import { ChartDataPoint } from '../types';
/**
 * Spatial indexing for efficient nearest neighbor searches
 * Uses a simple grid-based approach for O(1) average lookup
 */
export declare class SpatialIndex {
    /** Grid map storing points by grid cell */
    private grid;
    /** Size of each grid cell */
    private gridSize;
    /** Bounds of the data space */
    private bounds;
    /**
     * Creates a new spatial index
     * @param data - Array of data points to index
     * @param gridSize - Size of grid cells. If omitted, automatically computed based on data distribution.
     */
    constructor(data: ChartDataPoint[], gridSize?: number);
    private calculateBounds;
    private getGridKey;
    private buildIndex;
    /**
     * Find closest point within maxDistance
     * O(1) average case vs O(n) linear search
     */
    findClosest(x: number, y: number, maxDistance?: number): {
        dataPoint: ChartDataPoint;
        distance: number;
    } | null;
}