renamed to MaximumIntegerWeightBipartiteAuctionMatching

src/main/java/MaximumWeightBipartiteAuctionMatching.java

@@ -1,145 +0,0 @@
-import org.jgrapht.Graph;
-import org.jgrapht.GraphTests;
-import org.jgrapht.alg.interfaces.MatchingAlgorithm;
-
-import java.math.BigDecimal;
-import java.util.*;
-
-/*
-Maximum weight matching in bipartite graphs with strictly integer edge weights, found using the
-unscaled forward auction algorithm
- */
-
-public class MaximumWeightBipartiteAuctionMatching<V, E> implements MatchingAlgorithm<V, E> {
-
-    private final Graph<V, E> graph;
-    private final Set<V> partition1;
-    private final Set<V> partition2;
-    private final BigDecimal delta;
-    private final Set<E> matching;
-    private BigDecimal matchingWeight;
-    private boolean swappedPartitions = false;
-
-    public MaximumWeightBipartiteAuctionMatching(Graph<V, E> graph, Set<V> partition1, Set<V> partition2) {
-        this.graph = GraphTests.requireUndirected(graph);
-        this.partition1 = Objects.requireNonNull(partition1, "Partition 1 cannot be null");
-        this.partition2 = Objects.requireNonNull(partition2, "Partition 2 cannot be null");
-        int n = Math.max(partition1.size(), partition2.size());
-        this.delta = BigDecimal.valueOf(1 / ((double) n + 1));
-//        this.delta = BigDecimal.valueOf(n/2);
-        this.matching = new LinkedHashSet<>();
-        this.matchingWeight = BigDecimal.ZERO;
-    }
-
-
-    /*
-    Method coded using MaximumWeightBipartiteMatching.class from JgraphT as a model
-     */
-    @Override
-    public Matching<V, E> getMatching() {
-
-        /*
-         * Test input instance
-         */
-        if (!GraphTests.isSimple(graph)) {
-            throw new IllegalArgumentException("Only simple graphs supported");
-        }
-        if (!GraphTests.isBipartitePartition(graph, partition1, partition2)) {
-            throw new IllegalArgumentException("Graph partition is not bipartite");
-        }
-
-        /*
-        If the two partitions are different sizes, the bidders must be the smaller of the two partitions.
-         */
-        Set<V> items;
-        Set<V> bidders;
-        if (partition2.size() >= partition1.size()) {
-            bidders = partition1;
-            items = partition2;
-        }
-        else {
-            bidders = partition2;
-            items = partition1;
-            swappedPartitions = true;
-        }
-
-        /*
-        Create a map to track the owner of each item, which is initially null,
-        and a map to track the price of each item, which is initially 0.
-         */
-        Map<V, V> owners = new HashMap<>();
-        Map<V, BigDecimal> prices = new HashMap<>();
-        for(V item: items) {
-            owners.put(item, null);
-            prices.put(item, BigDecimal.ZERO);
-        }
-
-        //Initialize queue of all bidders that don't currently own an item
-        Queue<V> unmatchedBidders = new ArrayDeque<>();
-        for(V bidder: bidders) {
-            unmatchedBidders.offer(bidder);
-        }
-
-        while (unmatchedBidders.size() > 0) {
-            V bidder = unmatchedBidders.poll();
-            V item = null;
-            BigDecimal bestValue = BigDecimal.valueOf(-1.0);
-            //find the item that offers the best value for this bidder
-            for (E edge: graph.edgesOf(bidder)) {
-                double weight = graph.getEdgeWeight(edge);
-                if(weight == 0.0) {
-                    continue;
-                }
-                V tmp = getItem(bidder, edge);
-                BigDecimal value = BigDecimal.valueOf(weight).subtract(prices.get(tmp));
-                if (value.compareTo(bestValue) >= 0) {
-                    bestValue = value;
-                    item = tmp;
-                }
-            }
-            if(bestValue.compareTo(BigDecimal.ZERO) >= 0) {
-                V formerOwner = owners.get(item);
-                BigDecimal formerPrice = prices.get(item);
-                if (formerOwner != null) {
-                    unmatchedBidders.offer(formerOwner);
-                }
-                owners.put(item, bidder);
-                prices.put(item, formerPrice.add(delta));
-            }
-        }
-        for (V item: owners.keySet()) {
-            if (owners.get(item) != null) {
-                matching.add(graph.getEdge(item, owners.get(item)));
-            }
-        }
-
-        for(E edge: matching) {
-            this.matchingWeight = this.matchingWeight.add(BigDecimal.valueOf(graph.getEdgeWeight(edge)));
-        }
-
-
-        return new MatchingImpl<>(graph, matching, matchingWeight.doubleValue());
-    }
-
-    private V getItem(V bidder, E edge) {
-        if (swappedPartitions) {
-            return graph.getEdgeSource(edge);
-        }
-        else {
-            return graph.getEdgeTarget(edge);
-        }
-    }
-
-    private V getBidder(V item, E edge) {
-        if (swappedPartitions) {
-            return graph.getEdgeTarget(edge);
-        }
-        else {
-            return graph.getEdgeSource(edge);
-        }
-    }
-
-    public BigDecimal getMatchingWeight() {
-        return matchingWeight;
-    }
-}