/*
* 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.item;
import java.io.IOException;
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.TasteHadoopUtils;
import org.apache.mahout.cf.taste.hadoop.ToEntityPrefsMapper;
import org.apache.mahout.math.VarIntWritable;
import org.apache.mahout.math.VarLongWritable;
public final class ItemIDIndexMapper extends
Mapper<LongWritable,Text, VarIntWritable, VarLongWritable> {
private boolean transpose;
@Override
protected void setup(Context context) {
Configuration jobConf = context.getConfiguration();
transpose = jobConf.getBoolean(ToEntityPrefsMapper.TRANSPOSE_USER_ITEM, false);
}
@Override
protected void map(LongWritable key,
Text value,
Context context) throws IOException, InterruptedException {
String[] tokens = TasteHadoopUtils.splitPrefTokens(value.toString());
long itemID = Long.parseLong(tokens[transpose ? 0 : 1]);
int index = TasteHadoopUtils.idToIndex(itemID);
context.write(new VarIntWritable(index), new VarLongWritable(itemID));
}
}