def test_default(self):
geos = ccrs.RotatedGeodetic(30, 15, 27)
expected = [
'+datum=WGS84', 'ellps=WGS84', 'lon_0=210', 'no_defs',
'o_lat_p=15', 'o_lon_p=27', 'o_proj=latlon', 'proj=ob_tran',
'to_meter=0.0174532925199433'
]
self.check_proj4_params(geos, expected)
def test_as_cartopy_crs(self):
if cartopy.__version__ < '0.12':
with mock.patch('warnings.warn') as warn:
accrs = self.rp_crs.as_cartopy_crs()
self.assertEqual(warn.call_count, 1)
else:
accrs = self.rp_crs.as_cartopy_crs()
expected = ccrs.RotatedGeodetic(self.pole_lon, self.pole_lat,
self.rotation_about_new_pole)
self.assertEqual(sorted(accrs.proj4_init.split(' +')),
sorted(expected.proj4_init.split(' +')))
def rotate_pole(lons, lats, pole_lon, pole_lat):
"""
Convert arrays of lons and lats to ones on a rotated pole.
grid_lons, grid_lats = rotate_pole(lons, lats, pole_lon, pole_lat)
.. note:: Uses proj.4 to perform the conversion.
"""
src_proj = ccrs.Geodetic()
target_proj = ccrs.RotatedGeodetic(pole_longitude=pole_lon,
pole_latitude=pole_lat)
res = target_proj.transform_points(x=lons, y=lats, src_crs=src_proj)
rotated_lon = res[..., 0]
rotated_lat = res[..., 1]
return rotated_lon, rotated_lat
def unrotate_pole(rotated_lons, rotated_lats, pole_lon, pole_lat):
"""
Convert arrays of rotated-pole longitudes and latitudes to unrotated
arrays of longitudes and latitudes. The values of ``pole_lon`` and
``pole_lat`` should describe the location of the rotated pole that
describes the arrays of rotated-pole longitudes and latitudes.
As the arrays of rotated-pole longitudes and latitudes must describe a
rectilinear grid, the arrays of rotated-pole longitudes and latitudes must
be of the same shape as each other.
Example::
lons, lats = unrotate_pole(rotated_lons, rotated_lats, \
pole_lon, pole_lat)
.. note:: Uses proj.4 to perform the conversion.
Args:
* rotated_lons:
An array of rotated-pole longitude values.
* rotated_lats:
An array of rotated-pole latitude values.
* pole_lon:
The longitude of the rotated pole that describes the arrays of
rotated-pole longitudes and latitudes.
* pole_lat:
The latitude of the rotated pole that describes the arrays of
rotated-pole longitudes and latitudes.
Returns:
An array of unrotated longitudes and an array of unrotated latitudes.
"""
src_proj = ccrs.RotatedGeodetic(
pole_longitude=pole_lon, pole_latitude=pole_lat
)
target_proj = ccrs.Geodetic()
res = target_proj.transform_points(
x=rotated_lons, y=rotated_lats, src_crs=src_proj
)
unrotated_lon = res[..., 0]
unrotated_lat = res[..., 1]
return unrotated_lon, unrotated_lat
def test_transform_points_1D(self):
rlons = np.array([350., 352., 354., 356.])
rlats = np.array([-5., -0., 5., 10.])
src_proj = ccrs.RotatedGeodetic(pole_longitude=178.0,
pole_latitude=38.0)
target_proj = ccrs.Geodetic()
res = target_proj.transform_points(x=rlons, y=rlats, src_crs=src_proj)
unrotated_lon = res[..., 0]
unrotated_lat = res[..., 1]
# Solutions derived by proj4 direct.
solx = np.array(
[-16.42176094, -14.85892262, -12.88946157, -10.35078336])
soly = np.array([46.00724251, 51.29188893, 56.55031485, 61.77015703])
assert_arr_almost_eq(unrotated_lon, solx)
assert_arr_almost_eq(unrotated_lat, soly)
def test_transform_points_nD(self):
rlons = np.array([[350., 352., 354.], [350., 352., 354.]])
rlats = np.array([[-5., -0., 1.], [-4., -1., 0.]])
src_proj = ccrs.RotatedGeodetic(pole_longitude=178.0,
pole_latitude=38.0)
target_proj = ccrs.Geodetic()
res = target_proj.transform_points(x=rlons, y=rlats, src_crs=src_proj)
unrotated_lon = res[..., 0]
unrotated_lat = res[..., 1]
# Solutions derived by proj4 direct.
solx = np.array([[-16.42176094, -14.85892262, -11.90627520],
[-16.71055023, -14.58434624, -11.68799988]])
soly = np.array([[46.00724251, 51.29188893, 52.59101488],
[46.98728486, 50.30706042, 51.60004528]])
assert_arr_almost_eq(unrotated_lon, solx)
assert_arr_almost_eq(unrotated_lat, soly)
def unrotate_pole(rotated_lons, rotated_lats, pole_lon, pole_lat):
"""
Convert rotated-pole lons and lats to unrotated ones.
lons, lats = unrotate_pole(grid_lons, grid_lats, pole_lon, pole_lat)
.. note:: Uses proj.4 to perform the conversion.
"""
src_proj = ccrs.RotatedGeodetic(pole_longitude=pole_lon,
pole_latitude=pole_lat)
target_proj = ccrs.Geodetic()
res = target_proj.transform_points(x=rotated_lons,
y=rotated_lats,
src_crs=src_proj)
unrotated_lon = res[..., 0]
unrotated_lat = res[..., 1]
return unrotated_lon, unrotated_lat
def as_cartopy_crs(self):
return ccrs.RotatedGeodetic(**self._ccrs_kwargs())
def test_default():
geos = ccrs.RotatedGeodetic(30, 15, 27)
other_args = {'datum=WGS84', 'ellps=WGS84', 'lon_0=210', 'o_lat_p=15',
'o_lon_p=27'} | common_other_args
check_proj_params('ob_tran', geos, other_args)
false_northing=500_000,
standard_parallels=(64.25, 65.75),
globe=ccrs.Globe(ellipse="GRS80"),
)),
(
# Not sure how else to define this case other than copying what
# our cartopy -> pyproj converter does...
pyproj.CRS.from_epsg("""
+ellps=WGS84 +a=6371229 +b=6371229
+proj=ob_tran +o_proj=latlon +o_lon_p=0.0 +o_lat_p=177.5
+lon_0=217.5
+to_meter=0.0174532925199433 +no_defs
"""),
ccrs.RotatedGeodetic(
37.5,
177.5,
globe=ccrs.Globe(semimajor_axis=6371229, semiminor_axis=6371229),
)),
]
@pytest.mark.parametrize("source, target", cases)
def test_as_cartopy(source, target):
converted = util.crs.as_cartopy_crs(source)
# Cartopy implements equality by comparing proj4 strings, which may
# fail due to differences such as the order of parameters, or whether a
# number ends with ".0" or not. Instead, compare the underlying dicts.
assert converted.proj4_params == target.proj4_params
# Note that we can reuse the same cases, but labeled the other way round