如何在 C++ 中定义具有最大大小的值的键值对

Question

我想制作一个字典（可能类似于 std::multimap），其中包含同一个键的多个值。这里的主要内容是我希望值具有最大大小 (n)，如果出现第 (n+1) 个值，则应删除第一个值（如 boost::circular_buffer 或其他）。更具体地说，

我有一个结构

Struct A{
   double id;  //  key
   double x, y, z;  // value
}

那我定义

std::vector<A> a{}; 

while (condition)
{
    a = getFromSomeWhere();
   ////////////
   //  I DONT KNOW HOW TO STORE THE VALUES in `a` //
   //  THIS IS WHAT I AM LOOKING FOR //
   ////////////
}

调用getFromSomeWhere时，假设a在条件变为假之前得到以下值

{
a1, a2, a3, a4 
a1, a3, a4, a5
a2, a4, a6
}

我要找的答案应该是

{ a1.id : a1, a1      // can go to a maximum size of n before removing the 1st 
  a2.id : a2, a2      // can go to a maximum size of n before removing the 1st
  a3.id : a3, a3      // can go to a maximum size of n before removing the 1st
  a4.id : a4, a4, a4  // can go to a maximum size of n before removing the 1st
  a5.id : a5          // can go to a maximum size of n before removing the 1st
  a6.id : a6          // can go to a maximum size of n before removing the 1st
}

Answer 1

感谢大家的回复。我在 fCaponetto.

的帮助下解决了这个问题

#include<iostream>
#include <boost/circular_buffer.hpp>
#include <map>
#include <vector>

struct Vis
{
    double x;
    double y;
    double z;
    
    bool seen;
    uint id;
};


typedef boost::circular_buffer<Vis> VisBuffer;
typedef std::shared_ptr<VisBuffer> VisBufferPtr;

void makeVisMap(const std::vector<Vis> &b, std::map<uint, VisBufferPtr> &visMap)
{
    unsigned int const max = 500;
    for (const auto &v : b)
    {
        if (!visMap[v.id])
            visMap[v.id] = std::make_shared<VisBuffer>(max);
        visMap[v.id]->push_back(v);
    }
}


int main ()
{
    Vis s1{}, s2{}, s3{}, s4{}, s5{};
    s1.id = 1; s2.id = 2; s3.id = 3; s4.id = 4; s5.id = 5;
    s1.x = s1.y = s1.z = 1;   s2.x = s2.y = s2.z = 2;   s3.x = s3.y = s3.z = 3;   s4.x = s4.y = s4.z = 4;   s5.x = s5.y = s5.z = 5;

    std::vector<Vis> sv {s1, s2, s3, s4, s5, s2, s3, s4, s4, s4, s4};
    std::map<uint, VisBufferPtr> visMap{};

    makeVisMap(sv, visMap);

    return 0;

}

如何在 C++ 中定义具有最大大小的值的键值对

How to define a key value pair with values having a max size in c++

c++

data-structures