How to Sort Vector of Points Based on a Y-Axis?
13,246
Solution 1
#include "opencv2/core/core.hpp"
#include <algorithm> // std::sort
// This defines a binary predicate that,
// taking two values of the same type of those
// contained in the list, returns true if the first
// argument goes before the second argument
struct myclass {
bool operator() (cv::Point pt1, cv::Point pt2) { return (pt1.y < pt2.y);}
} myobject;
int main () {
// input data
std::vector<cv::Point> pts(5);
pts[0] = Point(10,40);
pts[1] = Point(9,27);
pts[2] = Point(5,68);
pts[3] = Point(7,55);
pts[4] = Point(8,15);
// sort vector using myobject as comparator
std::sort(pts.begin(), pts.end(), myobject);
}
Solution 2
You need to specify how exactly you are storing your group of coordinates.
The easiest way is to store them as a new struct you create and apply a basic bubble sort algorithm over the top of it, using the Y value as your sort parameter. Then when you "swap" the position of the structs, the X & Y stay together.
struct Vector {
float x;
float y;
};
Author by
anarchy99
Updated on July 29, 2022Comments
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anarchy99 almost 2 years
I have a group of coordinates for example :
10,40; 9,27; 5,68; 7,55; 8,15;
How do I sort those coordinates without losing the correct X-Axis of the sorted Y-Axis.
From the example above I want to sort the coordinates so the correct output will be:
8,15; 9,27; 10,40; 7,55; 5,68.
Any suggestion will be greatly appreciated. Thank you.
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anarchy99 almost 11 yearsThank you for your answer, actually I store the points with
std::vector<cv::Point>
. Do you have any other suggestion besides storing it again in astruct
? -
anarchy99 almost 11 yearsThank you for your suggestion, from the reference you posted may help me to solve the problem. I will try it first.
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Madhubalan K over 10 yearsHi @Alex its very usefully but in my case gives error within algorithm.cpp class "No matching function for call for object of type myclass".