org.apache.pig.piggybank.evaluation.string

Class REPLACE_MULTI

java.lang.Object

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

org.apache.pig.piggybank.evaluation.string.REPLACE_MULTI

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

REPLACE_MULTI implements eval function to replace all occurrences of search keys with replacement values. Search - Replacement values are specified in Map Example: input_data = LOAD 'input_data' as (name); -- name = 'Hello World!' replaced_name = FOREACH input_data GENERATE REPLACE_MULTI ( name, [ ' '#'_', '!'#'', 'e'#'a', 'o'#'oo' ] ); -- replaced_name = Halloo_Woorld The first argument is the source string on which REPLACE_MULTI operation is performed. The second argument is a map having search key - replacement value pairs.

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
REPLACE_MULTI()

Method Summary

Modifier and Type	Method and Description
java.lang.String	exec(Tuple input) Method invoked on every tuple during FOREACH evaluation.
java.util.List<FuncSpec>	getArgToFuncMapping() Allow a UDF to specify type specific implementations of itself.
Schema	outputSchema(Schema input) Report the schema of the output of this UDF.

Methods inherited from class org.apache.pig.EvalFunc

addCredentials, allowCompileTimeCalculation, finish, 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

REPLACE_MULTI

public REPLACE_MULTI()

Method Detail

exec

public java.lang.String exec(Tuple input)
                      throws java.io.IOException

Method invoked on every tuple during FOREACH evaluation. If source string or search replacement map is empty or null, source string is returned.

Specified by:

exec in class EvalFunc<java.lang.String>

Parameters:

input - tuple; First field value is the source string and second field is a map having search - replacement values.

Returns:

result, of type T.

Throws:

java.io.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<java.lang.String>

Parameters:

input - Schema of the input

Returns:

Schema of the output

getArgToFuncMapping

public java.util.List<FuncSpec> getArgToFuncMapping()
                                             throws FrontendException

Description copied from class: EvalFunc

Allow a UDF to specify type specific implementations of itself. For example, an implementation of arithmetic sum might have int and float implementations, since integer arithmetic performs much better than floating point arithmetic. Pig's typechecker will call this method and using the returned list plus the schema of the function's input data, decide which implementation of the UDF to use.

Overrides:

getArgToFuncMapping in class EvalFunc<java.lang.String>

Returns:

A List containing FuncSpec objects representing the EvalFunc class which can handle the inputs corresponding to the schema in the objects. Each FuncSpec should be constructed with a schema that describes the input for that implementation. For example, the sum function above would return two elements in its list:

1. FuncSpec(this.getClass().getName(), new Schema(new Schema.FieldSchema(null, DataType.DOUBLE)))
2. FuncSpec(IntSum.getClass().getName(), new Schema(new Schema.FieldSchema(null, DataType.INTEGER)))

This would indicate that the main implementation is used for doubles, and the special implementation IntSum is used for ints.

Throws:

FrontendException