org.elasticsearch.index.query.functionscore

Class DecayFunctionParser

java.lang.Object

org.elasticsearch.index.query.functionscore.DecayFunctionParser

All Implemented Interfaces:

ScoreFunctionParser

Direct Known Subclasses:

ExponentialDecayFunctionParser, GaussDecayFunctionParser, LinearDecayFunctionParser

public abstract class DecayFunctionParser
extends Object
implements ScoreFunctionParser

This class provides the basic functionality needed for adding a decay function. This parser parses this kind of input

 
 {
      "fieldname1" : {
          "origin" = "someValue",
          "scale" = "someValue"
      }

 
 

"origin" here refers to the reference point and "scale" to the level of uncertainty you have in your origin.

For example, you might want to retrieve an event that took place around the 20 May 2010 somewhere near Berlin. You are mainly interested in events that are close to the 20 May 2010 but you are unsure about your guess, maybe it was a week before or after that. Your "origin" for the date field would be "20 May 2010" and your "scale" would be "7d". This class parses the input and creates a scoring function from the parameters origin and scale.

To write a new scoring function, create a new class that inherits from this one and implement the getDistanceFunction(). Furthermore, to create a builder, override the getName() in DecayFunctionBuilder.

See GaussDecayFunctionBuilder and GaussDecayFunctionParser for an example. The parser furthermore needs to be registered in the ScoreFunctionParserMapper.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DecayFunctionParser.AbstractDistanceScoreFunction This is the base class for scoring a single field.

Field Summary

Fields

Modifier and Type	Field and Description
static ParseField	MULTI_VALUE_MODE

Constructor Summary

Constructors

Constructor and Description
DecayFunctionParser()

Method Summary

Methods

Modifier and Type	Method and Description
abstract DecayFunction	getDecayFunction() Override this function if you want to produce your own scorer.
ScoreFunction	parse(QueryParseContext parseContext, XContentParser parser) Parses bodies of the kind

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.elasticsearch.index.query.functionscore.ScoreFunctionParser

getNames

Field Detail

MULTI_VALUE_MODE

public static final ParseField MULTI_VALUE_MODE

Constructor Detail

DecayFunctionParser

public DecayFunctionParser()

Method Detail

getDecayFunction

public abstract DecayFunction getDecayFunction()

Override this function if you want to produce your own scorer.

parse

public ScoreFunction parse(QueryParseContext parseContext,
                  XContentParser parser)
                    throws IOException,
                           QueryParsingException

Parses bodies of the kind

 
 {
      "fieldname1" : {
          "origin" = "someValue",
          "scale" = "someValue"
      }

 }
 
 

Specified by:

parse in interface ScoreFunctionParser

Throws:

IOException

QueryParsingException