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# Copyright Crown and Cartopy Contributors
#
# This file is part of Cartopy and is released under the BSD 3-clause license.
# See LICENSE in the root of the repository for full licensing details.
"""
Tests for the Albers Equal Area coordinate system.
"""
import numpy as np
from numpy.testing import assert_almost_equal, assert_array_almost_equal
import pytest
import cartopy.crs as ccrs
from .helpers import check_proj_params
class TestAlbersEqualArea:
def test_default(self):
aea = ccrs.AlbersEqualArea()
other_args = {'ellps=WGS84', 'lon_0=0.0', 'lat_0=0.0', 'x_0=0.0',
'y_0=0.0', 'lat_1=20.0', 'lat_2=50.0'}
check_proj_params('aea', aea, other_args)
assert_almost_equal(np.array(aea.x_limits),
[-17702759.799178038, 17702759.799178038],
decimal=0)
assert_almost_equal(np.array(aea.y_limits),
[-4782937.05107294, 15922623.93176938],
decimal=4)
def test_eccentric_globe(self):
globe = ccrs.Globe(semimajor_axis=1000, semiminor_axis=500,
ellipse=None)
aea = ccrs.AlbersEqualArea(globe=globe)
other_args = {'a=1000', 'b=500', 'lon_0=0.0', 'lat_0=0.0', 'x_0=0.0',
'y_0=0.0', 'lat_1=20.0', 'lat_2=50.0'}
check_proj_params('aea', aea, other_args)
assert_almost_equal(np.array(aea.x_limits),
[-2323.47073363411, 2323.47073363411],
decimal=-2)
assert_almost_equal(np.array(aea.y_limits),
[-572.556243423972, 2402.36176984391],
decimal=10)
def test_eastings(self):
aea_offset = ccrs.AlbersEqualArea(false_easting=1234,
false_northing=-4321)
other_args = {'ellps=WGS84', 'lon_0=0.0', 'lat_0=0.0', 'x_0=1234',
'y_0=-4321', 'lat_1=20.0', 'lat_2=50.0'}
check_proj_params('aea', aea_offset, other_args)
@pytest.mark.parametrize('lon', [-10.0, 10.0])
def test_central_longitude(self, lon):
aea = ccrs.AlbersEqualArea()
aea_offset = ccrs.AlbersEqualArea(central_longitude=lon)
other_args = {'ellps=WGS84', f'lon_0={lon}', 'lat_0=0.0',
'x_0=0.0', 'y_0=0.0', 'lat_1=20.0', 'lat_2=50.0'}
check_proj_params('aea', aea_offset, other_args)
assert_array_almost_equal(
aea_offset.boundary.coords,
aea.boundary.coords,
decimal=0,
)
def test_standard_parallels(self):
aea = ccrs.AlbersEqualArea(standard_parallels=(13, 37))
other_args = {'ellps=WGS84', 'lon_0=0.0', 'lat_0=0.0', 'x_0=0.0',
'y_0=0.0', 'lat_1=13', 'lat_2=37'}
check_proj_params('aea', aea, other_args)
aea = ccrs.AlbersEqualArea(standard_parallels=(13, ))
other_args = {'ellps=WGS84', 'lon_0=0.0', 'lat_0=0.0', 'x_0=0.0',
'y_0=0.0', 'lat_1=13'}
check_proj_params('aea', aea, other_args)
aea = ccrs.AlbersEqualArea(standard_parallels=13)
other_args = {'ellps=WGS84', 'lon_0=0.0', 'lat_0=0.0', 'x_0=0.0',
'y_0=0.0', 'lat_1=13'}
check_proj_params('aea', aea, other_args)
def test_sphere_transform(self):
# USGS Professional Paper 1395, pg 291
globe = ccrs.Globe(semimajor_axis=1.0, semiminor_axis=1.0,
ellipse=None)
lat_1 = 29 + 30 / 60
lat_2 = 45 + 30 / 60
aea = ccrs.AlbersEqualArea(central_latitude=23.0,
central_longitude=-96.0,
standard_parallels=(lat_1, lat_2),
globe=globe)
geodetic = aea.as_geodetic()
other_args = {'a=1.0', 'b=1.0', 'lon_0=-96.0', 'lat_0=23.0', 'x_0=0.0',
'y_0=0.0', 'lat_1=29.5', 'lat_2=45.5'}
check_proj_params('aea', aea, other_args)
assert_almost_equal(np.array(aea.x_limits),
[-2.6525072042232, 2.6525072042232],
decimal=3)
assert_almost_equal(np.array(aea.y_limits),
[-1.09628087472359, 2.39834724057551],
decimal=10)
result = aea.transform_point(-75.0, 35.0, geodetic)
assert_almost_equal(result, [0.2952720, 0.2416774])
def test_ellipsoid_transform(self):
# USGS Professional Paper 1395, pp 292 -- 293
globe = ccrs.Globe(semimajor_axis=6378206.4,
flattening=1 - np.sqrt(1 - 0.00676866),
ellipse=None)
lat_1 = 29 + 30 / 60
lat_2 = 45 + 30 / 60
aea = ccrs.AlbersEqualArea(central_latitude=23.0,
central_longitude=-96.0,
standard_parallels=(lat_1, lat_2),
globe=globe)
geodetic = aea.as_geodetic()
other_args = {'a=6378206.4', 'f=0.003390076308689371', 'lon_0=-96.0',
'lat_0=23.0', 'x_0=0.0', 'y_0=0.0', 'lat_1=29.5',
'lat_2=45.5'}
check_proj_params('aea', aea, other_args)
assert_almost_equal(np.array(aea.x_limits),
[-16900972.674607, 16900972.674607],
decimal=-3)
assert_almost_equal(np.array(aea.y_limits),
[-6971893.11311231, 15298166.8919989],
decimal=1)
result = aea.transform_point(-75.0, 35.0, geodetic)
assert_almost_equal(result, [1885472.7, 1535925.0], decimal=1)
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