范围v3的总和 [英] Sum vector with range-v3

问题描述

我需要总结一些向量；也就是说，我想对每个向量的 nth 个元素求和，并用结果创建一个新向量。 （我已经确保输入向量的大小都相同。）我想使用出色的 range-v3 库。我已经尝试过此：

I need to sum up some vectors; that is, I want to sum the nth elements of every vector and make a new vector with the result. (I've already ensured that the input vectors are all the same size.) I'd like to do this with the excellent range-v3 library. I've tried this:

// This file is a "Hello, world!" in C++ language by GCC for wandbox.
#include <iostream>
#include <cstdlib>
#include <vector>
#include <cmath>
#include <map>
#include <range/v3/all.hpp>

int main()
{
   std::cout << "Hello, Wandbox!" << std::endl;

  std::vector< int > v1{ 1,1,1};
  std::vector< int> v2{1,1,1};

  auto va = ranges::view::zip( v1, v2 ) 
    | ranges::view::transform(
      [](auto&& tuple){ return ranges::accumulate( tuple, 0.0 ); }
    );

}

我收到了我无法致电 ranges :: accumulate 像这样。我觉得这是一件很简单的事情，我只是不太了解。

I get the error that I can't call to ranges::accumulate like this. I feel like this is a simple thing that I'm just not quite seeing.

请告知

编辑：
我在这里问一个后续问题：如何使用range-v3压缩向量的向量

推荐答案

您可以使用 std :: apply 对一个元组的值求和，而不是累加 ：

auto sum_tuple = [](auto&& tuple) { 
  return std::apply([](auto... v) { 
    return (v + ...); 
  }, tuple );
};

auto va = ranges::views::zip( v1, v2 ) 
        | ranges::views::transform(sum_tuple);

这里是演示。显示的示例也包含两个以上的向量。

Here's a demo. Show's an example with more than 2 vectors as well.

此外，请注意， ranges :: view 已过时赞成 ranges :: views 。

Also, note that ranges::view has been deprecated in favor of ranges::views.

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