Returns:

Schema of the output

accumulate

public void accumulate(Tuple b)
                throws IOException

Description copied from interface: Accumulator

Pass tuples to the UDF.

Specified by:

accumulate in interface Accumulator<Double>

Parameters:

b - A tuple containing a single field, which is a bag. The bag will contain the set of tuples being passed to the UDF in this iteration.

Throws:

IOException

cleanup

public void cleanup()

Description copied from interface: Accumulator

Called after getValue() to prepare processing for next key.

Specified by:

cleanup in interface Accumulator<Double>

getValue

public Double getValue()

Description copied from interface: Accumulator

Called when all tuples from current key have been passed to accumulate.

Specified by:

getValue in interface Accumulator<Double>

Returns:

the value for the UDF for this key.

setOp

protected void setOp(AlgebraicMathBase.KNOWN_OP op)

getInitial

public String getInitial()

Description copied from interface: Algebraic

Get the initial function.

Specified by:

getInitial in interface Algebraic

Returns:

A function name of f_init. f_init should be an eval func. The return type of f_init.exec() has to be Tuple

getIntermed

public String getIntermed()

Description copied from interface: Algebraic

Get the intermediate function.

Specified by:

getIntermed in interface Algebraic

Returns:

A function name of f_intermed. f_intermed should be an eval func. The return type of f_intermed.exec() has to be Tuple

getFinal

public String getFinal()

Description copied from interface: Algebraic

Get the final function.

Specified by:

getFinal in interface Algebraic

Returns:

A function name of f_final. f_final should be an eval func parametrized by the same datum as the eval func implementing this interface.