def test_area2gridmapping(self):
"""Test the conversion from pyresample area object to CF grid mapping."""
import xarray as xr
import pyresample.geometry
from satpy.writers.cf_writer import area2gridmapping
ds_base = xr.DataArray(data=[[1, 2], [3, 4]], dims=('y', 'x'), coords={'y': [1, 2], 'x': [3, 4]},
attrs={'name': 'var1'})
# a) Projection has a corresponding CF representation (e.g. geos)
a = 6378169.
b = 6356583.8
h = 35785831.
geos = pyresample.geometry.AreaDefinition(
area_id='geos',
description='geos',
proj_id='geos',
projection={'proj': 'geos', 'h': h, 'a': a, 'b': b},
width=2, height=2,
area_extent=[-1, -1, 1, 1])
geos_expected = xr.DataArray(data=0,
attrs={'perspective_point_height': h,
'latitude_of_projection_origin': None,
'longitude_of_projection_origin': None,
'grid_mapping_name': 'geostationary',
'semi_major_axis': a,
'semi_minor_axis': b,
'sweep_axis': None,
'name': 'geos'})
ds = ds_base.copy()
ds.attrs['area'] = geos
res, grid_mapping = area2gridmapping(ds)
self.assertEqual(res.attrs['grid_mapping'], 'geos')
self.assertEqual(grid_mapping, geos_expected)
# b) Projection does not have a corresponding CF representation (COSMO)
cosmo7 = pyresample.geometry.AreaDefinition(
area_id='cosmo7',
description='cosmo7',
proj_id='cosmo7',
projection={'proj': 'ob_tran', 'ellps': 'WGS84', 'lat_0': 46, 'lon_0': 4.535,
'o_proj': 'stere', 'o_lat_p': 90, 'o_lon_p': -5.465},
width=597, height=510,
area_extent=[-1812933, -1003565, 814056, 1243448]
)
proj_str = '+proj=ob_tran +ellps=WGS84 +lat_0=46.0 +lon_0=4.535 +o_proj=stere +o_lat_p=90.0 +o_lon_p=-5.465'
cosmo_expected = xr.DataArray(data=0, attrs={'name': 'proj4', 'proj4': proj_str})
ds = ds_base.copy()
ds.attrs['area'] = cosmo7
with mock.patch('satpy.writers.cf_writer.warnings.warn') as warn:
res, grid_mapping = area2gridmapping(ds)
warn.assert_called()
self.assertDictEqual(dict(pyresample.geometry.proj4_str_to_dict(res.attrs['grid_proj4'])),
dict(pyresample.geometry.proj4_str_to_dict(proj_str)))
self.assertEqual(grid_mapping, cosmo_expected)
def test_area2gridmapping(self):
"""Test the conversion from pyresample area object to CF grid mapping."""
import xarray as xr
import pyresample.geometry
from satpy.writers.cf_writer import area2gridmapping
def _gm_matches(gmapping, expected):
"""Assert that all keys in ``expected`` match the values in ``gmapping``."""
for attr_key, attr_val in expected.attrs.items():
test_val = gmapping.attrs[attr_key]
if attr_val is None or isinstance(attr_val, str):
self.assertEqual(test_val, attr_val)
else:
np.testing.assert_almost_equal(test_val,
attr_val,
decimal=3)
ds_base = xr.DataArray(data=[[1, 2], [3, 4]],
dims=('y', 'x'),
coords={
'y': [1, 2],
'x': [3, 4]
},
attrs={'name': 'var1'})
# a) Projection has a corresponding CF representation (e.g. geos)
a = 6378169.
b = 6356583.8
h = 35785831.
geos = pyresample.geometry.AreaDefinition(area_id='geos',
description='geos',
proj_id='geos',
projection={
'proj': 'geos',
'h': h,
'a': a,
'b': b
},
width=2,
height=2,
area_extent=[-1, -1, 1, 1])
geos_expected = xr.DataArray(data=0,
attrs={
'perspective_point_height': h,
'latitude_of_projection_origin': 0,
'longitude_of_projection_origin': 0,
'grid_mapping_name': 'geostationary',
'semi_major_axis': a,
'semi_minor_axis': b,
'sweep_axis': None,
'name': 'geos'
})
ds = ds_base.copy()
ds.attrs['area'] = geos
res, grid_mapping = area2gridmapping(ds)
self.assertEqual(res.attrs['grid_mapping'], 'geos')
_gm_matches(grid_mapping, geos_expected)
# b) Projection does not have a corresponding CF representation (COSMO)
cosmo7 = pyresample.geometry.AreaDefinition(
area_id='cosmo7',
description='cosmo7',
proj_id='cosmo7',
projection={
'proj': 'ob_tran',
'ellps': 'WGS84',
'lat_0': 46,
'lon_0': 4.535,
'o_proj': 'stere',
'o_lat_p': 90,
'o_lon_p': -5.465
},
width=597,
height=510,
area_extent=[-1812933, -1003565, 814056, 1243448])
ds = ds_base.copy()
ds.attrs['area'] = cosmo7
with mock.patch('satpy.writers.cf_writer.warnings.warn') as warn:
res, grid_mapping = area2gridmapping(ds)
warn.assert_called()
proj_dict = pyresample.geometry.proj4_str_to_dict(
res.attrs['grid_proj4'])
self.assertEqual(proj_dict['lon_0'], 4.535)
self.assertEqual(proj_dict['lat_0'], 46.0)
self.assertEqual(proj_dict['o_lon_p'], -5.465)
self.assertEqual(proj_dict['o_lat_p'], 90.0)
self.assertEqual(proj_dict['proj'], 'ob_tran')
self.assertEqual(proj_dict['o_proj'], 'stere')
self.assertEqual(proj_dict['ellps'], 'WGS84')
self.assertEqual(grid_mapping.attrs['name'], 'proj4')
# c) Projection Transverse Mercator
lat_0 = 36.5
lon_0 = 15.0
tmerc = pyresample.geometry.AreaDefinition(area_id='tmerc',
description='tmerc',
proj_id='tmerc',
projection={
'proj': 'tmerc',
'ellps': 'WGS84',
'lat_0': 36.5,
'lon_0': 15.0
},
width=2,
height=2,
area_extent=[-1, -1, 1, 1])
tmerc_expected = xr.DataArray(data=0,
attrs={
'latitude_of_projection_origin':
lat_0,
'longitude_of_central_meridian':
lon_0,
'grid_mapping_name':
'transverse_mercator',
'reference_ellipsoid_name': 'WGS84',
'false_easting': 0.,
'false_northing': 0.,
'name': 'tmerc'
})
ds = ds_base.copy()
ds.attrs['area'] = tmerc
res, grid_mapping = area2gridmapping(ds)
self.assertEqual(res.attrs['grid_mapping'], 'tmerc')
_gm_matches(grid_mapping, tmerc_expected)
# d) Projection that has a representation but no explicit a/b
h = 35785831.
geos = pyresample.geometry.AreaDefinition(area_id='geos',
description='geos',
proj_id='geos',
projection={
'proj': 'geos',
'h': h,
'datum': 'WGS84',
'ellps': 'GRS80'
},
width=2,
height=2,
area_extent=[-1, -1, 1, 1])
geos_expected = xr.DataArray(data=0,
attrs={
'perspective_point_height': h,
'latitude_of_projection_origin': 0,
'longitude_of_projection_origin': 0,
'grid_mapping_name': 'geostationary',
'semi_major_axis': 6378137.0,
'semi_minor_axis': 6356752.314,
'sweep_axis': None,
'name': 'geos'
})
ds = ds_base.copy()
ds.attrs['area'] = geos
res, grid_mapping = area2gridmapping(ds)
self.assertEqual(res.attrs['grid_mapping'], 'geos')
_gm_matches(grid_mapping, geos_expected)
# e) oblique Mercator
area = pyresample.geometry.AreaDefinition(
area_id='omerc_otf',
description='On-the-fly omerc area',
proj_id='omerc',
projection={
'alpha': '9.02638777018478',
'ellps': 'WGS84',
'gamma': '0',
'k': '1',
'lat_0': '-0.256794486098476',
'lonc': '13.7888658224205',
'proj': 'omerc',
'units': 'm'
},
width=2837,
height=5940,
area_extent=[
-1460463.0893, 3455291.3877, 1538407.1158, 9615788.8787
])
omerc_dict = {
'name': 'omerc',
'azimuth_of_central_line': 9.02638777018478,
'false_easting': 0.,
'false_northing': 0.,
'gamma': 0,
'geographic_crs_name': "unknown",
'grid_mapping_name': "oblique_mercator",
'horizontal_datum_name': "unknown",
'latitude_of_projection_origin': -0.256794486098476,
'longitude_of_projection_origin': 13.7888658224205,
'prime_meridian_name': "Greenwich",
'reference_ellipsoid_name': "WGS84"
}
omerc_expected = xr.DataArray(data=0, attrs=omerc_dict)
ds = ds_base.copy()
ds.attrs['area'] = area
res, grid_mapping = area2gridmapping(ds)
self.assertEqual(res.attrs['grid_mapping'], 'omerc')
_gm_matches(grid_mapping, omerc_expected)
def test_area2gridmapping(self):
"""Test the conversion from pyresample area object to CF grid mapping."""
import xarray as xr
import pyresample.geometry
from satpy.writers.cf_writer import area2gridmapping
def _gm_matches(gmapping, expected):
"""Assert that all keys in ``expected`` match the values in ``gmapping``."""
for attr_key, attr_val in expected.attrs.items():
test_val = gmapping.attrs[attr_key]
if attr_val is None or isinstance(attr_val, str):
self.assertEqual(test_val, attr_val)
else:
np.testing.assert_almost_equal(test_val, attr_val, decimal=3)
ds_base = xr.DataArray(data=[[1, 2], [3, 4]], dims=('y', 'x'), coords={'y': [1, 2], 'x': [3, 4]},
attrs={'name': 'var1'})
# a) Projection has a corresponding CF representation (e.g. geos)
a = 6378169.
b = 6356583.8
h = 35785831.
geos = pyresample.geometry.AreaDefinition(
area_id='geos',
description='geos',
proj_id='geos',
projection={'proj': 'geos', 'h': h, 'a': a, 'b': b,
'lat_0': 0, 'lon_0': 0},
width=2, height=2,
area_extent=[-1, -1, 1, 1])
geos_expected = xr.DataArray(data=0,
attrs={'perspective_point_height': h,
'latitude_of_projection_origin': 0,
'longitude_of_projection_origin': 0,
'grid_mapping_name': 'geostationary',
'semi_major_axis': a,
'semi_minor_axis': b,
# 'sweep_angle_axis': None,
})
ds = ds_base.copy()
ds.attrs['area'] = geos
new_ds, grid_mapping = area2gridmapping(ds)
if 'sweep_angle_axis' in grid_mapping.attrs:
# older versions of pyproj might not include this
self.assertEqual(grid_mapping.attrs['sweep_angle_axis'], 'y')
self.assertEqual(new_ds.attrs['grid_mapping'], 'geos')
_gm_matches(grid_mapping, geos_expected)
# should not have been modified
self.assertNotIn('grid_mapping', ds.attrs)
# b) Projection does not have a corresponding CF representation (COSMO)
cosmo7 = pyresample.geometry.AreaDefinition(
area_id='cosmo7',
description='cosmo7',
proj_id='cosmo7',
projection={'proj': 'ob_tran', 'ellps': 'WGS84', 'lat_0': 46, 'lon_0': 4.535,
'o_proj': 'stere', 'o_lat_p': 90, 'o_lon_p': -5.465},
width=597, height=510,
area_extent=[-1812933, -1003565, 814056, 1243448]
)
ds = ds_base.copy()
ds.attrs['area'] = cosmo7
new_ds, grid_mapping = area2gridmapping(ds)
self.assertIn('crs_wkt', grid_mapping.attrs)
wkt = grid_mapping.attrs['crs_wkt']
self.assertIn('ELLIPSOID["WGS 84"', wkt)
self.assertIn('PARAMETER["lat_0",46', wkt)
self.assertIn('PARAMETER["lon_0",4.535', wkt)
self.assertIn('PARAMETER["o_lat_p",90', wkt)
self.assertIn('PARAMETER["o_lon_p",-5.465', wkt)
self.assertEqual(new_ds.attrs['grid_mapping'], 'cosmo7')
# c) Projection Transverse Mercator
lat_0 = 36.5
lon_0 = 15.0
tmerc = pyresample.geometry.AreaDefinition(
area_id='tmerc',
description='tmerc',
proj_id='tmerc',
projection={'proj': 'tmerc', 'ellps': 'WGS84', 'lat_0': 36.5, 'lon_0': 15.0},
width=2, height=2,
area_extent=[-1, -1, 1, 1])
tmerc_expected = xr.DataArray(data=0,
attrs={'latitude_of_projection_origin': lat_0,
'longitude_of_central_meridian': lon_0,
'grid_mapping_name': 'transverse_mercator',
'reference_ellipsoid_name': 'WGS 84',
'false_easting': 0.,
'false_northing': 0.,
})
ds = ds_base.copy()
ds.attrs['area'] = tmerc
new_ds, grid_mapping = area2gridmapping(ds)
self.assertEqual(new_ds.attrs['grid_mapping'], 'tmerc')
_gm_matches(grid_mapping, tmerc_expected)
# d) Projection that has a representation but no explicit a/b
h = 35785831.
geos = pyresample.geometry.AreaDefinition(
area_id='geos',
description='geos',
proj_id='geos',
projection={'proj': 'geos', 'h': h, 'datum': 'WGS84', 'ellps': 'GRS80',
'lat_0': 0, 'lon_0': 0},
width=2, height=2,
area_extent=[-1, -1, 1, 1])
geos_expected = xr.DataArray(data=0,
attrs={'perspective_point_height': h,
'latitude_of_projection_origin': 0,
'longitude_of_projection_origin': 0,
'grid_mapping_name': 'geostationary',
# 'semi_major_axis': 6378137.0,
# 'semi_minor_axis': 6356752.314,
# 'sweep_angle_axis': None,
})
ds = ds_base.copy()
ds.attrs['area'] = geos
new_ds, grid_mapping = area2gridmapping(ds)
self.assertEqual(new_ds.attrs['grid_mapping'], 'geos')
_gm_matches(grid_mapping, geos_expected)
# e) oblique Mercator
area = pyresample.geometry.AreaDefinition(
area_id='omerc_otf',
description='On-the-fly omerc area',
proj_id='omerc',
projection={'alpha': '9.02638777018478', 'ellps': 'WGS84', 'gamma': '0', 'k': '1',
'lat_0': '-0.256794486098476', 'lonc': '13.7888658224205',
'proj': 'omerc', 'units': 'm'},
width=2837,
height=5940,
area_extent=[-1460463.0893, 3455291.3877, 1538407.1158, 9615788.8787]
)
omerc_dict = {'azimuth_of_central_line': 9.02638777018478,
'false_easting': 0.,
'false_northing': 0.,
# 'gamma': 0, # this is not CF compliant
'grid_mapping_name': "oblique_mercator",
'latitude_of_projection_origin': -0.256794486098476,
'longitude_of_projection_origin': 13.7888658224205,
# 'prime_meridian_name': "Greenwich",
'reference_ellipsoid_name': "WGS 84"}
omerc_expected = xr.DataArray(data=0, attrs=omerc_dict)
ds = ds_base.copy()
ds.attrs['area'] = area
new_ds, grid_mapping = area2gridmapping(ds)
self.assertEqual(new_ds.attrs['grid_mapping'], 'omerc_otf')
_gm_matches(grid_mapping, omerc_expected)
# f) Projection that has a representation but no explicit a/b
h = 35785831.
geos = pyresample.geometry.AreaDefinition(
area_id='geos',
description='geos',
proj_id='geos',
projection={'proj': 'geos', 'h': h, 'datum': 'WGS84', 'ellps': 'GRS80',
'lat_0': 0, 'lon_0': 0},
width=2, height=2,
area_extent=[-1, -1, 1, 1])
geos_expected = xr.DataArray(data=0,
attrs={'perspective_point_height': h,
'latitude_of_projection_origin': 0,
'longitude_of_projection_origin': 0,
'grid_mapping_name': 'geostationary',
'reference_ellipsoid_name': 'WGS 84',
})
ds = ds_base.copy()
ds.attrs['area'] = geos
new_ds, grid_mapping = area2gridmapping(ds)
self.assertEqual(new_ds.attrs['grid_mapping'], 'geos')
_gm_matches(grid_mapping, geos_expected)
