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Update k-nearest-neighbors algorithm and added example from @crhallberg (#59)
* Update k-nearest-neighbors algorithm and added example from @crhalberg * Removed test that took too long on circle/ci * removed unnecessary var * Updated knearest to be depth first * No need to sort points here. * Actually... you do need to sort here
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‎examples/closest_vis_qtree/index.html‎

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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="UTF-8">
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<meta http-equiv="X-UA-Compatible" content="IE=edge">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<title>QuadTree</title>
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<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.6.0/p5.min.js"></script>
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<script src="../../quadtree.js"></script>
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<script src="sketch.js"></script>
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</head>
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<body>
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</body>
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</html>

‎examples/closest_vis_qtree/sketch.js‎

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let qtree;
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let searchedQuads = [];
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function setup() {
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createCanvas(600, 600);
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rectMode(CENTER);
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qtree = QuadTree.create();
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for (let i = 0; i < 1000; i++) {
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let p = new Point(
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Math.round(Math.random() * width),
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Math.round(Math.random() * height),
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{
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searched: false,
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closest: false,
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}
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);
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qtree.insert(p);
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}
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console.log(qtree);
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}
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function draw() {
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background("#0e141f");
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noFill();
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stroke("#273445");
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drawQuads(qtree);
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stroke("#a56de2");
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for (let quad of searchedQuads) {
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rect(quad.x, quad.y, quad.w, quad.h);
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}
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noStroke();
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qtree.forEach((p) => {
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fill("#95a3ab");
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if (p.userData.searched) {
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fill("#ffa154");
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}
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if (p.userData.closest) {
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fill("#68b723");
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}
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rect(p.x, p.y, 6, 6);
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});
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}
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function drawQuads(tree) {
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rect(tree.boundary.x, tree.boundary.y, tree.boundary.w, tree.boundary.h);
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tree.children.map(drawQuads);
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}
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function kNearest(tree, searchPoint, maxCount = 1, maxDistance = Infinity, furthestDistance = 0, foundSoFar = 0) {
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if (typeof searchPoint === "undefined") {
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throw TypeError("Method 'closest' needs a point");
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}
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let found = [];
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tree.children.sort((a, b) => a.boundary.distanceFrom(searchPoint) - b.boundary.distanceFrom(searchPoint))
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.forEach((child) => {
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const distance = child.boundary.distanceFrom(searchPoint);
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if (distance > maxDistance) {
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return;
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} else if (foundSoFar < maxCount || distance < furthestDistance) {
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const result = kNearest(child, searchPoint, maxCount, maxDistance, furthestDistance, foundSoFar);
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searchedQuads.push(child.boundary);
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const childPoints = result.found;
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found = found.concat(childPoints);
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foundSoFar += childPoints.length;
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furthestDistance = result.furthestDistance;
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}
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});
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tree.points.sort((a, b) => a.distanceFrom(searchPoint) - b.distanceFrom(searchPoint))
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.forEach((p) => {
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const distance = p.distanceFrom(searchPoint);
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p.userData.searched = true;
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if (distance > maxDistance) {
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return;
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} else if (foundSoFar < maxCount || distance < furthestDistance) {
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found.push(p);
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furthestDistance = max(distance, furthestDistance);
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foundSoFar++;
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}
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});
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return {
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found: found.sort((a, b) => a.distanceFrom(searchPoint) - b.distanceFrom(searchPoint)).slice(0, maxCount),
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furthestDistance
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};
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}
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function mousePressed() {
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searchedQuads = [];
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qtree.forEach((p) => {
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p.userData = {
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searched: false,
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closest: false,
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};
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});
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let mp = new Point(mouseX, mouseY);
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let closest = kNearest(qtree, mp).found;
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closest.forEach((p) => {
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p.userData.closest = true;
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});
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}

‎quadtree.js‎

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return found;
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}
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closest(point, count = 1, maxDistance = Infinity, furthestFound = 0, foundSoFar = 0) {
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if (typeof point === "undefined") {
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closest(searchPoint, maxCount = 1, maxDistance = Infinity) {
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if (typeof searchPoint === "undefined") {
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throw TypeError("Method 'closest' needs a point");
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}
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var inRangePoints = this.points.filter((p) => {
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const distance = p.distanceFrom(point);
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if (distance <= maxDistance) {
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furthestFound = Math.max(distance, furthestFound);
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}
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return distance <= maxDistance
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});
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this.children.forEach(child => {
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// if the child quad tree is further away from the point than the furthest point we have found so far
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// and we have enough points already
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// then we can skip checking this entire quad tree
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// as there will be no points in it that we are interested in.
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if (
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(child.boundary.distanceFrom(point) < furthestFound || foundSoFar < count) &&
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child.boundary.distanceFrom(point) < maxDistance
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) {
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inRangePoints = inRangePoints.concat(child.closest(point, count, maxDistance, furthestFound, inRangePoints.length + foundSoFar));
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}
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});
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return this.kNearest(searchPoint, maxCount, maxDistance, 0, 0).found;
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}
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return inRangePoints
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.sort((a, b) => a.distanceFrom(point) - b.distanceFrom(point))
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.slice(0, count);
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kNearest(searchPoint, maxCount, maxDistance, furthestDistance, foundSoFar) {
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let found = [];
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this.children.sort((a, b) => a.boundary.distanceFrom(searchPoint) - b.boundary.distanceFrom(searchPoint))
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.forEach((child) => {
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const distance = child.boundary.distanceFrom(searchPoint);
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if (distance > maxDistance) {
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return;
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} else if (foundSoFar < maxCount || distance < furthestDistance) {
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const result = child.kNearest(searchPoint, maxCount, maxDistance, furthestDistance, foundSoFar);
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const childPoints = result.found;
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found = found.concat(childPoints);
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foundSoFar += childPoints.length;
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furthestDistance = result.furthestDistance;
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}
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});
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this.points.sort((a, b) => a.distanceFrom(searchPoint) - b.distanceFrom(searchPoint))
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.forEach((p) => {
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const distance = p.distanceFrom(searchPoint);
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if (distance > maxDistance) {
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return;
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} else if (foundSoFar < maxCount || distance < furthestDistance) {
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found.push(p);
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furthestDistance = Math.max(distance, furthestDistance);
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foundSoFar++;
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}
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});
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return {
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found: found.sort((a, b) => a.distanceFrom(searchPoint) - b.distanceFrom(searchPoint)).slice(0, maxCount),
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furthestDistance
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};
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}
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forEach(fn) {

‎test/k-nearest-neighbors.spec.js‎

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expect(qt.closest(point, 100000).length).to.equal(100000);
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});
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it('Stupid numnber of points', () => {
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const rect = new Rectangle(500, 500, 1000, 1000);
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let qt = new QuadTree(rect, 100);
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for(var i=0; i<1000000; ++i) {
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const x = Math.random() * 1000;
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const y = Math.random() * 1000;
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qt.insert(new Point(x, y));
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}
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const point = new Point(500, 500);
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expect(qt.closest(point, 10).length).to.equal(10);
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});
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});

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