/**
 * Isotonic regression
 */
export default class IsotonicRegression {
    /**
     * Fit model.
     * @param {number[]} x Training data
     * @param {number[]} y Target values
     */
    fit(x: number[], y: number[]): void;
    _x: number[];
    _g: number[];
    /**
     * Returns predicted values.
     * @param {number[]} x Sample data
     * @returns {number[]} Predicted values
     */
    predict(x: number[]): number[];
}