def test_view_of_view(matrix_type, subset_func, subset_func2):
    adata = gen_adata((30, 15), X_type=matrix_type)
    adata.raw = adata
    if subset_func is single_subset:
        pytest.xfail("Other subset generating functions have trouble with this")
    var_s1 = subset_func(adata.var_names, min_size=4)
    var_view1 = adata[:, var_s1]
    var_s2 = subset_func2(var_view1.var_names)
    var_view2 = var_view1[:, var_s2]
    assert var_view2._adata_ref is adata
    obs_s1 = subset_func(adata.obs_names, min_size=4)
    obs_view1 = adata[obs_s1, :]
    obs_s2 = subset_func2(obs_view1.obs_names)
    assert adata[obs_s1, :][:, var_s1][obs_s2, :]._adata_ref is adata

    view_of_actual_copy = adata[:, var_s1].copy()[obs_s1, :].copy()[:, var_s2].copy()

    view_of_view_copy = adata[:, var_s1][obs_s1, :][:, var_s2].copy()

    assert_equal(view_of_actual_copy, view_of_view_copy, exact=True)
def mmf(f, title='', ax=0):
    """plot magnetomotive force (mmf) of winding"""
    if ax == 0:
        ax = plt.gca()
    if title:
        ax.set_title(title)
    ax.plot(np.array(f['pos'])/np.pi*180, f['mmf'])
    ax.plot(np.array(f['pos_fft'])/np.pi*180, f['mmf_fft'])
    ax.set_xlabel('Position / Deg')

    phi = [f['alfa0']/np.pi*180, f['alfa0']/np.pi*180]
    y = [min(f['mmf_fft']), 1.1*max(f['mmf_fft'])]
    ax.plot(phi, y, '--')
    alfa0 = round(f['alfa0']/np.pi*180, 3)
    ax.text(phi[0]/2, y[0]+0.05, f"{alfa0}°",
            ha="center", va="bottom")
    ax.annotate(f"", xy=(phi[0], y[0]),
                xytext=(0, y[0]), arrowprops=dict(arrowstyle="->"))
    ax.grid()