org.apache.pig.builtin

Class STRSPLIT

java.lang.Object

org.apache.pig.EvalFunc<Tuple>

org.apache.pig.builtin.STRSPLIT

Direct Known Subclasses:

Split

public class STRSPLIT
extends EvalFunc<Tuple>

Wrapper around Java's String.split
input tuple: first column is assumed to have a string to split;
the optional second column is assumed to have the delimiter or regex to split on;
if not provided, it's assumed to be '\s' (space)
the optional third column may provide a limit to the number of results.
If limit is not provided, 0 is assumed, as per Java's split().

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
STRSPLIT()

Method Summary

Modifier and Type	Method and Description
boolean	allowCompileTimeCalculation() Whether the UDF should be evaluated at compile time if all inputs are constant.
Tuple	exec(Tuple input) Wrapper around Java's String.split
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

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

STRSPLIT

public STRSPLIT()

Method Detail

exec

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

Wrapper around Java's String.split

Specified by:

exec in class EvalFunc<Tuple>

Parameters:

input - tuple; first column is assumed to have a string to split; the optional second column is assumed to have the delimiter or regex to split on;
if not provided, it's assumed to be '\s' (space) the optional third column may provide a limit to the number of results.
If limit is not provided, 0 is assumed, as per Java's split().

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<Tuple>

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<Tuple>

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

allowCompileTimeCalculation

public boolean allowCompileTimeCalculation()

Description copied from class: EvalFunc

Whether the UDF should be evaluated at compile time if all inputs are constant. This is applicable for most UDF, however, if a UDF will access hdfs file which is not available at compile time, it has to be false

Overrides:

allowCompileTimeCalculation in class EvalFunc<Tuple>

Returns:

Whether or not compile time calculation is allowed, default to false to ensure legacy UDF will get the right behavior