ch.epfl.lsir.xin.algorithm.baseline.ItemAverage.java Source code

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Here is the source code for ch.epfl.lsir.xin.algorithm.baseline.ItemAverage.java

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//Copyright (C) 2014  Xin Liu
//
//RecMe: a lightweight recommendation algorithm library
//
//RecMe is free software; you can redistribute it and/or
//modify it under the terms of the GNU General Public License
//as published by the Free Software Foundation; either version 2
//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.

/**
 * This class implements the algorithm which predicts a rating by averaging the 
 * corresponding item's past ratings.
 * 
 * @author Xin Liu
 * */

package ch.epfl.lsir.xin.algorithm.baseline;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;

import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.PropertiesConfiguration;

import ch.epfl.lsir.xin.algorithm.IAlgorithm;
import ch.epfl.lsir.xin.datatype.RatingMatrix;

public class ItemAverage implements IAlgorithm {

    /**
     * the rating matrix
     * */
    private RatingMatrix ratingMatrix = null;

    /**
     * Configuration file for parameter setting.
     * */
    public PropertiesConfiguration config = new PropertiesConfiguration();

    /**
     * logger of the system
     * */
    private PrintWriter logger = null;

    /**
     * constructor
     * @param: input dataset
     * */
    public ItemAverage(RatingMatrix ratingMatrix) {
        //set configuration file for parameter setting.
        config.setFile(new File(".//conf//ItemAverage.properties"));
        try {
            config.load();
        } catch (ConfigurationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        this.ratingMatrix = ratingMatrix;
    }

    /**
     * constructor
     * @param: training ratings
     * @param: read a saved model or not
     * @param: file of a saved model 
     * */
    public ItemAverage(RatingMatrix ratingMatrix, boolean readModel, String file) {
        //set configuration file for parameter setting.
        config.setFile(new File(".//conf//ItemAverage.properties"));
        try {
            config.load();
        } catch (ConfigurationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        this.ratingMatrix = ratingMatrix;
        if (readModel)//read model from a local file
        {
            readModel(file);
        }
    }

    /**
     * this function predicts a rating from a user to an item
     * */
    public double predict(int userIndex, int itemIndex) {
        double value = this.ratingMatrix.getItemMean(itemIndex);
        if (Double.isNaN(value)) {
            return this.ratingMatrix.getAverageRating();
        } else {
            return value;
        }
    }

    @Override
    public void saveModel(String file) {
        // TODO Auto-generated method stub
        //each line corresponds to each item
        try {
            PrintWriter printer = new PrintWriter(file);
            for (int i = 0; i < this.ratingMatrix.getItemsMean().size(); i++) {
                printer.println(this.ratingMatrix.getItemsMean().get(i));
            }
            printer.flush();
            printer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void readModel(String file) {
        // TODO Auto-generated method stub
        try {
            BufferedReader reader = new BufferedReader(new FileReader(file));
            String line = null;
            ArrayList<Double> itemsMean = new ArrayList<Double>();
            while ((line = reader.readLine()) != null) {
                itemsMean.add(Double.parseDouble(line.trim()));
            }
            this.ratingMatrix.setItemsMean(itemsMean);
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void build() {
        // TODO Auto-generated method stub
        this.ratingMatrix.calculateItemsMean();
    }

    /**
     * @return the config
     */
    public PropertiesConfiguration getConfig() {
        return config;
    }

    /**
     * @param config the config to set
     */
    public void setConfig(PropertiesConfiguration config) {
        this.config = config;
    }

    /**
     * @return the logger
     */
    public PrintWriter getLogger() {
        return logger;
    }

    /**
     * @param logger the logger to set
     */
    public void setLogger(PrintWriter logger) {
        this.logger = logger;
    }

}