Example usage for weka.core RandomVariates nextGamma

Introduction

In this page you can find the example usage for weka.core RandomVariates nextGamma.

Prototype

public double nextGamma(double a) throws Exception

Source Link

Document

Generate a value of a variate following standard Gamma distribution with shape parameter a.

If a>1, it uses a rejection method developed by Minh(1988)"Generating Gamma Variates", ACM Trans.

Usage

From source file:milk.data.TLDData.java

License:Open Source License

public static void main(String[] args) {
    try {/* ww  w .  j a v  a2s.c  o  m*/
        int index = 0;
        String seedString = Utils.getOption('s', args);
        long seed = 1;
        if (seedString != "")
            seed = Long.parseLong(seedString);
        String fileName = args[index++];
        int numEx = Integer.parseInt(args[index++]), numAtts = Integer.parseInt(args[index++]);

        double[][] a = new double[2][numAtts], b = new double[2][numAtts], w = new double[2][numAtts],
                m = new double[2][numAtts];
        int SIZE = 0;

        for (int i = 0; i < 2; i++) {
            for (int j = 0; j < numAtts; j++) {
                a[i][j] = Double.parseDouble(args[index++]);
                b[i][j] = Double.parseDouble(args[index++]);
                w[i][j] = Double.parseDouble(args[index++]);
                m[i][j] = Double.parseDouble(args[index++]);
            }
        }
        RandomVariates ran = new RandomVariates(seed);

        PrintWriter pw = new PrintWriter(new FileWriter(fileName + ".arff"));
        pw.println("%Positive:");
        for (int j = 0; j < numAtts; j++)
            pw.println("%Att " + j + ": a=" + a[0][j] + ", b=" + b[0][j] + ", w=" + w[0][j] + ", m=" + m[0][j]);
        pw.println("%Negative:");
        for (int j = 0; j < numAtts; j++)
            pw.println("%Att " + j + ": a=" + a[1][j] + ", b=" + b[1][j] + ", w=" + w[1][j] + ", m=" + m[1][j]);

        double[][][] param = new double[numEx * 2][numAtts][2]; // mu and sigma for each dimension and bag

        // class 0
        int c = 0;
        for (int x = 0; x < numEx; x++) {
            for (int y = 0; y < numAtts; y++) {
                double variance = ran.nextGamma(b[c][y] / 2.0);
                while (variance <= 10e-9)
                    variance = ran.nextGamma(b[c][y] / 2.0);
                double sigma = Math.sqrt(0.5 * a[c][y] / variance),
                        mu = ran.nextGaussian() * Math.sqrt(w[c][y]) * sigma + m[c][y];
                param[x][y][0] = mu;
                param[x][y][1] = sigma;
            }
        }
        // class 1
        c = 1;
        for (int x = numEx; x < 2 * numEx; x++) {
            for (int y = 0; y < numAtts; y++) {
                double variance = ran.nextGamma(b[c][y] / 2.0);
                while (variance <= 10e-9)
                    variance = ran.nextGamma(b[c][y] / 2.0);
                double sigma = Math.sqrt(0.5 * a[c][y] / variance),
                        mu = ran.nextGaussian() * Math.sqrt(w[c][y]) * sigma + m[c][y];
                param[x][y][0] = mu;
                param[x][y][1] = sigma;
            }
        }

        pw.println("%seed=" + seed + "\n");
        pw.println("@relation " + fileName + "\n");
        pw.print("@attribute examplar {");

        StringBuffer[] bagID = new StringBuffer[numEx * 2];
        for (int j = 0; j < numEx * 2; j++) {
            bagID[j] = new StringBuffer(j + "_");
            // centroid
            for (int k = 0; k < numAtts - 1; k++)
                bagID[j].append(Utils.doubleToString(param[j][k][0], 3, 2) + "_"
                        + Utils.doubleToString(param[j][k][1], 3, 2) + "_");
            bagID[j].append(Utils.doubleToString(param[j][numAtts - 1][0], 3, 2) + "_"
                    + Utils.doubleToString(param[j][numAtts - 1][1], 3, 2));
        }

        for (int j = 0; j < numEx * 2; j++) {
            pw.print(bagID[j].toString());
            if (j == (2 * numEx - 1))
                pw.println("}");
            else
                pw.print(",");
        }

        for (int j = 1; j <= numAtts; j++)
            pw.println("@attribute X" + j + " numeric");
        pw.println("@attribute class {0,1}");
        pw.println("\n@data");

        for (int y = 0; y < 2 * numEx; y++) {
            int size = 1 + ran.nextInt(20); //size      
            double[][] data = createEx(size, param[y], ran);

            for (int p = 0; p < size; p++) {
                pw.print(bagID[y].toString() + ", ");
                for (int q = 0; q < numAtts; q++) {
                    pw.print(data[p][q] + ", ");
                }

                if (y < numEx)
                    pw.println(0);
                else
                    pw.println(1);
            }
        }

        pw.close();
    } catch (Exception ex) {
        System.err.println(ex.getMessage());
        ex.printStackTrace();
    }
}