Jens Thiele <ka...@karme.de> writes: > Adam Wulkiewicz via Boost-users <boost-users@lists.boost.org> writes: > >> W dniu 23.05.2021 o 17:33, Adam Wulkiewicz pisze: >>> I propose you to use query iterators instead of query function. Then >>> you can iterate over nearest boxes (passing the number of values >>> stored in the rtree into the nearest predicate). In the loop >>> calculate distances to linestrings and break when you have enough of >>> them. You should probably break when the number of linestrings you >>> have is equal to your K and the distance to the furthest linestring >>> is lesser than the distance to the current box returned by the rtree >>> query (because then you know that you will not get any closer >>> linestring). To track the furthest linestring you can use >>> std::priority_queue. >>> >>> Adam >> >> Correction: "the current box returned by the rtree query" >> >> I of course had in mind: "the current box returned by the query iterator" > > I followed that route and the results look correct but performance is > really bad.
the performance problem is fixed now [1] :-) - thanks again! Another problem I face now is that each run produces different results which is still correct (multiple linestrings might have the same distance to some point) but I would prefer a reproducible result. I guess the cause for this is that rtree_t::const_query_iterator it=t->qbegin(idx::nearest(pt, tree_size)); returns an iterator where the order isn't stable. Would it be difficult to fix the iteration order? Jens [1] s.a. https://github.com/boostorg/geometry/issues/867 _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org https://lists.boost.org/mailman/listinfo.cgi/boost-users
