feat(distance): add Radial neighborhood impls

- add radial/2/3/N() factories

packages/distance/package.json

@@ -97,6 +97,9 @@
 		"./nearest": {
 			"default": "./nearest.js"
 		},
+		"./radial": {
+			"default": "./radial.js"
+		},
 		"./squared": {
 			"default": "./squared.js"
 		}

packages/distance/src/index.ts

@@ -5,4 +5,5 @@ export * from "./haversine.js";
 export * from "./knearest.js";
 export * from "./manhattan.js";
 export * from "./nearest.js";
+export * from "./radial.js";
 export * from "./squared.js";

packages/distance/src/knearest.ts

@@ -9,7 +9,8 @@ import { DIST_SQ, DIST_SQ1, DIST_SQ2, DIST_SQ3 } from "./squared.js";
 /**
  * A {@link INeighborhood} implementation for K-nearest neighbor queries around
  * a given target location, initial query radius and {@link IDistance} metric to
- * determine proximity.
+ * determine proximity. See {@link Radial} for an unbounded and unsorted
+ * version.
  *
  * @remarks
  * The K-nearest neighbors will be accumulated via an internal

packages/distance/src/radial.ts

@@ -0,0 +1,138 @@
+import type { IDeref } from "@thi.ng/api";
+import { clamp0 } from "@thi.ng/math/interval";
+import type { ReadonlyVec } from "@thi.ng/vectors";
+import type { IDistance, INeighborhood, Neighbor } from "./api.js";
+import { DIST_SQ, DIST_SQ1, DIST_SQ2, DIST_SQ3 } from "./squared.js";
+
+/**
+ * A {@link INeighborhood} implementation for radial neighbor queries around a
+ * given target location, initial query radius and {@link IDistance} metric to
+ * determine proximity. Unbounded and unsorted version of {@link KNearest}.
+ *
+ * @remarks
+ * Qualifying neighbors will be accumulated in order of processing via an
+ * internal array and can be obtained via {@link Radial.deref} or
+ * {@link Radial.values}.
+ *
+ * @typeParam D - spatial position for distance metric
+ * @typeParam T - indexed value
+ */
+export class Radial<D, T>
+	implements INeighborhood<D, T>, IDeref<Neighbor<T>[]>
+{
+	protected _r!: number;
+	protected _items!: [number, T][];
+
+	constructor(
+		public readonly dist: IDistance<D>,
+		public target: D,
+		public radius = Infinity
+	) {
+		this.setRadius(radius);
+	}
+
+	/**
+	 * Clears current results.
+	 */
+	reset() {
+		this._items = [];
+		return this;
+	}
+
+	/**
+	 * Resets search/reference position and clears current results.
+	 *
+	 * @param target
+	 */
+	setTarget(target: D) {
+		this.target = target;
+		this.reset();
+	}
+
+	/**
+	 * Resets search/query radius and clears current results.
+	 *
+	 * @param r
+	 */
+	setRadius(r: number) {
+		this.radius = clamp0(r);
+		this._r = this.dist.to(this.radius);
+		this.reset();
+	}
+
+	/**
+	 * Returns an array of current neighbor result tuples (each `[dist, val]`).
+	 *
+	 * @remarks
+	 * Use {@link Radial.values} to obtain result values **without** their
+	 * distance metrics.
+	 */
+	deref() {
+		return this._items;
+	}
+
+	/**
+	 * Similar to {@link Radial.deref}, but returns array of result values **without**
+	 * their distance metrics.
+	 */
+	values() {
+		return this._items.map((x) => x[1]);
+	}
+
+	includesDistance(d: number, eucledian = true) {
+		return (eucledian ? this.dist.to(d) : d) <= this._r;
+	}
+
+	consider(pos: D, val: T) {
+		const d = this.dist.metric(this.target, pos);
+		if (d <= this._r) {
+			this._items.push([d, val]);
+		}
+		return d;
+	}
+}
+
+/**
+ * Defines a {@link Radial} instance for arbitrary length vector positions
+ * and, by default, using an infinite region radius and {@link DIST_SQ} distance
+ * metric.
+ *
+ * @param p -
+ * @param r -
+ * @param dist -
+ */
+export const radial = <T>(p: ReadonlyVec, r?: number, dist = DIST_SQ) =>
+	new Radial<ReadonlyVec, T>(dist, p, r);
+
+/**
+ * Defines a {@link Radial} instance for 2D vector positions and, by default,
+ * using an infinite region radius and {@link DIST_SQ2} distance metric.
+ *
+ * @param p -
+ * @param r -
+ * @param dist -
+ */
+export const radial2 = <T>(p: ReadonlyVec, r?: number, dist = DIST_SQ2) =>
+	new Radial<ReadonlyVec, T>(dist, p, r);
+
+/**
+ * Defines a {@link Radial} instance for 3D vector positions, by default,
+ * using an infinite region radius and {@link DIST_SQ3} distance metric.
+ *
+ * @param p -
+ * @param r -
+ * @param dist -
+ */
+export const radial3 = <T>(p: ReadonlyVec, r?: number, dist = DIST_SQ3) =>
+	new Radial<ReadonlyVec, T>(dist, p, r);
+
+/**
+ * Defines a {@link Radial} instance for numeric positions and, by default,
+ * using an infinite region radius and {@link DIST_SQ1} distance metric.
+ *
+ * @param p -
+ * @param r -
+ * @param dist -
+ */
+export const radialN = <T>(p: number, r?: number, dist = DIST_SQ1) =>
+	new Radial<number, T>(dist, p, r);