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pub struct Decay<T: Origin> { /* private fields */ }
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Decay functions score a document with a function that decays depending on the distance of a numeric field value of the document from a user given origin. This is similar to a range query, but with smooth edges instead of boxes.

To use distance scoring on a query that has numerical fields, the user has to define an origin and a scale for each field. The origin is needed to define the “central point” from which the distance is calculated, and the scale to define the rate of decay.

Implementations

Creates an instance of Decay

  • function - Decay function variant
  • field - Field to apply function to
  • origin - The point of origin used for calculating distance. Must be given as a number for numeric field, date for date fields and geo point for geo fields. Required for geo and numeric field. For date fields the default is now. Date math (for example now-1h) is supported for origin.
  • scale - Required for all types. Defines the distance from origin + offset at which the computed score will equal decay parameter. For geo fields: Can be defined as number+unit (1km, 12m,…​). Default unit is meters. For date fields: Can to be defined as a number+unit (“1h”, “10d”,…​). Default unit is milliseconds. For numeric field: Any number.

If an offset is defined, the decay function will only compute the decay function for documents with a distance greater than the defined offset.

The default is 0.

The decay parameter defines how documents are scored at the distance given at scale. If no decay is defined, documents at the distance scale will be scored 0.5.

Trait Implementations

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