org.apache.commons.math3.fitting

Class GaussianCurveFitter

java.lang.Object

org.apache.commons.math3.fitting.AbstractCurveFitter

org.apache.commons.math3.fitting.GaussianCurveFitter

public class GaussianCurveFitter
extends AbstractCurveFitter

Fits points to a Gaussian function.
The initial guess values must be passed in the following order:

• Normalization
• Mean
• Sigma

The optimal values will be returned in the same order.

Usage example:

   WeightedObservedPoints obs = new WeightedObservedPoints();
   obs.add(4.0254623,  531026.0);
   obs.add(4.03128248, 984167.0);
   obs.add(4.03839603, 1887233.0);
   obs.add(4.04421621, 2687152.0);
   obs.add(4.05132976, 3461228.0);
   obs.add(4.05326982, 3580526.0);
   obs.add(4.05779662, 3439750.0);
   obs.add(4.0636168,  2877648.0);
   obs.add(4.06943698, 2175960.0);
   obs.add(4.07525716, 1447024.0);
   obs.add(4.08237071, 717104.0);
   obs.add(4.08366408, 620014.0);
   double[] parameters = GaussianCurveFitter.create().fit(obs.toList());
 

Since:

3.3

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GaussianCurveFitter.ParameterGuesser Guesses the parameters norm, mean, and sigma of a Gaussian.Parametric based on the specified observed points.

Nested classes/interfaces inherited from class org.apache.commons.math3.fitting.AbstractCurveFitter

AbstractCurveFitter.TheoreticalValuesFunction

Field Summary

Fields

Modifier and Type	Field and Description
private static Gaussian.Parametric	FUNCTION Parametric function to be fitted.
private double[]	initialGuess Initial guess.
private int	maxIter Maximum number of iterations of the optimization algorithm.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	GaussianCurveFitter(double[] initialGuess, int maxIter) Contructor used by the factory methods.

Method Summary

Methods

Modifier and Type	Method and Description
static GaussianCurveFitter	create() Creates a default curve fitter.
protected LeastSquaresProblem	getProblem(java.util.Collection<WeightedObservedPoint> observations) Creates a least squares problem corresponding to the appropriate curve.
GaussianCurveFitter	withMaxIterations(int newMaxIter) Configure the maximum number of iterations.
GaussianCurveFitter	withStartPoint(double[] newStart) Configure the start point (initial guess).

Methods inherited from class org.apache.commons.math3.fitting.AbstractCurveFitter

fit, getOptimizer

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FUNCTION

private static final Gaussian.Parametric FUNCTION

Parametric function to be fitted.

initialGuess

private final double[] initialGuess

Initial guess.

maxIter

private final int maxIter

Maximum number of iterations of the optimization algorithm.

Constructor Detail

GaussianCurveFitter

private GaussianCurveFitter(double[] initialGuess,
                   int maxIter)

Contructor used by the factory methods.

Parameters:

initialGuess - Initial guess. If set to null, the initial guess will be estimated using the GaussianCurveFitter.ParameterGuesser.

maxIter - Maximum number of iterations of the optimization algorithm.

Method Detail

create

public static GaussianCurveFitter create()

Creates a default curve fitter. The initial guess for the parameters will be GaussianCurveFitter.ParameterGuesser computed automatically, and the maximum number of iterations of the optimization algorithm is set to Integer.MAX_VALUE.

Returns:

a curve fitter.

See Also:

withStartPoint(double[]), withMaxIterations(int)

withStartPoint

public GaussianCurveFitter withStartPoint(double[] newStart)

Configure the start point (initial guess).

Parameters:

newStart - new start point (initial guess)

Returns:

a new instance.

withMaxIterations

public GaussianCurveFitter withMaxIterations(int newMaxIter)

Configure the maximum number of iterations.

Parameters:

newMaxIter - maximum number of iterations

Returns:

a new instance.

getProblem

protected LeastSquaresProblem getProblem(java.util.Collection<WeightedObservedPoint> observations)

Creates a least squares problem corresponding to the appropriate curve.

Specified by:

getProblem in class AbstractCurveFitter

Parameters:

observations - Sample points.

Returns:

the least squares problem to use for fitting the curve to the given points.