Java tutorial
/* * LensKit, an open source recommender systems toolkit. * Copyright 2010-2014 LensKit Contributors. See CONTRIBUTORS.md. * Work on LensKit has been funded by the National Science Foundation under * grants IIS 05-34939, 08-08692, 08-12148, and 10-17697. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more * details. * * You should have received a copy of the GNU General Public License along with * this program; if not, write to the Free Software Foundation, Inc., 51 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ package org.grouplens.lenskit.cli; import com.google.common.base.Stopwatch; import net.sourceforge.argparse4j.impl.Arguments; import net.sourceforge.argparse4j.inf.ArgumentParser; import net.sourceforge.argparse4j.inf.Namespace; import org.grouplens.lenskit.ItemRecommender; import org.grouplens.lenskit.RecommenderBuildException; import org.grouplens.lenskit.core.*; import org.grouplens.lenskit.scored.ScoredId; import org.grouplens.lenskit.symbols.Symbol; import org.grouplens.lenskit.util.io.LKFileUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.util.List; import java.util.zip.GZIPInputStream; /** * Generate Top-N recommendations for users. * * @since 2.1 * @author <a href="http://www.grouplens.org">GroupLens Research</a> */ @CommandSpec(name = "recommend", help = "generate recommendations for users") public class Recommend implements Command { private final Logger logger = LoggerFactory.getLogger(Recommend.class); private final Namespace options; private final InputData input; private final ScriptEnvironment environment; public Recommend(Namespace opts) { options = opts; input = new InputData(opts); environment = new ScriptEnvironment(opts); } @Override public void execute() throws IOException, RecommenderBuildException { LenskitRecommenderEngine engine = loadEngine(); List<Long> users = options.get("users"); final int n = options.getInt("num_recs"); LenskitRecommender rec = engine.createRecommender(); ItemRecommender irec = rec.getItemRecommender(); if (irec == null) { logger.error("recommender has no item recommender"); throw new UnsupportedOperationException("no item recommender"); } logger.info("recommending for {} users", users.size()); Symbol pchan = getPrintChannel(); Stopwatch timer = Stopwatch.createStarted(); for (long user : users) { List<ScoredId> recs = irec.recommend(user, n); System.out.format("recommendations for user %d:\n", user); for (ScoredId item : recs) { System.out.format(" %d: %.3f", item.getId(), item.getScore()); if (pchan != null && item.hasUnboxedChannel(pchan)) { System.out.format(" (%f)", item.getUnboxedChannelValue(pchan)); } System.out.println(); } } timer.stop(); logger.info("recommended for {} users in {}", users.size(), timer); } private LenskitRecommenderEngine loadEngine() throws RecommenderBuildException, IOException { File modelFile = options.get("model_file"); if (modelFile == null) { logger.info("creating fresh recommender"); LenskitRecommenderEngineBuilder builder = LenskitRecommenderEngine.newBuilder(); for (LenskitConfiguration config : environment.loadConfigurations(getConfigFiles())) { builder.addConfiguration(config); } builder.addConfiguration(input.getConfiguration()); Stopwatch timer = Stopwatch.createStarted(); LenskitRecommenderEngine engine = builder.build(); timer.stop(); logger.info("built recommender in {}", timer); return engine; } else { logger.info("loading recommender from {}", modelFile); LenskitRecommenderEngineLoader loader = LenskitRecommenderEngine.newLoader(); for (LenskitConfiguration config : environment.loadConfigurations(getConfigFiles())) { loader.addConfiguration(config); } loader.addConfiguration(input.getConfiguration()); Stopwatch timer = Stopwatch.createStarted(); LenskitRecommenderEngine engine; InputStream input = new FileInputStream(modelFile); try { if (LKFileUtils.isCompressed(modelFile)) { input = new GZIPInputStream(input); } engine = loader.load(input); } finally { input.close(); } timer.stop(); logger.info("loaded recommender in {}", timer); return engine; } } List<File> getConfigFiles() { return options.getList("config_file"); } Symbol getPrintChannel() { String name = options.get("print_channel"); if (name == null) { return null; } else { return Symbol.of(name); } } public static void configureArguments(ArgumentParser parser) { InputData.configureArguments(parser); ScriptEnvironment.configureArguments(parser); parser.addArgument("-n", "--num-recs").type(Integer.class).setDefault(10).metavar("N") .help("generate up to N recommendations per user"); parser.addArgument("-c", "--config-file").type(File.class).action(Arguments.append()).metavar("FILE") .help("use configuration from FILE"); parser.addArgument("-m", "--model-file").type(File.class).metavar("FILE").help("load model from FILE"); parser.addArgument("--print-channel").metavar("CHAN").help("also print value from CHAN"); parser.addArgument("users").type(Long.class).nargs("+").metavar("USER").help("recommend for USERS"); } }