Question

我想以我设定的比例创建一个随机1和0的向量（在我称之为dropout的程序中）该向量与先前创建的向量CSUM的大小相同。

在MATLAB中它将是

dropout=0.9;
n_elements=size(CSUM)
drpoutmask = (rand(n_elements) > dropout);

在C ++中我有

size_t elements = Csum.size();
std::vector<float> y(elements);
std::uniform_real_distribution<float> distribution(0.0f, 1.0f); 
std::mt19937 engine; // Mersenne twister MT19937
auto generator = std::bind(distribution, engine);
std::generate_n(y.begin(), elements, generator);
std::vector<int> dropoutmask(elements,0);
float dropout=0.9;

for(int i=0; i<elements; i++)
  {
  if(y.at(i)>dropout)
    {
    dropoutmask.at(i)=1;
    }
  }
}

哪个有效，但对于大型向量非常慢，有更快的方法吗？我是C ++的新手。

非常感谢任何帮助

Answer 1

您确实知道bernoulli distribution，对吗？您可以使用它直接生成整数向量示例：

#include <iostream>
#include <algorithm>
#include <string>
#include <random>

int main()
{
    constexpr double dropout = 0.9; // Chance of 0
    constexpr size_t size = 1000;
    std::random_device rd;
    std::mt19937 gen(rd());
    std::bernoulli_distribution dist(1 - dropout); // bernoulli_distribution takes chance of true n constructor

    std::vector<int> dropoutmask(size);
    std::generate(dropoutmask.begin(), dropoutmask.end(), [&]{ return dist(gen); });
    size_t ones = std::count(dropoutmask.begin(), dropoutmask.end(), 1);
    std::cout << "vector contains " << ones << " 1's, out of " << size << ". " << ones/double(size) << "%\n";
    std::cout << "vector contains " << size - ones << " 0's, out of " << size << ". " << (size - ones)/double(size) << "%\n";
}

实例：http://coliru.stacked-crooked.com/a/a160743185ded5c5

或者，你可以创建一个所需大小的整数向量（这会将所有元素设置为0），将前N个元素设置为1，其中n是(1 - dropout) * size（你说你想要一个比例，不是随机量接近比例）然后随机播放矢量。

#include <iostream>
#include <algorithm>
#include <string>
#include <random>

int main()
{
    constexpr double dropout = 0.9; // Chance of 0
    constexpr size_t size = 77;
    std::random_device rd;
    std::mt19937 gen(rd());

    std::vector<int> dropoutmask(size);
    std::fill_n(dropoutmask.begin(), dropoutmask.size() * (1 - dropout), 1);
    std::shuffle(dropoutmask.begin(), dropoutmask.end(), gen);

    size_t ones = std::count(dropoutmask.begin(), dropoutmask.end(), 1);
    std::cout << "vector contains " << ones << " 1's, out of " << size << ". " << ones/double(size) << "%\n";
    std::cout << "vector contains " << size - ones << " 0's, out of " << size << ". " << (size - ones)/double(size) << "%\n";

    for (auto i :dropoutmask) {
        std::cout << i << ' ';   
    }
    std::cout << '\n';
}

实例：http://coliru.stacked-crooked.com/a/0a9dacd7629e1605

使用1和0 C ++创建随机std :: vector

1 个答案: