def get_least_orbits(atom_index, cell, site_symmetry, symprec=1e-5):
    """Find least orbits for a centering atom"""
    orbits = _get_orbits(atom_index, cell, site_symmetry, symprec)
    mapping = np.arange(cell.get_number_of_atoms())

    for i, orb in enumerate(orbits):
        for num in np.unique(orb):
            if mapping[num] > mapping[i]:
                mapping[num] = mapping[i]

    return np.unique(mapping)
Find least orbits for a centering atom