我应该如何将向量中的数据推送到带有整数键的地图中？

Question

How should I push the data in a vector into a map with integer key such that I should be able to append to the existing vector at a particular key?

#include <iostream>
#include<map>
#include<vector>

using namespace std;

int main()
{
   std::map<int, std::vector<double>> my_map;
   std::vector<double> data;
   int j=0;
   data.push_back(1.0);
   data.push_back(3.4);   
 
for(int k=0; k<2;k++)
my_map.insert(j, data[k] );  // but this wont allow me to append if the same key is to be used
   
 return 0;

}

Answer 1

#include <iostream>
#include <map>
#include <vector>

int main() {
  std::map<int, std::vector<double>> my_map;
  std::vector<double> data;
  int j = 0;
  data.push_back(1.0);
  data.push_back(3.4);

  for (int k = 0; k < 2; k++)
      my_map[j].push_back(data[k]);

  return 0;
}

EDIT: Simplified solution proposed. operator[]() will create a new item for the map if it does not exist, and append if it does.