Skip to content
Permalink
b1f2827cac
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Go to file
 
 
Cannot retrieve contributors at this time
305 lines (291 sloc) 8.07 KB
import java.util.*;
import java.util.Map.*;
import java.lang.Boolean;
int reset_x = 140;
int reset_y = 460;
int reset_w = 100;
int reset_h = 25;
int calc_x = 250;
int calc_y = 460;
int calc_w = 100;
int calc_h = 25;
PShape reset;
PShape calculate;
PVector centerPoint;
ArrayList<PVector> rawInput = new ArrayList<PVector>();
Comparator<PVector> compareX, compareXRev, compareY, compareYRev;
// Triple used for returning three items
private class ReturnTriple {
public float sum;
public float dist;
public HashMap<PVector, Float> memoize;
public ReturnTriple(float sum, float dist, HashMap<PVector, Float> memoize) {
this.sum = sum;
this.dist = dist;
this.memoize = memoize;
}
}
// Setup
void setup() {
background(255);
size(500,500,P2D);
// Create buttons
reset = createShape(RECT, reset_x, reset_y, reset_w, reset_h);
calculate = createShape(RECT, calc_x, calc_y, calc_w, calc_h);
noLoop();
compareX = new Comparator<PVector>() {
public int compare(PVector p1, PVector p2) {
if (p1.x < p2.x) {
return -1;
}
else if (p2.x < p1.x) {
return 1;
}
else {
return 0;
}
}
};
compareXRev = new Comparator<PVector>() {
public int compare(PVector p1, PVector p2) {
if (p1.x > p2.x) {
return -1;
}
else if (p2.x > p1.x) {
return 1;
}
else {
return 0;
}
}
};
compareY = new Comparator<PVector>() {
public int compare(PVector p1, PVector p2) {
if (p1.y < p2.y) {
return -1;
}
else if (p2.y < p1.y) {
return 1;
}
else {
return 0;
}
}
};
compareYRev = new Comparator<PVector>() {
public int compare(PVector p1, PVector p2) {
if (p1.y > p2.y) {
return -1;
}
else if (p2.y > p1.y) {
return 1;
}
else {
return 0;
}
}
};
}
// On mouse press
void mousePressed() {
// If mouse presses reset button
if ((mouseX >= reset_x && mouseX <= (reset_x + reset_w)) &&
(mouseY >= reset_y && mouseY <= (reset_y + reset_h))) {
// Reset input and background
rawInput.clear();
centerPoint = null;
}
// If mouse presses calculate button
else if ((mouseX >= calc_x && mouseX <= (calc_x + calc_w)) &&
(mouseY >= calc_y && mouseY <= (calc_y + calc_h))) {
// Run algorithm
centerPoint = approxCenterpoint(rawInput);
if (centerPoint != null) {
System.out.println("x-coordinate: " + Float.toString(centerPoint.x));
System.out.println("y-coordinate: " + Float.toString(centerPoint.y));
}
}
else {
PVector new_point = new PVector(mouseX, mouseY);
rawInput.add(new_point);
}
redraw();
}
// Get geometric median
PVector getGeometricMedian(ArrayList<PVector> input) {
if (input.size() == 0) {
System.out.println("You don't have any input points!");
return null;
}
else if (input.size() == 1) {
return input.get(0);
}
else {
// Get the point
HashMap<PVector, Float> total = new HashMap<PVector, Float>();
HashMap<PVector, Float> x = getAxisMin(input, false);
HashMap<PVector, Float> y = getAxisMin(input, true);
Set<PVector> keys = x.keySet();
for (PVector key : keys) {
total.put(key, x.get(key) + y.get(key));
}
ArrayList<Entry<PVector, Float>> sortedList = new ArrayList<Entry<PVector, Float>>(total.entrySet());
Collections.sort(sortedList, new Comparator<Entry<PVector, Float>>() {
public int compare(Entry<PVector, Float> entry1, Entry<PVector, Float> entry2) {
return (int)(entry1.getValue() - entry2.getValue());
}
});
return sortedList.get(0).getKey();
}
}
// Sample input points into sets of 4
ArrayList<ArrayList<PVector>> samplePoints(ArrayList<PVector> input) {
ArrayList<PVector> inputCopy = new ArrayList<PVector>(input);
ArrayList<ArrayList<PVector>> setList = new ArrayList<ArrayList<PVector>>();
ArrayList<PVector> pointList = new ArrayList<PVector>();
// While there are still points, split into sets
while (inputCopy.size() > 0) {
double rnd = new Random().nextDouble();
int index = (int)(rnd * 10) % inputCopy.size();
// Add to set
pointList.add(inputCopy.get(index));
inputCopy.remove(index);
// Create new set on max size
if (pointList.size() == 4) {
setList.add(pointList);
pointList = new ArrayList<PVector>();
}
}
// Add most recent unempty set to list
if (pointList.size() > 0) {
setList.add(pointList);
}
return setList;
}
// Approximate the centerpoint
PVector approxCenterpoint(ArrayList<PVector> input) {
if (input.size() == 0) {
System.out.println("You don't have any input points!");
return null;
}
else {
// Algorithm
// Repeat 1 - 3 until one point remains and return that point
while (input.size() > 1) {
// 1. Sample points into groups of 4
ArrayList<ArrayList<PVector>> setList = samplePoints(input);
// 2. Compute radon point of each group (geometric median)
ArrayList<PVector> radonList = new ArrayList<PVector>();
for (ArrayList<PVector> list : setList) {
PVector radonPoint = getGeometricMedian(list);
radonList.add(radonPoint);
// 3. Set input to be new radon points
}
input = radonList;
}
return input.get(0);
}
}
// Calculate the distance with the input, memoization
float calcDist(int i, PVector currentPoint, ArrayList<PVector> input, boolean isY) {
// For each point before i, calculate distance to i
PVector prevPoint;
float sum = 0;
for (int j = 0; j < i; j++) {
prevPoint = input.get(j);
if (isY) {
sum += currentPoint.y - prevPoint.y;
}
else {
sum += currentPoint.x - prevPoint.x;
}
}
return sum;
}
// Calculate prev sum (i - 1) and the point distance from i
ReturnTriple calcLastSum(int i, PVector currentPoint, PVector nextPoint, ArrayList<PVector> input, HashMap<PVector, Float> memoize, boolean isY) {
// Calculate for squares
float sum, dist;
// If possible, reuse solution
if (memoize.containsKey(currentPoint)) {
sum = memoize.get(currentPoint);
}
// Otherwise, calculate
else {
sum = calcDist(i, currentPoint, input, isY);
memoize.put(currentPoint, sum);
}
if (isY) {
dist = nextPoint.y - currentPoint.y;
}
else {
dist = nextPoint.x - currentPoint.x;
}
return new ReturnTriple(sum, dist, memoize);
}
// Get sums and sums of squares of distances for an input
HashMap<PVector, Float> getSums(ArrayList<PVector> input, boolean isY) {
// Memoization hash tables
HashMap<PVector, Float> sumSquaresMemoize = new HashMap<PVector, Float>();
ReturnTriple returnTriple = new ReturnTriple(0, 0, null);
PVector currentPoint, nextPoint;
float sum, dist;
for (int i = 0; i < input.size() - 1; i++) {
currentPoint = input.get(i);
nextPoint = input.get(i + 1);
// Calculate sum of squares
returnTriple = calcLastSum(i, currentPoint, nextPoint, input, sumSquaresMemoize, isY);
sumSquaresMemoize = returnTriple.memoize;
sumSquaresMemoize.put(nextPoint, returnTriple.sum + (float)(i * Math.pow(returnTriple.dist, 2)) + (2 * i * returnTriple.dist));
}
return sumSquaresMemoize;
}
// Get minimum point for given axis input
HashMap<PVector, Float> getAxisMin(ArrayList<PVector> input, boolean isY) {
HashMap<PVector, Float> sumSquaresLeft, sumSquaresRight;
HashMap<PVector, Float> totalSumSquares = new HashMap<PVector, Float>();
// Get left distances
if (isY) {
Collections.sort(input, compareY);
}
else {
Collections.sort(input, compareX);
}
sumSquaresLeft = getSums(input, isY);
// Get right distances
if (isY) {
Collections.sort(input, compareYRev);
}
else {
Collections.sort(input, compareXRev);
}
sumSquaresRight = getSums(input, isY);
// Calculate total sum and store it
for (int i = 0; i < sumSquaresLeft.size(); i++) {
PVector point = input.get(i);
totalSumSquares.put(point, sumSquaresLeft.get(point) + sumSquaresRight.get(point));
}
return totalSumSquares;
}
// Draw
void draw() {
background(255);
shape(reset);
shape(calculate);
fill(50);
textSize(20);
text("Geometric Separators", 140, 20);
textSize(12);
text("Reset.", reset_x + 30, reset_y + 15);
text("Calculate.", calc_x + 25, calc_y + 15);
// Draw input
for (PVector point : rawInput) {
strokeWeight(4);
point(point.x, point.y);
}
// Draw center point
if (centerPoint != null) {
strokeWeight(6);
point(centerPoint.x, centerPoint.y);
}
}