def test_insert_after():
l = BiList()
node = l.append(42)
l.append(44)
l.append(45)
l.insert_after(node, 43)
assert [el.value for el in l] == [42, 43, 44, 45]
def _pretriangulate(self):
""" 1.1 Initial triangulation of points
Return triangles and edges.
Yonghe et al. (2013) A Simple Sweep-line Delaunay Triangulation Algorithm
http://www.academicpub.org/jao/paperInfo.aspx?PaperID=15630
"""
# Sort points by x coordinate to prepare for sweep-line algorithm.
self.points.sort(key=lambda v: v.x)
triangles = []
# An edge is a tuple of indices for a pair of points, always ordered so the
# lower index comes before the higher. An edge is associated with a list of
# triangles sharing it (one or two).
triangle_edges = {}
# The hull is the current outer border of the triangulation. It is a
# bidirectional list of edges (a CCW polygon).
hull = BiList()
# Add the first triangle.
if self.point_on_left_side(self.points[0], self.points[1],
self.points[2]):
# print("p2 on left side of p0p1")
e0 = (0, 1)
e1 = (1, 2)
e2 = (2, 0)
triangles.append(self.Triangle(self.points, 0, 1, 2))
else:
# print("p2 on right side of p0p1")
e0 = (1, 0)
e1 = (0, 2)
e2 = (2, 1)
triangles.append(self.Triangle(self.points, 1, 0, 2))
hull.append(e0)
hull.append(e1)
hull.append(e2)
triangle_edges[self.edge_tuple(e0)] = [0]
triangle_edges[self.edge_tuple(e1)] = [0]
triangle_edges[self.edge_tuple(e2)] = [0]
pts_index = 3
for pts_index in range(3, len(self.points)):
next_pt = self.points[pts_index]
ix = 0
while ix < len(hull):
node = hull[ix]
i0 = node.value[0]
i1 = node.value[1]
p0 = self.points[i0]
p1 = self.points[i1]
if not self.point_on_left_side(p0, p1, next_pt):
tl = len(triangles)
triangles.append(
self.Triangle(self.points, i1, i0, pts_index))
ab = self.edge_tuple(i0, i1)
if ab not in triangle_edges:
triangle_edges[ab] = []
triangle_edges[ab].append(tl)
ab = self.edge_tuple(i1, pts_index)
if ab not in triangle_edges:
triangle_edges[ab] = []
triangle_edges[ab].append(tl)
ab = self.edge_tuple(pts_index, i0)
if ab not in triangle_edges:
triangle_edges[ab] = []
triangle_edges[ab].append(tl)
# Add in reverse order.
succ = node.succ
pred = node.pred
if not succ:
succ = hull[0]
if not pred:
pred = hull[-1]
if succ.value == (i1, pts_index):
hull.remove(succ)
else:
hull.insert_after(node, (pts_index, i1))
ix += 1
if pred.value == (pts_index, i0):
hull.remove(pred)
ix -= 1
else:
hull.insert_after(node, (i0, pts_index))
ix += 1
hull.remove(node)
ix -= 1
ix += 1
return triangles, triangle_edges