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Support south-north scanning mode for bounding box and area #1017

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Merged
sandorkertesz merged 1 commit into from
Jun 11, 2026
Merged

Support south-north scanning mode for bounding box and area #1017

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19 changes: 15 additions & 4 deletions src/earthkit/data/field/grib/geography.py
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Original file line number Diff line number Diff line change
Expand Up @@ -86,11 +86,19 @@ def bounding_box(self):
"""
from earthkit.data.utils.bbox import BoundingBox

north = self.handle.get("latitudeOfFirstGridPointInDegrees", default=None)
south = self.handle.get("latitudeOfLastGridPointInDegrees", default=None)
if south is not None and north is not None and south > north:
# latitudes are in the wrong order, swap them
north, south = south, north
west = self.handle.get("longitudeOfFirstGridPointInDegrees", default=None)
east = self.handle.get("longitudeOfLastGridPointInDegrees", default=None)

return BoundingBox(
north=self.handle.get("latitudeOfFirstGridPointInDegrees", default=None),
south=self.handle.get("latitudeOfLastGridPointInDegrees", default=None),
west=self.handle.get("longitudeOfFirstGridPointInDegrees", default=None),
east=self.handle.get("longitudeOfLastGridPointInDegrees", default=None),
north=north,
south=south,
west=west,
east=east,
)

def projection(self):
Expand Down Expand Up @@ -164,6 +172,9 @@ def _get_grid_spec_from_handle(self):
def area(self):
north = self.handle.get("latitudeOfFirstGridPointInDegrees")
south = self.handle.get("latitudeOfLastGridPointInDegrees")
if south is not None and north is not None and south > north:
# latitudes are in the wrong order, swap them
north, south = south, north
west = self.handle.get("longitudeOfFirstGridPointInDegrees")
east = self.handle.get("longitudeOfLastGridPointInDegrees")
return tuple([north, west, south, east])
Expand Down
Binary file added tests/data/ll_sn_scanning_mode.grib
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55 changes: 22 additions & 33 deletions tests/grib/test_grib_geography.py
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Original file line number Diff line number Diff line change
Expand Up @@ -293,7 +293,7 @@ def test_grib_projection_mercator(fl_type):

@pytest.mark.parametrize("fl_type", FL_TYPES)
@pytest.mark.parametrize(
"filename,expected_shape, expected_lat, expected_lon, expected_area",
"filename,expected_shape, expected_lat, expected_lon, expected_area, expected_bbox",
[
(
"mercator.grib",
Expand All @@ -303,28 +303,32 @@ def test_grib_projection_mercator(fl_type):
),
[16.9775, 16.9775, 16.9775, 16.9775],
[291.9722, 291.9841626, 291.9961252, 292.0080878],
[16.9775, 291.9722, 19.5221, 296.0156],
[19.5221, 291.9722, 16.9775, 296.0156],
[19.5221, -68.0278, 16.9775, -63.9844],
),
(
"rgg_small_subarea_cellarea_ref.grib",
(340,),
[89.87647835, 89.80635732, 89.73614327, 89.66589394],
[45.0, 38.57142857, 45.0, 40.0],
[89.877, 36.233, 84.815, 46.185],
[89.877, 36.233, 84.815, 46.185],
),
(
"rotated_N32_subarea.grib",
(225,),
[85.489232, 84.81188, 83.171928, 81.086144],
[140.0, 110.950144, 92.460416, 82.07156],
[26.511, 0.0, -12.558, 39.375],
[26.511, 0.0, -12.558, 39.375],
),
(
"rotated_wind_20x20.grib",
(9, 18),
[30.0, 29.351052, 27.504876, 24.734374],
[140.0, 136.09296, 132.770576, 130.469424],
[80.0, 0.0, -80.0, 340.0],
[80.0, 0.0, -80.0, 340.0],
),
(
"ll_10_20.grib",
Expand All @@ -335,24 +339,38 @@ def test_grib_projection_mercator(fl_type):
[80.0, 80.0, 80.0, 80.0],
[0.0, 10.0, 20.0, 30.0],
[80.0, 0.0, -80.0, 350.0],
[80.0, 0.0, -80.0, 350.0],
),
(
"shifted_ll_subarea.grib",
(11, 19),
[73.0, 73.0, 73.0, 73.0],
[-27.0, -23.0, -19.0, -15.0],
[73, -27, 33, 45],
[73, -27, 33, 45],
),
(
"shifted_ll_3x3_subarea.grib",
(19, 29),
[79.0, 79.0, 79.0, 79.0],
[-25.0, -22.0, -19.0, -16.0],
[79, -25, 25, 59],
[79, -25, 25, 59],
),
# TODO: enable this test when support for the SN scanning is fixed in eccodes
# (
# "ll_sn_scanning_mode.grib",
# (37, 72),
# [-90., -90., -90., -90.],
# [ 0., 5., 10., 15.],
# [90., 0., -90., 355.],
# [90., 0., -90., 355.],
# ),
],
)
def test_grib_latlon_various_grids_1(fl_type, filename, expected_shape, expected_lat, expected_lon, expected_area):
def test_grib_latlon_various_grids_1(
fl_type, filename, expected_shape, expected_lat, expected_lon, expected_area, expected_bbox
):
ds, _ = load_grib_data(filename, fl_type, folder="data")

lat, lon = ds[0].geography.latlons()
Expand All @@ -361,6 +379,7 @@ def test_grib_latlon_various_grids_1(fl_type, filename, expected_shape, expected
assert np.allclose(lat.flatten()[:4], expected_lat)
assert np.allclose(lon.flatten()[:4], expected_lon)
assert np.allclose(np.asarray(ds[0].geography.area()), np.asarray(expected_area))
assert np.allclose(np.asarray(ds[0].geography.bounding_box().as_tuple()), np.asarray(expected_bbox))


@pytest.mark.skipif(IN_GITHUB, reason="Skipping test on GitHub CI")
Expand Down Expand Up @@ -510,36 +529,6 @@ def test_grib_healpix_grid(fl_type):
assert r["grid_type"] == "healpix"


@pytest.mark.skipif(IN_GITHUB, reason="Skipping test on GitHub CI")
@pytest.mark.parametrize("fl_type", ["file"])
def test_grib_grid_spec_copy_1(fl_type):
fl, _ = load_grib_data("test.grib", fl_type)

f = fl[0]
gs = f.geography.grid_spec()
gs_ori = gs.copy()
assert isinstance(gs, dict)
gs["new_key"] = "new_value" # modify the returned grid spec
assert f.geography.grid_spec() == gs_ori # check that the original grid spec is not modified
assert "new_key" not in gs_ori


@pytest.mark.skipif(IN_GITHUB, reason="Skipping test on GitHub CI")
@pytest.mark.cache
def test_grib_grid_spec_copy_2():
fl = earthkit.data.from_source(
"url", earthkit_remote_test_data_file("xr_engine/grid", "icon_ch1.grib2")
).to_fieldlist()

f = fl[0]
gs = f.geography.grid_spec()
gs_ori = gs.copy()
assert isinstance(gs, dict)
gs["new_key"] = "new_value" # modify the returned grid spec
assert f.geography.grid_spec() == gs_ori # check that the original grid spec is not modified
assert "new_key" not in gs_ori


if __name__ == "__main__":
from earthkit.data.utils.testing import main

Expand Down
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