info.debatty.java.graphs.build.Brute Maven / Gradle / Ivy

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Algorithms that build k-nearest neighbors graph (k-nn graph): Brute-force, NN-Descent,...

There is a newer version: 0.41

package info.debatty.java.graphs.build;

import info.debatty.java.graphs.Graph;
import info.debatty.java.graphs.Neighbor;
import info.debatty.java.graphs.NeighborList;
import info.debatty.java.graphs.Node;
import java.util.HashMap;
import java.util.List;

/**
 *
 * @author Thibault Debatty
 */
public class Brute extends GraphBuilder {
    
    @Override
    protected Graph _computeGraph(List> nodes) {
        
        int n = nodes.size();
        
        // Initialize all NeighborLists
        Graph graph = new Graph(n);
        for (Node node : nodes) {
            graph.put(node, new NeighborList(k));
        }
        
        computed_similarities = 0;
        double sim;
        Node n1;
        Node n2;
        HashMap data = new HashMap();
        
        for (int i = 0; i < n; i++) {
            
            n1 = nodes.get(i);
            for (int j = 0; j < i; j++) {
                n2 = nodes.get(j);
                sim = similarity.similarity((t) n1.value, (t) n2.value);
                computed_similarities++;
                
                graph.get(n1).add(new Neighbor(n2, sim));
                graph.get(n2).add(new Neighbor(n1, sim));
            }
            
            if (callback != null) {
                data.put("node_id", n1.id);
                data.put("computed_similarities", computed_similarities);
                callback.call(data);
                
            }
        }
        
        return graph;
    }
}