org.apache.datasketches.pig.cpc

Class GetEstimateAndErrorBounds

java.lang.Object

org.apache.pig.EvalFunc<org.apache.pig.data.Tuple>

org.apache.datasketches.pig.cpc.GetEstimateAndErrorBounds

public class GetEstimateAndErrorBounds
extends org.apache.pig.EvalFunc<org.apache.pig.data.Tuple>

This is a User Defined Function (UDF) for obtaining the distinct count estimate along with a lower and upper bound from a given CpcSketch.

The result is a tuple with three double values: estimate, lower bound and upper bound. The bounds are best estimates for the confidence interval given kappa, which represents the number of standard deviations from the mean (1, 2 or 3).

Author:

Alexander Saydakov

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
GetEstimateAndErrorBounds() Constructor with default kappa and seed
GetEstimateAndErrorBounds(String kappa) Constructor with given kappa and default seed
GetEstimateAndErrorBounds(String kappa, String seed) Constructor with given kappa and seed

Method Summary

Modifier and Type	Method and Description
org.apache.pig.data.Tuple	exec(org.apache.pig.data.Tuple sketchTuple)
org.apache.pig.impl.logicalLayer.schema.Schema	outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input) The output is a Sketch Result Tuple Schema.

Methods inherited from class org.apache.pig.EvalFunc

allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLoadCaster, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, getShipFiles, isAsynchronous, needEndOfAllInputProcessing, progress, setEndOfAllInput, 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

GetEstimateAndErrorBounds

public GetEstimateAndErrorBounds()

Constructor with default kappa and seed

GetEstimateAndErrorBounds

public GetEstimateAndErrorBounds(String kappa)

Constructor with given kappa and default seed

Parameters:

kappa - in a form of a String

GetEstimateAndErrorBounds

public GetEstimateAndErrorBounds(String kappa,
                                 String seed)

Constructor with given kappa and seed

Parameters:

kappa - in a form of a String

seed - in a form of a String

Method Detail

exec

public org.apache.pig.data.Tuple exec(org.apache.pig.data.Tuple sketchTuple)
                               throws IOException

Specified by:

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

Throws:

IOException

outputSchema

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

The output is a Sketch Result Tuple Schema.

Overrides:

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