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capsule tsp round trip computation in a private method

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chaupow 2015-05-27 01:32:59 +02:00 committed by Huyen Chau Nguyen
parent 108f87678a
commit b570e89dbd
1 changed files with 119 additions and 113 deletions
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232
plugins/round_trip.hpp
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@ -59,6 +59,122 @@ template <class DataFacadeT> class RoundTripPlugin final : public BasePlugin
DataFacadeT *facade; DataFacadeT *facade;
std::unique_ptr<SearchEngine<DataFacadeT>> search_engine_ptr; std::unique_ptr<SearchEngine<DataFacadeT>> search_engine_ptr;
void NearestNeighbour(const RouteParameters & route_parameters,
const PhantomNodeArray & phantom_node_vector,
std::vector<EdgeWeight> & result_table,
InternalRouteResult & min_route,
std::vector<int> & min_loc_permutation) {
//////////////////////////////////////////////////////////////////////////////////////////////////
// START GREEDY NEAREST NEIGHBOUR HERE
// 1. grab a random location and mark as starting point
// 2. find the nearest unvisited neighbour, set it as the current location and mark as visited
// 3. repeat 2 until there is no unvisited location
// 4. return route back to starting point
// 5. compute route
// 6. repeat 1-5 with different starting points and choose iteration with shortest trip
// 6. DONE!
//////////////////////////////////////////////////////////////////////////////////////////////////
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 = result_table.begin() + (start_node * number_of_locations);
auto start_dist_end = result_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);
loc_permutation[start_node] = 0;
// visited[i] indicates whether node i was already visited by the salesman
std::vector<bool> visited(number_of_locations, false);
visited[start_node] = true;
PhantomNodes viapoint;
// 3. REPEAT FOR EVERY UNVISITED NODE
for(int via_point = 1; via_point < number_of_locations; ++via_point)
{
int min_dist = std::numeric_limits<int>::max();
int min_id = -1;
// 2. FIND NEAREST NEIGHBOUR
auto row_begin_iterator = result_table.begin() + (curr_node * number_of_locations);
auto row_end_iterator = result_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)
{
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);
curr_node = min_id;
}
}
// 4. ROUTE BACK TO STARTING POINT
viapoint = PhantomNodes{raw_route.segment_end_coordinates.back().target_phantom, phantom_node_vector[start_node][0]};
raw_route.segment_end_coordinates.emplace_back(viapoint);
// 5. COMPUTE ROUTE
search_engine_ptr->shortest_path(raw_route.segment_end_coordinates, route_parameters.uturns, raw_route);
// check round trip with this starting point is shorter than the shortest round trip found till now
if (raw_route.shortest_path_length < min_route.shortest_path_length) {
min_route = raw_route;
min_loc_permutation = loc_permutation;
}
}
SimpleLogger().Write() << "Shortest route " << min_route.shortest_path_length;
}
public: public:
explicit RoundTripPlugin(DataFacadeT *facade) explicit RoundTripPlugin(DataFacadeT *facade)
: descriptor_string("trip"), facade(facade) : descriptor_string("trip"), facade(facade)
@ -104,7 +220,7 @@ template <class DataFacadeT> class RoundTripPlugin final : public BasePlugin
} }
// compute the distance table of all phantom nodes // compute the distance table of all phantom nodes
std::shared_ptr<std::vector<EdgeWeight>> result_table = const std::shared_ptr<std::vector<EdgeWeight>> result_table =
search_engine_ptr->distance_table(phantom_node_vector); search_engine_ptr->distance_table(phantom_node_vector);
if (!result_table) if (!result_table)
@ -112,120 +228,10 @@ template <class DataFacadeT> class RoundTripPlugin final : public BasePlugin
return 400; return 400;
} }
////////////////////////////////////////////////////////////////////////////////////////////////// // compute TSP round trip
// START GREEDY NEAREST NEIGHBOUR HERE
// 1. grab a random location and mark as starting point
// 2. find the nearest unvisited neighbour, set it as the current location and mark as visited
// 3. repeat 2 until there is no unvisited location
// 4. return route back to starting point
// 5. compute route
// 6. repeat 1-5 with different starting points and choose iteration with shortest trip
// 6. DONE!
//////////////////////////////////////////////////////////////////////////////////////////////////
const auto number_of_locations = phantom_node_vector.size();
// min_route is the shortest route found
InternalRouteResult min_route; InternalRouteResult min_route;
min_route.shortest_path_length = std::numeric_limits<int>::max();
// min_loc_permutation stores the order of visited locations of the shortest route
std::vector<int> min_loc_permutation; std::vector<int> min_loc_permutation;
NearestNeighbour(route_parameters, phantom_node_vector, *result_table, min_route, min_loc_permutation);
// 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 = result_table->begin() + (start_node * number_of_locations);
auto start_dist_end = result_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);
loc_permutation[start_node] = 0;
// visited[i] indicates whether node i was already visited by the salesman
std::vector<bool> visited(number_of_locations, false);
visited[start_node] = true;
PhantomNodes viapoint;
// 3. REPEAT FOR EVERY UNVISITED NODE
for(int via_point = 1; via_point < number_of_locations; ++via_point)
{
int min_dist = std::numeric_limits<int>::max();
int min_id = -1;
// 2. FIND NEAREST NEIGHBOUR
auto row_begin_iterator = result_table->begin() + (curr_node * number_of_locations);
auto row_end_iterator = result_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)
{
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);
curr_node = min_id;
}
}
// 4. ROUTE BACK TO STARTING POINT
viapoint = PhantomNodes{raw_route.segment_end_coordinates.back().target_phantom, phantom_node_vector[start_node][0]};
raw_route.segment_end_coordinates.emplace_back(viapoint);
// 5. COMPUTE ROUTE
search_engine_ptr->shortest_path(raw_route.segment_end_coordinates, route_parameters.uturns, raw_route);
// SimpleLogger().Write() << "Route starting at " << start_node << " with length " << raw_route.shortest_path_length;
// check round trip with this starting point is shorter than the shortest round trip found till now
if (raw_route.shortest_path_length < min_route.shortest_path_length) {
min_route = raw_route;
min_loc_permutation = loc_permutation;
}
}
SimpleLogger().Write() << "Shortest route " << min_route.shortest_path_length;
// return result to json // return result to json
std::unique_ptr<BaseDescriptor<DataFacadeT>> descriptor; std::unique_ptr<BaseDescriptor<DataFacadeT>> descriptor;