// a nearest neighbor in the set to point p; null if the set is empty
public Point2D nearest(Point2D p) {
if (p == null) throw new NullPointerException("point");
Point2D nearestPoint = null;
double nearestDist = MAX_DISTANCE;
for (Point2D currPoint : points) {
double currDist = currPoint.distanceTo(p);
if (currDist < nearestDist) {
nearestDist = currDist;
nearestPoint = currPoint;
}
}
return nearestPoint;
}
public Point2D nearest(Point2D p, Point2D nearest) {
if (slightlyEquals(p, nearest)) return nearest;
double minDistance = p.distanceSquaredTo(nearest);
if (left != null) {
final double distanceTo = p.distanceTo(left.value);
if (distanceTo <= minDistance) {
minDistance = distanceTo;
nearest = left.value;
}
}
if (right != null) {
final double distanceTo = p.distanceTo(right.value);
if (distanceTo <= minDistance) {
minDistance = distanceTo;
nearest = right.value;
}
}
Point2D lnearest = nearest;
if (left != null && left.rect.distanceTo(nearest) < minDistance) {
lnearest = left.nearest(p, nearest);
}
Point2D rnearest = nearest;
if (right != null && right.rect.distanceTo(nearest) < minDistance) {
rnearest = right.nearest(p, nearest);
}
final double ldist = p.distanceTo(lnearest);
final double rdist = p.distanceTo(rnearest);
if (ldist < minDistance) {
nearest = lnearest;
minDistance = ldist;
}
if (rdist < minDistance) {
nearest = rnearest;
minDistance = rdist;
}
return nearest;
}
private void nearest(
final Node node, final Holder<Point2D> nearest, final Point2D p, final boolean vertical) {
if (node == null) {
return;
} else if (node.key.compareTo(p) == 0) {
nearest.value = node.key;
return;
} else if (p.distanceTo(node.key) < p.distanceTo(nearest.value)) {
nearest.value = node.key;
}
if (onTheLeft(p, node.key, vertical)) {
nearest(node.left, nearest, p, !vertical);
if (distanceToVertical(p, node.key, vertical) < p.distanceTo(nearest.value)) {
nearest(node.right, nearest, p, !vertical);
}
} else if (onTheRight(p, node.key, vertical)) {
nearest(node.right, nearest, p, !vertical);
if (distanceToVertical(p, node.key, vertical) < p.distanceTo(nearest.value)) {
nearest(node.left, nearest, p, !vertical);
}
}
}
private Point2D find(KdNode nd, double curDist, Point2D target, int turn) {
Point2D curClosest = null;
if (nd == null) return curClosest;
// Pruning
if (nd.rect.distanceTo(target) > curDist) {
return null;
}
if (nd.point.distanceTo(target) < curDist) {
curClosest = nd.point;
curDist = nd.point.distanceTo(target);
}
// Always search the plane that target is on according to
// current node
if ((turn == 0 && target.x() < nd.point.x()) || (turn == 1 && target.y() < nd.point.y())) {
Point2D left = find(nd.left, curDist, target, 1 - turn);
if (left != null && left.distanceTo(target) < curDist) {
curClosest = left;
curDist = left.distanceTo(target);
}
Point2D right = find(nd.right, curDist, target, 1 - turn);
if (right != null && right.distanceTo(target) < curDist) {
curClosest = right;
curDist = right.distanceTo(target);
}
} else {
Point2D right = find(nd.right, curDist, target, 1 - turn);
if (right != null && right.distanceTo(target) < curDist) {
curClosest = right;
curDist = right.distanceTo(target);
}
Point2D left = find(nd.left, curDist, target, 1 - turn);
if (left != null && left.distanceTo(target) < curDist) {
curClosest = left;
curDist = left.distanceTo(target);
}
}
return curClosest;
}
private double distanceTo(Point2D p1, Point2D p2) {
if (p2 == null) return Double.MAX_VALUE;
return p1.distanceTo(p2);
}