def METHOD_NAME(self, filename):
    all_lattices = []
    with open(filename) as f:
        lattice = []
        for line in f:
            if line[0] == '#':
                continue
            lattice.append([float(x) for x in line.split()])
            if len(lattice) == 3:
                all_lattices.append(lattice)
                lattice = []
    return np.array(all_lattices)