RandomWalkJava.java Source code

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Here is the source code for RandomWalkJava.java

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/*
* Copyright 2014 Twitter, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this
* file except in compliance with the License. You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed
* under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
* CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*/

/**
 * The Java version of the RandomWalk example.
 */

import com.google.common.base.Functions;
import com.google.common.collect.Ordering;
import com.twitter.cassovary.graph.DirectedGraph;
import com.twitter.cassovary.graph.DirectedPath;
import com.twitter.cassovary.graph.GraphDir;
import com.twitter.cassovary.graph.GraphUtils;
import com.twitter.cassovary.graph.GraphUtils.RandomWalkParams;
import com.twitter.cassovary.graph.StoredGraphDir;
import com.twitter.cassovary.graph.TestGraphs;
import com.twitter.util.Duration;
import it.unimi.dsi.fastutil.ints.Int2IntMap;
import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
import it.unimi.dsi.fastutil.objects.Object2IntMap;
import java.lang.Integer;
import java.lang.System;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import scala.Option;
import scala.Tuple2;

public class RandomWalkJava {

    public static void main(String[] args) {
        int numNodes = 3;
        if (args.length > 0)
            numNodes = Integer.parseInt(args[0]);
        System.out.printf("Generating a random graph with %d nodes...\n", numNodes);
        DirectedGraph graph = TestGraphs.generateRandomGraph(numNodes,
                TestGraphs.getProbEdgeRandomDirected(numNodes, Math.min(10, numNodes)), StoredGraphDir.BothInOut());
        System.out.printf("Generated a random directed graph with %s nodes and %s edges.\n", graph.nodeCount(),
                graph.edgeCount());

        // Generate walk parameters
        long numSteps = 1000 * 1000;
        final scala.Option<Object> wpNone = scala.Option.apply(null);
        final scala.Option<Object> wpTwo = scala.Option.apply((Object) 2);
        RandomWalkParams walkParams = new RandomWalkParams(numSteps, 0.1, wpNone, wpTwo, wpNone, false,
                GraphDir.OutDir(), false, false);
        GraphUtils graphUtils = new GraphUtils(graph);

        // Do the walk and measure how long it took
        System.out.printf("Now doing a random walk of %s steps from Node 0...\n", numSteps);
        long startTime = System.nanoTime();
        Tuple2<Int2IntMap, scala.Option<Int2ObjectMap<Object2IntMap<DirectedPath>>>> lm = graphUtils
                .calculatePersonalizedReputation(0, walkParams);
        long endTime = System.nanoTime();
        Int2IntMap neighbors = lm._1;
        System.out.printf("Random walk visited %s nodes in %s ms:\n", neighbors.size(),
                (endTime - startTime) / 1000000);

        // Sort neighbors (or nodes) in descending number of visits and take the top 10 neighbors
        List<Integer> topNeighbors = Ordering.natural().onResultOf(Functions.forMap(neighbors)).reverse()
                .immutableSortedCopy(neighbors.keySet());

        if (topNeighbors.size() > 10)
            topNeighbors = topNeighbors.subList(0, 10);

        // Print the top 10 neighbors (and paths)
        System.out.printf("%8s%10s\t%s\n", "NodeID", "#Visits", "Top 2 Paths with counts");
        for (int id : topNeighbors) {
            int numVisits = neighbors.get(id);
            System.out.printf("%8s%10s\t", id, numVisits);
            if (lm._2.isDefined()) { // If Option is not None
                Object2IntMap<DirectedPath> paths = lm._2.get().get(id);
                int remaining = paths.size();
                for (Map.Entry<DirectedPath, Integer> ef : paths.entrySet()) {
                    // Print a directed path and #visits along that path
                    int[] nodes = ef.getKey().nodes();
                    for (int i = 0; i < nodes.length; i++) {
                        if (i != 0)
                            System.out.printf("->%d", nodes[i]);
                        else
                            System.out.printf("%d", nodes[i]);
                    }
                    System.out.printf(" (%d)", ef.getValue());
                    if (remaining > 1)
                        System.out.printf(" | ");
                    remaining--;
                }
            }
            System.out.println();
        }
    }
}