def METHOD_NAME(self, num_atoms):
    np.random.seed(17809)
    self.coords_1 = np.random.random_sample((num_atoms, 3)).astype(
        np.float32
    )
    np.random.seed(9008716)
    self.coords_2 = np.random.random_sample((num_atoms, 3)).astype(
        np.float32
    )
    np.random.seed(15809)
    self.coords_3 = np.random.random_sample((num_atoms, 3)).astype(
        np.float32
    )
    np.random.seed(871600)
    self.coords_4 = np.random.random_sample((num_atoms, 3)).astype(
        np.float32
    )
    self.allocated_array_2D = np.empty(
        (num_atoms, num_atoms), dtype=np.float64
    )
    self.array_shape_1D = int(num_atoms * (num_atoms - 1) / 2.0)
    self.allocated_array_1D = np.empty(
        self.array_shape_1D, dtype=np.float64
    )
    self.u = mda.Universe(GRO)
    self.ag1 = self.u.atoms[:num_atoms]
    self.ag2 = self.u.atoms[num_atoms: 2 * num_atoms]
    self.ag3 = self.u.atoms[-num_atoms:]