C++ function not getting called - c++

Question

I have a function that takes 2d-vector and outputs a 2d-vector. For some reason, the function is not getting called.
Here is the link to reproduce the issue: Google Colab.
In the link to check for correctness, I have added another code that uses the exact same function but doesn't take a 2d-vector array as an argument instead it runs on static input.
mycode.cpp:
#include <vector>
#include "geomutils.h"
#include "mycode.h"
#include <iostream>
using namespace std;
vector< vector<double> > customComputeConvexHull(vector< vector<double> > i_matrix){
cout <<"\nDone1.1";
Polygon custompts, customhull;
for (int r = 0; r < i_matrix.size(); r++){
custompts.push_back(Point(i_matrix[r][0], i_matrix[r][1]));
}
computeConvexHull(custompts, customhull);
// vector< vector<double> > res;
vector<vector<double>> res( customhull.size() , vector<double> (2));
for(int i = 0;i < customhull.size();i ++) {
res[i][0] = customhull[i].x;
res[i][1] = customhull[i].y;
}
return res;
}
void print_polygon(Polygon &h, int name){
std::cout << "\nHull in "<< name << ": \n"<<"[";
for(int i = 0;i < h.size();i ++) {
std::cout << "("<< h[i].x<< ", "<< h[i].y<<"), ";
}
std::cout <<"]\n";
}
void get_convex_hull_custom(){
Polygon custompts;
Polygon customhull;
custompts.push_back(Point(0,0));
custompts.push_back(Point(4.58,7.14));
custompts.push_back(Point(0,7.14));
computeConvexHull(custompts, customhull);
print_polygon(customhull, -99999);
}
int main()
{
// Create an empty vector
vector< vector<double> > mat,mat2;
vector<double> myRow1(0,0);
mat.push_back(myRow1);
vector<double> myRow2(7.61,9.48);
mat.push_back(myRow2);
vector<double> myRow3(0,9.48);
mat.push_back(myRow3);
cout <<"Done1\n";
get_convex_hull_custom();
mat2 = customComputeConvexHull(mat);
cout <<"Done2";
return 0;
}
mycode.h:
#ifndef _code
#define _code
#include <vector>
std::vector< std::vector<double> > customComputeConvexHull (std::vector< std::vector<double> > i_matrix);
#endif
geomutils.cpp:
#include "geomutils.h"
#include <iostream>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/adapted/boost_tuple.hpp>
BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS(cs::cartesian)
void computeConvexHull(Polygon &pts, Polygon &chull) {
chull.clear();
if(pts.size() == 1) {
chull.push_back(pts[0]);
chull.push_back(pts[0]);
return;
} else if(pts.size() == 2) {
chull.push_back(pts[0]);
chull.push_back(pts[1]);
chull.push_back(pts[0]);
return;
}
typedef boost::tuple<double, double> point;
typedef boost::geometry::model::multi_point<point> mpoints;
typedef boost::geometry::model::polygon<point> polygon;
mpoints mpts;
for(int i = 0;i < pts.size();i ++) {
boost::geometry::append(mpts,point(pts[i].x,pts[i].y));
}
polygon hull;
// Polygon is closed
boost::geometry::convex_hull(mpts, hull);
for(auto pt : hull.outer()) {
chull.push_back(Point(pt.get<0>(), pt.get<1>()));
}
}
geomutils.h:
#ifndef GEOMUTILS_H
#define GEOMUTILS_H
#include <vector>
struct Point {
double x,y;
Point(){}
Point(double x, double y):x(x),y(y){}
};
typedef std::vector<Point> Polygon;
void computeConvexHull(Polygon &pts, Polygon &chull);
#endif // GEOMUTILS_H
When I compile the code and try to run it.
Only Done1 gets printed on the console. It neither gives any error nor any message.
Output:
Done1
Hull in -99999:
[(0, 0), (0, 7.14), (4.58, 7.14), (0, 0), ]

Answer 1

There's some issue on your code. First of all in main to correctly initialize the vector you have to use the {} syntax. Further in customComputeConvexHull you are setting values inside the res vector which are not yet present. You have to use push_back to populate res. Below a version of your code which works (I put everything into one cpp file for semplicity.
#include <vector>
//#include "geomutils.h"
//#include "mycode.h"
#include <iostream>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/adapted/boost_tuple.hpp>
using namespace std;
struct Point {
double x, y;
Point() {}
Point(double x, double y) :x(x), y(y) {}
};
typedef std::vector<Point> Polygon;
BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS(cs::cartesian);
void computeConvexHull(Polygon& pts, Polygon& chull) {
chull.clear();
if (pts.size() == 1) {
chull.push_back(pts[0]);
chull.push_back(pts[0]);
return;
}
else if (pts.size() == 2) {
chull.push_back(pts[0]);
chull.push_back(pts[1]);
chull.push_back(pts[0]);
return;
}
typedef boost::tuple<double, double> point;
typedef boost::geometry::model::multi_point<point> mpoints;
typedef boost::geometry::model::polygon<point> polygon;
mpoints mpts;
for (int i = 0; i < pts.size(); i++) {
boost::geometry::append(mpts, point(pts[i].x, pts[i].y));
}
polygon hull;
// Polygon is closed
boost::geometry::convex_hull(mpts, hull);
for (auto pt : hull.outer()) {
chull.push_back(Point(pt.get<0>(), pt.get<1>()));
}
}
vector< vector<double> > customComputeConvexHull(vector< vector<double> > i_matrix) {
cout << "\nDone1.1";
Polygon custompts, customhull;
for (int r = 0; r < i_matrix.size(); r++) {
custompts.push_back(Point(i_matrix[r][0], i_matrix[r][1]));
}
computeConvexHull(custompts, customhull);
vector< vector<double> > res;
for (int i = 0; i < 3; i++)
{
vector<double> v1{ customhull[i].x, customhull[i].y };
res.push_back(v1);
}
return res;
}
int main()
{
// Create an empty vector
vector< vector<double> > mat, mat2;
vector<double> myRow1{0, 0};
mat.push_back(myRow1);
vector<double> myRow2{ 7.61, 9.48 };
mat.push_back(myRow2);
vector<double> myRow3{ 0, 9.48 };
mat.push_back(myRow3);
cout << "Done1";
mat2 = customComputeConvexHull(mat);
cout << "Done2";
return 0;
}