MATH-1014

"GaussianCurveFitter" as replacement of "GaussianCurveFitter".


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1516896 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Gilles Sadowski 2013-08-23 15:39:55 +00:00
parent 95ce549b40
commit eb1a3f00a2
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/*
* 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.fitting;
import java.util.List;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Collection;
import java.util.Collections;
import org.apache.commons.math3.analysis.function.Gaussian;
import org.apache.commons.math3.linear.DiagonalMatrix;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.NumberIsTooSmallException;
import org.apache.commons.math3.exception.OutOfRangeException;
import org.apache.commons.math3.exception.ZeroException;
import org.apache.commons.math3.exception.NotStrictlyPositiveException;
import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.fitting.leastsquares.LevenbergMarquardtOptimizer;
import org.apache.commons.math3.fitting.leastsquares.WithStartPoint;
import org.apache.commons.math3.fitting.leastsquares.WithMaxIterations;
import org.apache.commons.math3.util.FastMath;
/**
* Fits points to a {@link
* org.apache.commons.math3.analysis.function.Gaussian.Parametric Gaussian}
* function.
* <br/>
* The {@link #withStartPoint(double[]) initial guess values} must be passed
* in the following order:
* <ul>
* <li>Normalization</li>
* <li>Mean</li>
* <li>Sigma</li>
* </ul>
* The optimal values will be returned in the same order.
*
* <p>
* Usage example:
* <pre>
* GaussianCurveFitter fitter = GaussianCurveFitter.create();
* fitter.add(4.0254623, 531026.0);
* fitter.add(4.03128248, 984167.0);
* fitter.add(4.03839603, 1887233.0);
* fitter.add(4.04421621, 2687152.0);
* fitter.add(4.05132976, 3461228.0);
* fitter.add(4.05326982, 3580526.0);
* fitter.add(4.05779662, 3439750.0);
* fitter.add(4.0636168, 2877648.0);
* fitter.add(4.06943698, 2175960.0);
* fitter.add(4.07525716, 1447024.0);
* fitter.add(4.08237071, 717104.0);
* fitter.add(4.08366408, 620014.0);
* double[] parameters = fitter.fit();
* </pre>
*
* @version $Id$
* @since 3.3
*/
public class GaussianCurveFitter extends AbstractCurveFitter<LevenbergMarquardtOptimizer>
implements WithStartPoint<GaussianCurveFitter>,
WithMaxIterations<GaussianCurveFitter> {
/** Parametric function to be fitted. */
private static final Gaussian.Parametric FUNCTION = new Gaussian.Parametric() {
@Override
public double value(double x, double ... p) {
double v = Double.POSITIVE_INFINITY;
try {
v = super.value(x, p);
} catch (NotStrictlyPositiveException e) { // NOPMD
// Do nothing.
}
return v;
}
@Override
public double[] gradient(double x, double ... p) {
double[] v = { Double.POSITIVE_INFINITY,
Double.POSITIVE_INFINITY,
Double.POSITIVE_INFINITY };
try {
v = super.gradient(x, p);
} catch (NotStrictlyPositiveException e) { // NOPMD
// Do nothing.
}
return v;
}
};
/** Initial guess. */
private final double[] initialGuess;
/** Maximum number of iterations of the optimization algorithm. */
private final int maxIter;
/**
* Contructor used by the factory methods.
*
* @param initialGuess Initial guess. If set to {@code null}, the initial guess
* will be estimated using the {@link ParameterGuesser}.
* @param maxIter Maximum number of iterations of the optimization algorithm.
*/
private GaussianCurveFitter(double[] initialGuess,
int maxIter) {
this.initialGuess = initialGuess;
this.maxIter = maxIter;
}
/**
* Creates a default curve fitter.
* The initial guess for the parameters will be {@link ParameterGuesser}
* computed automatically, and the maximum number of iterations of the
* optimization algorithm is set to {@link Integer#MAX_VALUE}.
*
* @return a curve fitter.
*
* @see #withStartPoint(double[])
* @see #withMaxIterations(int)
*/
public static GaussianCurveFitter create() {
return new GaussianCurveFitter(null, Integer.MAX_VALUE);
}
/** {@inheritDoc} */
public GaussianCurveFitter withStartPoint(double[] start) {
return new GaussianCurveFitter(start.clone(),
maxIter);
}
/** {@inheritDoc} */
public GaussianCurveFitter withMaxIterations(int max) {
return new GaussianCurveFitter(initialGuess,
max);
}
/** {@inheritDoc} */
@Override
protected LevenbergMarquardtOptimizer getOptimizer(Collection<WeightedObservedPoint> observations) {
// Prepare least-squares problem.
final int len = observations.size();
final double[] target = new double[len];
final double[] weights = new double[len];
int i = 0;
for (WeightedObservedPoint obs : observations) {
target[i] = obs.getY();
weights[i] = obs.getWeight();
++i;
}
final AbstractCurveFitter.TheoreticalValuesFunction model
= new AbstractCurveFitter.TheoreticalValuesFunction(FUNCTION,
observations);
final double[] startPoint = initialGuess != null ?
initialGuess :
// Compute estimation.
new ParameterGuesser(observations).guess();
// Return a new optimizer set up to fit a Gaussian curve to the
// observed points.
return LevenbergMarquardtOptimizer.create()
.withMaxEvaluations(Integer.MAX_VALUE)
.withMaxIterations(maxIter)
.withStartPoint(startPoint)
.withTarget(target)
.withWeight(new DiagonalMatrix(weights))
.withModelAndJacobian(model.getModelFunction(),
model.getModelFunctionJacobian());
}
/**
* Guesses the parameters {@code norm}, {@code mean}, and {@code sigma}
* of a {@link org.apache.commons.math3.analysis.function.Gaussian.Parametric}
* based on the specified observed points.
*/
public static class ParameterGuesser {
/** Normalization factor. */
private final double norm;
/** Mean. */
private final double mean;
/** Standard deviation. */
private final double sigma;
/**
* Constructs instance with the specified observed points.
*
* @param observations Observed points from which to guess the
* parameters of the Gaussian.
* @throws NullArgumentException if {@code observations} is
* {@code null}.
* @throws NumberIsTooSmallException if there are less than 3
* observations.
*/
public ParameterGuesser(Collection<WeightedObservedPoint> observations) {
if (observations == null) {
throw new NullArgumentException(LocalizedFormats.INPUT_ARRAY);
}
if (observations.size() < 3) {
throw new NumberIsTooSmallException(observations.size(), 3, true);
}
final List<WeightedObservedPoint> sorted = sortObservations(observations);
final double[] params = basicGuess(sorted.toArray(new WeightedObservedPoint[0]));
norm = params[0];
mean = params[1];
sigma = params[2];
}
/**
* Gets an estimation of the parameters.
*
* @return the guessed parameters, in the following order:
* <ul>
* <li>Normalization factor</li>
* <li>Mean</li>
* <li>Standard deviation</li>
* </ul>
*/
public double[] guess() {
return new double[] { norm, mean, sigma };
}
/**
* Sort the observations.
*
* @param unsorted Input observations.
* @return the input observations, sorted.
*/
private List<WeightedObservedPoint> sortObservations(Collection<WeightedObservedPoint> unsorted) {
final List<WeightedObservedPoint> observations = new ArrayList<WeightedObservedPoint>(unsorted);
final Comparator<WeightedObservedPoint> cmp = new Comparator<WeightedObservedPoint>() {
public int compare(WeightedObservedPoint p1,
WeightedObservedPoint p2) {
if (p1 == null && p2 == null) {
return 0;
}
if (p1 == null) {
return -1;
}
if (p2 == null) {
return 1;
}
if (p1.getX() < p2.getX()) {
return -1;
}
if (p1.getX() > p2.getX()) {
return 1;
}
if (p1.getY() < p2.getY()) {
return -1;
}
if (p1.getY() > p2.getY()) {
return 1;
}
if (p1.getWeight() < p2.getWeight()) {
return -1;
}
if (p1.getWeight() > p2.getWeight()) {
return 1;
}
return 0;
}
};
Collections.sort(observations, cmp);
return observations;
}
/**
* Guesses the parameters based on the specified observed points.
*
* @param points Observed points, sorted.
* @return the guessed parameters (normalization factor, mean and
* sigma).
*/
private double[] basicGuess(WeightedObservedPoint[] points) {
final int maxYIdx = findMaxY(points);
final double n = points[maxYIdx].getY();
final double m = points[maxYIdx].getX();
double fwhmApprox;
try {
final double halfY = n + ((m - n) / 2);
final double fwhmX1 = interpolateXAtY(points, maxYIdx, -1, halfY);
final double fwhmX2 = interpolateXAtY(points, maxYIdx, 1, halfY);
fwhmApprox = fwhmX2 - fwhmX1;
} catch (OutOfRangeException e) {
// TODO: Exceptions should not be used for flow control.
fwhmApprox = points[points.length - 1].getX() - points[0].getX();
}
final double s = fwhmApprox / (2 * FastMath.sqrt(2 * FastMath.log(2)));
return new double[] { n, m, s };
}
/**
* Finds index of point in specified points with the largest Y.
*
* @param points Points to search.
* @return the index in specified points array.
*/
private int findMaxY(WeightedObservedPoint[] points) {
int maxYIdx = 0;
for (int i = 1; i < points.length; i++) {
if (points[i].getY() > points[maxYIdx].getY()) {
maxYIdx = i;
}
}
return maxYIdx;
}
/**
* Interpolates using the specified points to determine X at the
* specified Y.
*
* @param points Points to use for interpolation.
* @param startIdx Index within points from which to start the search for
* interpolation bounds points.
* @param idxStep Index step for searching interpolation bounds points.
* @param y Y value for which X should be determined.
* @return the value of X for the specified Y.
* @throws ZeroException if {@code idxStep} is 0.
* @throws OutOfRangeException if specified {@code y} is not within the
* range of the specified {@code points}.
*/
private double interpolateXAtY(WeightedObservedPoint[] points,
int startIdx,
int idxStep,
double y)
throws OutOfRangeException {
if (idxStep == 0) {
throw new ZeroException();
}
final WeightedObservedPoint[] twoPoints
= getInterpolationPointsForY(points, startIdx, idxStep, y);
final WeightedObservedPoint p1 = twoPoints[0];
final WeightedObservedPoint p2 = twoPoints[1];
if (p1.getY() == y) {
return p1.getX();
}
if (p2.getY() == y) {
return p2.getX();
}
return p1.getX() + (((y - p1.getY()) * (p2.getX() - p1.getX())) /
(p2.getY() - p1.getY()));
}
/**
* Gets the two bounding interpolation points from the specified points
* suitable for determining X at the specified Y.
*
* @param points Points to use for interpolation.
* @param startIdx Index within points from which to start search for
* interpolation bounds points.
* @param idxStep Index step for search for interpolation bounds points.
* @param y Y value for which X should be determined.
* @return the array containing two points suitable for determining X at
* the specified Y.
* @throws ZeroException if {@code idxStep} is 0.
* @throws OutOfRangeException if specified {@code y} is not within the
* range of the specified {@code points}.
*/
private WeightedObservedPoint[] getInterpolationPointsForY(WeightedObservedPoint[] points,
int startIdx,
int idxStep,
double y)
throws OutOfRangeException {
if (idxStep == 0) {
throw new ZeroException();
}
for (int i = startIdx;
idxStep < 0 ? i + idxStep >= 0 : i + idxStep < points.length;
i += idxStep) {
final WeightedObservedPoint p1 = points[i];
final WeightedObservedPoint p2 = points[i + idxStep];
if (isBetween(y, p1.getY(), p2.getY())) {
if (idxStep < 0) {
return new WeightedObservedPoint[] { p2, p1 };
} else {
return new WeightedObservedPoint[] { p1, p2 };
}
}
}
// Boundaries are replaced by dummy values because the raised
// exception is caught and the message never displayed.
// TODO: Exceptions should not be used for flow control.
throw new OutOfRangeException(y,
Double.NEGATIVE_INFINITY,
Double.POSITIVE_INFINITY);
}
/**
* Determines whether a value is between two other values.
*
* @param value Value to test whether it is between {@code boundary1}
* and {@code boundary2}.
* @param boundary1 One end of the range.
* @param boundary2 Other end of the range.
* @return {@code true} if {@code value} is between {@code boundary1} and
* {@code boundary2} (inclusive), {@code false} otherwise.
*/
private boolean isBetween(double value,
double boundary1,
double boundary2) {
return (value >= boundary1 && value <= boundary2) ||
(value >= boundary2 && value <= boundary1);
}
}
}

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/*
* 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.fitting;
import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.TooManyIterationsException;
import org.junit.Assert;
import org.junit.Test;
/**
* Tests {@link GaussianCurveFitter}.
*
* @version $Id$
*/
public class GaussianCurveFitterTest {
/** Good data. */
protected static final double[][] DATASET1 = new double[][] {
{4.0254623, 531026.0},
{4.02804905, 664002.0},
{4.02934242, 787079.0},
{4.03128248, 984167.0},
{4.03386923, 1294546.0},
{4.03580929, 1560230.0},
{4.03839603, 1887233.0},
{4.0396894, 2113240.0},
{4.04162946, 2375211.0},
{4.04421621, 2687152.0},
{4.04550958, 2862644.0},
{4.04744964, 3078898.0},
{4.05003639, 3327238.0},
{4.05132976, 3461228.0},
{4.05326982, 3580526.0},
{4.05585657, 3576946.0},
{4.05779662, 3439750.0},
{4.06038337, 3220296.0},
{4.06167674, 3070073.0},
{4.0636168, 2877648.0},
{4.06620355, 2595848.0},
{4.06749692, 2390157.0},
{4.06943698, 2175960.0},
{4.07202373, 1895104.0},
{4.0733171, 1687576.0},
{4.07525716, 1447024.0},
{4.0778439, 1130879.0},
{4.07978396, 904900.0},
{4.08237071, 717104.0},
{4.08366408, 620014.0}
};
/** Poor data: right of peak not symmetric with left of peak. */
protected static final double[][] DATASET2 = new double[][] {
{-20.15, 1523.0},
{-19.65, 1566.0},
{-19.15, 1592.0},
{-18.65, 1927.0},
{-18.15, 3089.0},
{-17.65, 6068.0},
{-17.15, 14239.0},
{-16.65, 34124.0},
{-16.15, 64097.0},
{-15.65, 110352.0},
{-15.15, 164742.0},
{-14.65, 209499.0},
{-14.15, 267274.0},
{-13.65, 283290.0},
{-13.15, 275363.0},
{-12.65, 258014.0},
{-12.15, 225000.0},
{-11.65, 200000.0},
{-11.15, 190000.0},
{-10.65, 185000.0},
{-10.15, 180000.0},
{ -9.65, 179000.0},
{ -9.15, 178000.0},
{ -8.65, 177000.0},
{ -8.15, 176000.0},
{ -7.65, 175000.0},
{ -7.15, 174000.0},
{ -6.65, 173000.0},
{ -6.15, 172000.0},
{ -5.65, 171000.0},
{ -5.15, 170000.0}
};
/** Poor data: long tails. */
protected static final double[][] DATASET3 = new double[][] {
{-90.15, 1513.0},
{-80.15, 1514.0},
{-70.15, 1513.0},
{-60.15, 1514.0},
{-50.15, 1513.0},
{-40.15, 1514.0},
{-30.15, 1513.0},
{-20.15, 1523.0},
{-19.65, 1566.0},
{-19.15, 1592.0},
{-18.65, 1927.0},
{-18.15, 3089.0},
{-17.65, 6068.0},
{-17.15, 14239.0},
{-16.65, 34124.0},
{-16.15, 64097.0},
{-15.65, 110352.0},
{-15.15, 164742.0},
{-14.65, 209499.0},
{-14.15, 267274.0},
{-13.65, 283290.0},
{-13.15, 275363.0},
{-12.65, 258014.0},
{-12.15, 214073.0},
{-11.65, 182244.0},
{-11.15, 136419.0},
{-10.65, 97823.0},
{-10.15, 58930.0},
{ -9.65, 35404.0},
{ -9.15, 16120.0},
{ -8.65, 9823.0},
{ -8.15, 5064.0},
{ -7.65, 2575.0},
{ -7.15, 1642.0},
{ -6.65, 1101.0},
{ -6.15, 812.0},
{ -5.65, 690.0},
{ -5.15, 565.0},
{ 5.15, 564.0},
{ 15.15, 565.0},
{ 25.15, 564.0},
{ 35.15, 565.0},
{ 45.15, 564.0},
{ 55.15, 565.0},
{ 65.15, 564.0},
{ 75.15, 565.0}
};
/** Poor data: right of peak is missing. */
protected static final double[][] DATASET4 = new double[][] {
{-20.15, 1523.0},
{-19.65, 1566.0},
{-19.15, 1592.0},
{-18.65, 1927.0},
{-18.15, 3089.0},
{-17.65, 6068.0},
{-17.15, 14239.0},
{-16.65, 34124.0},
{-16.15, 64097.0},
{-15.65, 110352.0},
{-15.15, 164742.0},
{-14.65, 209499.0},
{-14.15, 267274.0},
{-13.65, 283290.0}
};
/** Good data, but few points. */
protected static final double[][] DATASET5 = new double[][] {
{4.0254623, 531026.0},
{4.03128248, 984167.0},
{4.03839603, 1887233.0},
{4.04421621, 2687152.0},
{4.05132976, 3461228.0},
{4.05326982, 3580526.0},
{4.05779662, 3439750.0},
{4.0636168, 2877648.0},
{4.06943698, 2175960.0},
{4.07525716, 1447024.0},
{4.08237071, 717104.0},
{4.08366408, 620014.0}
};
/**
* Basic.
*/
@Test
public void testFit01() {
GaussianCurveFitter fitter = GaussianCurveFitter.create();
double[] parameters = fitter.fit(createDataset(DATASET1).toList());
Assert.assertEquals(3496978.1837704973, parameters[0], 1e-4);
Assert.assertEquals(4.054933085999146, parameters[1], 1e-4);
Assert.assertEquals(0.015039355620304326, parameters[2], 1e-4);
}
@Test
public void testWithMaxIterations1() {
final int maxIter = 20;
final double[] init = { 3.5e6, 4.2, 0.1 };
GaussianCurveFitter fitter = GaussianCurveFitter.create();
double[] parameters = fitter
.withMaxIterations(maxIter)
.withStartPoint(init)
.fit(createDataset(DATASET1).toList());
Assert.assertEquals(3496978.1837704973, parameters[0], 1e-2);
Assert.assertEquals(4.054933085999146, parameters[1], 1e-4);
Assert.assertEquals(0.015039355620304326, parameters[2], 1e-4);
}
@Test(expected=TooManyIterationsException.class)
public void testWithMaxIterations2() {
final int maxIter = 1; // Too few iterations.
final double[] init = { 3.5e6, 4.2, 0.1 };
GaussianCurveFitter fitter = GaussianCurveFitter.create();
double[] parameters = fitter
.withMaxIterations(maxIter)
.withStartPoint(init)
.fit(createDataset(DATASET1).toList());
}
@Test
public void testWithStartPoint() {
final double[] init = { 3.5e6, 4.2, 0.1 };
GaussianCurveFitter fitter = GaussianCurveFitter.create();
double[] parameters = fitter
.withStartPoint(init)
.fit(createDataset(DATASET1).toList());
Assert.assertEquals(3496978.1837704973, parameters[0], 1e-2);
Assert.assertEquals(4.054933085999146, parameters[1], 1e-4);
Assert.assertEquals(0.015039355620304326, parameters[2], 1e-4);
}
/**
* Zero points is not enough observed points.
*/
@Test(expected=MathIllegalArgumentException.class)
public void testFit02() {
GaussianCurveFitter.create().fit(new WeightedObservedPoints().toList());
}
/**
* Two points is not enough observed points.
*/
@Test(expected=MathIllegalArgumentException.class)
public void testFit03() {
GaussianCurveFitter fitter = GaussianCurveFitter.create();
fitter.fit(createDataset(new double[][] {
{4.0254623, 531026.0},
{4.02804905, 664002.0}
}).toList());
}
/**
* Poor data: right of peak not symmetric with left of peak.
*/
@Test
public void testFit04() {
GaussianCurveFitter fitter = GaussianCurveFitter.create();
double[] parameters = fitter.fit(createDataset(DATASET2).toList());
Assert.assertEquals(233003.2967252038, parameters[0], 1e-4);
Assert.assertEquals(-10.654887521095983, parameters[1], 1e-4);
Assert.assertEquals(4.335937353196641, parameters[2], 1e-4);
}
/**
* Poor data: long tails.
*/
@Test
public void testFit05() {
GaussianCurveFitter fitter = GaussianCurveFitter.create();
double[] parameters = fitter.fit(createDataset(DATASET3).toList());
Assert.assertEquals(283863.81929180305, parameters[0], 1e-4);
Assert.assertEquals(-13.29641995105174, parameters[1], 1e-4);
Assert.assertEquals(1.7297330293549908, parameters[2], 1e-4);
}
/**
* Poor data: right of peak is missing.
*/
@Test
public void testFit06() {
GaussianCurveFitter fitter = GaussianCurveFitter.create();
double[] parameters = fitter.fit(createDataset(DATASET4).toList());
Assert.assertEquals(285250.66754309234, parameters[0], 1e-4);
Assert.assertEquals(-13.528375695228455, parameters[1], 1e-4);
Assert.assertEquals(1.5204344894331614, parameters[2], 1e-4);
}
/**
* Basic with smaller dataset.
*/
@Test
public void testFit07() {
GaussianCurveFitter fitter = GaussianCurveFitter.create();
double[] parameters = fitter.fit(createDataset(DATASET5).toList());
Assert.assertEquals(3514384.729342235, parameters[0], 1e-4);
Assert.assertEquals(4.054970307455625, parameters[1], 1e-4);
Assert.assertEquals(0.015029412832160017, parameters[2], 1e-4);
}
@Test
public void testMath519() {
// The optimizer will try negative sigma values but "GaussianCurveFitter"
// will catch the raised exceptions and return NaN values instead.
final double[] data = {
1.1143831578403364E-29,
4.95281403484594E-28,
1.1171347211930288E-26,
1.7044813962636277E-25,
1.9784716574832164E-24,
1.8630236407866774E-23,
1.4820532905097742E-22,
1.0241963854632831E-21,
6.275077366673128E-21,
3.461808994532493E-20,
1.7407124684715706E-19,
8.056687953553974E-19,
3.460193945992071E-18,
1.3883326374011525E-17,
5.233894983671116E-17,
1.8630791465263745E-16,
6.288759227922111E-16,
2.0204433920597856E-15,
6.198768938576155E-15,
1.821419346860626E-14,
5.139176445538471E-14,
1.3956427429045787E-13,
3.655705706448139E-13,
9.253753324779779E-13,
2.267636001476696E-12,
5.3880460095836855E-12,
1.2431632654852931E-11
};
final WeightedObservedPoints obs = new WeightedObservedPoints();
for (int i = 0; i < data.length; i++) {
obs.add(i, data[i]);
}
final double[] p = GaussianCurveFitter.create().fit(obs.toList());
Assert.assertEquals(53.1572792, p[1], 1e-7);
Assert.assertEquals(5.75214622, p[2], 1e-8);
}
@Test
public void testMath798() {
// When the data points are not commented out below, the fit stalls.
// This is expected however, since the whole dataset hardly looks like
// a Gaussian.
// When commented out, the fit proceeds fine.
final WeightedObservedPoints obs = new WeightedObservedPoints();
obs.add(0.23, 395.0);
//obs.add(0.68, 0.0);
obs.add(1.14, 376.0);
//obs.add(1.59, 0.0);
obs.add(2.05, 163.0);
//obs.add(2.50, 0.0);
obs.add(2.95, 49.0);
//obs.add(3.41, 0.0);
obs.add(3.86, 16.0);
//obs.add(4.32, 0.0);
obs.add(4.77, 1.0);
final double[] p = GaussianCurveFitter.create().fit(obs.toList());
// Values are copied from a previous run of this test.
Assert.assertEquals(420.8397296167364, p[0], 1e-12);
Assert.assertEquals(0.603770729862231, p[1], 1e-15);
Assert.assertEquals(1.0786447936766612, p[2], 1e-14);
}
/**
* Adds the specified points to specified <code>GaussianCurveFitter</code>
* instance.
*
* @param points Data points where first dimension is a point index and
* second dimension is an array of length two representing the point
* with the first value corresponding to X and the second value
* corresponding to Y.
* @return the collection of observed points.
*/
private static WeightedObservedPoints createDataset(double[][] points) {
final WeightedObservedPoints obs = new WeightedObservedPoints();
for (int i = 0; i < points.length; i++) {
obs.add(points[i][0], points[i][1]);
}
return obs;
}
}