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chore: changes for code compliance with checkstyle (#18)
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@thegeekyasian
thegeekyasian authored Mar 9, 2023
1 parent e0b258e commit 68f06bc
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Showing 8 changed files with 162 additions and 119 deletions.
4 changes: 3 additions & 1 deletion src/main/java/com/thegeekyasian/geoassist/core/GeoAssistException.java
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Original file line number Diff line number Diff line change
@@ -1,7 +1,9 @@
package com.thegeekyasian.geoassist.core;

/**
* @author thegeekyasian
* This is a custom runtime exception for any issues that might arise.
*
* @author The Geeky Asian
*/
public class GeoAssistException extends RuntimeException {
public GeoAssistException(String message) {
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9 changes: 7 additions & 2 deletions src/main/java/com/thegeekyasian/geoassist/examples/kdtree/Search.java
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Original file line number Diff line number Diff line change
Expand Up @@ -7,9 +7,14 @@
import com.thegeekyasian.geoassist.kdtree.geometry.Point;

/**
* @author thegeekyasian
* Search provides an example implementation and usage of KDTrees.
*
* @author The Geeky Asian
*/
public class Search {
public final class Search {

private Search() {
}

public static void main(String... args) {

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133 changes: 76 additions & 57 deletions src/main/java/com/thegeekyasian/geoassist/kdtree/KDTree.java
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Original file line number Diff line number Diff line change
@@ -1,8 +1,5 @@
package com.thegeekyasian.geoassist.kdtree;

import com.thegeekyasian.geoassist.core.GeoAssistException;
import com.thegeekyasian.geoassist.kdtree.geometry.BoundingBox;
import com.thegeekyasian.geoassist.kdtree.geometry.Point;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
Expand All @@ -11,9 +8,11 @@
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

import com.thegeekyasian.geoassist.core.GeoAssistException;
import com.thegeekyasian.geoassist.kdtree.geometry.BoundingBox;
import com.thegeekyasian.geoassist.kdtree.geometry.Point;

/**
* @author thegeekyasian
*
* <p>
* This is an implementation of a two-dimensional KD-Tree that enables
* efficient range searching and lookup for point data. Points can be
Expand All @@ -35,6 +34,8 @@
* @param <O>
* describes the object that is inserted in the tree.
* For example Vendor, Restaurant, Franchise, etc.
*
* @author The Geeky Asian
*/
public class KDTree<T, O> implements Serializable {

Expand All @@ -61,8 +62,8 @@ public KDTree() {
*
* @param kdTreeObject KDTreeObject holds the custom object,
* identifier along with the Point (latitude/longitude coordinates) of the object.
*
* @throws GeoAssistException is thrown when a duplicate ID is provided.
*
* @throws GeoAssistException is thrown when a duplicate ID is provided.
* */
public void insert(KDTreeObject<T, O> kdTreeObject) {
insertObject(kdTreeObject);
Expand All @@ -74,14 +75,14 @@ private void insertObject(KDTreeObject<T, O> object) {
throw new GeoAssistException("Duplicate object provided.");
}

if (root == null) {
root = new KDTreeNode<>(object, null);
updateState(root);
if (this.root == null) {
this.root = new KDTreeNode<>(object, null);
updateState(this.root);
return;
}

KDTreeNode<T, O> current = root;
KDTreeNode<T, O> parent = root;
KDTreeNode<T, O> current = this.root;
KDTreeNode<T, O> parent = this.root;
Point point = object.getPoint();
double[] coordinates = { point.getLatitude(), point.getLongitude() };
boolean isLatitude = true;
Expand All @@ -92,17 +93,23 @@ private void insertObject(KDTreeObject<T, O> object) {
parent = current;

// Determine whether to move to the left or right subtree based on the comparison of the current dimension's coordinate value
isLessThanCurrentValue = Double.compare(coordinates[isLatitude ? 0 : 1], current.value(isLatitude)) < 0;
isLessThanCurrentValue =
Double.compare(coordinates[isLatitude ? 0 : 1], current.value(isLatitude)) < 0;
current = isLessThanCurrentValue ? current.getLeft() : current.getRight();

// If the next node in the tree has the same coordinate value along the current dimension, move to the next dimension and repeat the process
if (current != null && Double.compare(coordinates[isLatitude ? 0 : 1], current.value(isLatitude)) == 0) {
if (current != null
&& Double.compare(coordinates[isLatitude ? 0 : 1], current.value(isLatitude))
== 0) {
isLatitude = !isLatitude;
isLessThanCurrentValue = Double.compare(coordinates[isLatitude ? 0 : 1], current.value(isLatitude)) < 0;
isLessThanCurrentValue =
Double.compare(coordinates[isLatitude ? 0 : 1], current.value(isLatitude)) < 0;
current = isLessThanCurrentValue ? current.getLeft() : current.getRight();

// If the next node in the tree has the same coordinate value along the alternate dimension, it already exists in the tree and should be returned
if (current != null && Double.compare(coordinates[isLatitude ? 0 : 1], current.value(isLatitude)) == 0) {
if (current != null
&& Double.compare(coordinates[isLatitude ? 0 : 1], current.value(isLatitude))
== 0) {
return;
}
}
Expand All @@ -124,15 +131,15 @@ private void insertObject(KDTreeObject<T, O> object) {
private void updateState(KDTreeNode<T, O> node) {

KDTreeObject<T, O> kdTreeObject = node.getKdTreeObject();
if(kdTreeObject == null) {
if (kdTreeObject == null) {
return;
}
size.incrementAndGet();
this.size.incrementAndGet();

if (kdTreeObject.getId() == null) {
return;
}
map.put(kdTreeObject.getId(), node);
this.map.put(kdTreeObject.getId(), node);
}

/**
Expand All @@ -151,12 +158,13 @@ public List<KDTreeObject<T, O>> findNearestNeighbor(Point point, double distance
// Initialize a list to store the closest points
List<KDTreeObject<T, O>> closestPoints = new ArrayList<>();
// Call the recursive helper method with the root node, point, distance, and closestPoints list
findNearestNeighbor(root, point, distance, closestPoints, 0);
// Return the list of closest points
findNearestNeighbor(this.root, point, distance, closestPoints, 0);
// Return the list of the closest points
return closestPoints;
}

private void findNearestNeighbor(KDTreeNode<T, O> node, Point point, double distance, List<KDTreeObject<T, O>> closestPoints, int depth) {
private void findNearestNeighbor(KDTreeNode<T, O> node, Point point, double distance,
List<KDTreeObject<T, O>> closestPoints, int depth) {
if (node == null) {
return;
}
Expand All @@ -179,7 +187,9 @@ private void findNearestNeighbor(KDTreeNode<T, O> node, Point point, double dist

// check if the difference in latitudes is less than or equal to the provided distance
// if so, also search the right subtree
if (node.getRight() != null && Math.abs(node.getKdTreeObject().getPoint().getLatitude() - point.getLatitude()) <= distance) {
if (node.getRight() != null &&
Math.abs(node.getKdTreeObject().getPoint().getLatitude() - point.getLatitude())
<= distance) {
findNearestNeighbor(node.getRight(), point, distance, closestPoints, depth + 1);
}
}
Expand All @@ -191,7 +201,9 @@ private void findNearestNeighbor(KDTreeNode<T, O> node, Point point, double dist

// check if the difference in latitudes is less than or equal to the provided distance
// if so, also search the left subtree
if (node.getLeft() != null && Math.abs(node.getKdTreeObject().getPoint().getLatitude() - point.getLatitude()) <= distance) {
if (node.getLeft() != null &&
Math.abs(node.getKdTreeObject().getPoint().getLatitude() - point.getLatitude())
<= distance) {
findNearestNeighbor(node.getLeft(), point, distance, closestPoints, depth + 1);
}
}
Expand All @@ -200,13 +212,17 @@ private void findNearestNeighbor(KDTreeNode<T, O> node, Point point, double dist
// using the same logic as above but for longitude i.e. the second dimension.
if (point.getLongitude() < node.getKdTreeObject().getPoint().getLongitude()) {
findNearestNeighbor(node.getLeft(), point, distance, closestPoints, depth + 1);
if (node.getRight() != null && Math.abs(node.getKdTreeObject().getPoint().getLongitude() - point.getLongitude()) <= distance) {
if (node.getRight() != null && Math.abs(
node.getKdTreeObject().getPoint().getLongitude() - point.getLongitude())
<= distance) {
findNearestNeighbor(node.getRight(), point, distance, closestPoints, depth + 1);
}
}
else {
findNearestNeighbor(node.getRight(), point, distance, closestPoints, depth + 1);
if (node.getLeft() != null && Math.abs(node.getKdTreeObject().getPoint().getLongitude() - point.getLongitude()) <= distance) {
if (node.getLeft() != null && Math.abs(
node.getKdTreeObject().getPoint().getLongitude() - point.getLongitude())
<= distance) {
findNearestNeighbor(node.getLeft(), point, distance, closestPoints, depth + 1);
}
}
Expand All @@ -224,12 +240,12 @@ private void findNearestNeighbor(KDTreeNode<T, O> node, Point point, double dist
*/
public List<KDTreeObject<T, O>> findInRange(BoundingBox boundingBox) {
List<KDTreeObject<T, O>> result = new ArrayList<>();
search(root, boundingBox, true, result);
search(this.root, boundingBox, true, result);
return result;
}

private void search(KDTreeNode<T, O> node, BoundingBox boundingBox, boolean isLatitude,
List<KDTreeObject<T, O>> result) {
List<KDTreeObject<T, O>> result) {
if (node == null) {
return;
}
Expand All @@ -239,7 +255,7 @@ private void search(KDTreeNode<T, O> node, BoundingBox boundingBox, boolean isLa
Point lowerPoint = boundingBox.getLowerPoint();
Point upperPoint = boundingBox.getUpperPoint();
if (latitude >= lowerPoint.getLatitude() && latitude <= upperPoint.getLatitude()
&& longitude >= lowerPoint.getLongitude() && longitude <= upperPoint.getLongitude()) {
&& longitude >= lowerPoint.getLongitude() && longitude <= upperPoint.getLongitude()) {
result.add(kdTreeObject);
}
if (isLatitude) {
Expand Down Expand Up @@ -287,9 +303,9 @@ public int getSize() {
* */
public KDTreeObject<T, O> getById(T id) {
return Optional.ofNullable(id)
.flatMap(i -> Optional.ofNullable(map.get(id))
.map(KDTreeNode::getKdTreeObject))
.orElse(null);
.flatMap(i -> Optional.ofNullable(this.map.get(id))
.map(KDTreeNode::getKdTreeObject))
.orElse(null);
}

/**
Expand All @@ -302,11 +318,11 @@ public KDTreeObject<T, O> getById(T id) {
* @throws GeoAssistException is thrown an object with provided ID is not found.
* */
public void update(T id, O data) {
Optional.ofNullable(map.get(id))
.map(node -> {
node.getKdTreeObject().setData(data);
return node.getKdTreeObject();
}).orElseThrow(() -> new GeoAssistException("No object found for provided ID"));
Optional.ofNullable(this.map.get(id))
.map(node -> {
node.getKdTreeObject().setData(data);
return node.getKdTreeObject();
}).orElseThrow(() -> new GeoAssistException("No object found for provided ID"));
}

/**
Expand All @@ -318,9 +334,9 @@ public void update(T id, O data) {
* and `false` otherwise.
* */
public boolean delete(T id) {
return Optional.ofNullable(map.get(id)).map(node -> {
return Optional.ofNullable(this.map.get(id)).map(node -> {
deleteNode(node);
map.remove(id);
this.map.remove(id);
return true;
}).orElse(false);
}
Expand Down Expand Up @@ -380,7 +396,7 @@ else if (node.getRight() == null) {
* @return true if the tree is balanced, false otherwise.
*/
public boolean isBalanced() {
return isBalanced(root) != -1;
return isBalanced(this.root) != -1;
}

private int isBalanced(KDTreeNode<T, O> node) {
Expand Down Expand Up @@ -436,17 +452,17 @@ private int isBalanced(KDTreeNode<T, O> node) {
*
*/
public void balance() {
root = buildBalancedTree(getNodes(), null, true);
this.root = buildBalancedTree(getNodes(), null, true);
}

private List<KDTreeNode<T, O>> getNodes() {
if (map.isEmpty() || map.size() < size.get()) {
if (this.map.isEmpty() || this.map.size() < this.size.get()) {
List<KDTreeNode<T, O>> nodes = new ArrayList<>();
flattenTree(root, nodes);
flattenTree(this.root, nodes);
return nodes;
}

return new ArrayList<>(map.values());
return new ArrayList<>(this.map.values());
}

private void flattenTree(KDTreeNode<T, O> node, List<KDTreeNode<T, O>> nodes) {
Expand All @@ -459,31 +475,34 @@ private void flattenTree(KDTreeNode<T, O> node, List<KDTreeNode<T, O>> nodes) {
}

private KDTreeNode<T, O> buildBalancedTree(List<KDTreeNode<T, O>> nodes,
KDTreeNode<T, O> parent, boolean isLatitude) {
KDTreeNode<T, O> parent, boolean isLatitude) {
if (nodes.isEmpty()) {
return null;
}

// Sort the nodes along the splitting dimension (latitude or longitude)
nodes.sort((o1, o2) -> {
Point o1Point = o1.getKdTreeObject().getPoint();
Point o2Point = o2.getKdTreeObject().getPoint();
if (isLatitude) {
return Double.compare(o1Point.getLatitude(),
o2Point.getLatitude());
}
return Double.compare(o1Point.getLongitude(),
o2Point.getLongitude());
Point o1Point = o1.getKdTreeObject().getPoint();
Point o2Point = o2.getKdTreeObject().getPoint();
if (isLatitude) {
return Double.compare(o1Point.getLatitude(),
o2Point.getLatitude());
}
return Double.compare(o1Point.getLongitude(),
o2Point.getLongitude());
}
);

// Find the index of the median node in the list of nodes
int medianIndex = nodes.size() / 2;
KDTreeNode<T, O> medianNode = nodes.get(medianIndex);

medianNode.setParent(parent);
medianNode.setLeft(buildBalancedTree(nodes.subList(0, medianIndex), medianNode, !isLatitude));
medianNode.setRight(buildBalancedTree(nodes.subList(medianIndex + 1, nodes.size()), medianNode, !isLatitude));
medianNode.setLeft(
buildBalancedTree(nodes.subList(0, medianIndex), medianNode, !isLatitude));
medianNode.setRight(
buildBalancedTree(nodes.subList(medianIndex + 1, nodes.size()), medianNode,
!isLatitude));
return medianNode;
}

Expand All @@ -500,8 +519,8 @@ private double getHaversineDistance(Point point1, Point point2) {
lat2 = Math.toRadians(lat2);

double a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
Math.sin(dLon / 2) * Math.sin(dLon / 2) * Math.cos(lat1) * Math.cos(lat2);
Math.sin(dLon / 2) * Math.sin(dLon / 2) * Math.cos(lat1) * Math.cos(lat2);
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
return R * c;
}
}
}
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