NearestSpotList SpotSearch::findNearestSpots(const Instance& tour, int tournode, unsigned int k, bool skipUsed)
{
unsigned spot = tour.getSpotIndex(tournode);
std::vector<unsigned>* nearest = nearestSpots[spot+1];
// return a vector containing the first k entries
if (k > nearest->size()) k = nearest->size();
NearestSpotList pairs;
if (skipUsed) {
pairs.reserve(k);
for (unsigned nearestspot : *nearest) {
if (tour.containsSpot(nearestspot)) continue;
pairs.push_back( std::make_pair(tournode, nearestspot) );
if (pairs.size() >= k) break;
}
} else {
pairs.resize(k);
std::transform(nearest->begin(), nearest->begin() + k, pairs.begin(),
[tournode](unsigned ns) {
return std::make_pair(tournode, ns);
} );
}
return pairs;
}
NearestSpotList SpotSearch::findNearestTourSpots(const Instance& tour, unsigned int k, bool uniqueSpots, bool skipUsed)
{
NearestSpotList nearest;
nearest.reserve(k);
std::vector<double> dist;
dist.reserve(k);
std::set<unsigned> foundSpots;
// initialize with nearest spots to hotel
nearest = findNearestSpots(tour, -1, k, skipUsed);
for (const auto& spot : nearest) {
if (uniqueSpots) foundSpots.insert(spot.second);
dist.push_back(problem.getDistance(problem.getStartAsSpot(), problem.getSpot(spot.second)));
}
// keep track of the maximum distance of the k neighbors found so far
double maxDist = dist.back();
int tourIndex = 0;
for(const auto& node : tour.getTour()) {
// get k nearest spots for every node in the tour, compare with current nearest spots
std::vector<unsigned>* spots = nearestSpots[node.spot+1];
for (unsigned spotIndex : *spots) {
if (skipUsed && tour.containsSpot(spotIndex)) continue;
if (uniqueSpots && !foundSpots.insert(spotIndex).second) continue;
double spotDist = problem.getDistance(problem.getSpot(node.spot), problem.getSpot(spotIndex));
// check if the list is already at size k. we can assume that if !skipUsed
bool listFull = !skipUsed || dist.size() >= k;
// All other spots will actually be further out, so we can stop looking
// This will implicitly stop after at most k iterations, dist(spots[k]) will always be > maxDist!
// (otherwise we would have added all k nearer spots to our list already)
if (listFull && spotDist >= maxDist) break;
// need to insert new spot into list.
if (listFull) {
nearest.pop_back();
dist.pop_back();
}
auto distIt = std::upper_bound(dist.begin(), dist.end(), spotDist);
dist.insert(distIt, spotDist);
nearest.insert(nearest.begin() + (distIt - dist.begin()), std::make_pair(tourIndex, spotIndex));
maxDist = dist.back();
}
tourIndex++;
}
return nearest;
}
NearestSpot SpotSearch::findNearestSpot(const Instance& instance, int tournode, bool skipUsed)
{
unsigned spot = instance.getSpotIndex(tournode);
std::vector<unsigned>* nearest = nearestSpots[spot+1];
for (unsigned nearestspot : *nearest) {
if (skipUsed && instance.containsSpot(nearestspot)) continue;
return std::make_pair(tournode,nearestspot);
}
// Should never be reached
assert(false && "Trying to find nearest spot, but all spots are used");
return std::make_pair(tournode,-1);
}
NearestNodesList SpotSearch::findNearestTourNodes(const Instance& tour, unsigned int k)
{
NearestNodesList nearest;
nearest.reserve(k);
std::vector<double> dist;
dist.reserve(k);
double maxDist = 0.0;
int tourIndex = 0;
for (const auto& node : tour.getTour()) {
std::vector<unsigned>* spots = nearestSpots[node.spot+1];
for (unsigned spotIndex : *spots) {
// To avoid adding duplicate entries, only add pairs where first.spot < second.spot.
if (node.spot > spotIndex) continue;
// skip all spots that are not on the tour
if (!tour.containsSpot(spotIndex)) continue;
double spotDist = problem.getDistance(problem.getSpot(node.spot), problem.getSpot(spotIndex));
if (dist.size() >= k && spotDist >= maxDist) break;
// We need to get the index of the node in the tour for the nearest spot
unsigned nearestnode = tour.getNodeIndex(spotIndex);
if (dist.size() >= k) {
nearest.pop_back();
dist.pop_back();
}
auto distIt = std::upper_bound(dist.begin(), dist.end(), spotDist);
dist.insert(distIt, spotDist);
nearest.insert(nearest.begin() + (distIt - dist.begin()), std::make_pair(tourIndex, nearestnode));
maxDist = dist.back();
}
tourIndex++;
}
return nearest;
}
