com.github.rinde.rinsim.central.RandomSolver.java Source code

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Here is the source code for com.github.rinde.rinsim.central.RandomSolver.java

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/*
 * Copyright (C) 2011-2016 Rinde van Lon, iMinds-DistriNet, KU Leuven
 *
 * 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.
 */
package com.github.rinde.rinsim.central;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.Lists.newArrayList;
import static com.google.common.collect.Sets.newLinkedHashSet;

import java.util.Collections;
import java.util.List;
import java.util.Set;

import org.apache.commons.math3.random.MersenneTwister;
import org.apache.commons.math3.random.RandomAdaptor;
import org.apache.commons.math3.random.RandomGenerator;

import com.github.rinde.rinsim.central.GlobalStateObject.VehicleStateObject;
import com.github.rinde.rinsim.core.model.pdp.Parcel;
import com.github.rinde.rinsim.util.StochasticSupplier;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.LinkedListMultimap;

/**
 * A {@link Solver} that constructs random solutions. For each order it first
 * randomly selects a vehicle. When all orders are assigned to a vehicle the
 * ordering of the pickups and deliveries is shuffled randomly.
 *
 * @author Rinde van Lon
 */
public final class RandomSolver implements Solver {
    private final RandomGenerator randomGenerator;

    RandomSolver(RandomGenerator rng) {
        randomGenerator = rng;
    }

    @Override
    public ImmutableList<ImmutableList<Parcel>> solve(GlobalStateObject state) {
        checkArgument(!state.getVehicles().isEmpty(), "Need at least one vehicle.");
        final LinkedListMultimap<VehicleStateObject, Parcel> map = LinkedListMultimap.create();

        final Set<Parcel> available = newLinkedHashSet(state.getAvailableParcels());
        final Set<Parcel> destinations = newLinkedHashSet();
        for (final VehicleStateObject vso : state.getVehicles()) {
            destinations.addAll(vso.getDestination().asSet());
        }
        available.removeAll(destinations);

        // do random assignment of available parcels
        for (final Parcel p : available) {
            final int index = randomGenerator.nextInt(state.getVehicles().size());
            map.put(state.getVehicles().get(index), p);
            map.put(state.getVehicles().get(index), p);
        }

        final ImmutableList.Builder<ImmutableList<Parcel>> builder = ImmutableList.builder();
        // insert contents, shuffle ordering, insert destination if applicable
        for (final VehicleStateObject vso : state.getVehicles()) {
            final List<Parcel> assigned = newArrayList(map.get(vso));
            final List<Parcel> conts = newArrayList(vso.getContents());
            conts.removeAll(vso.getDestination().asSet());
            assigned.addAll(conts);
            if (vso.getDestination().isPresent()
                    && state.getAvailableParcels().contains(vso.getDestination().get())) {
                assigned.add(vso.getDestination().get());
            }
            Collections.shuffle(assigned, new RandomAdaptor(randomGenerator));
            if (vso.getDestination().isPresent()) {
                assigned.add(0, vso.getDestination().get());
            }
            builder.add(ImmutableList.copyOf(assigned));
        }
        return builder.build();
    }

    /**
     * Creates a new {@link RandomSolver} with the specified random seed.
     * @param seed The random seed.
     * @return A new random solver instance.
     */
    public static Solver create(long seed) {
        return new RandomSolver(new MersenneTwister(seed));
    }

    /**
     * @return A {@link StochasticSupplier} for {@link RandomSolver} instances.
     */
    public static StochasticSupplier<Solver> supplier() {
        return RandomSolverSupplier.INSTANCE;
    }

    enum RandomSolverSupplier implements StochasticSupplier<Solver> {
        INSTANCE {
            @Override
            public Solver get(long seed) {
                return create(seed);
            }

            @Override
            public String toString() {
                return RandomSolver.class.getSimpleName() + ".supplier()";
            }
        }
    }
}