def _check_angles_calculation(self, angles_in_degrees=True,
nan_angles_mask=None):
# Check basic maths on a 2d latlon grid.
u_cube = sample_2d_latlons(regional=True, transformed=True)
u_cube.units = 'ms-1'
u_cube.rename('dx')
u_cube.data[...] = 0
v_cube = u_cube.copy()
v_cube.name('dy')
# Define 6 different vectors, repeated in each data row.
in_vu = np.array([(0, 1), (2, -1), (-1, -1), (-3, 1), (2, 0), (0, 0)])
in_angs = np.rad2deg(np.arctan2(in_vu[..., 0], in_vu[..., 1]))
in_mags = np.sqrt(np.sum(in_vu * in_vu, axis=1))
v_cube.data[...] = in_vu[..., 0]
u_cube.data[...] = in_vu[..., 1]
# Define 5 different test rotation angles, one for each data row.
rotation_angles = np.array([0., -45., 135, -140., 90.])
ang_cube_data = np.broadcast_to(rotation_angles[:, None],
u_cube.shape)
ang_cube = u_cube.copy()
if angles_in_degrees:
ang_cube.units = 'degrees'
else:
ang_cube.units = 'radians'
ang_cube_data = np.deg2rad(ang_cube_data)
ang_cube.data[:] = ang_cube_data
if nan_angles_mask is not None:
ang_cube.data[nan_angles_mask] = np.nan
# Rotate all vectors by all the given angles.
result = rotate_grid_vectors(u_cube, v_cube, ang_cube)
out_u, out_v = [cube.data for cube in result]
# Check that vector magnitudes were unchanged.
out_mags = np.sqrt(out_u * out_u + out_v * out_v)
expect_mags = in_mags[None, :]
self.assertArrayAllClose(out_mags, expect_mags)
# Check that vector angles are all as expected.
out_angs = np.rad2deg(np.arctan2(out_v, out_u))
expect_angs = in_angs[None, :] + rotation_angles[:, None]
ang_diffs = out_angs - expect_angs
# Fix for null vectors, and +/-360 differences.
ang_diffs[np.abs(out_mags) < 0.001] = 0.0
ang_diffs = ang_diffs % 360.0
# Check that any differences are very small.
self.assertArrayAllClose(ang_diffs, 0.0)
# Check that results are always masked arrays, masked at NaN angles.
self.assertTrue(np.ma.isMaskedArray(out_u))
self.assertTrue(np.ma.isMaskedArray(out_v))
if nan_angles_mask is not None:
self.assertArrayEqual(out_u.mask, nan_angles_mask)
self.assertArrayEqual(out_v.mask, nan_angles_mask)
def _check_angles_calculation(self,
angles_in_degrees=True,
nan_angles_mask=None):
# Check basic maths on a 2d latlon grid.
u_cube = sample_2d_latlons(regional=True, transformed=True)
u_cube.units = "ms-1"
u_cube.rename("dx")
u_cube.data[...] = 0
v_cube = u_cube.copy()
v_cube.name("dy")
# Define 6 different vectors, repeated in each data row.
in_vu = np.array([(0, 1), (2, -1), (-1, -1), (-3, 1), (2, 0), (0, 0)])
in_angs = np.rad2deg(np.arctan2(in_vu[..., 0], in_vu[..., 1]))
in_mags = np.sqrt(np.sum(in_vu * in_vu, axis=1))
v_cube.data[...] = in_vu[..., 0]
u_cube.data[...] = in_vu[..., 1]
# Define 5 different test rotation angles, one for each data row.
rotation_angles = np.array([0.0, -45.0, 135, -140.0, 90.0])
ang_cube_data = np.broadcast_to(rotation_angles[:, None], u_cube.shape)
ang_cube = u_cube.copy()
if angles_in_degrees:
ang_cube.units = "degrees"
else:
ang_cube.units = "radians"
ang_cube_data = np.deg2rad(ang_cube_data)
ang_cube.data[:] = ang_cube_data
if nan_angles_mask is not None:
ang_cube.data[nan_angles_mask] = np.nan
# Rotate all vectors by all the given angles.
result = rotate_grid_vectors(u_cube, v_cube, ang_cube)
out_u, out_v = [cube.data for cube in result]
# Check that vector magnitudes were unchanged.
out_mags = np.sqrt(out_u * out_u + out_v * out_v)
expect_mags = in_mags[None, :]
self.assertArrayAllClose(out_mags, expect_mags)
# Check that vector angles are all as expected.
out_angs = np.rad2deg(np.arctan2(out_v, out_u))
expect_angs = in_angs[None, :] + rotation_angles[:, None]
ang_diffs = out_angs - expect_angs
# Fix for null vectors, and +/-360 differences.
ang_diffs[np.abs(out_mags) < 0.001] = 0.0
ang_diffs = ang_diffs % 360.0
# Check that any differences are very small.
self.assertArrayAllClose(ang_diffs, 0.0)
# Check that results are always masked arrays, masked at NaN angles.
self.assertTrue(np.ma.isMaskedArray(out_u))
self.assertTrue(np.ma.isMaskedArray(out_v))
if nan_angles_mask is not None:
self.assertArrayEqual(out_u.mask, nan_angles_mask)
self.assertArrayEqual(out_v.mask, nan_angles_mask)
def test_angles_from_grid(self):
# Check it will gets angles from 'u_cube', and pass any kwargs on to
# the angles routine.
u_cube = sample_2d_latlons(regional=True, transformed=True)
u_cube = u_cube[:2, :3]
u_cube.units = 'ms-1'
u_cube.rename('dx')
u_cube.data[...] = 1.0
v_cube = u_cube.copy()
v_cube.name('dy')
v_cube.data[...] = 0.0
# Setup a fake angles result from the inner call to 'gridcell_angles'.
angles_result_data = np.array([[0.0, 90.0, 180.0],
[-180.0, -90.0, 270.0]])
angles_result_cube = Cube(angles_result_data, units='degrees')
angles_kwargs = {'this': 2}
angles_call_patch = self.patch(
'iris.analysis._grid_angles.gridcell_angles',
Mock(return_value=angles_result_cube))
# Call the routine.
result = rotate_grid_vectors(u_cube, v_cube,
grid_angles_kwargs=angles_kwargs)
self.assertEqual(angles_call_patch.call_args_list,
[mock_call(u_cube, this=2)])
out_u, out_v = [cube.data for cube in result]
# Records what results should be for the various n*90deg rotations.
expect_u = np.array([[1.0, 0.0, -1.0],
[-1.0, 0.0, 0.0]])
expect_v = np.array([[0.0, 1.0, 0.0],
[0.0, -1.0, -1.0]])
# Check results are as expected.
self.assertArrayAllClose(out_u, expect_u)
self.assertArrayAllClose(out_v, expect_v)
def test_angles_from_grid(self):
# Check it will gets angles from 'u_cube', and pass any kwargs on to
# the angles routine.
u_cube = sample_2d_latlons(regional=True, transformed=True)
u_cube = u_cube[:2, :3]
u_cube.units = "ms-1"
u_cube.rename("dx")
u_cube.data[...] = 1.0
v_cube = u_cube.copy()
v_cube.name("dy")
v_cube.data[...] = 0.0
# Setup a fake angles result from the inner call to 'gridcell_angles'.
angles_result_data = np.array([[0.0, 90.0, 180.0],
[-180.0, -90.0, 270.0]])
angles_result_cube = Cube(angles_result_data, units="degrees")
angles_kwargs = {"this": 2}
angles_call_patch = self.patch(
"iris.analysis._grid_angles.gridcell_angles",
Mock(return_value=angles_result_cube),
)
# Call the routine.
result = rotate_grid_vectors(u_cube,
v_cube,
grid_angles_kwargs=angles_kwargs)
self.assertEqual(angles_call_patch.call_args_list,
[mock_call(u_cube, this=2)])
out_u, out_v = [cube.data for cube in result]
# Records what results should be for the various n*90deg rotations.
expect_u = np.array([[1.0, 0.0, -1.0], [-1.0, 0.0, 0.0]])
expect_v = np.array([[0.0, 1.0, 0.0], [0.0, -1.0, -1.0]])
# Check results are as expected.
self.assertArrayAllClose(out_u, expect_u)
self.assertArrayAllClose(out_v, expect_v)