def build_sub_lattice(lattice, symbol):
    """Generate a sub-lattice of the lattice based on equivalent atomic species.

    Args:
        lattice (ASE crystal class): Input lattice
        symbol (string): Symbol of species identifying sub-lattice

    Returns:
        list of lists:
            sub_lattice: Cartesian coordinates of the sub-lattice of symbol
    """

    sub_lattice = []
    i = 0
    atomic_labels = lattice.get_chemical_symbols()
    positions = lattice.get_scaled_positions()
    for atom in atomic_labels:
        if atom == symbol:
            sub_lattice.append(positions[i])
        i = i + 1
    return sub_lattice