def test_deepcopy_subset(adata, spmat: type):
    adata.obsp["arr"] = np.zeros((adata.n_obs, adata.n_obs))
    adata.obsp["spmat"] = spmat((adata.n_obs, adata.n_obs))

    adata = deepcopy(adata[:10].copy())

    assert isinstance(adata.obsp["arr"], np.ndarray)
    assert not isinstance(adata.obsp["arr"], ArrayView)
    np.testing.assert_array_equal(adata.obsp["arr"].shape, (10, 10))

    assert isinstance(adata.obsp["spmat"], spmat)
    assert not isinstance(
        adata.obsp["spmat"],
        SparseCSRView if spmat is sparse.csr_matrix else SparseCSCView,
    )
    np.testing.assert_array_equal(adata.obsp["spmat"].shape, (10, 10))
def airgap_fft(airgap, bmin=1e-2, ax=0):
    """plot airgap harmonics"""
    unit = 'T'
    if ax == 0:
        ax = plt.gca()
    ax.set_title('Airgap Flux Density Harmonics / {}'.format(unit))
    ax.grid(True)
    order, fluxdens = np.array([(n, b) for n, b in zip(airgap['nue'],
                                                       airgap['B_nue']) if b > bmin]).T
    try:
        markerline1, stemlines1, _ = ax.stem(order, fluxdens, '-.', basefmt=" ",
                                             use_line_collection=True)
        ax.set_xticks(order)
    except ValueError:  # empty sequence
        pass