111 lines
2.9 KiB
Java
111 lines
2.9 KiB
Java
package presenter.algorithms.naiv;
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import model.Line;
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import model.Point;
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import presenter.algorithms.Algorithm;
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import presenter.util.FastElementSelector;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.LinkedList;
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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: 15.09.2017.
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*/
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public class NaivLeastMedianOfSquaresEstimator implements Algorithm {
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private ArrayList<Point> set = new ArrayList<>();
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private int n;
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private double ds, b, m;
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/**
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* Konstruktor
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* @param lines Liste des Geraden
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*/
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public NaivLeastMedianOfSquaresEstimator(LinkedList<Line> lines) {
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for (Line l : lines) {
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set.add(new Point(l.getM(), l.getB()));
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}
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}
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/**
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* Crude Algorithmus zum berechnen des LSM-Schätzers.
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*/
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private void crudeAlg() {
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ds = Double.MAX_VALUE;
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b = 0d;
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m = 0d;
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ArrayList<Point> triple = new ArrayList<>();
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double beta;
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double alpha;
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double dijk;
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System.out.println("=== S T A R T - naiv L M S ===");
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long start;
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long end;
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start = System.currentTimeMillis();
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for (Point i : set) {
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for (Point j : set) {
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for (Point k : set) {
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triple.add(i);
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triple.add(j);
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triple.add(k);
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Collections.sort(triple);
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beta = (triple.get(0).getY() - triple.get(2).getY()) / (triple.get(0).getX() - triple.get(2).getX());
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alpha = (triple.get(1).getY() + triple.get(2).getY() - (beta * (triple.get(1).getX() + triple.get(2).getX()))) / 2f;
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dijk = f(alpha, beta);
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if (dijk < ds) {
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ds = dijk;
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b = alpha;
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m = beta;
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}
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triple.clear();
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}
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}
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}
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end = System.currentTimeMillis();
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System.out.println("Zeit: "+ ((end-start)/1000));
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}
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/**
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* Berechnet die Gerade mit dem medianen Fehler
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* @param a y-Achsenabschnitt
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* @param b Steigung
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* @return medianer Fehler
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*/
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private Double f(double a, double b) {
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ArrayList<Double> res = new ArrayList<>();
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for (Point p : set) {
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res.add(Math.abs(p.getY() - (a + b * p.getX())));
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}
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return FastElementSelector.randomizedSelect(res, res.size() / 2);
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}
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@Override
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public void run() {
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crudeAlg();
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}
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@Override
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public void pepareResult() {
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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 getB() {
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return b * -1;
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}
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/**
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* @return Steigung
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*/
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public Double getM() {
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return m * -1;
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}
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}
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