def gen_noncrossing_edges(query_edges, boundary_edges, allpoints):
"""
Yield query edges which do not intersect boundary edges.
@param query_edges: point index pairs
@param boundary_edges: point index pairs
@param allpoints: ordered points as pairs of coordinates
"""
for query in query_edges:
q0 = CompGeom.Point(allpoints[query[0]])
q1 = CompGeom.Point(allpoints[query[1]])
for boundary in boundary_edges:
b0 = CompGeom.Point(allpoints[boundary[0]])
b1 = CompGeom.Point(allpoints[boundary[1]])
if CompGeom.line_segments_intersect(q0, q1, b0, b1):
break
else:
yield query
def get_intersecting_edges(points, edges):
"""
Edges that share an endpoint do not count as conflicting.
@param points: a list of numpy arrays each of length 2
@param edges: a list of point index pairs
@return: the set of edges that intersect at least one other edge
"""
conflicts = set()
sedgewick_points = [CompGeom.Point(p.tolist()) for p in points]
for ea, eb in itertools.combinations(edges, 2):
# only check intersection when each endpoint is unique
if len(set([ea[0], ea[1], eb[0], eb[1]])) == 4:
a = sedgewick_points[ea[0]]
b = sedgewick_points[ea[1]]
c = sedgewick_points[eb[0]]
d = sedgewick_points[eb[1]]
if CompGeom.line_segments_intersect(a, b, c, d):
conflicts.add(ea)
conflicts.add(eb)
return conflicts
def gen_noncrossing_edges(query_edges, boundary_edges, allpoints):
"""
Yield query edges which do not intersect boundary edges.
@param query_edges: point index pairs
@param boundary_edges: point index pairs
@param allpoints: ordered points as pairs of coordinates
"""
for query in query_edges:
q0 = CompGeom.Point(allpoints[query[0]])
q1 = CompGeom.Point(allpoints[query[1]])
for boundary in boundary_edges:
b0 = CompGeom.Point(allpoints[boundary[0]])
b1 = CompGeom.Point(allpoints[boundary[1]])
if CompGeom.line_segments_intersect(q0, q1, b0, b1):
break
else:
yield query
def sample_with_rejection(npoints, poly, limit):
"""
@param npoints: sample this many points with rejection
@param poly: reject points outside the polygon
@param limit: a sanity limit for rejection sampling
@return: the sampled points
"""
xpoly, ypoly = zip(*poly)
xlow, xhigh = min(xpoly), max(xpoly)
ylow, yhigh = min(ypoly), max(ypoly)
points = []
for i in range(limit):
x = random.uniform(xlow, xhigh)
y = random.uniform(ylow, yhigh)
if CompGeom.point_in_poly(x, y, poly):
points.append((x, y))
if len(points) == npoints:
break
return points
def sample_with_rejection(npoints, poly, limit):
"""
@param npoints: sample this many points with rejection
@param poly: reject points outside the polygon
@param limit: a sanity limit for rejection sampling
@return: the sampled points
"""
xpoly, ypoly = zip(*poly)
xlow, xhigh = min(xpoly), max(xpoly)
ylow, yhigh = min(ypoly), max(ypoly)
points = []
for i in range(limit):
x = random.uniform(xlow, xhigh)
y = random.uniform(ylow, yhigh)
if CompGeom.point_in_poly(x, y, poly):
points.append((x, y))
if len(points) == npoints:
break
return points
def get_intersecting_edges(points, edges):
"""
Edges that share an endpoint do not count as conflicting.
@param points: a list of numpy arrays each of length 2
@param edges: a list of point index pairs
@return: the set of edges that intersect at least one other edge
"""
conflicts = set()
sedgewick_points = [CompGeom.Point(p.tolist()) for p in points]
for ea, eb in itertools.combinations(edges, 2):
# only check intersection when each endpoint is unique
if len(set([ea[0], ea[1], eb[0], eb[1]])) == 4:
a = sedgewick_points[ea[0]]
b = sedgewick_points[ea[1]]
c = sedgewick_points[eb[0]]
d = sedgewick_points[eb[1]]
if CompGeom.line_segments_intersect(a, b, c, d):
conflicts.add(ea)
conflicts.add(eb)
return conflicts
