/**
 * TF-IDF Vectorizer for character n-grams
 */
import type { VectorizerOptions, VectorizerData } from '../types';
export declare class TfidfVectorizer {
    private _minN;
    private _maxN;
    private _maxFeatures;
    private _vocabulary;
    private _idf;
    private _fitted;
    constructor(options?: VectorizerOptions);
    /**
     * Get configuration
     */
    get minN(): number;
    get maxN(): number;
    get maxFeatures(): number;
    get vocabularySize(): number;
    get isFitted(): boolean;
    /**
     * Fit the vectorizer on training texts
     * @param texts - Array of training texts
     * @returns this
     */
    fit(texts: string[]): this;
    /**
     * Transform text to TF-IDF vector
     * @param text - Input text
     * @returns TF-IDF vector
     */
    transform(text: string): number[];
    /**
     * Fit and transform in one step
     * @param texts - Training texts
     * @returns Array of TF-IDF vectors
     */
    fitTransform(texts: string[]): number[][];
    /**
     * Export model for saving
     * @returns Serializable model data
     */
    toJSON(): VectorizerData;
    /**
     * Load model from saved data
     * @param data - Saved model data
     * @returns Loaded vectorizer
     */
    static fromJSON(data: VectorizerData): TfidfVectorizer;
}
export default TfidfVectorizer;
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