@thi.ng/distance/nearest.js

N-dimensional distance metrics & K-nearest neighborhoods for point queries

import { clamp0 } from "@thi.ng/math/interval";
import { DIST_SQ, DIST_SQ1, DIST_SQ2, DIST_SQ3 } from "./squared.js";
class Nearest {
  constructor(dist, target, radius = Infinity) {
    this.dist = dist;
    this.target = target;
    this.radius = clamp0(radius);
    this.reset();
  }
  radius;
  _currR;
  value;
  reset() {
    this._currR = this.dist.to(this.radius);
    this.value = void 0;
    return this;
  }
  /**
   * Returns current nearest neighbor result tuple (`[dist, val]`) or
   * undefined, if no such result exists (yet).
   */
  deref() {
    return this.value != void 0 ? [this._currR, this.value] : void 0;
  }
  includesDistance(d, eucledian = true) {
    return (eucledian ? this.dist.to(d) : d) <= this._currR;
  }
  includesPosition(pos) {
    return this.dist.metric(this.target, pos) < this._currR;
  }
  consider(pos, val) {
    const d = this.dist.metric(this.target, pos);
    if (d <= this._currR) {
      this._currR = d;
      this.value = val;
    }
    return d;
  }
}
const nearest = (p, r, dist = DIST_SQ) => new Nearest(dist, p, r);
const nearest2 = (p, r, dist = DIST_SQ2) => new Nearest(dist, p, r);
const nearest3 = (p, r, dist = DIST_SQ3) => new Nearest(dist, p, r);
const nearestN = (p, r, dist = DIST_SQ1) => new Nearest(dist, p, r);
export {
  Nearest,
  nearest,
  nearest2,
  nearest3,
  nearestN
};