def _transform_grid(cls, grid_cart, R_b_to_dbcs, ibulkv_dbcs_par, frame):
"""Transforms the grid from the frame of interest to the
instrument frame. Returns the grid expressed in the spherical system.
Parameters
----------
grid_s
the transformed grid, in spherical coordinates, (3, N, N, N)
grid_cart
cartesian interpolation grid, (3, N, N, N)
R_b_to_dbcs
rotation matrix from B to DBCS, (3, 3)
ibulkv_dbcs_par
ion bulk velocity at particles' time, (3,)
frame: str
frame of interest.
"""
# This copy of grid_cart will be rotated, every scan differently.
grid_c = grid_cart.copy()
# For now grid_c is in the frame of interest, EB, GSE, or any.
if frame == 'instrument':
pass
elif frame == 'B':
grid_c = np.dot(R_b_to_dbcs, grid_c.reshape(3, -1)).reshape(
grid_cart.shape) ## Rotation.
grid_c += ibulkv_dbcs_par[:, None, None, None] ## Translation.
else:
raise ValueError('{}: unknown frame.'.format(frame))
# We now go for the spherical system, the natural instrument
# coordinate system. Here, the -1 is reversing velocity vector to
# viewing direction, in which the instrument tables are expressed.
grid_s = vdfu.cart2spher(-1 * grid_c)
return grid_s
def test_cart2spher():
"""Unit test on vdfu.cart2spher method."""
reso = 5
grid_cart_dummy = np.ones((3, reso, reso, reso))
grid_spher = vdfu.cart2spher(grid_cart_dummy)
assert grid_spher.shape == (3, reso, reso, reso)
assert np.allclose(grid_cart_dummy, vdfu.spher2cart(grid_spher))
def test_init_grid():
"""Unit test on vdfu.init_grid method."""
reso = 5
grid_cart, grid_spher, grid_cyl, \
dvvv = vdfu.init_grid(v_max=1., resolution=reso,
grid_geom='spher')
assert grid_cart.shape == (3, reso, reso, reso)
assert grid_spher.shape == (3, reso, reso, reso)
assert grid_cyl.shape == (3, reso, reso, reso)
assert dvvv.shape == (reso, reso, reso)
# Testing that the grid values are strictly increasing.
assert np.all(grid_spher[0][1:] > grid_spher[0][:-1])
assert np.all(grid_spher[1][:, 1:] > grid_spher[1][:, :-1])
assert np.all(grid_spher[2][:, :, 1:] > grid_spher[2][:, :, :-1])
# Testing that grid_cart and grid_spher are one and the same grid.
assert np.allclose(grid_spher, vdfu.cart2spher(grid_cart))
assert np.allclose(grid_cyl, vdfu.cart2cyl(grid_cart))
def test_transform_grid():
"""Unit test on AidaAccessorVDF.transform_grid method."""
reso = 5
grid_cart = np.zeros((3, reso, reso, reso))
grid_cart[0] = 1.
frame = 'instrument'
R_b_to_dbcs = np.eye(3)
ibulkv_dbcs_par = np.zeros(3)
grid_s = AidaAccessorVDF._transform_grid(grid_cart, R_b_to_dbcs,
ibulkv_dbcs_par, frame)
assert grid_s.shape == (3, reso, reso, reso)
assert np.allclose(grid_s, vdfu.cart2spher(-1 * grid_cart))
frame = 'B'
grid_s = AidaAccessorVDF._transform_grid(grid_cart, R_b_to_dbcs,
ibulkv_dbcs_par, frame)
assert np.allclose(grid_s[0], 1.)
assert np.allclose(grid_s[1], np.pi / 2.)
assert np.allclose(grid_s[2], np.pi)