def test_views():
    X = np.array(X_list)
    adata = ad.AnnData(X, obs=obs_dict, var=var_dict, uns=uns_dict, dtype="int32")

    assert adata[:, 0].is_view
    assert adata[:, 0].X.tolist() == np.reshape([1, 4, 7], (3, 1)).tolist()

    adata[:2, 0].X = [0, 0]

    assert adata[:, 0].X.tolist() == np.reshape([0, 0, 7], (3, 1)).tolist()

    adata_subset = adata[:2, [0, 1]]

    assert adata_subset.is_view
    # now transition to actual object
    adata_subset.obs["foo"] = range(2)
    assert not adata_subset.is_view

    assert adata_subset.obs["foo"].tolist() == list(range(2))
def _testrefastpath(repat):
    """Test if a re pattern can use fast path.

    That is, for every "$A/$B" path the pattern matches, "$A" must also be
    matched,

    Return True if we're sure it is. Return False otherwise.
    """
    # XXX: It's very hard to implement this. These are what need to be
    # supported in production and tests. Very hacky. But we plan to get rid
    # of re matchers eventually.

    # Rules like "(?!experimental/)"
    if repat.startswith("(?!") and repat.endswith(")") and repat.count(")") == 1:
        return True

    # Rules used in doctest
    if repat == "(i|j)$":
        return True

    return False