org.apache.commons.math.optimization.fitting
Class GaussianParametersGuesser

java.lang.Object
  org.apache.commons.math.optimization.fitting.GaussianParametersGuesser

public class GaussianParametersGuesser
extends java.lang.Object

Guesses the parameters (a, b, c, and d) of a ParametricGaussianFunction based on the specified observed points.

Since:

2.2

Version:

$Revision: 983921 $ $Date: 2010-08-10 12:46:06 +0200 (mar. 10 août 2010) $

Field Summary

private WeightedObservedPoint[]	observations Observed points.
private double[]	parameters Resulting guessed parameters.

Constructor Summary

GaussianParametersGuesser(WeightedObservedPoint[] observations)
Constructs instance with the specified observed points.

Method Summary

private double[]	basicGuess(WeightedObservedPoint[] points) Guesses the parameters based on the specified observed points.
private java.util.Comparator<WeightedObservedPoint>	createWeightedObservedPointComparator() Factory method creating Comparator for comparing WeightedObservedPoint instances.
private int	findMaxY(WeightedObservedPoint[] points) Finds index of point in specified points with the largest Y.
private int	findMinY(WeightedObservedPoint[] points) Finds index of point in specified points with the smallest Y.
private WeightedObservedPoint[]	getInterpolationPointsForY(WeightedObservedPoint[] points, int startIdx, int idxStep, double y) Gets the two bounding interpolation points from the specified points suitable for determining X at the specified Y.
double[]	guess() Guesses the parameters based on the observed points.
private double	interpolateXAtY(WeightedObservedPoint[] points, int startIdx, int idxStep, double y) Interpolates using the specified points to determine X at the specified Y.
private boolean	isBetween(double value, double boundary1, double boundary2) Determines whether a value is between two other values.

Methods inherited from class java.lang.Object

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

Field Detail

observations

private final WeightedObservedPoint[] observations

Observed points.

parameters

private double[] parameters

Resulting guessed parameters.

Constructor Detail

GaussianParametersGuesser

public GaussianParametersGuesser(WeightedObservedPoint[] observations)

Constructs instance with the specified observed points.

Parameters:

observations - observed points upon which should base guess

Method Detail

guess

public double[] guess()

Guesses the parameters based on the observed points.

Returns:

guessed parameters array {a, b, c, d}

basicGuess

private double[] basicGuess(WeightedObservedPoint[] points)

Guesses the parameters based on the specified observed points.

Parameters:

points - observed points upon which should base guess

Returns:

guessed parameters array {a, b, c, d}

findMinY

private int findMinY(WeightedObservedPoint[] points)

Finds index of point in specified points with the smallest Y.

Parameters:

points - points to search

Returns:

index in specified points array

findMaxY

private int findMaxY(WeightedObservedPoint[] points)

Finds index of point in specified points with the largest Y.

Parameters:

points - points to search

Returns:

index in specified points array

interpolateXAtY

private double interpolateXAtY(WeightedObservedPoint[] points,
                               int startIdx,
                               int idxStep,
                               double y)
                        throws OutOfRangeException

Interpolates using the specified points to determine X at the specified Y.

Parameters:

points - points to use for interpolation

startIdx - index within points from which to start search for interpolation bounds points

idxStep - index step for search for interpolation bounds points

y - Y value for which X should be determined

Returns:

value of X at the specified Y

Throws:

java.lang.IllegalArgumentException - if idxStep is 0

OutOfRangeException - if specified y is not within the range of the specified points

getInterpolationPointsForY

private WeightedObservedPoint[] getInterpolationPointsForY(WeightedObservedPoint[] points,
                                                           int startIdx,
                                                           int idxStep,
                                                           double y)
                                                    throws OutOfRangeException

Gets the two bounding interpolation points from the specified points suitable for determining X at the specified Y.

Parameters:

points - points to use for interpolation

startIdx - index within points from which to start search for interpolation bounds points

idxStep - index step for search for interpolation bounds points

y - Y value for which X should be determined

Returns:

array containing two points suitable for determining X at the specified Y

Throws:

java.lang.IllegalArgumentException - if idxStep is 0

OutOfRangeException - if specified y is not within the range of the specified points

isBetween

private boolean isBetween(double value,
                          double boundary1,
                          double boundary2)

Determines whether a value is between two other values.

Parameters:

value - value to determine whether is between boundary1 and boundary2

boundary1 - one end of the range

boundary2 - other end of the range

Returns:

true if value is between boundary1 and boundary2 (inclusive); false otherwise

createWeightedObservedPointComparator

private java.util.Comparator<WeightedObservedPoint> createWeightedObservedPointComparator()

Factory method creating Comparator for comparing WeightedObservedPoint instances.

Returns:

new Comparator instance