org.apache.pig.piggybank.evaluation.decode

Class Decode

java.lang.Object

org.apache.pig.EvalFunc<java.lang.String>

org.apache.pig.piggybank.evaluation.decode.Decode

public class Decode
extends EvalFunc<java.lang.String>

Syntax:

String Decode(expression, value1, mapping_string1, ..., valueN, mapping_stringN, other_string).

Logic:

if (expression==value1) return mapping_string1;
......
else if (expression==valueN) return mapping_stringN;
else return other_string;

expression can be any simple types

Nested Class Summary

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

EvalFunc.SchemaType

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Constructors

Constructor and Description
Decode()

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.String	exec(Tuple tuple) This callback method must be implemented by all subclasses.
Schema	outputSchema(Schema input) Report the schema of the output of this UDF.

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

Decode

public Decode()

Method Detail

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<java.lang.String>

Parameters:

input - Schema of the input

Returns:

Schema of the output

exec

public java.lang.String exec(Tuple tuple)
                      throws java.io.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<java.lang.String>

Parameters:

tuple - the Tuple to be processed.

Returns:

result, of type T.

Throws:

java.io.IOException