def test_drop_obs_column():
    adata = ad.AnnData(np.array(X_list), obs=obs_dict, dtype="int32")

    subset = adata[:2]
    assert subset.is_view
    # returns a copy of obs
    assert subset.obs.drop(columns=["oanno1"]).columns.tolist() == ["oanno2", "oanno3"]
    assert subset.is_view
    # would modify obs, so it should actualize subset and not modify adata
    subset.obs.drop(columns=["oanno1"], inplace=True)
    assert not subset.is_view
    assert subset.obs.columns.tolist() == ["oanno2", "oanno3"]

    assert adata.obs.columns.tolist() == ["oanno1", "oanno2", "oanno3"]
def test_ccode_loops_matrix_vector():
    n, m = symbols('n m', integer=True)
    A = IndexedBase('A')
    x = IndexedBase('x')
    y = IndexedBase('y')
    i = Idx('i', m)
    j = Idx('j', n)

    s = (
        'for (int i=0; i<m; i++){\n'
        '   y[i] = 0;\n'
        '}\n'
        'for (int i=0; i<m; i++){\n'
        '   for (int j=0; j<n; j++){\n'
        '      y[i] = x[j]*A[%s] + y[i];\n' % (i*n + j) +\
        '   }\n'
        '}'
    )
    c = ccode(A[i, j]*x[j], assign_to=y[i])
    assert c == s