Overview

An aggregation combines multiple confidence values into a single value. In order to determine if two entities are duplicates it is usually not sufficient to compare a single property. For instance, when comparing geographic entities, an aggregation may aggregate the similarities between the names of the entities and the similarities based on the distance between the entities.

Parameters

Required (Optional)

The required attribute can be set if the aggregation only should generate a result if a specific suboperator return a value

Weights (Optional)
Some comparison operators might be more relevant for the correct establishment of a link between two resources than others. For example, depending on data formats/quality, matching labels might be considered less important than matching geocoordinates when linking cities. If this modifier is not supplied, a default weight of 1 will be assumed. The weight is only considered in the aggregation types average, quadraticMean and geometricMean.

Type
The function according to the similarity values are aggregated. The following functions are included in Silk:

Examples

XML

<Aggregate type="average">
    <Compare metric="jaro" required="true">
      <Input path="?a/rdfs:label" />
      <Input path="?b/gn:name" />
    </Compare>
    <Compare metric="num">
      <Input path="?a/dbpedia:populationTotal" />
      <Input path="?b/gn:population" />
    </Compare>
  </Aggregate>

Scala API

Aggregation(
  id = "id1",
  required = false,
  weight = 1,
  operators = operators,
  aggregator = MaximumAggregator()
)