java - 如何在 LibSVM 中使用 'svm_toy' Applet 示例？

Question

我正在使用 LIBSVM。下载包中有一个svm_toy.java文件。我不知道它是如何工作的。这是源代码:

import libsvm.*;
import java.applet.*;
import java.awt.*;
import java.util.*;
import java.awt.event.*;
import java.io.*;

/**
 * SVM package 
 * @author unknown
 *
 */
public class svm_toy extends Applet {

    static final String DEFAULT_PARAM="-t 2 -c 100";
    int XLEN;
    int YLEN;

    // off-screen buffer

    Image buffer;
    Graphics buffer_gc;

    // pre-allocated colors

    final static Color colors[] =
    {
      new Color(0,0,0),
      new Color(0,120,120),
      new Color(120,120,0),
      new Color(120,0,120),
      new Color(0,200,200),
      new Color(200,200,0),
      new Color(200,0,200)
    };

    class point {
        point(double x, double y, byte value)
        {
            this.x = x;
            this.y = y;
            this.value = value;
        }
        double x, y;
        byte value;
    }

    Vector<point> point_list = new Vector<point>();
    byte current_value = 1;

    public void init()
    {
        setSize(getSize());

        final Button button_change = new Button("Change");
        Button button_run = new Button("Run");
        Button button_clear = new Button("Clear");
        Button button_save = new Button("Save");
        Button button_load = new Button("Load");
        final TextField input_line = new TextField(DEFAULT_PARAM);

        BorderLayout layout = new BorderLayout();
        this.setLayout(layout);

        Panel p = new Panel();
        GridBagLayout gridbag = new GridBagLayout();
        p.setLayout(gridbag);

        GridBagConstraints c = new GridBagConstraints();
        c.fill = GridBagConstraints.HORIZONTAL;
        c.weightx = 1;
        c.gridwidth = 1;
        gridbag.setConstraints(button_change,c);
        gridbag.setConstraints(button_run,c);
        gridbag.setConstraints(button_clear,c);
        gridbag.setConstraints(button_save,c);
        gridbag.setConstraints(button_load,c);
        c.weightx = 5;
        c.gridwidth = 5;
        gridbag.setConstraints(input_line,c);

        button_change.setBackground(colors[current_value]);

        p.add(button_change);
        p.add(button_run);
        p.add(button_clear);
        p.add(button_save);
        p.add(button_load);
        p.add(input_line);
        this.add(p,BorderLayout.SOUTH);

        button_change.addActionListener(new ActionListener()
        { public void actionPerformed (ActionEvent e)
          { button_change_clicked(); button_change.setBackground(colors[current_value]); }});

        button_run.addActionListener(new ActionListener()
        { public void actionPerformed (ActionEvent e)
          { button_run_clicked(input_line.getText()); }});

        button_clear.addActionListener(new ActionListener()
        { public void actionPerformed (ActionEvent e)
          { button_clear_clicked(); }});

        button_save.addActionListener(new ActionListener()
        { public void actionPerformed (ActionEvent e)
          { button_save_clicked(input_line.getText()); }});

        button_load.addActionListener(new ActionListener()
        { public void actionPerformed (ActionEvent e)
          { button_load_clicked(); }});

        input_line.addActionListener(new ActionListener()
        { public void actionPerformed (ActionEvent e)
          { button_run_clicked(input_line.getText()); }});

        this.enableEvents(AWTEvent.MOUSE_EVENT_MASK);
    }

    void draw_point(point p)
    {
        Color c = colors[p.value+3];

        Graphics window_gc = getGraphics();
        buffer_gc.setColor(c);
        buffer_gc.fillRect((int)(p.x*XLEN),(int)(p.y*YLEN),4,4);
        window_gc.setColor(c);
        window_gc.fillRect((int)(p.x*XLEN),(int)(p.y*YLEN),4,4);
    }

    void clear_all()
    {
        point_list.removeAllElements();
        if(buffer != null)
        {
            buffer_gc.setColor(colors[0]);
            buffer_gc.fillRect(0,0,XLEN,YLEN);
        }
        repaint();
    }

    void draw_all_points()
    {
        int n = point_list.size();
        for(int i=0;i<n;i++)
            draw_point(point_list.elementAt(i));
    }

    void button_change_clicked()
    {
        ++current_value;
        if(current_value > 3) current_value = 1;
    }

    private static double atof(String s)
    {
        return Double.valueOf(s).doubleValue();
    }

    private static int atoi(String s)
    {
        return Integer.parseInt(s);
    }

    void button_run_clicked(String args)
    {
        // guard
        if(point_list.isEmpty()) return;

        svm_parameter param = new svm_parameter();

        // default values
        param.svm_type = svm_parameter.C_SVC;
        param.kernel_type = svm_parameter.RBF;
        param.degree = 3;
        param.gamma = 0;
        param.coef0 = 0;
        param.nu = 0.5;
        param.cache_size = 40;
        param.C = 1;
        param.eps = 1e-3;
        param.p = 0.1;
        param.shrinking = 1;
        param.probability = 0;
        param.nr_weight = 0;
        param.weight_label = new int[0];
        param.weight = new double[0];

        // parse options
        StringTokenizer st = new StringTokenizer(args);
        String[] argv = new String[st.countTokens()];
        for(int i=0;i<argv.length;i++)
            argv[i] = st.nextToken();

        for(int i=0;i<argv.length;i++)
        {
            if(argv[i].charAt(0) != '-') break;
            if(++i>=argv.length)
            {
                System.err.print("unknown option\n");
                break;
            }
            switch(argv[i-1].charAt(1))
            {
                case 's':
                    param.svm_type = atoi(argv[i]);
                    break;
                case 't':
                    param.kernel_type = atoi(argv[i]);
                    break;
                case 'd':
                    param.degree = atoi(argv[i]);
                    break;
                case 'g':
                    param.gamma = atof(argv[i]);
                    break;
                case 'r':
                    param.coef0 = atof(argv[i]);
                    break;
                case 'n':
                    param.nu = atof(argv[i]);
                    break;
                case 'm':
                    param.cache_size = atof(argv[i]);
                    break;
                case 'c':
                    param.C = atof(argv[i]);
                    break;
                case 'e':
                    param.eps = atof(argv[i]);
                    break;
                case 'p':
                    param.p = atof(argv[i]);
                    break;
                case 'h':
                    param.shrinking = atoi(argv[i]);
                    break;
                case 'b':
                    param.probability = atoi(argv[i]);
                    break;
                case 'w':
                    ++param.nr_weight;
                    {
                        int[] old = param.weight_label;
                        param.weight_label = new int[param.nr_weight];
                        System.arraycopy(old,0,param.weight_label,0,param.nr_weight-1);
                    }

                    {
                        double[] old = param.weight;
                        param.weight = new double[param.nr_weight];
                        System.arraycopy(old,0,param.weight,0,param.nr_weight-1);
                    }

                    param.weight_label[param.nr_weight-1] = atoi(argv[i-1].substring(2));
                    param.weight[param.nr_weight-1] = atof(argv[i]);
                    break;
                default:
                    System.err.print("unknown option\n");
            }
        }

        // build problem
        svm_problem prob = new svm_problem();
        prob.l = point_list.size();
        prob.y = new double[prob.l];

        if(param.kernel_type == svm_parameter.PRECOMPUTED)
        {
        }
        else if(param.svm_type == svm_parameter.EPSILON_SVR ||
            param.svm_type == svm_parameter.NU_SVR)
        {
            if(param.gamma == 0) param.gamma = 1;
            prob.x = new svm_node[prob.l][1];
            for(int i=0;i<prob.l;i++)
            {
                point p = point_list.elementAt(i);
                prob.x[i][0] = new svm_node();
                prob.x[i][0].index = 1;
                prob.x[i][0].value = p.x;
                prob.y[i] = p.y;
            }

            // build model & classify
            svm_model model = svm.svm_train(prob, param);
            svm_node[] x = new svm_node[1];
            x[0] = new svm_node();
            x[0].index = 1;
            int[] j = new int[XLEN];

            Graphics window_gc = getGraphics();
            for (int i = 0; i < XLEN; i++)
            {
                x[0].value = (double) i / XLEN;
                j[i] = (int)(YLEN*svm.svm_predict(model, x));
            }

            buffer_gc.setColor(colors[0]);
            buffer_gc.drawLine(0,0,0,YLEN-1);
            window_gc.setColor(colors[0]);
            window_gc.drawLine(0,0,0,YLEN-1);

            int p = (int)(param.p * YLEN);
            for(int i=1;i<XLEN;i++)
            {
                buffer_gc.setColor(colors[0]);
                buffer_gc.drawLine(i,0,i,YLEN-1);
                window_gc.setColor(colors[0]);
                window_gc.drawLine(i,0,i,YLEN-1);

                buffer_gc.setColor(colors[5]);
                window_gc.setColor(colors[5]);
                buffer_gc.drawLine(i-1,j[i-1],i,j[i]);
                window_gc.drawLine(i-1,j[i-1],i,j[i]);

                if(param.svm_type == svm_parameter.EPSILON_SVR)
                {
                    buffer_gc.setColor(colors[2]);
                    window_gc.setColor(colors[2]);
                    buffer_gc.drawLine(i-1,j[i-1]+p,i,j[i]+p);
                    window_gc.drawLine(i-1,j[i-1]+p,i,j[i]+p);

                    buffer_gc.setColor(colors[2]);
                    window_gc.setColor(colors[2]);
                    buffer_gc.drawLine(i-1,j[i-1]-p,i,j[i]-p);
                    window_gc.drawLine(i-1,j[i-1]-p,i,j[i]-p);
                }
            }
        }
        else
        {
            if(param.gamma == 0) param.gamma = 0.5;
            prob.x = new svm_node [prob.l][2];
            for(int i=0;i<prob.l;i++)
            {
                point p = point_list.elementAt(i);
                prob.x[i][0] = new svm_node();
                prob.x[i][0].index = 1;
                prob.x[i][0].value = p.x;
                prob.x[i][1] = new svm_node();
                prob.x[i][1].index = 2;
                prob.x[i][1].value = p.y;
                prob.y[i] = p.value;
            }

            // build model & classify
            svm_model model = svm.svm_train(prob, param);
            svm_node[] x = new svm_node[2];
            x[0] = new svm_node();
            x[1] = new svm_node();
            x[0].index = 1;
            x[1].index = 2;

            Graphics window_gc = getGraphics();
            for (int i = 0; i < XLEN; i++)
                for (int j = 0; j < YLEN ; j++) {
                    x[0].value = (double) i / XLEN;
                    x[1].value = (double) j / YLEN;
                    double d = svm.svm_predict(model, x);
                    if (param.svm_type == svm_parameter.ONE_CLASS && d<0) d=2;
                    buffer_gc.setColor(colors[(int)d]);
                    window_gc.setColor(colors[(int)d]);
                    buffer_gc.drawLine(i,j,i,j);
                    window_gc.drawLine(i,j,i,j);
            }
        }

        draw_all_points();
    }

    void button_clear_clicked()
    {
        clear_all();
    }

    void button_save_clicked(String args)
    {
        FileDialog dialog = new FileDialog(new Frame(),"Save",FileDialog.SAVE);
        dialog.setVisible(true);
        String filename = dialog.getDirectory() + dialog.getFile();
        if (filename == null) return;
        try {
            DataOutputStream fp = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(filename)));

            int svm_type = svm_parameter.C_SVC;
            int svm_type_idx = args.indexOf("-s ");
            if(svm_type_idx != -1)
            {
                StringTokenizer svm_str_st = new StringTokenizer(args.substring(svm_type_idx+2).trim());
                svm_type = atoi(svm_str_st.nextToken());
            }

            int n = point_list.size();
            if(svm_type == svm_parameter.EPSILON_SVR || svm_type == svm_parameter.NU_SVR)
            {
                for(int i=0;i<n;i++)
                {
                    point p = point_list.elementAt(i);
                    fp.writeBytes(p.y+" 1:"+p.x+"\n");
                }
            }
            else
            {
                for(int i=0;i<n;i++)
                {
                    point p = point_list.elementAt(i);
                    fp.writeBytes(p.value+" 1:"+p.x+" 2:"+p.y+"\n");
                }
            }
            fp.close();
        } catch (IOException e) { System.err.print(e); }
    }

    void button_load_clicked()
    {
        FileDialog dialog = new FileDialog(new Frame(),"Load",FileDialog.LOAD);
        dialog.setVisible(true);
        String filename = dialog.getDirectory() + dialog.getFile();
        if (filename == null) return;
        clear_all();
        try {
            BufferedReader fp = new BufferedReader(new FileReader(filename));
            String line;
            while((line = fp.readLine()) != null)
            {
                StringTokenizer st = new StringTokenizer(line," \t\n\r\f:");
                if(st.countTokens() == 5)
                {
                    byte value = (byte)atoi(st.nextToken());
                    st.nextToken();
                    double x = atof(st.nextToken());
                    st.nextToken();
                    double y = atof(st.nextToken());
                    point_list.addElement(new point(x,y,value));
                }
                else if(st.countTokens() == 3)
                {
                    double y = atof(st.nextToken());
                    st.nextToken();
                    double x = atof(st.nextToken());
                    point_list.addElement(new point(x,y,current_value));
                }else
                    break;
            }
            fp.close();
        } catch (IOException e) { System.err.print(e); }
        draw_all_points();
    }

    protected void processMouseEvent(MouseEvent e)
    {
        if(e.getID() == MouseEvent.MOUSE_PRESSED)
        {
            if(e.getX() >= XLEN || e.getY() >= YLEN) return;
            point p = new point((double)e.getX()/XLEN,
                        (double)e.getY()/YLEN,
                        current_value);
            point_list.addElement(p);
            draw_point(p);
        }
    }

    public void paint(Graphics g)
    {
        // create buffer first time
        if(buffer == null) {
            buffer = this.createImage(XLEN,YLEN);
            buffer_gc = buffer.getGraphics();
            buffer_gc.setColor(colors[0]);
            buffer_gc.fillRect(0,0,XLEN,YLEN);
        }
        g.drawImage(buffer,0,0,this);
    }

    public Dimension getPreferredSize() { return new Dimension(XLEN,YLEN+50); }

    public void setSize(Dimension d) { setSize(d.width,d.height); }
    public void setSize(int w,int h) {
        super.setSize(w,h);
        XLEN = w;
        YLEN = h-50;
        clear_all();
    }

    public static void main(String[] argv)
    {
        new AppletFrame("svm_toy",new svm_toy(),500,500+50);
    }
}

class AppletFrame extends Frame {
    AppletFrame(String title, Applet applet, int width, int height)
    {
        super(title);
        this.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        applet.init();
        applet.setSize(width,height);
        applet.start();
        this.add(applet);
        this.pack();
        this.setVisible(true);
    }

}

有人可以给我一个例子或解释吗？我还想扩展我的训练数据。哪里是扩展的正确位置？

谢谢

Answer 1

SVM 玩具

顾名思义，SVM Toy 是一个简单的玩具，由 LIBSVM 开发团队构建，不推荐用于“高效”可视化 SVM 的决策边界。

此外，查看 svm_toy 的源代码可以清楚地看出，该工具仅支持 2D vector 。

相关代码片段取自button_load_clicked()方法:

while ((line = fp.readLine()) != null) {
    StringTokenizer st = new StringTokenizer(line, " \t\n\r\f:");
        if (st.countTokens() == 5) {
            byte value = (byte) atoi(st.nextToken());
            st.nextToken();
            double x = atof(st.nextToken());
            st.nextToken();
            double y = atof(st.nextToken());
            point_list.addElement(new point(x, y, value));
        } else if (st.countTokens() == 3) {
            double y = atof(st.nextToken());
            st.nextToken();
            double x = atof(st.nextToken());
            point_list.addElement(new point(x, y, current_value));
        } else {
            break;
        }
    }

如您所见，svm_toy 实现只能处理二维 vector ，这意味着它只支持由两个特征构成的 vector 。

这意味着，您只能读取和显示仅由两个功能构建的文件，例如 fourclass LIBSVM 作者提供的数据集。然而，这个实现似乎不支持这个特性。

我认为，该工具是为交互式可视化而设计的。您可以更改颜色并单击黑色应用程序屏幕。设置一些点(每种颜色代表自己的类别)后，您可以单击“运行”并显示决策边界。

在高维 vector 空间中显示决策边界甚至几乎是不可能的。我建议不要将此工具实现用于任何生产/科学目的。

缩放

训练数据的缩放应在将其转换为数字表示之后以及继续使用此数据训练 SVM 之前完成。

简而言之，您必须在使用 svm_train 之前执行以下步骤

1. 为每个数据点构建数字表示(借助特征选择，...)
2. 分析每个数据点的结果数字表示
3. 将数据缩放到 [-1,1] 等范围
4. 继续训练您的 SVM 模型。请注意，您必须重复 1-3 来预测未知数据点。唯一的区别是，您已经知道必要的特征，因此无需进行特征选择。