def test_view_failed_delitem(attr):
    adata = gen_adata((10, 10))
    view = adata[5:7, :][:, :5]
    adata_hash = joblib.hash(adata)
    view_hash = joblib.hash(view)

    with pytest.raises(KeyError):
        getattr(view, attr).__delitem__("not a key")

    assert view.is_view
    assert adata_hash == joblib.hash(adata)
    assert view_hash == joblib.hash(view)
def loss_density(isa, subreg=[], ax=0):
    """plot loss density of NC/I7/ISA7 model
    Args:
      isa: Isa7/NC object
    """
    if subreg:
        if isinstance(subreg, list):
            sr = subreg
        else:
            sr = [subreg]
        elements = [e for s in sr for sre in isa.get_subregion(s).elements()
                    for e in sre]
    else:
        elements = [e for e in isa.elements]

    lossd = np.array([e.loss_density*1e-3 for e in elements])
    _contour(ax, 'Loss Density kW/m³', elements, lossd)