Question

我正在使用LIBSVM。在下载包中是svm_toy.java文件。我无法弄清楚它是如何工作的。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。哪个地方适合扩展？

由于

Answer 1

<强> SVM-玩具

SVM Toy - 顾名思义 - 由LIBSVM开发团队构建一个简单的玩具，不推荐用于“高效”可视化 SVM的决定边界。

此外，查看svm_toy的源代码，很明显，此工具仅支持2D向量。

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2D向量，这意味着它只支持由两个特征构造的向量。

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LIBSVM作者提供的fourclass数据集。但是，似乎在此实现中不支持此功能。

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（每种颜色代表一个自己的类）后，可以单击“运行”并显示决策边界。

在高维向量空间中显示desicion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。

<强>缩放

在将训练数据转换为数字表示之后，以及在您使用此数据训练SVM之前，应该对您的训练数据进行缩放。

简而言之，这意味着您必须在使用svm_train

之前执行以下步骤

构造每个数据点的数字表示（借助于特征选择，......）
分析每个数据点的结果数字表示
将您的数据扩展为例如[-1,1]
继续训练您的SVM模型。请注意，您必须重复1-3以预测未知数据点。唯一的区别是，您已经知道必要的功能，因此无需选择功能。

如何在LibSVM中使用'svm_toy'Applet示例？

1 个答案: