将boost accumulator_set存储在STL映射中

Question

我想在一个stl映射中存储多个boost accumulataor_set。

我读到的所有示例都使用accumulator_set作为局部变量：

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，我想将accumulator_set存储在一个映射中。我试着写这样的代码，但我被卡住了：

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]) ;
}

如何创建如上例所示的accumulator_set并将其(引用或对象)存储在映射中？

Answer 1

您可以使用insert()：

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*/) ));
}