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Java example source code file (HarmonicFitterTest.java)

This example Java source code file (HarmonicFitterTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

deprecated, harmonicfitter, harmonicfittertest, harmonicoscillator, levenbergmarquardtoptimizer, random, test, util, weightedobservedpoint

The HarmonicFitterTest.java Java example source code

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package org.apache.commons.math3.optimization.fitting;

import java.util.Random;

import org.apache.commons.math3.analysis.function.HarmonicOscillator;
import org.apache.commons.math3.optimization.general.LevenbergMarquardtOptimizer;
import org.apache.commons.math3.exception.NumberIsTooSmallException;
import org.apache.commons.math3.exception.MathIllegalStateException;
import org.apache.commons.math3.util.FastMath;
import org.apache.commons.math3.util.MathUtils;
import org.junit.Test;
import org.junit.Assert;

@Deprecated
public class HarmonicFitterTest {
    @Test(expected=NumberIsTooSmallException.class)
    public void testPreconditions1() {
        HarmonicFitter fitter =
            new HarmonicFitter(new LevenbergMarquardtOptimizer());

        fitter.fit();
    }

    // This test fails (throwing "ConvergenceException" instead).
//     @Test(expected=ZeroException.class)
//     public void testPreconditions2() {
//         HarmonicFitter fitter =
//             new HarmonicFitter(new LevenbergMarquardtOptimizer());

//         final double x = 1.2;
//         fitter.addObservedPoint(1, x, 1);
//         fitter.addObservedPoint(1, x, -1);
//         fitter.addObservedPoint(1, x, 0.5);
//         fitter.addObservedPoint(1, x, 0);

//         final double[] fitted = fitter.fit();
//     }

    @Test
    public void testNoError() {
        final double a = 0.2;
        final double w = 3.4;
        final double p = 4.1;
        HarmonicOscillator f = new HarmonicOscillator(a, w, p);

        HarmonicFitter fitter =
            new HarmonicFitter(new LevenbergMarquardtOptimizer());
        for (double x = 0.0; x < 1.3; x += 0.01) {
            fitter.addObservedPoint(1, x, f.value(x));
        }

        final double[] fitted = fitter.fit();
        Assert.assertEquals(a, fitted[0], 1.0e-13);
        Assert.assertEquals(w, fitted[1], 1.0e-13);
        Assert.assertEquals(p, MathUtils.normalizeAngle(fitted[2], p), 1e-13);

        HarmonicOscillator ff = new HarmonicOscillator(fitted[0], fitted[1], fitted[2]);

        for (double x = -1.0; x < 1.0; x += 0.01) {
            Assert.assertTrue(FastMath.abs(f.value(x) - ff.value(x)) < 1e-13);
        }
    }

    @Test
    public void test1PercentError() {
        Random randomizer = new Random(64925784252l);
        final double a = 0.2;
        final double w = 3.4;
        final double p = 4.1;
        HarmonicOscillator f = new HarmonicOscillator(a, w, p);

        HarmonicFitter fitter =
            new HarmonicFitter(new LevenbergMarquardtOptimizer());
        for (double x = 0.0; x < 10.0; x += 0.1) {
            fitter.addObservedPoint(1, x,
                                    f.value(x) + 0.01 * randomizer.nextGaussian());
        }

        final double[] fitted = fitter.fit();
        Assert.assertEquals(a, fitted[0], 7.6e-4);
        Assert.assertEquals(w, fitted[1], 2.7e-3);
        Assert.assertEquals(p, MathUtils.normalizeAngle(fitted[2], p), 1.3e-2);
    }

    @Test
    public void testTinyVariationsData() {
        Random randomizer = new Random(64925784252l);

        HarmonicFitter fitter =
            new HarmonicFitter(new LevenbergMarquardtOptimizer());
        for (double x = 0.0; x < 10.0; x += 0.1) {
            fitter.addObservedPoint(1, x, 1e-7 * randomizer.nextGaussian());
        }

        fitter.fit();
        // This test serves to cover the part of the code of "guessAOmega"
        // when the algorithm using integrals fails.
    }

    @Test
    public void testInitialGuess() {
        Random randomizer = new Random(45314242l);
        final double a = 0.2;
        final double w = 3.4;
        final double p = 4.1;
        HarmonicOscillator f = new HarmonicOscillator(a, w, p);

        HarmonicFitter fitter =
            new HarmonicFitter(new LevenbergMarquardtOptimizer());
        for (double x = 0.0; x < 10.0; x += 0.1) {
            fitter.addObservedPoint(1, x,
                                    f.value(x) + 0.01 * randomizer.nextGaussian());
        }

        final double[] fitted = fitter.fit(new double[] { 0.15, 3.6, 4.5 });
        Assert.assertEquals(a, fitted[0], 1.2e-3);
        Assert.assertEquals(w, fitted[1], 3.3e-3);
        Assert.assertEquals(p, MathUtils.normalizeAngle(fitted[2], p), 1.7e-2);
    }

    @Test
    public void testUnsorted() {
        Random randomizer = new Random(64925784252l);
        final double a = 0.2;
        final double w = 3.4;
        final double p = 4.1;
        HarmonicOscillator f = new HarmonicOscillator(a, w, p);

        HarmonicFitter fitter =
            new HarmonicFitter(new LevenbergMarquardtOptimizer());

        // build a regularly spaced array of measurements
        int size = 100;
        double[] xTab = new double[size];
        double[] yTab = new double[size];
        for (int i = 0; i < size; ++i) {
            xTab[i] = 0.1 * i;
            yTab[i] = f.value(xTab[i]) + 0.01 * randomizer.nextGaussian();
        }

        // shake it
        for (int i = 0; i < size; ++i) {
            int i1 = randomizer.nextInt(size);
            int i2 = randomizer.nextInt(size);
            double xTmp = xTab[i1];
            double yTmp = yTab[i1];
            xTab[i1] = xTab[i2];
            yTab[i1] = yTab[i2];
            xTab[i2] = xTmp;
            yTab[i2] = yTmp;
        }

        // pass it to the fitter
        for (int i = 0; i < size; ++i) {
            fitter.addObservedPoint(1, xTab[i], yTab[i]);
        }

        final double[] fitted = fitter.fit();
        Assert.assertEquals(a, fitted[0], 7.6e-4);
        Assert.assertEquals(w, fitted[1], 3.5e-3);
        Assert.assertEquals(p, MathUtils.normalizeAngle(fitted[2], p), 1.5e-2);
    }

    @Test(expected=MathIllegalStateException.class)
    public void testMath844() {
        final double[] y = { 0, 1, 2, 3, 2, 1,
                             0, -1, -2, -3, -2, -1,
                             0, 1, 2, 3, 2, 1,
                             0, -1, -2, -3, -2, -1,
                             0, 1, 2, 3, 2, 1, 0 };
        final int len = y.length;
        final WeightedObservedPoint[] points = new WeightedObservedPoint[len];
        for (int i = 0; i < len; i++) {
            points[i] = new WeightedObservedPoint(1, i, y[i]);
        }

        // The guesser fails because the function is far from an harmonic
        // function: It is a triangular periodic function with amplitude 3
        // and period 12, and all sample points are taken at integer abscissae
        // so function values all belong to the integer subset {-3, -2, -1, 0,
        // 1, 2, 3}.
        new HarmonicFitter.ParameterGuesser(points);
    }
}

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