def test_identity_feature():
# Test subclassing Feature
class IdentityFeature(dipymetric.Feature):
def __init__(self):
super(IdentityFeature, self).__init__(is_order_invariant=False)
def infer_shape(self, streamline):
return streamline.shape
def extract(self, streamline):
return streamline
for feature in [dipymetric.IdentityFeature(), IdentityFeature()]:
for s in [s1, s2, s3, s4]:
# Test method infer_shape
assert_equal(feature.infer_shape(s), s.shape)
# Test method extract
features = feature.extract(s)
assert_equal(features.shape, s.shape)
assert_array_equal(features, s)
# This feature type is not order invariant
assert_false(feature.is_order_invariant)
for s in [s1, s2, s3, s4]:
features = feature.extract(s)
features_flip = feature.extract(s[::-1])
assert_array_equal(features_flip, s[::-1])
assert_true(np.any(np.not_equal(features, features_flip)))
def test_metric_minimum_average_direct_flip():
feature = dipymetric.IdentityFeature()
class MinimumAverageDirectFlipMetric(dipymetric.Metric):
def __init__(self, feature):
super(MinimumAverageDirectFlipMetric,
self).__init__(feature=feature)
@property
def is_order_invariant(self):
return True # Ordering is handled in the distance computation
def are_compatible(self, shape1, shape2):
return shape1[0] == shape2[0]
def dist(self, v1, v2):
def average_euclidean(x, y):
return np.mean(norm(x - y, axis=1))
dist_direct = average_euclidean(v1, v2)
dist_flipped = average_euclidean(v1, v2[::-1])
return min(dist_direct, dist_flipped)
for metric in [
MinimumAverageDirectFlipMetric(feature),
dipymetric.MinimumAverageDirectFlipMetric(feature)
]:
# Test special cases of the MDF distance.
assert_equal(metric.dist(s, s), 0.)
assert_equal(metric.dist(s, s[::-1]), 0.)
# Translation
offset = np.array([0.8, 1.3, 5], dtype=dtype)
assert_almost_equal(metric.dist(s, s + offset), norm(offset), 5)
# Scaling
M_scaling = np.diag([1.2, 2.8, 3]).astype(dtype)
s_mean = np.mean(s, axis=0)
s_zero_mean = s - s_mean
s_scaled = np.dot(M_scaling, s_zero_mean.T).T + s_mean
d = np.mean(norm((np.diag(M_scaling) - 1) * s_zero_mean, axis=1))
assert_almost_equal(metric.dist(s, s_scaled), d, 5)
# Rotation
from dipy.core.geometry import rodrigues_axis_rotation
rot_axis = np.array([1, 2, 3], dtype=dtype)
M_rotation = rodrigues_axis_rotation(rot_axis, 60.).astype(dtype)
s_mean = np.mean(s, axis=0)
s_zero_mean = s - s_mean
s_rotated = np.dot(M_rotation, s_zero_mean.T).T + s_mean
opposite = norm(np.cross(rot_axis, s_zero_mean),
axis=1) / norm(rot_axis)
distances = np.sqrt(2 * opposite**2 *
(1 - np.cos(60. * np.pi / 180.))).astype(dtype)
d = np.mean(distances)
assert_almost_equal(metric.dist(s, s_rotated), d, 5)
# All possible pairs
for s1, s2 in itertools.product(*[streamlines] * 2):
# Extract features since metric doesn't work
# directly on streamlines
f1 = metric.feature.extract(s1)
f2 = metric.feature.extract(s2)
# Test method are_compatible
same_nb_points = f1.shape[0] == f2.shape[0]
assert_equal(metric.are_compatible(f1.shape, f2.shape),
same_nb_points)
# Test method dist if features are compatible
if metric.are_compatible(f1.shape, f2.shape):
distance = metric.dist(f1, f2)
if np.all(f1 == f2):
assert_equal(distance, 0.)
assert_almost_equal(distance, dipymetric.dist(metric, s1, s2))
assert_almost_equal(distance, dipymetric.mdf(s1, s2))
assert_true(distance >= 0.)
# This metric type is order invariant
assert_true(metric.is_order_invariant)
# All possible pairs
for s1, s2 in itertools.product(*[streamlines] * 2):
f1 = metric.feature.extract(s1)
f2 = metric.feature.extract(s2)
if not metric.are_compatible(f1.shape, f2.shape):
continue
f1_flip = metric.feature.extract(s1[::-1])
f2_flip = metric.feature.extract(s2[::-1])
distance = metric.dist(f1, f2)
assert_almost_equal(metric.dist(f1_flip, f2_flip), distance)
if not np.all(f1_flip == f2_flip):
assert_true(np.allclose(metric.dist(f1, f2_flip), distance))
assert_true(np.allclose(metric.dist(f1_flip, f2), distance))