bernoulli_distribution 类

生成伯努利分布。

class bernoulli_distribution { public:     // types     typedef bool result_type;     struct param_type;     // constructors and reset functions     explicit bernoulli_distribution(double p = 0.5);     explicit bernoulli_distribution(const param_type& parm);     void reset();     // generating functions     template<class URNG>     result_type operator()(URNG& gen);     template<class URNG>     result_type operator()(URNG& gen, const param_type& parm);     // property functions     double p() const;     param_type param() const;     void param(const param_type& parm);     result_type min() const;     result_type max() const; };

备注

该类描述了产生 bool 类型的值的分布，根据伯努利分布离散型概率函数进行分布。 下表链接到有关各个成员的文章。

bernoulli_distribution::bernoulli_distribution	bernoulli_distribution::p	bernoulli_distribution::param
bernoulli_distribution::operator()		bernoulli_distribution::param_type

属性函数 p() 将返回当前存储的分布参数值 p。

有关分布类及其成员的详细信息，请参阅 <random>。

有关伯努利分布离散型概率函数的详细信息，请参阅 Wolfram MathWorld 文章伯努利分布。

示例

 

// compile with: /EHsc /W4
#include <random> 
#include <iostream>
#include <iomanip>
#include <string>
#include <map>

void test(const double p, const int s) {

    // uncomment to use a non-deterministic seed
    //    std::random_device rd;
    //    std::mt19937 gen(rd());
    std::mt19937 gen(1729);

    std::bernoulli_distribution distr(p);

    std::cout << "p == " << distr.p() << std::endl;

    // generate the distribution as a histogram
    std::map<bool, int> histogram;
    for (int i = 0; i < s; ++i) {
        ++histogram[distr(gen)];
    }

    // print results
    std::cout << "Histogram for " << s << " samples:" << std::endl;
    for (const auto& elem : histogram) {
        std::cout << std::boolalpha << std::setw(5) << elem.first << ' ' << std::string(elem.second, ':') << std::endl;
    }
    std::cout << std::endl;
}

int main()
{
    double p_dist = 0.5;
    int samples = 100;

    std::cout << "Use CTRL-Z to bypass data entry and run using default values." << std::endl;
    std::cout << "Enter a double value for p distribution (where 0.0 <= p <= 1.0): ";
    std::cin >> p_dist;
    std::cout << "Enter an integer value for a sample count: ";
    std::cin >> samples;

    test(p_dist, samples);
}

输出

Use CTRL-Z to bypass data entry and run using default values.
Enter a double value for p distribution (where 0.0 <= p <= 1.0): .45
Enter an integer value for a sample count: 100
p == 0.45
Histogram for 100 samples:
false :::::::::::::::::::::::::::::::::::::::::::::::::::::
 true :::::::::::::::::::::::::::::::::::::::::::::::

要求

标头：<random>

命名空间: std

请参见

参考

<random>