排序和删除向量中的重复项<vectors< double>>

Question

您好，我知道有一些类似的问题，但我无法解决我的问题。 我需要在笛卡尔坐标的球体上生成一组独特的点，即从球形转换为笛卡尔坐标。当我这样做时，我将点存储在向量的向量中。但是，创建了一些重复项并删除它们，我尝试使用排序擦除和独特功能。问题是 sort 看不到对我的整个向量进行排序，我不明白为什么？它适用于我只是将数字推回的向量向量，但不适用于我的笛卡尔函数生成的向量向量。我知道这很简单，我已经被困 3 天了，我敢肯定它正盯着我看！！！代码和输出如下

#include <iostream>
#include <math.h>
#include <algorithm>
#include <vector>
#include <stdio.h>  

int main(int argc, const char * argv[]){
  std::vector<double> locations;    //center of the bubble
  locations.push_back(1.0);
  locations.push_back(1.0);
  locations.push_back(1.0);
  std::vector<std::vector<double> > points;   //set of points to be created around the bubble
  double PI=atan(1)*4;

 for(int dr=1; dr<2; dr++){
     for (int phi=0; phi<180; phi+=90){
         for (int theta=0; theta<360; theta+=90){

             std::vector<double>  row;
             double x=locations[0]+(dr*sin(theta*(PI/180))*cos(phi*(PI/180)));
             double y=locations[1]+(dr*cos(theta*(PI/180)));
             double z=locations[2]+(dr*sin(theta*(PI/180))*sin(phi*(PI/180)));
             row.push_back(x);
             row.push_back(y);
             row.push_back(z);

             points.push_back(row);


         }
     }
 }



std::sort(points.begin(), points.end());    //sort points
std::cout<<"sorted points \n";
for (int i =0; i<points.size(); i++){
    std::cout<<points[i][0]<<" "<<points[i][1]<<" "<<points[i][2]<<"\n";
}

points.erase(std::unique(points.begin(), points.end()), points.end());  //erase duplicates

 std::cout<<"duplicates removed \n";
 for (int i =0; i<points.size(); i++){
    std::cout<< points[i][0]<<" "<<points[i][1]<<" "<<points[i][2]<<"\n";
}

}

输出

sorted points 
0 1 1
1 1 0
1 0 1         THIS HASN'T BEEN SORTED CORRECTLY
1 1 2
1 2 1
1 2 1
1 0 1          THIS HASN'T BEEN SORTED CORRECTLY
2 1 1
duplicates removed 
0 1 1
1 1 0
1 0 1
1 1 2
1 2 1
1 0 1
2 1 1

Answer 1

如果换行：

std::cout << points[i][0] << " " << points[i][1] << " " << points[i][2] << "\n";

with（你还需要包括<limits>和<iomanip>）：

std::cout << std::fixed << std::setprecision(std::numeric_limits<double>::digits10+2) << points[i][0] << " " << points[i][1] << " " << points[i][2] << "\n";

你会看到输出是：

sorted points
0.00000000000000000 0.99999999999999978 1.00000000000000000
0.99999999999999989 0.99999999999999978 0.00000000000000000
1.00000000000000000 0.00000000000000000 1.00000000000000022
1.00000000000000000 1.00000000000000000 2.00000000000000000
1.00000000000000000 2.00000000000000000 1.00000000000000000
1.00000000000000000 2.00000000000000000 1.00000000000000000
1.00000000000000022 0.00000000000000000 1.00000000000000000
2.00000000000000000 1.00000000000000000 1.00000000000000000
duplicates removed 
0.00000000000000000 0.99999999999999978 1.00000000000000000
0.99999999999999989 0.99999999999999978 0.00000000000000000
1.00000000000000000 0.00000000000000000 1.00000000000000022
1.00000000000000000 1.00000000000000000 2.00000000000000000
1.00000000000000000 2.00000000000000000 1.00000000000000000
1.00000000000000022 0.00000000000000000 1.00000000000000000
2.00000000000000000 1.00000000000000000 1.00000000000000000

因此考虑近似值向量已正确排序。

PS 您可以在 std::sort() 调用中使用自定义比较器，在 std::unique 调用中使用自定义二进制谓词。