def test_negative_scalar_index(adata, index: int, obs: bool):
    pos_index = index + (adata.n_obs if obs else adata.n_vars)

    if obs:
        adata_pos_subset = adata[pos_index]
        adata_neg_subset = adata[index]
    else:
        adata_pos_subset = adata[:, pos_index]
        adata_neg_subset = adata[:, index]

    np.testing.assert_array_equal(
        adata_pos_subset.obs_names, adata_neg_subset.obs_names
    )
    np.testing.assert_array_equal(
        adata_pos_subset.var_names, adata_neg_subset.var_names
    )
def i1beta_psim(i1, beta, psim, ax=0):
    """creates a surface plot of psim vs i1, beta"""
    if ax == 0:
        _create_3d_axis()
        ax = plt.gca()
    _plot_surface(ax, i1, beta, psim,
                  (u'I1/A', u'Beta/°', u'Psi m/Vs'),
                  azim=60)