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how to delete repeating coordinates of vector<Point2f>

asked 2014-08-08 03:35:57 -0600

justrookie gravatar image

I passed coordinates of points into vector, and there are some repeating points, so I want to delete other repeating points and just keep the only points.

for example:

vector<Point2f>  points;

points[0]=Point2f(1,1); 
points[1]=Point2f(2,3); 
points[2]=Point2f(1,1); 
points[3]=Point2f(2,3); 
points[4]=Point2f(1,1); 
points[5]=Point2f(4,1);

I want to get the result like this:

points[0]=Point2f(1,1);
points[1]=Point2f(2,3);
points[2]=Point2f(4,1);

PS The order of remaining elements is unchanged.

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3 answers

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1

answered 2014-08-08 05:53:57 -0600

thdrksdfthmn gravatar image

updated 2014-08-08 09:46:21 -0600

Use a std::set. Push every point and duplicates are not kept.

... but, yes, the order is not kept...

Maybe you can create the container that you need using Boost.Multiindex, see example

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Comments

1

But there is no guarantee that the order is preserved!

FooBar gravatar imageFooBar ( 2014-08-08 09:24:32 -0600 )edit

try std::unordered_set

konstunn gravatar imagekonstunn ( 2014-08-08 21:41:00 -0600 )edit
1

answered 2014-08-10 08:31:24 -0600

justrookie gravatar image

I have got a solution from StackOverflow, see the post:

#include <vector>
#include <unordered_set>


struct Point2f
{
    float x;
    float y;
    Point2f(float a, float b) : x(a), y(b) {}
    Point2f() : x(0), y(0) {}
};

bool operator==(const Point2f& pt1, const Point2f& pt2)
{
    return ((pt1.x == pt2.x) && (pt1.y == pt2.y));
}

namespace std
{
    template<>
    struct hash<Point2f>
    {
        size_t operator()(Point2f const& pt) const
        {
            return (size_t)(pt.x*100 + pt.y);
        }
    };
}


void removedupes(std::vector<Point2f> & vec)
{
    std::unordered_set<Point2f> pointset;

    auto itor = vec.begin();
    while (itor != vec.end())
    {
        if (pointset.find(*itor) != pointset.end())
        {
            itor = vec.erase(itor);
        }
        else
        {
            pointset.insert(*itor);
            itor++;
        }
    }
}


int main(int argc, char* argv[])
{
    std::vector<Point2f>  pointTemp;

    pointTemp.resize(6);

    pointTemp[0]=Point2f(1,1);
    pointTemp[1]=Point2f(2,3);
    pointTemp[2]=Point2f(1,1);
    pointTemp[3]=Point2f(2,3);
    pointTemp[4]=Point2f(1,1);
    pointTemp[5]=Point2f(4,1);

    removedupes(pointTemp);

    return 0;
}
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-2

answered 2014-08-08 05:18:00 -0600

gfx gravatar image

updated 2014-08-08 05:22:46 -0600

you need really these????

if ((point[0].x != yourmemorypoint.x) & (point[0].y != yourmemorypoint.y))
{yourmemorypoint.x = point[0].x;
yourmemorypoint.y = point[0].y;}
else { .... cancel point ...

in a FOR cycle (... absolutely not tested ....)

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Asked: 2014-08-08 03:35:57 -0600

Seen: 2,711 times

Last updated: Aug 17 '14