org.apache.mahout.cf.taste.hadoop.ToEntityPrefsMapper.java Source code

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Here is the source code for org.apache.mahout.cf.taste.hadoop.ToEntityPrefsMapper.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 org.apache.mahout.cf.taste.hadoop;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.mahout.cf.taste.hadoop.item.RecommenderJob;
import org.apache.mahout.math.VarLongWritable;

import java.io.IOException;
import java.util.regex.Pattern;

public abstract class ToEntityPrefsMapper extends Mapper<LongWritable, Text, VarLongWritable, VarLongWritable> {

    public static final String TRANSPOSE_USER_ITEM = ToEntityPrefsMapper.class + "transposeUserItem";
    public static final String RATING_SHIFT = ToEntityPrefsMapper.class + "shiftRatings";

    private static final Pattern DELIMITER = Pattern.compile("[\t,]");

    private boolean booleanData;
    private boolean transpose;
    private final boolean itemKey;
    private float ratingShift;

    ToEntityPrefsMapper(boolean itemKey) {
        this.itemKey = itemKey;
    }

    @Override
    protected void setup(Context context) {
        Configuration jobConf = context.getConfiguration();
        booleanData = jobConf.getBoolean(RecommenderJob.BOOLEAN_DATA, false);
        transpose = jobConf.getBoolean(TRANSPOSE_USER_ITEM, false);
        ratingShift = Float.parseFloat(jobConf.get(RATING_SHIFT, "0.0"));
    }

    @Override
    public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
        String[] tokens = DELIMITER.split(value.toString());
        long userID = Long.parseLong(tokens[0]);
        long itemID = Long.parseLong(tokens[1]);
        if (itemKey ^ transpose) {
            // If using items as keys, and not transposing items and users, then users are items!
            // Or if not using items as keys (users are, as usual), but transposing items and users,
            // then users are items! Confused?
            long temp = userID;
            userID = itemID;
            itemID = temp;
        }
        if (booleanData) {
            context.write(new VarLongWritable(userID), new VarLongWritable(itemID));
        } else {
            float prefValue = tokens.length > 2 ? Float.parseFloat(tokens[2]) + ratingShift : 1.0f;
            context.write(new VarLongWritable(userID), new EntityPrefWritable(itemID, prefValue));
        }
    }

}