Geometry Boost List: [geometry] sort points on single coordinate

Subject: [geometry] sort points on single coordinate
From: Hussein Almashouq (hussein.almashouq_at_[hidden])
Date: 2015-07-15 14:11:14

Greeting to all,

Currently I'm using std::sort  on boost points on x-coordinte as follows

typedef bg::model::point<long long, 2, bg::cs::cartesian> point;

typedef std::pair<point, long long>  value_type;

 std::vector<value_type> values;

// for single attribute sort on point data sets
// std::sort needs custom comparison operator

struct PointLessX {
    bool operator()(const value_type& p, const value_type& q) const
    {
        return bg::get<0>(p.first) < bg::get<0>(q.first);
    }
};

    std::cout << "Sorting the data " << std::endl;
    PointLessX x;
    std::sort(values.begin(), values.end(), x);

The above code is working fine but a bit slow when the # of points exceeds
10M.

I looked at boost sort package and it seems it overcomes this issue

http://www.boost.org/doc/libs/1_58_0/libs/sort/doc/html/index.html#sort.overview.intro

However , I could not  figure out how to adapt it to sort my boost points
which are of value type long. It seem that  I have to define some bit shift
operator.

Any suggestion please ?

Hussein Almashouq

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