@thi.ng/distance/manhattan.d.ts

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

import type { ReadonlyVec } from "@thi.ng/vectors";
import type { IDistance, Metric } from "./api.js";
/**
 * Manhattan distance metric and conversion to/from Eucledian distances.
 *
 * @remarks
 * The conversion are always based on n-D squares, i.e. the assumption that the
 * distance is equally shared in each dimension.
 *
 * E.g. a Manhattan distance of 30 could be obtained from `[0,0]` -> `[10,20]`,
 * but would be interpreted here as distance from `[0,0]` -> `[15,15]`, which
 * produces the same Manhattan value, but yields a different Eucledian result.
 * For lack of any other information about the distance values, this is however
 * the only way to approach conversion and is sufficient for the purposes of
 * this package...
 *
 * @example
 * ```ts tangle:../export/manhattan.ts
 * import { MANHATTAN2 } from "@thi.ng/distance";
 *
 * console.log(MANHATTAN2.metric([0,0], [10,20]));
 * // 30
 *
 * console.log(MANHATTAN2.from(30));
 * // 21.213203435596427
 *
 * console.log(Math.hypot(15, 15)); // <-- diagonal of manhattan square
 * // 21.213203435596427
 *
 * console.log(Math.hypot(10, 20)); // <-- actual eucledian dist
 * // 22.360679774997898
 *
 * console.log(MANHATTAN2.to(21.213203435596427));
 * // 30
 *
 * // however, starting w/ eucledian dist first
 * const e = Math.hypot(10, 20)
 * // 22.360679774997898
 *
 * const m = MANHATTAN2.to(e)
 * // 31.622776601683793
 *
 * console.log(MANHATTAN2.from(m) === e);
 * // true
 * ```
 */
export declare class Manhattan<T> implements IDistance<T> {
    readonly dim: number;
    readonly metric: Metric<T>;
    protected _invD: number;
    constructor(dim: number, metric: Metric<T>);
    to(x: number): number;
    from(x: number): number;
}
/**
 * Returns a new Manhattan distance metric for n-D vectors of dimension `dim`.
 */
export declare const defManhattan: (dim: number) => Manhattan<ReadonlyVec>;
/**
 * Manhattan distance metric for 2d vectors.
 */
export declare const MANHATTAN2: Manhattan<ReadonlyVec>;
/**
 * Manhattan distance metric for 3d vectors.
 */
export declare const MANHATTAN3: Manhattan<ReadonlyVec>;
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