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Neo4j Graph Data Science :: Procedures :: Centrality

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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.gds.pagerank;

import org.neo4j.gds.api.IdMap;
import org.neo4j.gds.common.CentralityStreamResult;
import org.neo4j.gds.executor.AlgorithmSpec;
import org.neo4j.gds.executor.ComputationResultConsumer;
import org.neo4j.gds.executor.ExecutionContext;
import org.neo4j.gds.executor.GdsCallable;
import org.neo4j.gds.executor.NewConfigFunction;

import java.util.stream.LongStream;
import java.util.stream.Stream;

import static org.neo4j.gds.LoggingUtil.runWithExceptionLogging;
import static org.neo4j.gds.executor.ExecutionMode.STREAM;
import static org.neo4j.gds.pagerank.PageRankProcCompanion.PAGE_RANK_DESCRIPTION;

@GdsCallable(name = "gds.pageRank.stream", description = PAGE_RANK_DESCRIPTION, executionMode = STREAM)
public class PageRankStreamSpec implements AlgorithmSpec,PageRankAlgorithmFactory> {

    @Override
    public String name() {
        return "PageRankStream";
    }

    @Override
    public PageRankAlgorithmFactory algorithmFactory(ExecutionContext executionContext) {
        return new PageRankAlgorithmFactory<>();
    }

    @Override
    public NewConfigFunction newConfigFunction() {
        return (___,config) -> PageRankStreamConfig.of(config);
    }

    @Override
    public ComputationResultConsumer> computationResultConsumer() {
        return (computationResult, executionContext) -> runWithExceptionLogging(
            "Result streaming failed",
            executionContext.log(),
            () -> computationResult.result()
                .map(result -> {
                    var graph = computationResult.graph();
                    var scores = result.scores();
                    return LongStream.range(IdMap.START_NODE_ID, graph.nodeCount())
                        .mapToObj(nodeId -> new CentralityStreamResult(
                            graph.toOriginalNodeId(nodeId),
                            scores.get(nodeId)
                        ));
                }).orElseGet(Stream::empty)
        );
    }
}