iterable-iterator/convolution

import {_chain} from '@iterable-iterator/chain';
import {map, starmap} from '@iterable-iterator/map';
import {reduce} from '@iterable-iterator/reduce';
import {nrepeat} from '@iterable-iterator/repeat';
import {_window} from '@iterable-iterator/window';
import {_zip2} from '@iterable-iterator/zip';

/**
 * _convolution.
 *
 * @param {Array} rKernel
 * @param {Iterable} signal
 * @param {{add: Function, mul: Function, zero: any}} options
 * @return {IterableIterator}
 */
const _convolution = (rKernel, signal, {add, mul, zero}) => {
    const n = rKernel.length;
    return map(
        (slidingWindow) => reduce(add, starmap(mul, _zip2(rKernel, slidingWindow))),
        _window(n, _chain([nrepeat(zero, n - 1), signal, nrepeat(zero, n - 1)])),
    );
};

export default _convolution;