Function test_differentiate_datetime

xarray/tests/test_dataset.py:7961–8006

(dask)

@pytest.mark.parametrize("dask", [True, False])
def test_differentiate_datetime(dask) -> None:
    rs = np.random.default_rng(42)
    coord = np.array(
        [
            "2004-07-13",
            "2006-01-13",
            "2010-08-13",
            "2010-09-13",
            "2010-10-11",
            "2010-12-13",
            "2011-02-13",
            "2012-08-13",
        ],
        dtype="datetime64",
    )

    da = xr.DataArray(
        rs.random((8, 6)),
        dims=["x", "y"],
        coords={"x": coord, "z": 3, "x2d": (("x", "y"), rs.random((8, 6)))},
    )
    if dask and has_dask:
        da = da.chunk({"x": 4})

    # along x
    actual = da.differentiate("x", edge_order=1, datetime_unit="D")
    expected_x = xr.DataArray(
        np.gradient(
            da, da["x"].variable._to_numeric(datetime_unit="D"), axis=0, edge_order=1
        ),
        dims=da.dims,
        coords=da.coords,
    )
    assert_equal(expected_x, actual)

    actual2 = da.differentiate("x", edge_order=1, datetime_unit="h")
    assert np.allclose(actual, actual2 * 24)

    # for datetime variable
    actual = da["x"].differentiate("x", edge_order=1, datetime_unit="D")
    assert np.allclose(actual, 1.0)

    # with different date unit
    da = xr.DataArray(coord.astype("datetime64[ms]"), dims=["x"], coords={"x": coord})
    actual = da.differentiate("x", edge_order=1)
    assert np.allclose(actual, 1.0)


@requires_cftime