def horizons_by_balancing_type_init(mod, bt):
    """
    **Set Name**: HRZS_BY_BLN_TYPE
    **Defined Over**: BLN_TYPES

    Re-arranges the 2-dimensional BLN_TYPE_HRZS set into a 1-dimensional set of
    horizons by balancing type.
    """
    horizons_of_balancing_type = []
    for (b, h) in mod.BLN_TYPE_HRZS:
        if b == bt:
            horizons_of_balancing_type.append(h)

    return horizons_of_balancing_type