/** Build step-interpolated polyline points from data values. */
export declare function stepPoints(data: number[], toXY: (i: number, v: number) => [number, number]): number[];
/** Catmull-Rom spline through points [[x,y],...] */
export declare function catmullRomPath(points: [number, number][], tension?: number): string;
export declare function pointsToPairs(points: number[]): [number, number][];