boostingPL.boosting.InstancesHelper.java Source code

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Here is the source code for boostingPL.boosting.InstancesHelper.java

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/*
 *   BoostingPL - Scalable and Parallel Boosting with MapReduce 
 *   Copyright (C) 2012  Ranler Cao  findfunaax@gmail.com
 *
 *   This program 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 3 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, see <http://www.gnu.org/licenses/>.   
 */

package boostingPL.boosting;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.util.LineReader;

import weka.core.Attribute;
import weka.core.DenseInstance;
import weka.core.Instance;
import weka.core.Instances;

public class InstancesHelper {

    public static Instance createInstance(String text, Instances insts) {
        // numeric attributes
        String[] items = text.split(",");
        double[] ds = new double[items.length];
        for (int i = 0; i < ds.length - 1; i++) {
            ds[i] = Double.parseDouble(items[i]);
        }

        // nominal class attribute
        ds[items.length - 1] = insts.classAttribute().indexOfValue(items[items.length - 1]);

        Instance inst = new DenseInstance(1, ds);
        inst.setDataset(insts);
        return inst;
    }

    /**
     * create instances header from metadata,
     * the metadata like this:
     * 
     *   <br/>
     *   <p>attributesNum:100</p>
     *   <p>classes:+1,-1</p>
     *   <br/>
     * 
     * @param in
     * @return
     * @throws IOException
     */
    public static Instances createInstancesFromMetadata(LineReader in) throws IOException {
        int attributesNum = 0;
        ArrayList<Attribute> attInfo = null;
        List<String> classItems = null;

        Text line = new Text();
        while (in.readLine(line) > 0) {
            String sline = line.toString();
            if (sline.startsWith("attributesNum:")) {
                attributesNum = Integer.parseInt(sline.substring(14));
                attInfo = new ArrayList<Attribute>(attributesNum + 1);
                for (int i = 0; i < attributesNum; i++) {
                    attInfo.add(new Attribute("attr" + i));
                }

                System.out.println("AttributeNum:" + attributesNum);
            } else if (sline.startsWith("classes:")) {
                String classes = sline.substring(8);
                String[] citems = classes.split(",");
                classItems = new ArrayList<String>(citems.length);
                for (String s : citems) {
                    classItems.add(s);
                }

                System.out.println("classes:" + classes);
            }
        }

        attInfo.add(new Attribute("class", classItems));
        Instances insts = new Instances("BoostingPL-dataset", attInfo, 0);
        insts.setClassIndex(insts.numAttributes() - 1);

        return insts;
    }

    /**
     * create instances header from a instance
     * 
     * @param instance
     * @return instances
     */
    public static Instances createInstances(String text) {
        String[] items = text.split(" ");

        ArrayList<Attribute> attInfo = new ArrayList<Attribute>();
        for (int i = 0; i < items.length - 1; i++) {
            attInfo.add(new Attribute("attr" + i));
        }

        List<String> classItems = new ArrayList<String>(2);
        classItems.add("1");
        classItems.add("-1");
        attInfo.add(new Attribute("class", classItems));
        Instances insts = new Instances("BoostingPL-dataset", attInfo, 0);
        insts.setClassIndex(insts.numAttributes() - 1);

        return insts;
    }

    /*
    private void saveInstances(Instances dataset) {
        ArffSaver saver = new ArffSaver();
        saver.setInstances(dataset);
        try {
     saver.setFile(new File("/tmp/test.arff"));
     saver.writeBatch();
       } catch (IOException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
       }
    }
    */
}