def get_indices(aperiodic_mode):
    """Get a dictionary mapping indices of FOOOF params to column labels.

    Parameters
    ----------
    aperiodic_mode : {'fixed', 'knee'}
        Which approach taken to fit the aperiodic component.

    Returns
    -------
    indices : dict
        Mapping of the column indices for the FOOOF model fit params.
    """

    indices = {
        'CF' : 0,
        'PW' : 1,
        'BW' : 2,
        'offset' : 0,
        'knee' : 1 if aperiodic_mode == 'knee' else None,
        'exponent' : 1 if aperiodic_mode == 'fixed' else 2
    }

    return indices