org.apache.pig.builtin
Class DoubleBase

java.lang.Object
  extended by org.apache.pig.EvalFunc<Double>
      extended by org.apache.pig.builtin.Base
          extended by org.apache.pig.builtin.DoubleBase
Direct Known Subclasses:
ACOS, ASIN, ATAN, CBRT, CEIL, COS, COSH, EXP, FLOOR, LOG, LOG10, SIN, SINH, SQRT, TAN, TANH

public abstract class DoubleBase
extends Base

base class for math udfs that return Double value


Field Summary
 
Fields inherited from class org.apache.pig.EvalFunc
log, pigLogger, reporter, returnType
 
Constructor Summary
DoubleBase()
           
 
Method Summary
 Double exec(Tuple input)
          java level API
 List<FuncSpec> getArgToFuncMapping()
          Allow a UDF to specify type specific implementations of itself.
 
Methods inherited from class org.apache.pig.builtin.Base
outputSchema
 
Methods inherited from class org.apache.pig.EvalFunc
finish, getCacheFiles, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, isAsynchronous, progress, setPigLogger, setReporter, warn
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

DoubleBase

public DoubleBase()
Method Detail

exec

public Double exec(Tuple input)
            throws IOException
java level API

Specified by:
exec in class EvalFunc<Double>
Parameters:
input - expects a tuple with a single Double value
Returns:
output returns a Double value
Throws:
IOException

getArgToFuncMapping

public 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<Double>
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


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