/**
* Estimation based on K<sup>th</sup> selection. This may be overridden in specific enums to
* compute slightly different estimations.
*
* @param work array of numbers to be used for finding the percentile
* @param pos indicated positional index prior computed from calling {@link #index(double, int)}
* @param pivotsHeap an earlier populated cache if exists; will be used
* @param length size of array considered
* @param kthSelector a {@link KthSelector} used for pivoting during search
* @return estimated percentile
*/
protected double estimate(
final double[] work,
final int[] pivotsHeap,
final double pos,
final int length,
final KthSelector kthSelector) {
final double fpos = FastMath.floor(pos);
final int intPos = (int) fpos;
final double dif = pos - fpos;
if (pos < 1) {
return kthSelector.select(work, pivotsHeap, 0);
}
if (pos >= length) {
return kthSelector.select(work, pivotsHeap, length - 1);
}
final double lower = kthSelector.select(work, pivotsHeap, intPos - 1);
final double upper = kthSelector.select(work, pivotsHeap, intPos);
return lower + dif * (upper - lower);
}
/**
* Get the {@link PivotingStrategyInterface} used in KthSelector for computation.
*
* @return the pivoting strategy set
*/
public PivotingStrategyInterface getPivotingStrategy() {
return kthSelector.getPivotingStrategy();
}