def test_out_of_bound_pixel_index(self):
"""We expect it to fail."""
parents = self.parents.copy()
with self.assertRaises(IndexError):
mtlib.find_pixel_parent(parents, 42)
def test_wrong_parents_data(self):
"""The parents image should contains pixel valid indices"""
wrong_parents = np.array([0, 3, 2, 10, 49, 50])
# We expect it to fail.
with self.assertRaises(IndexError):
mtlib.find_pixel_parent(wrong_parents, 3)
def test_negative_pixel_index(self):
"""We expect it to fail."""
parents = self.parents.copy()
# Warning: in numpy you can fetch in both ways.
self.assertEqual(
mtlib.find_pixel_parent(parents, -3),
mtlib.find_pixel_parent(parents, len(parents) - 3))
self.assertEqual(
mtlib.find_pixel_parent(parents, -1),
mtlib.find_pixel_parent(parents, len(parents) -1))
def test_union_find_canonization(input, R):
input_flat = input.flatten()
resolution = input_flat.size
# Unique value telling if a pixel is defined in the max tree or not.
undefined_node = resolution + 2
# We generate an extra vector of pixels that order nodes downard.
# This vector allow to traverse the tree both upward and downard
# without having to sort childrens of each node.
# Initially, we sort pixel by increasing value and add indices in it.
sorted_pixels = np.copy(R)
# We store in the parent node of each pixel in an image.
# To do so we use the index of the pixel (x + y * width).
parents = np.full(resolution, fill_value=undefined_node, dtype=np.uint32)
# zparents make root finding much faster.
zparents = parents.copy()
j = resolution - 1
# We go through sorted pixels in the reverse order.
for pi in sorted_pixels[::-1]:
# Make a node.
# By default, a pixel is its own parent.
parents[pi] = pi
zparents[pi] = pi
zp = pi
neighbors = max_tree.get_neighbors_2d(4, input.shape, pi, input.size)
# Filter neighbors.
neighbors = [n for n in neighbors if parents[n] != undefined_node]
# Go through neighbors.
for nei_pi in neighbors:
zn = max_tree.find_pixel_parent(zparents, nei_pi)
if zn != zp:
if input_flat[zp] == input_flat[zn]:
zp, zn = zn, zp
# Merge sets.
zparents[zn] = zp
parents[zn] = zp
sorted_pixels[j] = zn
j -= 1
max_tree.canonize(input_flat, parents, sorted_pixels)
return parents
def test_parents(self):
parents = self.parents.copy()
self.assertEqual(mtlib.find_pixel_parent(parents, 1), 1)
self.assertEqual(mtlib.find_pixel_parent(parents, 3), 1)
self.assertEqual(mtlib.find_pixel_parent(parents, 0), 1)
self.assertEqual(mtlib.find_pixel_parent(parents, 2), 1)
self.assertEqual(mtlib.find_pixel_parent(parents, 4), 1)
self.assertEqual(mtlib.find_pixel_parent(parents, 5), 1)