def sort_orbitals(element_pdos):
    """Sort the orbitals of an element's projected density of states.

    Sorts the orbitals based on a standard format. E.g. s < p < d.
    Will also sort lm decomposed orbitals. This is useful for plotting/saving.

    Args:
        element_pdos (dict): An element's pdos. Should be formatted as a
            :obj:`dict` of ``{orbital: dos}``. Where dos is a
            :obj:`~pymatgen.electronic_structure.dos.Dos` object. For example::

                {'s': dos, 'px': dos}

    Returns:
        list: The sorted orbitals.
    """
    sorted_orbitals = ['s', 'p', 'py', 'pz', 'px', 'd', 'dxy', 'dyz', 'dz2',
        'dxz', 'dx2', 'f', 'f_3', 'f_2', 'f_1', 'f0', 'f1', 'f2', 'f3']
    unsorted_keys = element_pdos.keys()
    sorted_keys = []
    for key in sorted_orbitals:
        if key in unsorted_keys:
            sorted_keys.append(key)
    return sorted_keys
