c++ - 将 boost accumulator_set 存储在 STL 映射中

Question

我想将多个 boost accumulataor_set 存储在 stl 地图中。

我阅读的所有示例都accumulator_set用作局部变量：

accumulator_set<int, stats<tag::rolling_mean> > acc(tag::rolling_window::window_size = 5);

acc(1);
acc(2);
acc(3);

cout << rolling_mean(acc);

但是我想存储accumulator_set在地图中。我试着写这样的代码，但我卡住了：

map<int, accumulator_set<long, stats<tag::rolling_mean> > > avg;

void update(int id, long data){
    if(avg.count(id)==0){
        //key doesn't exist in map
        avg[id]= ;// How to create acc as in above example and store it in map?
    }
    accumulator_set<long, stats<tag::rolling_mean> > &acc = avg[id];
    acc(data);
}

void read(int id){
    cout << rolling_mean(avg[id]) ;
}

如何accumulator_set在上面的示例中创建一个并将其（引用或对象）存储在地图中？

Answer 1

您可以使用插入（）：

typedef accumulator_set<long, stats<tag::rolling_mean> > acc_set_t;

if(avg.count(id)==0){
    //key doesn't exist in map
    avg.insert( std::make_pair(id, acc_set_t(/*init parameters here*/) ));
}