com.cloudera.hts.utils.math.PolyFit.java Source code

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Here is the source code for com.cloudera.hts.utils.math.PolyFit.java

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package com.cloudera.hts.utils.math;

import java.util.ArrayList;
import java.util.Arrays;
import org.apache.commons.math3.fitting.PolynomialCurveFitter;
import org.apache.commons.math3.fitting.WeightedObservedPoint;
import org.apache.commons.math3.fitting.WeightedObservedPoints;

/**
 *
 * @author kamir
 */
public class PolyFit {

    public static void main(String[] args) {

        double[] x = { -5.0, -4.0, -3.0, -2.0, 0, 2, 3, 4 };
        double[] y = { 21, 13, 7, 3, 1, 7, 13, 21 };

        WeightedObservedPoints obs = new WeightedObservedPoints();

        // Add points here; for instance,
        int i = 0;
        for (double xc : x) {

            WeightedObservedPoint point = new WeightedObservedPoint(xc, y[i], 1.0);
            obs.add(xc, y[i]);

            System.out.println(xc + " " + y[i]);

            i++;

        }

        // Instantiate a third-degree polynomial fitter.
        PolynomialCurveFitter fitter = PolynomialCurveFitter.create(2);

        // Retrieve fitted parameters (coefficients of the polynomial function).
        final double[] coeff = fitter.fit(obs.toList());

        System.out.println(Arrays.toString(coeff));

    }

}