com.cloudera.oryx.app.serving.als.MostPopularItems.java Source code

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Here is the source code for com.cloudera.oryx.app.serving.als.MostPopularItems.java

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/*
 * Copyright (c) 2014, Cloudera and Intel, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. licenses this file to you 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
 *
 * This software 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.cloudera.oryx.app.serving.als;

import java.util.List;
import java.util.Map;
import javax.ws.rs.DefaultValue;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.MediaType;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Ordering;

import com.cloudera.oryx.app.als.Rescorer;
import com.cloudera.oryx.app.als.RescorerProvider;
import com.cloudera.oryx.app.serving.OryxServingException;
import com.cloudera.oryx.common.collection.Pair;
import com.cloudera.oryx.common.collection.PairComparators;
import com.cloudera.oryx.app.serving.CSVMessageBodyWriter;
import com.cloudera.oryx.app.serving.IDCount;
import com.cloudera.oryx.app.serving.als.model.ALSServingModel;

/**
 * <p>Responds to a GET request to
 * {@code /mostPopularItems(?howMany=n)(&offset=o)(&rescorerParams=...)}</p>
 *
 * <p>Results are items that the most users have interacted with, as item and count pairs.</p>
 *
 * <p>{@code howMany} and {@code offset} behavior are as in {@link Recommend}. Output
 * is also the same, except that item IDs are returned with integer counts rather than
 * scores.</p>
 *
 * @see MostActiveUsers
 */
@Path("/mostPopularItems")
public final class MostPopularItems extends AbstractALSResource {

    @GET
    @Produces({ MediaType.TEXT_PLAIN, CSVMessageBodyWriter.TEXT_CSV, MediaType.APPLICATION_JSON })
    public List<IDCount> get(@DefaultValue("10") @QueryParam("howMany") int howMany,
            @DefaultValue("0") @QueryParam("offset") int offset,
            @QueryParam("rescorerParams") List<String> rescorerParams) throws OryxServingException {
        ALSServingModel model = getALSServingModel();
        RescorerProvider rescorerProvider = model.getRescorerProvider();
        Rescorer rescorer = null;
        if (rescorerProvider != null) {
            rescorer = rescorerProvider.getMostPopularItemsRescorer(rescorerParams);
        }
        return mapTopCountsToIDCounts(model.getItemCounts(), howMany, offset, rescorer);
    }

    static List<IDCount> mapTopCountsToIDCounts(Map<String, Integer> counts, int howMany, int offset,
            final Rescorer rescorer) {
        Iterable<Pair<String, Integer>> countPairs = Iterables.transform(counts.entrySet(),
                new Function<Map.Entry<String, Integer>, Pair<String, Integer>>() {
                    @Override
                    public Pair<String, Integer> apply(Map.Entry<String, Integer> input) {
                        return new Pair<>(input.getKey(), input.getValue());
                    }
                });

        if (rescorer != null) {
            countPairs = Iterables.filter(countPairs, new Predicate<Pair<String, Integer>>() {
                @Override
                public boolean apply(Pair<String, Integer> input) {
                    return !rescorer.isFiltered(input.getFirst());
                }
            });
        }

        List<Pair<String, Integer>> allTopCountPairs = Ordering.from(PairComparators.<Integer>bySecond())
                .greatestOf(countPairs, howMany + offset);
        List<Pair<String, Integer>> topCountPairs = selectedSublist(allTopCountPairs, howMany, offset);

        return Lists.transform(topCountPairs, new Function<Pair<String, Integer>, IDCount>() {
            @Override
            public IDCount apply(Pair<String, Integer> idCount) {
                return new IDCount(idCount.getFirst(), idCount.getSecond());
            }
        });
    }

}