def test_view_retains_ndarray_subclass():
    adata = ad.AnnData(np.zeros((10, 10)))
    adata.obsm["foo"] = np.zeros((10, 5)).view(NDArraySubclass)

    view = adata[:5, :]

    assert isinstance(view.obsm["foo"], NDArraySubclass)
    assert view.obsm["foo"].shape == (5, 5)
def test_impl(n):
            df = pd.DataFrame({'A': np.arange(0, n, 1, np.float32)})
            df.A[0:100] = np.nan
            df.A[200:331] = np.nan
            return df.A.quantile(.25)