com.medlog.webservice.util.MathUtl.java Source code

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Here is the source code for com.medlog.webservice.util.MathUtl.java

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package com.medlog.webservice.util;

import java.math.BigDecimal;
import org.apache.commons.math3.stat.correlation.PearsonsCorrelation;
import org.apache.commons.math3.stat.correlation.SpearmansCorrelation;

/**
 *
 * @author westy
 */
public class MathUtl {

    /**
     *
     * Generate Correlation from values.
     *
     * @param ax
     * @param by
     * @return r
     */
    public static double correlation(double[] ax, double[] by) {
        // TODO: check here that arrays are not null, of the same length etc

        double sx = 0.0;
        double sy = 0.0;
        double sxx = 0.0;
        double syy = 0.0;
        double sxy = 0.0;

        int n = ax.length;

        for (int i = 0; i < n; ++i) {
            double x = ax[i];
            double y = by[i];

            sx += x;
            sy += y;
            sxx += x * x;
            syy += y * y;
            sxy += x * y;
        }
        double corr = new org.apache.commons.math3.stat.correlation.PearsonsCorrelation().correlation(ax, by);

        System.out.println(corr);
        // coV
        double cov = sxy / n - sx * sy / n / n;
        // std(x)
        double sigmax = Math.sqrt(sxx / n - sx * sx / n / n);
        // std(y)
        double sigmay = Math.sqrt(syy / n - sy * sy / n / n);
        // cor
        return cov / sigmax / sigmay;
    }

    public static void main(String[] args) {
        BigDecimal d;
        d = new BigDecimal(0);
        double[] xs = { 30, 80, 90, 70, 70, 80, 50, 50, 50, 100, 10, 40, 80, 100 };

        double ys[] = { 52.9676423, 28.14739166, 45.22978518, 60.54520645, 58.43671379, 15.94587142, 58.869,
                57.8465, 58.686, 40.38026666, 55.8178, 60.3812, 88.1389, 61.1895 };

        double r = new PearsonsCorrelation().correlation(xs, ys);
        double rb = new SpearmansCorrelation().correlation(xs, ys);
        System.out.println("com.medlog.webservice.util.MathUtl.main()" + r * r);

        System.out.println("com.medlog.webservice.util.MathUtl.main()" + rb * rb);

    }
}