def sfs_folded_scaled(ac, n=None):
    """Compute the folded site frequency spectrum scaled such that a constant
    value is expected across the spectrum for neutral variation and constant
    population size.

    Parameters
    ----------
    ac : array_like, int, shape (n_variants, 2)
        Allele counts array.
    n : int, optional
        The total number of chromosomes called.

    Returns
    -------
    sfs_folded_scaled : ndarray, int, shape (n_chromosomes//2,)
        An array where the value of the kth element is the number of variants
        with minor allele count k, multiplied by the scaling factor
        (k * (n - k) / n).

    """

    # check input
    ac, n = _check_ac_n(ac, n)

    # compute the site frequency spectrum
    s = sfs_folded(ac, n=n)

    # apply scaling
    s = scale_sfs_folded(s, n)

    return s
Compute the folded site frequency spectrum scaled such that a constant
    value is expected across the spectrum for neutral variation and constant
    population size.

    Parameters
    ----------
    ac : array_like, int, shape (n_variants, 2)
        Allele counts array.
    n : int, optional
        The total number of chromosomes called.

    Returns
    -------
    sfs_folded_scaled : ndarray, int, shape (n_chromosomes//2,)
        An array where the value of the kth element is the number of variants
        with minor allele count k, multiplied by the scaling factor
        (k * (n - k) / n).