Method test_resample

xarray/tests/test_groupby.py:1897–1943

(
        self, use_cftime: bool, shuffle: bool, resample_freq: ResampleCompatible
    )

        ],
    )
    def test_resample(
        self, use_cftime: bool, shuffle: bool, resample_freq: ResampleCompatible
    ) -> None:
        if use_cftime and not has_cftime:
            pytest.skip()
        times = xr.date_range(
            "2000-01-01", freq="6h", periods=10, use_cftime=use_cftime
        )

        def resample_as_pandas(array, *args, **kwargs):
            array_ = array.copy(deep=True)
            if use_cftime:
                array_["time"] = times.to_datetimeindex(time_unit="ns")
            result = DataArray.from_series(
                array_.to_series().resample(*args, **kwargs).mean()
            )
            if use_cftime:
                result = result.convert_calendar(
                    calendar="standard", use_cftime=use_cftime
                )
            return result

        array = DataArray(np.arange(10), [("time", times)])

        rs = array.resample(time=resample_freq)
        shuffled = rs.shuffle_to_chunks().resample(time=resample_freq)
        actual = rs.mean()
        expected = resample_as_pandas(array, resample_freq)
        assert_identical(expected, actual)
        assert_identical(expected, shuffled.mean())

        assert_identical(expected, rs.reduce(np.mean))
        assert_identical(expected, shuffled.reduce(np.mean))

        rs = array.resample(time="24h", closed="right")
        actual = rs.mean()
        shuffled = rs.shuffle_to_chunks().resample(time="24h", closed="right")
        expected = resample_as_pandas(array, "24h", closed="right")
        assert_identical(expected, actual)
        assert_identical(expected, shuffled.mean())

        with pytest.raises(ValueError, match=r"Index must be monotonic"):
            array[[2, 0, 1]].resample(time=resample_freq)

        reverse = array.isel(time=slice(-1, None, -1))
        with pytest.raises(ValueError):
            reverse.resample(time=resample_freq).mean()

    def test_resample_doctest(self, use_cftime: bool) -> None:
        # run the doctest example here so we are not surprised