net.myrrix.online.MultiRescorerProvider.java Source code

Introduction

Here is the source code for net.myrrix.online.MultiRescorerProvider.java

Source

/*
 * Copyright Myrrix Ltd
 *
 * 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 net.myrrix.online;

import java.util.List;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import org.apache.mahout.cf.taste.recommender.IDRescorer;
import org.apache.mahout.cf.taste.recommender.Rescorer;
import org.apache.mahout.common.LongPair;

import net.myrrix.common.MyrrixRecommender;

/**
 * Convenience implementation that will aggregate the behavior of multiple {@link RescorerProvider}s.
 * It will filter an item if any of the given instances filter it, and will rescore by applying
 * the rescorings in the given order.
 *
 * @author Sean Owen
 * @since 1.0
 * @see MultiRescorer
 * @see MultiLongPairRescorer
 */
public final class MultiRescorerProvider extends AbstractRescorerProvider {

    private final RescorerProvider[] providers;

    public MultiRescorerProvider(RescorerProvider... providers) {
        Preconditions.checkNotNull(providers);
        Preconditions.checkArgument(providers.length > 0, "providers is empty");
        this.providers = providers;
    }

    public MultiRescorerProvider(List<RescorerProvider> providers) {
        Preconditions.checkNotNull(providers);
        Preconditions.checkArgument(!providers.isEmpty());
        this.providers = providers.toArray(new RescorerProvider[providers.size()]);
    }

    @Override
    public IDRescorer getRecommendRescorer(long[] userIDs, MyrrixRecommender recommender, String... args) {
        List<IDRescorer> rescorers = Lists.newArrayListWithCapacity(providers.length);
        for (RescorerProvider provider : providers) {
            IDRescorer rescorer = provider.getRecommendRescorer(userIDs, recommender, args);
            if (rescorer != null) {
                rescorers.add(rescorer);
            }
        }
        return buildRescorer(rescorers);
    }

    @Override
    public IDRescorer getRecommendToAnonymousRescorer(long[] itemIDs, MyrrixRecommender recommender,
            String... args) {
        List<IDRescorer> rescorers = Lists.newArrayListWithCapacity(providers.length);
        for (RescorerProvider provider : providers) {
            IDRescorer rescorer = provider.getRecommendToAnonymousRescorer(itemIDs, recommender, args);
            if (rescorer != null) {
                rescorers.add(rescorer);
            }
        }
        return buildRescorer(rescorers);
    }

    @Override
    public IDRescorer getMostPopularItemsRescorer(MyrrixRecommender recommender, String... args) {
        List<IDRescorer> rescorers = Lists.newArrayListWithCapacity(providers.length);
        for (RescorerProvider provider : providers) {
            IDRescorer rescorer = provider.getMostPopularItemsRescorer(recommender, args);
            if (rescorer != null) {
                rescorers.add(rescorer);
            }
        }
        return buildRescorer(rescorers);
    }

    private static IDRescorer buildRescorer(List<IDRescorer> rescorers) {
        int numRescorers = rescorers.size();
        if (numRescorers == 0) {
            return null;
        }
        if (numRescorers == 1) {
            return rescorers.get(0);
        }
        return new MultiRescorer(rescorers);
    }

    @Override
    public Rescorer<LongPair> getMostSimilarItemsRescorer(MyrrixRecommender recommender, String... args) {
        List<Rescorer<LongPair>> rescorers = Lists.newArrayListWithCapacity(providers.length);
        for (RescorerProvider provider : providers) {
            Rescorer<LongPair> rescorer = provider.getMostSimilarItemsRescorer(recommender, args);
            if (rescorer != null) {
                rescorers.add(rescorer);
            }
        }
        int numRescorers = rescorers.size();
        if (numRescorers == 0) {
            return null;
        }
        if (numRescorers == 1) {
            return rescorers.get(0);
        }
        return new MultiLongPairRescorer(rescorers);
    }

}