/**
* Number generator that implements the RandomGenerator interface, and returns pseudo-random numbers
* drawn from an empirical distribution. This class is primarily a wrapper for the Colt package's
* Empirical class.
*/
public class RandomGenerator_Kernel implements RandomGenerator, Cloneable {
private double[] weights = new double[] {.125, .250, .375, .5, .625, .75, .875, 1};
private Empirical emp =
new Empirical(weights, Empirical.LINEAR_INTERPOLATION, RandomEngine.makeDefault());
private boolean rotate = true;
private double inc = 1d / (weights.length * 2d);
/** Returns a clone/copy of the instance. */
@Override
public RandomGenerator_Kernel clone() {
RandomGenerator_Kernel rgk = new RandomGenerator_Kernel();
rgk.weights = Arrays.copyOf(this.weights, weights.length);
rgk.emp = (Empirical) emp.clone();
rgk.rotate = rotate;
rgk.inc = inc;
return rgk;
}
/**
* Returns the next pseudo-random value from the generator. If the rotate parameter is true, then
* the random number is rotated such that the midpoint of the first bin will fall at zero. e.g. If
* there are eight bins, and the random number falls in the first bin, .0625 is subtracted from
* the number. A modulus of 1 is then applied so that values will remain in the interval zero to
* 1. This way, the values can be post-multiplied by tau=2*pi to get an angle.
*/
@Override
public Number getNext() {
double val = emp.nextDouble();
return rotate ? (1 + (val - inc)) % 1d : val;
}
/**
* Sets whether probability values should be rotated so that the midpoint of the first bin falls
* on zero.
*
* @param rotate - indicates whether probability values should be rotated.
*/
public void setRotate(boolean rotate) {
this.rotate = rotate;
}
/**
* Sets the weights (and number) of the bins
*
* @param weights - the pdf to be used to weight the bins
*/
public void setWeights(double[] weights) {
this.weights = weights;
inc = 1d / (weights.length * 2d);
emp.setState(weights, Empirical.LINEAR_INTERPOLATION);
}
}
