com.recsys.factorizer.CustomAbstractFactorizer.java Source code

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Here is the source code for com.recsys.factorizer.CustomAbstractFactorizer.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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
 *
 * 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.recsys.factorizer;

import java.util.Collection;
import java.util.concurrent.Callable;

import org.apache.mahout.cf.taste.common.Refreshable;
import org.apache.mahout.cf.taste.common.TasteException;
import org.apache.mahout.cf.taste.impl.common.FastByIDMap;
import org.apache.mahout.cf.taste.impl.common.LongPrimitiveIterator;
import org.apache.mahout.cf.taste.impl.common.RefreshHelper;
import org.apache.mahout.cf.taste.impl.recommender.svd.Factorization;
import org.apache.mahout.cf.taste.impl.recommender.svd.Factorizer;
import org.apache.mahout.cf.taste.model.DataModel;

/**
 * base class for {@link Factorizer}s, provides ID to index mapping
 */
public abstract class CustomAbstractFactorizer implements Factorizer {

    private final DataModel dataModel;
    private FastByIDMap<Integer> userIDMapping;
    private FastByIDMap<Integer> itemIDMapping;
    private final RefreshHelper refreshHelper;

    protected CustomAbstractFactorizer(DataModel dataModel) throws TasteException {
        this.dataModel = dataModel;
        buildMappings();
        refreshHelper = new RefreshHelper(new Callable<Object>() {
            @Override
            public Object call() throws TasteException {
                buildMappings();
                return null;
            }
        });
        refreshHelper.addDependency(dataModel);
    }

    private void buildMappings() throws TasteException {
        userIDMapping = createIDMapping(dataModel.getNumUsers(), dataModel.getUserIDs());
        itemIDMapping = createIDMapping(dataModel.getNumItems(), dataModel.getItemIDs());
    }

    protected Factorization createFactorization(double[][] userFeatures, double[][] itemFeatures) {
        return new Factorization(userIDMapping, itemIDMapping, userFeatures, itemFeatures);
    }

    protected Factorization createUpdatedFactorization(double[][] userFeatures, double[][] itemFeatures,
            long newItem) {
        itemIDMapping.put(newItem, itemIDMapping.size());
        return new Factorization(userIDMapping, itemIDMapping, userFeatures, itemFeatures);
    }

    protected Integer userIndex(long userID) {
        Integer userIndex = userIDMapping.get(userID);
        if (userIndex == null) {
            userIndex = userIDMapping.size();
            userIDMapping.put(userID, userIndex);
        }
        return userIndex;
    }

    protected Integer itemIndex(long itemID) {
        Integer itemIndex = itemIDMapping.get(itemID);
        if (itemIndex == null) {
            itemIndex = itemIDMapping.size();
            itemIDMapping.put(itemID, itemIndex);
        }
        return itemIndex;
    }

    private static FastByIDMap<Integer> createIDMapping(int size, LongPrimitiveIterator idIterator) {
        FastByIDMap<Integer> mapping = new FastByIDMap<Integer>(size);
        int index = 0;
        while (idIterator.hasNext()) {
            mapping.put(idIterator.nextLong(), index++);
        }
        return mapping;
    }

    @Override
    public void refresh(Collection<Refreshable> alreadyRefreshed) {
        refreshHelper.refresh(alreadyRefreshed);
    }

}