Java tutorial
/* * Seldon -- open source prediction engine * ======================================= * * Copyright 2011-2015 Seldon Technologies Ltd and Rummble Ltd (http://www.seldon.io/) * * ******************************************************************************************** * * 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 io.seldon.recommendation.baseline.jdo; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.Map; import java.util.Set; import javax.jdo.Query; import io.seldon.db.jdo.ClientPersistable; import io.seldon.recommendation.baseline.IBaselineRecommenderUtils; import org.apache.commons.lang.StringUtils; public class SqlBaselineRecommenderUtils extends ClientPersistable implements IBaselineRecommenderUtils { public SqlBaselineRecommenderUtils(String clientName) { super(clientName); } @Override public Map<Long, Double> getPopularItems(int dimension, int numRecommendations) { String sql = "select ip.item_id,opsum from items_popular ip join item_map_enum ime on (ip.item_id=ime.item_id) join dimension d on (ime.attr_id=d.attr_id and ime.value_id=d.value_id) where dim_id=? order by opsum desc limit " + numRecommendations; Query query = getPM().newQuery("javax.jdo.query.SQL", sql); ArrayList<Object> args = new ArrayList<>(); args.add(dimension); Collection<Object[]> results = (Collection<Object[]>) query.executeWithArray(args.toArray()); Map<Long, Double> map = new HashMap<>(); Double topScore = null; for (Object[] res : results) { if (topScore == null) topScore = (Double) res[1]; Long item = (Long) res[0]; Double score = (Double) res[1]; map.put(item, score / topScore); } query.closeAll(); return map; } @Override public Map<Long, Double> reorderByMostPopular(Set<Long> itemIds) { String idStr = StringUtils.join(itemIds, ","); String sql = "select ip.item_id,opsum from items_popular where item_id in (" + idStr + ") order by opsum desc"; Query query = getPM().newQuery("javax.jdo.query.SQL", sql); Collection<Object[]> results = (Collection<Object[]>) query.execute(); Map<Long, Double> map = new HashMap<>(); Double topScore = null; for (Object[] res : results) { if (topScore == null) topScore = (Double) res[1]; Long item = (Long) res[0]; Double score = (Double) res[1]; map.put(item, score / topScore); } query.closeAll(); return map; } @Override public Map<Long, Double> getAllItemPopularity() { String sql = "select item_id,opsum from items_popular order by opsum desc"; Query query = getPM().newQuery("javax.jdo.query.SQL", sql); Collection<Object[]> results = (Collection<Object[]>) query.execute(); Map<Long, Double> map = new HashMap<>(); Double topScore = null; for (Object[] res : results) { if (topScore == null) topScore = (Double) res[1]; Long item = (Long) res[0]; Double score = (Double) res[1]; map.put(item, score / topScore); } query.closeAll(); return map; } }