/*
* Sifarish: Recommendation Engine
* Author: Pranab Ghosh
*
* 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 org.sifarish.common;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.ToolRunner;
import org.chombo.mr.Transformer;
import org.chombo.redis.RedisCache;
/**
* Item novelty aggregated over all users. Novelty has an inverse relationship with user's engagement
* with an item. Input: itemID, rating, rating distr
* @author pranab
*
*/
public class GlobalNovelty extends Transformer {
@Override
public int run(String[] args) throws Exception {
return start("Global novelty MR", GlobalNovelty.class, GlobalNovelty.NoveltyMapper.class, args);
}
/**
* @author pranab
*
*/
public static class NoveltyMapper extends Transformer.TransformerMapper {
/* (non-Javadoc)
* @see org.chombo.mr.Transformer.TransformerMapper#setup(org.apache.hadoop.mapreduce.Mapper.Context)
*/
protected void setup(Context context) throws IOException, InterruptedException {
super.setup(context);
Configuration config = context.getConfiguration();
String strategy = config.get("gln.novelty.gen.strategy", "selfInformation");
int maxRating = config.getInt("gln.rating.scale", 100);
RedisCache cache = RedisCache.createRedisCache(config, "ch");
if (strategy.equals("selfInformation")) {
//based on rating distribution
String countMaxValueKeyPrefix = config.get("gln.count.max.value.key.prefix");
int engaementDistrScale = cache.getIntMax(countMaxValueKeyPrefix);
registerTransformers(1, new Transformer.NullTransformer());
registerTransformers(2, new IndividualNovelty.SelfInformation(engaementDistrScale, maxRating));
} else if (strategy.equals("nonLinearInverse")) {
//based on rating
double param = config.getFloat("gln.quadratic.param", (float) 0.8);
String ratingMaxValueKeyPrefix = config.get("gln.rating.max.value.key.prefix");
int maxRatingInData = cache.getIntMax(ratingMaxValueKeyPrefix);
registerTransformers(1, new IndividualNovelty.NonLinearInverse(maxRating, param, maxRatingInData));
registerTransformers(2, new Transformer.NullTransformer());
}
}
}
/**
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
int exitCode = ToolRunner.run(new GlobalNovelty(), args);
System.exit(exitCode);
}
}