def test_load_tmerc_grid_with_projection_origin(self):
# Test loading a single CF-netCDF file with a transverse Mercator
# grid_mapping that uses longitude_of_projection_origin and
# scale_factor_at_projection_origin instead of
# longitude_of_central_meridian and scale_factor_at_central_meridian.
cube = iris.load_cube(
tests.get_data_path((
"NetCDF",
"transverse_mercator",
"projection_origin_attributes.nc",
)))
expected = icoord_systems.TransverseMercator(
latitude_of_projection_origin=49.0,
longitude_of_central_meridian=-2.0,
false_easting=400000.0,
false_northing=-100000.0,
scale_factor_at_central_meridian=0.9996012717,
ellipsoid=icoord_systems.GeogCS(semi_major_axis=6377563.396,
semi_minor_axis=6356256.91),
)
self.assertEqual(
cube.coord("projection_x_coordinate").coord_system, expected)
self.assertEqual(
cube.coord("projection_y_coordinate").coord_system, expected)
def different_projection(self, method, ancillary_data, additional_data,
expected, **kwargs):
"""Test that the plugin copes with non-lat/lon grids."""
src_crs = ccrs.PlateCarree()
trg_crs = ccrs.TransverseMercator(central_latitude=0,
central_longitude=0)
trg_crs_iris = coord_systems.TransverseMercator(0, 0, 0, 0, 1.0)
lons = [-50, 50]
lats = [-25, 25]
x, y = [], []
for lon, lat in zip(lons, lats):
x_trg, y_trg = trg_crs.transform_point(lon, lat, src_crs)
x.append(x_trg)
y.append(y_trg)
new_x = DimCoord(np.linspace(x[0], x[1], 20),
standard_name='projection_x_coordinate',
units='m',
coord_system=trg_crs_iris)
new_y = DimCoord(np.linspace(y[0], y[1], 20),
standard_name='projection_y_coordinate',
units='m',
coord_system=trg_crs_iris)
new_cube = Cube(np.zeros(400).reshape(20, 20),
long_name="air_temperature",
dim_coords_and_dims=[(new_y, 0), (new_x, 1)],
units="K")
cube = self.cube.copy()
cube = cube.regrid(new_cube, iris.analysis.Nearest())
if ancillary_data is not None:
ancillary_data['orography'] = ancillary_data['orography'].regrid(
new_cube, iris.analysis.Nearest())
if additional_data is not None:
for ad in additional_data.keys():
additional_data[ad] = additional_data[ad].regrid(
new_cube, iris.analysis.Nearest())
# Define neighbours on this new projection
self.neighbour_list['i'] = 11
self.neighbour_list['j'] = 11
plugin = Plugin(method)
with iris.FUTURE.context(cell_datetime_objects=True):
cube = cube.extract(self.time_extract)
result = plugin.process(cube, self.sites, self.neighbour_list,
ancillary_data, additional_data, **kwargs)
self.assertEqual(cube.coord_system(), trg_crs_iris)
self.assertAlmostEqual(result.data, expected)
self.assertEqual(result.coord(axis='y').name(), 'latitude')
self.assertEqual(result.coord(axis='x').name(), 'longitude')
self.assertAlmostEqual(result.coord(axis='y').points, 4.74)
self.assertAlmostEqual(result.coord(axis='x').points, 9.47)