Function test_differentiate_cftime

xarray/tests/test_dataset.py:8011–8036

(dask)

@requires_cftime
@pytest.mark.parametrize("dask", [True, False])
def test_differentiate_cftime(dask) -> None:
    rs = np.random.default_rng(42)
    coord = xr.date_range("2000", periods=8, freq="2ME", use_cftime=True)

    da = xr.DataArray(
        rs.random((8, 6)),
        coords={"time": coord, "z": 3, "t2d": (("time", "y"), rs.random((8, 6)))},
        dims=["time", "y"],
    )

    if dask and has_dask:
        da = da.chunk({"time": 4})

    actual = da.differentiate("time", edge_order=1, datetime_unit="D")
    expected_data = np.gradient(
        da, da["time"].variable._to_numeric(datetime_unit="D"), axis=0, edge_order=1
    )
    expected = xr.DataArray(expected_data, coords=da.coords, dims=da.dims)
    assert_equal(expected, actual)

    actual2 = da.differentiate("time", edge_order=1, datetime_unit="h")
    assert_allclose(actual, actual2 * 24)

    # Test the differentiation of datetimes themselves
    actual = da["time"].differentiate("time", edge_order=1, datetime_unit="D")
    assert_allclose(actual, xr.ones_like(da["time"]).astype(float))


@pytest.mark.parametrize("dask", [True, False])