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

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

import type { FnU2, IReset, Pair } from "@thi.ng/api";
/**
 * Distance metric function
 */
export type Metric<T> = FnU2<T, number>;
/**
 * Tuple of `[distance, T]`
 */
export type Neighbor<T> = Pair<number, T>;
/**
 * Distance metric implementation & conversions from/to raw distances.
 */
export interface IDistance<T> {
    /**
     * The actual distance function metric.
     */
    readonly metric: Metric<T>;
    /**
     * Converts "untransformed" raw distance `x` into the metric of this instance.
     *
     * @param x -
     */
    to(x: number): number;
    /**
     * Converts `x` from the metric of this instance into an "untransformed" raw
     * value.
     *
     * @param x -
     */
    from(x: number): number;
}
export interface INeighborhood<P, T> extends IReset {
    /**
     * The distance metric used by this neighborhood
     */
    readonly dist: IDistance<P>;
    /**
     * The neighborhood's target position / centroid
     */
    readonly target: P;
    /**
     * The neighborhood's original radius (Eucledian metric)
     */
    readonly radius: number;
    /**
     * Returns true, if distance `d` is <= current radius of this neighborhood.
     * If `untransformed` is true (default: true), then `d` will first be
     * converted into the metric used by this neighborhood using
     * {@link IDistance.to}, otherwise it is expected to be already in that
     * metric's space.
     *
     * @param d -
     * @param untransformed -
     */
    includesDistance(d: number, untransformed?: boolean): boolean;
    /**
     * Computes distance metric between `pos` and this neighborhood's target
     * pos. Returns true if result is <= current radius.
     *
     * @param pos
     */
    includesPosition(pos: P): boolean;
    /**
     * Computes distance metric between `pos` and this neighborhood's target
     * pos. If result distance is <= current radius, adds `val` to neighborhood
     * and shrinks neighborhood radius to new distance. Returns distance metric.
     *
     * @param pos -
     * @param val -
     */
    consider(pos: P, val: T): number;
}
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