README.md

Geometry

Point location

This Java library provides an efficient algorithm for point location: given N points and O(N log N) preprocessing time, the algorithm can find the closest point to a given query point in O(log N) time. The library uses Fortune's algorithm to construct a Voronoi diagram, and a trapezoidal map to answer point location queries in O(log N) expected time. (The construction of the trapezoidal map involves inserting edges in a randomized order, so the runtime is expected O(log N) for all inputs.)

Usage:

    import io.github.ejif.geometry.Point;
    import io.github.ejif.geometry.algorithm.PointSet;

    List<Point> points = /* points */
    Point query = /* query point */
    PointSet pointSet = new PointSet(points);
    Point closestPoint = pointSet.findClosestPoint(query);

This library is extensively tested for both randomized point configurations and discrete point configurations with collinear and concyclic points. There are no arbitrary floating point scale requirements (e.g. checks for whether two points are within EPSILON = 1e-6), so this library supports points at any scale.

Maven

The geometry library is published at the following Maven coordinates. See the Github releases page for the latest version.

    <dependency>
        <groupId>io.github.ejif.geometry</groupId>
        <artifactId>geometry</artifactId>
        <version>{version}</version>
    </dependency>