export declare type Stack<T> = {
    datum: T;
    to: number;
    base: number;
    group: string;
    category: string | number;
    value: number;
};
export interface StackNarrowProps<T extends object> {
    data: T[];
    getGroup: (d: T) => string;
    categories: string[];
    getCategory: (d: T) => string | number;
    getValue: (d: T) => number;
}
export declare const stackNarrow: <T extends object>({ data, categories, getCategory, getGroup, getValue, }: StackNarrowProps<T>) => Stack<T>[];