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 dfs(self, num, target, pos, cur_str, cur_val, mul, ret):
        if pos >= len(num):
            if cur_val == target:
                ret.append(cur_str)
        else:
            for i in xrange(pos, len(num)):
                if i != pos and num[pos] == "0":
                    continue
                nxt_val = int(num[pos:i+1])

                if not cur_str:
                    self.dfs(num, target, i+1, "%d"%nxt_val, nxt_val, nxt_val, ret)
                else:
                    self.dfs(num, target, i+1, cur_str+"+%d"%nxt_val, cur_val+nxt_val, nxt_val, ret)
                    self.dfs(num, target, i+1, cur_str+"-%d"%nxt_val, cur_val-nxt_val, -nxt_val, ret)
                    self.dfs(num, target, i+1, cur_str+"*%d"%nxt_val, cur_val-mul+mul*nxt_val, mul*nxt_val, ret)