import { BaseEstimator, Params } from '../base/estimator';
/**
 * Structural contract for the wrapped single-output estimator. Validated at
 * runtime by shape so any estimator following the BaseEstimator contract
 * works.
 */
export interface SingleOutputEstimator extends BaseEstimator {
    fit(X: number[][], y: number[], sampleWeight?: number[]): void;
    predict(X: number[][]): number[];
    predictProba?(X: number[][]): number[][];
}
export declare function validateSingleOutputEstimator(estimator: unknown, wrapper: string): SingleOutputEstimator;
/** Validate the 2-D multi-output target matrix against X. */
export declare function validateMultiOutputTargets(X: number[][], Y: number[][], wrapper: string): void;
/**
 * Split params into the wrapper's own params and nested params addressed as
 * `estimator__<param>` (grid-search style, mirroring Pipeline's
 * `step__param` addressing).
 */
export declare function splitEstimatorParams(params: Params, className: string): {
    own: Params;
    nested: Params;
};