/** For internal use only */
export declare type PolynomialFeaturesConfig = {
    degree: number;
    homogeneous: boolean;
    interactionOnly: boolean;
    nFeaturesIn: number;
};
/**
 * Transforms feature vectors to vectors of certain monomials thereof.
 *
 * E.g. after setting options (degree, homogeneous, interactionOnly), and
 * *fit()*ing, *transform()*s lists of feature vectors like [a, b, c], where a,
 * b and c are numbers, into the following possible outputs
 *
 * - [a^2, ba, ca, a, b^2, cb, b, c^2, c, 1] (degree = 2), that is, all
 *   monomials in a, b, c up to degree two.
 *
 * - [a^2, ba, ca, b^2, cb, c^2] (degree = 2, homogeneous = true), that is, all
 *   monomials in a, b, c of degree exactly equal to two.
 *
 * - [ab, ac, bc] (degree = 2, homogeneous = true, interactionOnly = true), that
 *   is, all monomials in a, b, c of degree exactly equal to two and no feature
 *   raised to a power larger than one.
 *
 * - [ab, ac, a, bc, b, c, 1] (degree = 2, homogeneous = false, interactionOnly
 *   = true), that is, all monomials in a, b, c of degree at most two and no
 *   feature raised to a power larger than one.
 *
 * Of course, the number of features is not restricted to three, but must be the
 * same in each feature vector of the list to be *transformed()*.
 */
export declare class PolynomialFeatures {
    private _degree;
    private _nFeaturesIn;
    private _homogeneous;
    private _interactionOnly;
    /**
     * Basic configuration. You can skip configuration by providing no arguments.
     *
     * In case no arguments are given you have to use the method fromConfig(...)
     * to set up a configuration in order to use the methods fit(...),
     * transform(...) and fitTransform(...).
     *
     * @param degree Highest order of the monomials
     * @param homogeneous Whether to include only highest order monomials
     * @param interactionOnly Whether to disallow higher powers of single features
     */
    constructor(degree?: number, homogeneous?: boolean, interactionOnly?: boolean);
    /** Configuration option 'degree' */
    get degree(): number;
    /** Configuration option 'homogenous' */
    get homogenous(): boolean;
    /** Configuration option 'interactionOnly' */
    get interactionOnly(): boolean;
    /**
     * Number of input features.
     *
     * The only configuration option which is set by the fit method.
     */
    get nFeaturesIn(): number;
    /** Saves configuration to a simple option-bag.
     *
     * The configuration specifies the internal state of PolynomialFeatures
     * completely. Hence the config of the transformer can be used to save it to a
     * file.
    */
    get config(): PolynomialFeaturesConfig;
    /** Loads configuration from simple option-bag. */
    fromConfig(config: PolynomialFeaturesConfig): void;
    /** Sets the number of input features.
     *
     * Call this method before transform(...). Afterwards the transform(...)
     * method will only accept input with the correct number of features.
    */
    fit(x: number[][]): void;
    /**
     * Returns the list of polynomial features corresponding to x.
     *
     * @param x List of features vectors (with same number of features each).
     */
    transform(x: number[][]): number[][];
    /**
     * Same as applying first fit(...) and then transform(...) to x.
     *
     * @param x List of features vectors.
     */
    fitTransform(x: number[][]): number[][];
    /**
     * Throw error in case of invalid configuration.
     */
    assertValidConfig(): void;
}