Package dev.langchain4j.rag.content.aggregator

Class ReRankingContentAggregator

java.lang.Object

dev.langchain4j.rag.content.aggregator.ReRankingContentAggregator

All Implemented Interfaces:

ContentAggregator

public class ReRankingContentAggregator
extends Object
implements ContentAggregator

A ContentAggregator that performs re-ranking using a ScoringModel, such as Cohere.
The ScoringModel scores Contents against a (single) Query. If multiple Querys are input to this aggregator (for example, when using ExpandingQueryTransformer), a querySelector must be provided to select a Query for ranking all Contents. Alternatively, a custom implementation can be created to score Contents against the Querys that were used for their retrieval (instead of a single Query), and then re-rank based on those scores. Although potentially more costly, this method may yield better results when the Querys are significantly different.

Before the use of a ScoringModel, all Contents are fused in the same way as by the DefaultContentAggregator. For detailed information, please refer to its Javadoc.

Configurable parameters (optional):
- minScore: the minimum score for Contents to be returned. Contents scoring below this threshold (as determined by the ScoringModel) are excluded from the results.

See Also:

• DefaultContentAggregator

Field Summary

Fields

Modifier and Type	Field	Description
static final Function<Map<Query,Collection<List<Content>>>,Query>	DEFAULT_QUERY_SELECTOR

Constructor Summary

Constructors

Constructor	Description
ReRankingContentAggregator(ScoringModel scoringModel)
ReRankingContentAggregator(ScoringModel scoringModel, Function<Map<Query,Collection<List<Content>>>,Query> querySelector, Double minScore)

Method Summary

Modifier and Type	Method	Description
List<Content>	aggregate(Map<Query,Collection<List<Content>>> queryToContents)	Aggregates all Contents retrieved by all ContentRetrievers using all Querys.
protected Map<Query,List<Content>>	fuse(Map<Query,Collection<List<Content>>> queryToContents)
protected List<Content>	reRankAndFilter(List<Content> contents, Query query)

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_QUERY_SELECTOR

public static final Function<Map<Query,Collection<List<Content>>>,Query> DEFAULT_QUERY_SELECTOR

Constructor Details

ReRankingContentAggregator

public ReRankingContentAggregator(ScoringModel scoringModel)

ReRankingContentAggregator

public ReRankingContentAggregator(ScoringModel scoringModel,
 Function<Map<Query,Collection<List<Content>>>,Query> querySelector,
 Double minScore)

Method Details

aggregate

public List<Content> aggregate(Map<Query,Collection<List<Content>>> queryToContents)

Description copied from interface: ContentAggregator

Aggregates all Contents retrieved by all ContentRetrievers using all Querys. The Contents, both on input and output, are sorted by relevance, with the most relevant Contents appearing at the beginning of List<Content>.

Specified by:

aggregate in interface ContentAggregator

Parameters:

queryToContents - A map from a Query to all List<Content> retrieved with that Query. Given that each Query can be routed to multiple ContentRetrievers, the value of this map is a Collection<List<Content>> rather than a simple List<Content>.

Returns:

A list of aggregated Contents.

fuse

protected Map<Query,List<Content>> fuse(Map<Query,Collection<List<Content>>> queryToContents)

reRankAndFilter

protected List<Content> reRankAndFilter(List<Content> contents,
 Query query)