com.bakdata.dedupe.matching.Assigner Maven / Gradle / Ivy
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/*
* MIT License
*
* Copyright (c) 2019 bakdata GmbH
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package com.bakdata.dedupe.matching;
import com.bakdata.util.StreamUtil;
import java.util.Collection;
import java.util.Set;
import java.util.stream.Collectors;
import lombok.NonNull;
/**
* Implements an algorithm that solves an assignment problem.
* "It consists of finding, in a [undirected], weighted bipartite graph, a matching in which the sum of weights of
* the edges is as large as possible."[1]
* Unless explicitly stated otherwise by the implementation, the two types of vertexes may be of different size and
* edges do not need to be complete; that is, certain assignments may be impossible from the start. Edges may be
* negatively weighted if the implementation supports it and it is up to the implementation to either see them as
* discouraged or impossible, where non-existing edges should always be treated as impossible.
* A generalization of Assigner is the {@link BipartiteMatcher} that operators on directed, weighted bipartite
* graphs.
*
* [1]
* https://en.wikipedia.org/wiki/Assignment_problem
*
* @param the type of the record
* @see BipartiteMatcher
*/
@FunctionalInterface
public interface Assigner {
/**
* Finds the set of edges forming a matching that maximizes the sum of the edge weights.
* Vertexes are implicitly given through the edges. Vertexes without any edge cannot be passed and are ignored.
* It's up to the caller to handle such cases.
*
* @param weightedEdges the set of possible edges and their respective weights.
* @return the set of edges.
* @apiNote The interface may use Iterables as the parameters in the future to facilitate an online applications.
* Use {@link #assignMaterialized(Collection)} if you need an explicit {@link Set}.
*/
@NonNull Iterable> assign(@NonNull Collection<@NonNull WeightedEdge> weightedEdges);
/**
* Finds the set of edges forming a matching that maximizes the sum of the edge weights.
* Vertexes are implicitly given through the edges. Vertexes without any edge cannot be passed and are ignored.
* It's up to the caller to handle such cases.
*
* @param weightedEdges the set of possible edges and their respective weights.
* @return the set of edges.
*/
default @NonNull Set> assignMaterialized(
final @NonNull Collection<@NonNull WeightedEdge> weightedEdges) {
return StreamUtil.stream(this.assign(weightedEdges)).collect(Collectors.toSet());
}
}