org.elasticsearch.index.query.functionscore

Interface DecayFunction

public interface DecayFunction

Implement this interface to provide a decay function that is executed on a distance. For example, this could be an exponential drop of, a triangle function or something of the kind. This is used, for example, by GaussDecayFunctionParser.

Method Summary

Methods

Modifier and Type	Method and Description
double	evaluate(double value, double scale)
org.apache.lucene.search.Explanation	explainFunction(String valueString, double value, double scale)
double	processScale(double scale, double decay) The final scale parameter is computed from the scale parameter given by the user and a value.

Method Detail

evaluate

double evaluate(double value,
              double scale)

explainFunction

org.apache.lucene.search.Explanation explainFunction(String valueString,
                                                   double value,
                                                   double scale)

processScale

double processScale(double scale,
                  double decay)

The final scale parameter is computed from the scale parameter given by the user and a value. This value is the value that the decay function should compute if document distance and user defined scale equal. The scale parameter for the function must be adjusted accordingly in this function

Parameters:

scale - the raw scale value given by the user

decay - the value which decay function should take once the distance reaches this scale