368 lines
11 KiB
Java
368 lines
11 KiB
Java
package de.wwwu.awolf.presenter.algorithms.advanced;
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import de.wwwu.awolf.model.Interval;
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import de.wwwu.awolf.model.Line;
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import de.wwwu.awolf.model.communication.AlgorithmData;
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import de.wwwu.awolf.model.communication.Data;
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import de.wwwu.awolf.model.communication.SubscriberType;
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import de.wwwu.awolf.presenter.Presenter;
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import de.wwwu.awolf.presenter.algorithms.Algorithm;
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import de.wwwu.awolf.presenter.util.FastElementSelector;
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import de.wwwu.awolf.presenter.util.IntersectionCounter;
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import de.wwwu.awolf.presenter.util.Logging;
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import de.wwwu.awolf.presenter.util.RandomSampler;
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import java.util.ArrayList;
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import java.util.HashMap;
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import java.util.List;
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import java.util.Map;
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import java.util.concurrent.Flow;
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/**
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* Implementierung verschiedener Algorithmen zur Berechnung von Ausgleichsgeraden.
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*
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* @Author: Armin Wolf
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* @Email: a_wolf28@uni-muenster.de
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* @Date: 28.05.2017.
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*/
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public class RepeatedMedianEstimator implements Algorithm, Flow.Publisher<Data> {
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private Presenter presenter;
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private List<Line> set;
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private Map<Line, Double> medianIntersections = new HashMap<>();
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private Map<Line, ArrayList<Double>> intersectionAbscissas = new HashMap<>();
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private Interval interval;
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//in der Literatur als L_i, C_i, und R_i bekannt
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private List<Double> countLeftSlab;
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private List<Double> countCenterSlab;
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private List<Double> countRightSlab;
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//die Mengen L,C und R
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private List<Line> linesInLeftSlab;
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private List<Line> linesInCenterSlab;
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private List<Line> linesInRightSlab;
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private double r;
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private int n;
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private double k;
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private double kLow;
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private double kHigh;
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private double beta;
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private double thetaLow;
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private double thetaHigh;
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private double slope;
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private double yInterception;
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private Flow.Subscriber<? super AlgorithmData> subscriber;
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/**
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* Konstruktor
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*
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* @param set Liste der Geraden
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* @param presenter Presenter (Beobachter)
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*/
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public RepeatedMedianEstimator(List<Line> set, Presenter presenter) {
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this.set = set;
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this.presenter = presenter;
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interval = new Interval(-10000, 10000);
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n = set.size();
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beta = 0.5;
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countLeftSlab = new ArrayList<>();
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countCenterSlab = new ArrayList<>();
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countRightSlab = new ArrayList<>();
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for (int i = 0; i < n; i++) {
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countLeftSlab.add(0d);
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countRightSlab.add(0d);
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countCenterSlab.add(n - 1.0);
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intersectionAbscissas.put(set.get(i), new ArrayList<>());
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}
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linesInLeftSlab = new ArrayList<>();
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linesInCenterSlab = new ArrayList<>(set);
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linesInRightSlab = new ArrayList<>();
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subscribe(presenter);
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}
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/**
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* Konstruktor
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*
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* @param set Liste der Geraden
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*/
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public RepeatedMedianEstimator(List<Line> set) {
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this(set, null);
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}
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/**
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* Führt den Algortihmus zur Berechnung des RM-Schätzers durch.
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* <p>
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* Paper:
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* Matousek, Jiri, D. M. Mount und N. S. Netanyahu
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* „Efficient Randomized Algorithms for the Repeated Median Line Estimator“. 1998
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* Algorithmica 20.2, S. 136–150
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*/
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public void run() {
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Logging.logInfo("=== S T A R T - R M ===");
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long start;
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long end;
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start = System.currentTimeMillis();
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while (linesInCenterSlab.size() != 1) {
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n = linesInCenterSlab.size();
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r = Math.ceil(Math.pow(n, beta));
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List<Line> lines = RandomSampler.run(linesInCenterSlab, r, linesInCenterSlab.size());
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//Für jede Gerade aus der Stichprobe wird der Schnittpunkt mit der medianen
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//x-Koordinate bestimmt
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List<Double> medianIntersectionAbscissas = new ArrayList<>();
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for (Line l : lines) {
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Double abscissa = estimateMedianIntersectionAbscissas(l);
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medianIntersections.put(l, abscissa);
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medianIntersectionAbscissas.add(abscissa);
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}
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//Rang vom RM-Wert in C
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k = Math.max(1, Math.min(set.size(), (Math.ceil(n * 0.5) - linesInLeftSlab.size())));
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//berechne k_lo und k_hi
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computeSlabBorders();
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//Berechne die Elemente mit dem Rang Theta_lo und Theta_hi
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thetaLow = FastElementSelector.randomizedSelect(medianIntersectionAbscissas, kLow);
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thetaHigh = FastElementSelector.randomizedSelect(medianIntersectionAbscissas, kHigh);
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//Für jede Gerade in C wird die Anzahl der Schnittpunkte die im Intervall liegen hochgezählt
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countNumberOfIntersectionsAbscissas();
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//verkleinere das Intervall
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contractIntervals();
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}
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end = System.currentTimeMillis();
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Logging.logInfo("Zeit: " + ((end - start) / 1000));
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pepareResult();
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}
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/**
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* Berechnet die mediane x-Koordinate über den Schnittpunkten.
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*
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* @param sampledLine Stichprobe von Geraden
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* @return mediane x-Koordinate über den Schnittpunkten
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*/
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public Double estimateMedianIntersectionAbscissas(Line sampledLine) {
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int index = Integer.parseInt(sampledLine.getId());
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IntersectionCounter intersectionCounter = new IntersectionCounter();
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List<Double> intersections = intersectionCounter.calculateIntersectionAbscissas(linesInCenterSlab, sampledLine);
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double ki = Math.ceil((n - 1) * 0.5) - FastElementSelector.randomizedSelect(countLeftSlab, index);
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double i = (Math.ceil((Math.sqrt(n) * ki) / FastElementSelector.randomizedSelect(countCenterSlab, index)));
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int accessIndex;
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if (i < 0)
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accessIndex = 0;
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else if (i >= intersections.size())
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accessIndex = intersections.size() - 1;
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else
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accessIndex = (int) i;
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return FastElementSelector.randomizedSelect(intersections, accessIndex);
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}
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/**
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* Berechnet die potenziell neuen Intervallgrenzen.
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*/
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public void computeSlabBorders() {
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kLow = Math.max(1, Math.floor(((r * k) / (linesInCenterSlab.size()))
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- ((3 * Math.sqrt(r)) * (0.5))));
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kHigh = Math.min(r, Math.floor(((r * k) / (linesInCenterSlab.size()))
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+ ((3 * Math.sqrt(r)) * (0.5))));
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}
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/**
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* Berechnet die Anzahl der Schnittpunkte pro Bereich. Insgesammt gibt es drei Bereiche:
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* Im Intervall => (a,b], vor dem Intervall => (a', a], hinter dem Intervall => (b, b'].
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*/
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public void countNumberOfIntersectionsAbscissas() {
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for (Line line : linesInCenterSlab) {
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List<Double> intersections = intersectionAbscissas.get(line);
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int index = Integer.parseInt(line.getId());
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int left = 0;
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int center = 0;
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int right = 0;
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for (Double intersection : intersections) {
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if (intersection <= thetaLow) {
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left++;
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} else if (intersection > thetaLow && intersection <= thetaHigh) {
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center++;
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} else if (intersection > thetaHigh) {
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right++;
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}
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}
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countLeftSlab.set(index, (double) left);
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countCenterSlab.set(index, (double) center);
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countRightSlab.set(index, (double) right);
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}
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}
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/**
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* TODO bad idea!!!
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* Verkleinert das aktuelle Intervall. Eines der drei Bereiche wird als neues Intervall gewählt.
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* Auf diesem Intervall werden dann in der nächsten Iteration wieder drei Bereiche bestimmt.
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*/
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public void contractIntervals() {
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for (int i = 0; i < linesInCenterSlab.size(); i++) {
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double left = countLeftSlab.get(i);
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double center = countCenterSlab.get(i);
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double right = countRightSlab.get(i);
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double max = Math.max(left, Math.max(center, right));
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if (left == max) {
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linesInLeftSlab.add(linesInCenterSlab.get(i));
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linesInCenterSlab.remove(i);
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} else if (right == max) {
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linesInRightSlab.add(linesInCenterSlab.get(i));
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linesInCenterSlab.remove(i);
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}
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}
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//wähle C als C
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if (linesInLeftSlab.size() < Math.ceil(n * 0.5) && Math.ceil(n * 0.5) <= linesInLeftSlab.size() + linesInCenterSlab.size()) {
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interval.setLower(thetaLow + 0.1);
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interval.setUpper(thetaHigh);
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}
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// wähle L als C
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else if (Math.ceil(n * 0.5) <= linesInLeftSlab.size()) {
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interval.setUpper(thetaLow);
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}
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//wähle R als C
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else if (linesInLeftSlab.size() + linesInCenterSlab.size() < Math.ceil(n * 0.5) && Math.ceil(n * 0.5) <= (linesInLeftSlab.size() + linesInCenterSlab.size() + linesInRightSlab.size())) {
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interval.setLower(thetaHigh - 0.1);
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}
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}
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@Override
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public void pepareResult() {
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if (this.subscriber != null) {
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double m = thetaLow;
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double b = (-1) * (
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(linesInCenterSlab.get(0).getM() * (thetaLow)) + linesInCenterSlab.get(0)
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.getB());
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slope = m;
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yInterception = b;
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AlgorithmData data = new AlgorithmData();
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data.setType(SubscriberType.RM);
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data.setLineData(new Line(m, b));
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this.subscriber.onNext(data);
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} else {
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double m = thetaLow;
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double b = (-1) * ((linesInCenterSlab.get(0).getM() * (thetaLow)) + linesInCenterSlab.get(0).getB());
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slope = m;
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yInterception = b;
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}
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}
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/**
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* @return Anzahl der Geraden
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*/
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public Integer getN() {
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return n;
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}
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/**
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* @param n Anzahl der Geraden
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*/
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public void setN(Integer n) {
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this.n = n;
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}
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/**
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* @param beta Parameter Beta
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*/
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public void setBeta(Double beta) {
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this.beta = beta;
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}
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/**
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* @return Steigung
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*/
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public Double getSlope() {
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return slope;
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}
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/**
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* @return y-Achsenabschnitt
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*/
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public Double getyInterception() {
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return yInterception;
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}
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/**
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* @return temporäres untere Intervallgrenze
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*/
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public Double getkLow() {
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return kLow;
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}
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/**
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* @param kLow temporäres untere Intervallgrenze
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*/
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public void setkLow(Double kLow) {
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this.kLow = kLow;
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}
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/**
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* @return temporäres oberes Intervallgrenze
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*/
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public Double getkHigh() {
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return kHigh;
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}
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/**
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* @param kHigh temporäres oberes Intervallgrenze
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*/
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public void setkHigh(Double kHigh) {
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this.kHigh = kHigh;
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}
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/**
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* @return verteilung der Punkte
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*/
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public List<Double> getCountLeftSlab() {
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return countLeftSlab;
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}
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/**
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* @return verteilung der Punkte
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*/
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public List<Double> getCountCenterSlab() {
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return countCenterSlab;
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}
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/**
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* @return verteilung der Punkte
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*/
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public List<Double> getCountRightSlab() {
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return countRightSlab;
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}
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@Override
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public void subscribe(Flow.Subscriber<? super Data> subscriber) {
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this.subscriber = subscriber;
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}
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}
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