Open-Harbor/osrm-backend
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases 3 Wiki Activity

remove attention on unaccessible locations as we filter them beforehand

Browse Source
This commit is contained in:
Chau Nguyen
2015-07-01 11:32:23 +02:00
committed by Huyen Chau Nguyen
parent a40b3a98dc
commit 6eeadddd4d
5 changed files with 133 additions and 51 deletions
Download Patch File Download Diff File Expand all files Collapse all files
routing_algorithms/tsp_nearest_neighbour.hpp
+7 -50
View File
@@ -66,38 +66,10 @@ void NearestNeighbourTSP(const PhantomNodeArray & phantom_node_vector,
const auto number_of_locations = phantom_node_vector.size();
min_route.shortest_path_length = std::numeric_limits<int>::max();
// is_lonely_island[i] indicates whether node i is a node that cannot be reached from other nodes
// 1 means that node i is a lonely island
// 0 means that it is not known for node i
// -1 means that node i is not a lonely island but a reachable, connected node
std::vector<int> is_lonely_island(number_of_locations, 0);
int count_unreachables;
// ALWAYS START AT ANOTHER STARTING POINT
for(int start_node = 0; start_node < number_of_locations; ++start_node)
{
if (is_lonely_island[start_node] >= 0)
{
// if node is a lonely island it is an unsuitable node to start from and shall be skipped
if (is_lonely_island[start_node])
continue;
count_unreachables = 0;
auto start_dist_begin = dist_table.begin() + (start_node * number_of_locations);
auto start_dist_end = dist_table.begin() + ((start_node + 1) * number_of_locations);
for (auto it2 = start_dist_begin; it2 != start_dist_end; ++it2) {
if (*it2 == 0 || *it2 == std::numeric_limits<int>::max()) {
++count_unreachables;
}
}
if (count_unreachables >= number_of_locations) {
is_lonely_island[start_node] = 1;
continue;
}
}
int curr_node = start_node;
is_lonely_island[curr_node] = -1;
InternalRouteResult raw_route;
//TODO: Should we always use the same vector or does it not matter at all because of loop scope?
std::vector<int> loc_permutation(number_of_locations, -1);
@@ -119,33 +91,18 @@ void NearestNeighbourTSP(const PhantomNodeArray & phantom_node_vector,
auto row_end_iterator = dist_table.begin() + ((curr_node + 1) * number_of_locations);
for (auto it = row_begin_iterator; it != row_end_iterator; ++it) {
auto index = std::distance(row_begin_iterator, it);
if (is_lonely_island[index] < 1 && !visited[index] && *it < min_dist)
if (!visited[index] && *it < min_dist)
{
min_dist = *it;
min_id = index;
}
}
// in case there was no unvisited and reachable node found, it means that all remaining (unvisited) nodes must be lonely islands
if (min_id == -1)
{
for(int loc = 0; loc < visited.size(); ++loc) {
if (!visited[loc]) {
is_lonely_island[loc] = 1;
}
}
break;
}
// set the nearest unvisited location as the next via_point
else
{
is_lonely_island[min_id] = -1;
loc_permutation[min_id] = via_point;
visited[min_id] = true;
viapoint = PhantomNodes{phantom_node_vector[curr_node][0], phantom_node_vector[min_id][0]};
raw_route.segment_end_coordinates.emplace_back(viapoint);
trip_dist += min_dist;
curr_node = min_id;
}
loc_permutation[min_id] = via_point;
visited[min_id] = true;
viapoint = PhantomNodes{phantom_node_vector[curr_node][0], phantom_node_vector[min_id][0]};
raw_route.segment_end_coordinates.emplace_back(viapoint);
trip_dist += min_dist;
curr_node = min_id;
}
// 4. ROUTE BACK TO STARTING POINT