/**
* Finds the x value corresponding to the maximum function value within the range of the provided
* data set.
*
* @param type one of the Fitter.FunctionType predefined functions
* @param parms parameters describing the function. These need to match the selected function or
* an IllegalArgumentEception will be thrown
* @param data JFreeChart series, used to bracket the range in which the maximum will be found
* @return x value corresponding to the maximum function value
*/
public static double getXofMaxY(XYSeries data, FunctionType type, double[] parms) {
double xAtMax = 0.0;
double minX = data.getMinX();
double maxX = data.getMaxX();
switch (type) {
case NoFit:
// find the position in data with the highest y value
double highestScore = data.getY(0).doubleValue();
int highestIndex = 0;
for (int i = 1; i < data.getItemCount(); i++) {
double newVal = data.getY(i).doubleValue();
if (newVal > highestScore) {
highestScore = newVal;
highestIndex = i;
}
}
return data.getX(highestIndex).doubleValue();
case Pol1:
case Pol2:
case Pol3:
checkParms(type, parms);
PolynomialFunction derivativePolFunction =
(new PolynomialFunction(parms)).polynomialDerivative();
final double relativeAccuracy = 1.0e-12;
final double absoluteAccuracy = 1.0e-8;
final int maxOrder = 5;
UnivariateSolver solver =
new BracketingNthOrderBrentSolver(relativeAccuracy, absoluteAccuracy, maxOrder);
xAtMax = solver.solve(100, derivativePolFunction, minX, maxX);
break;
case Gaussian:
// for a Gaussian we can take the mean and be sure it is the maximum
// note that this may be outside our range of X values, but
// this will be caught by our sanity checks below
xAtMax = parms[1];
}
// sanity checks
if (xAtMax > maxX) xAtMax = maxX;
if (xAtMax < minX) xAtMax = minX;
return xAtMax;
}
/**
* Given a JFreeChart dataset and a commons math function, return a JFreeChart dataset in which
* the original x values are now accompanied by the y values predicted by the function
*
* @param data input JFreeChart data set
* @param type one of the Fitter.FunctionType predefined functions
* @param parms parameters describing the function. These need to match the selected function or
* an IllegalArgumentEception will be thrown
* @return JFreeChart dataset with original x values and fitted y values.
*/
public static XYSeries getFittedSeries(XYSeries data, FunctionType type, double[] parms) {
XYSeries result = new XYSeries(data.getItemCount() * 10);
double minRange = data.getMinX();
double maxRange = data.getMaxX();
double xStep = (maxRange - minRange) / (data.getItemCount() * 10);
switch (type) {
case NoFit:
{
try {
XYSeries resCopy = data.createCopy(0, data.getItemCount() - 1);
return resCopy;
} catch (CloneNotSupportedException ex) {
return null;
}
}
case Pol1:
case Pol2:
case Pol3:
checkParms(type, parms);
PolynomialFunction polFunction = new PolynomialFunction(parms);
for (int i = 0; i < data.getItemCount() * 10; i++) {
double x = minRange + i * xStep;
double y = polFunction.value(x);
result.add(x, y);
}
break;
case Gaussian:
checkParms(type, parms);
Gaussian.Parametric gf = new Gaussian.Parametric();
for (int i = 0; i < data.getItemCount() * 10; i++) {
double x = minRange + i * xStep;
double[] gparms = new double[3];
System.arraycopy(parms, 0, gparms, 0, 3);
double y = gf.value(x, gparms) + parms[3];
result.add(x, y);
}
break;
}
return result;
}
