def test_quaternion_reconstruction():
# Test reconstruction of arbitrary unit quaternions
for q in unit_quats:
M = nq.quat2mat(q)
qt = nq.mat2quat(M)
# Accept positive or negative match
posm = np.allclose(q, qt)
negm = np.allclose(q, -qt)
yield assert_true, posm or negm
def test_quats():
for x, y, z in eg_rots:
M1 = nea.euler2mat(z, y, x)
quatM = nq.mat2quat(M1)
quat = nea.euler2quat(z, y, x)
yield nq.nearly_equivalent, quatM, quat
quatS = sympy_euler2quat(z, y, x)
yield nq.nearly_equivalent, quat, quatS
zp, yp, xp = nea.quat2euler(quat)
# The parameters may not be the same as input, but they give the
# same rotation matrix
M2 = nea.euler2mat(zp, yp, xp)
yield assert_array_almost_equal, M1, M2
import nipy.io.imageformats.eulerangles as nea
# Example rotations '''
eg_rots = []
params = (-pi,pi,pi/2)
zs = np.arange(*params)
ys = np.arange(*params)
xs = np.arange(*params)
for z in zs:
for y in ys:
for x in xs:
eg_rots.append(nea.euler2mat(z,y,x))
# Example quaternions (from rotations)
eg_quats = []
for M in eg_rots:
eg_quats.append(nq.mat2quat(M))
# M, quaternion pairs
eg_pairs = zip(eg_rots, eg_quats)
# Set of arbitrary unit quaternions
unit_quats = set()
params = range(-2,3)
for w in params:
for x in params:
for y in params:
for z in params:
q = (w, x, y, z)
Nq = np.sqrt(np.dot(q, q))
if not Nq == 0:
q = tuple([e / Nq for e in q])
unit_quats.add(q)
