是否可以使用带向量的增压累加器？

I wanted to use boost accumulators to calculate statistics of a variable that is a vector. Is there a simple way to do this. I think it's not possible to use the dumbest thing:

我想使用boost accumulators来计算作为向量的变量的统计信息。有一个简单的方法来做到这一点。我认为不可能使用最愚蠢的事情：

  using namespace boost::accumulators;
  //stuff...

  accumulator_set<vector<double>, stats<tag::mean> > acc;
  vector<double> some_vetor;
  //stuff 
  some_vector = doStuff();
  acc(some_vector);

maybe this is obvious, but I tried anyway. :P

也许这很明显，但无论如何我都试过了。：P

What I wanted was to have an accumulator that would calculate a vector which is the mean of the components of many vectors. Is there an easy way out?

我想要的是有一个累加器来计算一个向量，它是许多向量的分量的平均值。有一个简单的方法吗？

EDIT:

编辑：

I don't know if I was thoroughly clear. I don't want this:

我不知道我是否彻底清楚。我不想要这个：

 for_each(vec.begin(), vec.end(),acc);

This would calculate the mean of the entries of a given vector. What I need is different. I have a function that will spit vectors:

这将计算给定矢量的条目的平均值。我需要的是不同的。我有一个将吐向量的函数：

 vector<double> doSomething(); 
 // this is a monte carlo simulation;

And I need to run this many times and calculate the vectorial mean of those vectors:

我需要多次运行并计算这些向量的矢量平均值：

  for(int i = 0; i < numberOfMCSteps; i++){
  vec = doSomething();
  acc(vec);
  }
  cout << mean(acc);

And I want mean(acc) to be a vector itself, whose entry [i] would be the means of the entries [i] of the accumulated vectors.

我希望mean（acc）是一个向量本身，其条目[i]将是累积向量的条目[i]的平均值。

Theres a hint about this in the docs of Boost, but nothing explicit. And I'm a bit dumb. :P

在Boost的文档中有一个暗示，但没有任何明确的。而我有点愚蠢。：P

3 个解决方案

#1

I've looked into your question a bit, and it seems to me that Boost.Accumulators already provides support for std::vector. Here is what I could find in a section of the user's guide :

我已经调查了一下你的问题，在我看来，Boost.Accumulators已经为std :: vector提供了支持。以下是我在用户指南的一部分中可以找到的内容：

Another example where the Numeric Operators Sub-Library is useful is when a type does not define the operator overloads required to use it for some statistical calculations. For instance, std::vector<> does not overload any arithmetic operators, yet it may be useful to use std::vector<> as a sample or variate type. The Numeric Operators Sub-Library defines the necessary operator overloads in the boost::numeric::operators namespace, which is brought into scope by the Accumulators Framework with a using directive.

数值运算符子库有用的另一个示例是，类型未定义将其用于某些统计计算所需的运算符重载。例如，std :: vector <>不会重载任何算术运算符，但使用std :: vector <>作为样本或变量类型可能很有用。 Numeric Operators子库在boost :: numeric :: operators命名空间中定义必要的运算符重载，该命名空间由Accumulators Framework使用using指令引入范围。

Indeed, after verification, the file boost/accumulators/numeric/functional/vector.hpp does contain the necessary operators for the 'naive' solution to work.

实际上，在验证之后，文件boost / accumulators / numeric / functional / vector.hpp确实包含了“天真”解决方案工作所必需的运算符。

I believe you should try :

我相信你应该尝试：

Including either
- boost/accumulators/numeric/functional/vector.hpp before any other accumulators header
- 在任何其他累加器头之前的boost / accumulators / numeric / functional / vector.hpp
- boost/accumulators/numeric/functional.hpp while defining BOOST_NUMERIC_FUNCTIONAL_STD_VECTOR_SUPPORT
- 定义BOOST_NUMERIC_FUNCTIONAL_STD_VECTOR_SUPPORT时的boost / accumulators / numeric / functional.hpp
在定义BOOST_NUMERIC_FUNCTIONAL_STD_VECTOR_SUPPORT时，在任何其他累加器头文件boost / accumulators / numeric / functional.hpp之前包括boost / accumulators / numeric / functional / vector.hpp
Bringing the operators into scope with a using namespace boost::numeric::operators;.
使用使用命名空间boost :: numeric :: operators;将操作符带入范围。

There's only one last detail left : execution will break at runtime because the initial accumulated value is default-constructed, and an assertion will occur when trying to add a vector of size n to an empty vector. For this, it seems you should initialize the accumulator with (where n is the number of elements in your vector) :

剩下的只有最后一个细节：执行将在运行时中断，因为初始累计值是默认构造的，并且在尝试将大小为n的向量添加到空向量时会发生断言。为此，您似乎应该使用（其中n是向量中的元素数）初始化累加器：

accumulator_set<std::vector<double>, stats<tag::mean> > acc(std::vector<double>(n));

I tried the following code, mean gives me a std::vector of size 2 :

我尝试了下面的代码，意思是给我一个大小为2的std :: vector：

int main()
{
    accumulator_set<std::vector<double>, stats<tag::mean> > acc(std::vector<double>(2));

    const std::vector<double> v1 = boost::assign::list_of(1.)(2.);
    const std::vector<double> v2 = boost::assign::list_of(2.)(3.);
    const std::vector<double> v3 = boost::assign::list_of(3.)(4.);
    acc(v1);
    acc(v2);
    acc(v3);

    const std::vector<double> &meanVector = mean(acc);
}

I believe this is what you wanted ?

我相信这就是你想要的？

#2

I don't have it set up to try right now, but if all boost::accumulators need is properly defined mathematical operators, then you might be able to get away with a different vector type: http://www.boost.org/doc/libs/1_37_0/libs/numeric/ublas/doc/vector.htm

我没有设置现在尝试，但如果所有boost :: accumulators需要正确定义的数学运算符，那么你可能能够使用不同的向量类型：http：//www.boost.org /doc/libs/1_37_0/libs/numeric/ublas/doc/vector.htm

#3

-3

And what about the documentation?

那文档怎么样？

// The data for which we wish to calculate statistical properties:
std::vector< double > data( /* stuff */ );

// The accumulator set which will calculate the properties for us:    
accumulator_set< double, features< tag::min, tag::mean > > acc;

// Use std::for_each to accumulate the statistical properties:
acc = std::for_each( data.begin(), data.end(), acc );

#1