import { LabelVector } from '../clustering/types';
/**
 * - 'arithmetic': (H(U) + H(V)) / 2
 * - 'geometric': sqrt(H(U) * H(V))
 * - 'min': min(H(U), H(V))
 * - 'max': max(H(U), H(V))
 */
export type NMIAverage = 'arithmetic' | 'geometric' | 'min' | 'max';
/** @throws Error if label vectors have different lengths or are empty */
export declare function normalized_mutual_info(labels_true: LabelVector, labels_pred: LabelVector, average?: NMIAverage): number;