def test_layers_view():
    X = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
    L = np.array([[10, 11, 12], [13, 14, 15], [16, 17, 18]])
    real_adata = ad.AnnData(X)
    real_adata.layers["L"] = L
    view_adata = real_adata[1:, 1:]
    real_hash = joblib.hash(real_adata)
    view_hash = joblib.hash(view_adata)

    assert view_adata.is_view

    with pytest.raises(ValueError):
        view_adata.layers["L2"] = L + 2

    assert view_adata.is_view  # Failing to set layer item makes adata not view
    assert real_hash == joblib.hash(real_adata)
    assert view_hash == joblib.hash(view_adata)

    view_adata.layers["L2"] = L[1:, 1:] + 2

    assert not view_adata.is_view
    assert real_hash == joblib.hash(real_adata)
    assert view_hash != joblib.hash(view_adata)
def _contour(ax, title, elements, values, label='', isa=None):
    from matplotlib.patches import Polygon
    from matplotlib.collections import PatchCollection
    if ax == 0:
        ax = plt.gca()
    ax.set_aspect('equal')
    ax.set_title(title, fontsize=18)
    if isa:
        for se in isa.superelements:
            ax.add_patch(Polygon([n.xy
                                  for nc in se.nodechains
                                  for n in nc.nodes],
                                 color='gray', alpha=0.1, lw=0))
    valid_values = np.logical_not(np.isnan(values))
    patches = np.array([Polygon([v.xy for v in e.vertices])
                       for e in elements])[valid_values]
    # , cmap=matplotlib.cm.jet, alpha=0.4)
    p = PatchCollection(patches, alpha=1.0, match_original=False)
    p.set_array(np.asarray(values)[valid_values])
    ax.add_collection(p)
    cb = plt.colorbar(p)
    for patch in np.array([Polygon([v.xy for v in e.vertices],
                                   fc='white', alpha=1.0)
                           for e in elements])[np.isnan(values)]:
        ax.add_patch(patch)
    if label:
        cb.set_label(label=label, fontsize=18)
    ax.autoscale(enable=True)
    ax.axis('off')