def _octile(self, id1, id2):
"""
Returns the octile distance in KM between the two ID'd vertices.
(x1, y1)
[1]
|
|
|
[3]
| .
| .
| .
| .
| .
| 45( .
[ ]----------[2]
returns dist(1, 3) + dist(2, 3)
"""
x1, y1 = self.coords[id1]
x2, y2 = self.coords[id2]
dx, dy = abs(x2 - x1), abs(y2 - y1)
if dx > dy:
x3 = max(x1, x2) - dy
y3 = y1
elif dx > dy:
x3 = x1
y3 = max(y1, y2) - dx
else:
return haversine(x1, y1, x2, y2)
return haversine(x3, y3, x2, y2) + haversine(x3, y3, x1, y1)
def _octile(self, id1, id2):
"""
Returns the octile distance in KM between the two ID'd vertices.
(x1, y1)
[1]
|
|
|
[3]
| .
| .
| .
| .
| .
| 45( .
[ ]----------[2]
returns dist(1, 3) + dist(2, 3)
"""
x1, y1 = self.coords[id1]
x2, y2 = self.coords[id2]
dx, dy = abs(x2 - x1), abs(y2 - y1)
if dx > dy:
x3 = max(x1, x2) - dy
y3 = y1
elif dx > dy:
x3 = x1
y3 = max(y1, y2) - dx
else:
return haversine(x1, y1, x2, y2)
return haversine(x3, y3, x2, y2) + haversine(x3, y3, x1, y1)
def worker(landmarks, graph, graph_coords, pids, out_q, counter):
""" The worker function, invoked in a process. 'nums' is a
list of numbers to factor. The results are placed in
a dictionary that's pushed to a queue.
"""
lm_est = {}
for lm_id, lm_coord in landmarks:
lm_est[lm_id] = {}
x, y = lm_coord
for pid, coord in graph_coords.items():
lm_est[lm_id][pid] = haversine(x, y, coord[0], coord[1])
qtree = point_dict_to_quadtree(graph_coords, multiquadtree=True)
lm_dists = defaultdict(list)
l = len(graph_coords)
for pid in pids:
counter.value += 1
print counter.value, '/', l, ':', pid
for landmark, _ in landmarks:
try:
d = lm_exact_dist(pid, landmark, graph, graph_coords,
lm_est)
except KeyError:
d = None
lm_dists[pid].append(d)
out_q.put(lm_dists)
def _manhattan(self, id1, id2):
"""
Returns the Manhattan distance in KM between the two ID'd vertices.
(x1, y1)
[1]
|
|
|
| (x2, y2)
[3]-----------[2]
(x1, y2)
returns dist(1, 3) + dist(2, 3)
"""
x1, y1 = self.coords[id1]
x2, y2 = self.coords[id2]
x3, y3 = x1, y2
return haversine(x3, y3, x2, y2) + haversine(x3, y3, x1, y1)
def _euclidean(self, id1, id2):
"""
Returns the distance in KM between the two ID'd vertices.
Arguments:
id1, id2 -- IDs matching vertices in self.coords
"""
x1, y1 = self.coords[id1]
x2, y2 = self.coords[id2]
return haversine(x1, y1, x2, y2)
def _manhattan(self, id1, id2):
"""
Returns the Manhattan distance in KM between the two ID'd vertices.
(x1, y1)
[1]
|
|
|
| (x2, y2)
[3]-----------[2]
(x1, y2)
returns dist(1, 3) + dist(2, 3)
"""
x1, y1 = self.coords[id1]
x2, y2 = self.coords[id2]
x3, y3 = x1, y2
return haversine(x3, y3, x2, y2) + haversine(x3, y3, x1, y1)
def _euclidean(self, id1, id2):
"""
Returns the distance in KM between the two ID'd vertices.
Arguments:
id1, id2 -- IDs matching vertices in self.coords
"""
x1, y1 = self.coords[id1]
x2, y2 = self.coords[id2]
return haversine(x1, y1, x2, y2)
def find_closest_node(target, quadtree, rng=.01):
x, y = target
close_nodes = quadtree.query_range(x - rng, x + rng, y - rng, y + rng)
best_node = None
best_dist = float("inf")
for point, nodes in close_nodes.items():
dist = haversine(point[0], point[1], target[0], target[1])
if dist < best_dist:
best_dist = dist
best_node = nodes
if best_node:
return best_node[0]
else:
return None
def find_closest_node(target, quadtree, rng=.01):
x, y = target
close_nodes = quadtree.query_range(x - rng, x + rng, y - rng, y + rng)
best_node = None
best_dist = float("inf")
for point, nodes in close_nodes.iteritems():
dist = haversine(point[0], point[1], target[0], target[1])
if dist < best_dist:
best_dist = dist
best_node = nodes
if best_node:
return best_node[0]
else:
return None
def planar_landmark_selection(k, origin, coords, graph, qtree):
origin_id = find_closest_node(origin, qtree)
origin = coords[origin_id]
sectors = section_plane(k, origin, coords)
landmarks = []
for sector in sectors:
max_dist = float("-inf")
best_candidate = None
for pid, coord in sector:
cur_dist = haversine(origin[0], origin[1], coord[0], coord[1])
if cur_dist > max_dist and exact_dist(pid, origin_id, graph, coords):
max_dist = cur_dist
best_candidate = coord
landmarks.append(best_candidate)
return landmarks
def farthest_landmark_selection(k, origin, coords):
landmarks = [origin]
for _ in xrange(k):
max_dist = float("-inf")
best_candidate = None
for pid, coord in coords.items():
cur_dist = 0
for lm in landmarks:
cur_dist += haversine(lm[0], lm[1], coord[0], coord[1])
if cur_dist > max_dist and not coord in landmarks:
max_dist = cur_dist
best_candidate = coord
landmarks.append(best_candidate)
if len(landmarks) > k:
landmarks.pop(0)
return landmarks
def planar_landmark_selection(k, origin, coords, graph, qtree):
origin_id = find_closest_node(origin, qtree)
origin = coords[origin_id]
sectors = section_plane(k, origin, coords)
landmarks = []
for sector in sectors:
max_dist = float("-inf")
best_candidate = None
for pid, coord in sector:
cur_dist = haversine(origin[0], origin[1], coord[0], coord[1])
if cur_dist > max_dist and exact_dist(pid, origin_id, graph,
coords):
max_dist = cur_dist
best_candidate = coord
landmarks.append(best_candidate)
return landmarks
def farthest_landmark_selection(k, origin, coords):
landmarks = [origin]
for _ in xrange(k):
max_dist = float("-inf")
best_candidate = None
for pid, coord in coords.iteritems():
cur_dist = 0
for lm in landmarks:
cur_dist += haversine(lm[0], lm[1], coord[0], coord[1])
if cur_dist > max_dist and not coord in landmarks:
max_dist = cur_dist
best_candidate = coord
landmarks.append(best_candidate)
if len(landmarks) > k:
landmarks.pop(0)
return landmarks
def landmark_distances(landmarks, graph, graph_coords):
lm_est = {}
for lm_id, lm_coord in landmarks:
lm_est[lm_id] = {}
x,y = lm_coord
for pid, coord in graph_coords.iteritems():
lm_est[lm_id][pid] = haversine(x, y, coord[0], coord[1])
qtree = point_dict_to_quadtree(graph_coords, multiquadtree=True)
lm_dists = defaultdict(list)
l = len(graph_coords)
for i, pid in enumerate(graph_coords):
print i, '/', l, ':', pid
for landmark, _ in landmarks:
try:
d = lm_exact_dist(pid, landmark, graph, graph_coords, lm_est)
except KeyError:
d = None
lm_dists[pid].append(d)
return lm_dists
def landmark_distances(landmarks, graph, graph_coords):
lm_est = {}
for lm_id, lm_coord in landmarks:
lm_est[lm_id] = {}
x, y = lm_coord
for pid, coord in graph_coords.items():
lm_est[lm_id][pid] = haversine(x, y, coord[0], coord[1])
qtree = point_dict_to_quadtree(graph_coords, multiquadtree=True)
lm_dists = defaultdict(list)
l = len(graph_coords)
for i, pid in enumerate(graph_coords):
print i, '/', l, ':', pid
for landmark, _ in landmarks:
try:
d = lm_exact_dist(pid, landmark, graph, graph_coords, lm_est)
except KeyError:
d = None
lm_dists[pid].append(d)
return lm_dists
def exact_dist(source, dest, graph, coords):
dest_x, dest_y = coords[dest]
pred_list = {source : 0}
closed_set = set()
unseen = [(0, source)] # keeps a set and heap structure
while unseen:
_, vert = heappop(unseen)
if vert in closed_set:
# needed because we dont have a heap with decrease-key
continue
elif vert == dest:
return pred_list[vert]
closed_set.add(vert)
for arc, arc_len in graph[vert]:
if arc not in closed_set:
new_dist = (pred_list[vert] + arc_len)
if arc not in pred_list or new_dist < pred_list[arc]:
pred_list[arc] = new_dist
x, y = coords[arc]
heappush(unseen, (new_dist + haversine(x, y, dest_x, dest_y), arc))
return None # no valid path found
def _find_closest_vertex(self, target, rng=.01):
"""
Using the query_range function of the given quadtree, locate a vertex
in the graph that is closest to the given point.
Arguments:
target -- (x, y) point to be matched to the graph.
Returns:
The ID of the vertex that is closest to the given point.
"""
x, y = target
close_vertices = self.qtree.query_range(x - rng, x + rng, y - rng, y + rng)
best_vertex = None
best_dist = float("inf")
for point, vertices in close_vertices.iteritems():
dist = haversine(point[0], point[1], target[0], target[1])
if dist < best_dist:
best_dist = dist
best_vertex = vertices[0]
return best_vertex
def exact_dist(source, dest, graph, coords):
dest_x, dest_y = coords[dest]
pred_list = {source: 0}
closed_set = set()
unseen = [(0, source)] # keeps a set and heap structure
while unseen:
_, vert = heappop(unseen)
if vert in closed_set:
# needed because we dont have a heap with decrease-key
continue
elif vert == dest:
return pred_list[vert]
closed_set.add(vert)
for arc, arc_len in graph[vert]:
if arc not in closed_set:
new_dist = (pred_list[vert] + arc_len)
if arc not in pred_list or new_dist < pred_list[arc]:
pred_list[arc] = new_dist
x, y = coords[arc]
heappush(unseen,
(new_dist + haversine(x, y, dest_x, dest_y), arc))
return None # no valid path found
def _find_closest_vertex(self, target, rng=.01):
"""
Using the query_range function of the given quadtree, locate a vertex
in the graph that is closest to the given point.
Arguments:
target -- (x, y) point to be matched to the graph.
Returns:
The ID of the vertex that is closest to the given point.
"""
x, y = target
close_vertices = self.qtree.query_range(x - rng, x + rng, y - rng,
y + rng)
best_vertex = None
best_dist = float("inf")
for point, vertices in close_vertices.items():
dist = haversine(point[0], point[1], target[0], target[1])
if dist < best_dist:
best_dist = dist
best_vertex = vertices[0]
return best_vertex
def worker(landmarks, graph, graph_coords, pids, out_q, counter):
""" The worker function, invoked in a process. 'nums' is a
list of numbers to factor. The results are placed in
a dictionary that's pushed to a queue.
"""
lm_est = {}
for lm_id, lm_coord in landmarks:
lm_est[lm_id] = {}
x,y = lm_coord
for pid, coord in graph_coords.iteritems():
lm_est[lm_id][pid] = haversine(x, y, coord[0], coord[1])
qtree = point_dict_to_quadtree(graph_coords, multiquadtree=True)
lm_dists = defaultdict(list)
l = len(graph_coords)
for pid in pids:
counter.value += 1
print counter.value, '/', l, ':', pid
for landmark, _ in landmarks:
try:
d = lm_exact_dist(pid, landmark, graph, graph_coords, lm_est)
except KeyError:
d = None
lm_dists[pid].append(d)
out_q.put(lm_dists)