случайный заголовок в C ++ | Набор 3 (Распределения)
Опубликовано: 7 Января, 2022
Мы обсудили генераторы в Наборе 1. Мы также обсудили три дистрибутива в Наборе 2. В этом посте обсуждаются другие дистрибутивы.
IV.Распределение по ставкам:
| распределение Пуассона | Распределение Пуассона |
| экспоненциальное_распределение | Экспоненциальное распределение |
| gamma_distribution | Гамма-распределение |
| weibull_distribution | Распределение Вейбулла |
| extreme_value_distribution | Распределение экстремальных ценностей |
1. poisson_distribution: это распределение, которое производит целые числа в соответствии с распределением Пуассона, которое задается следующей функцией массы вероятности: 
// Illustrating the use of operator() in // poisson_distribution #include <iostream>#include <chrono>#include <random>using namespace std; // Driver Programint main(){ // construct a trivial random generator // engine from a time-based seed: unsigned seed = chrono::system_clock::now().time_since_epoch().count(); default_random_engine generator (seed); poisson_distribution<int> distribution (7.1); cout << "Poisson-distribution(mean=5.0): "; for (int i=0; i<10; ++i) // use of operator() cout << distribution(generator) << " "; cout << endl; return 0;} |
Output:
Poisson-distribution(mean=5.0): 11 5 5 9 10 6 15 3 6 5
2. exponential_distribution: It is a random number distribution that produces floating-point values according to an exponential distribution, given by:
// Illustrating the use of operator() in // exponential_distribution #include <iostream>#include <chrono>#include <thread>#include <random>using namespace std; // Driver programint main(){ // It constructs a trivial random // generator engine from a time-based seed int seed = chrono::system_clock::now().time_since_epoch().count(); default_random_engine generator (seed); exponential_distribution<double> distribution (1.0); cout << "Hi"s separated by 2 seconds, on average:
"; for (int i=0; i<5; ++i) { // use of operator() double number = distribution(generator); chrono::duration<double> period (number); // It makes the thread sleep // for the time period(i.e. number) this_thread::sleep_for( period ); cout << "Hi,Geeks!!" << endl; } return 0;} |
Output:
Hi"s separated by 2 seconds, on average: Hi,Geeks!! Hi,Geeks!!
3. gamma_distribution: It is a random number distribution that produces floating-point values according to a gamma distribution, given by:
// Illustrating the use of reset in gamma_distribution#include <iostream>#include <random>using namespace std; // Driver programint main(){ // Random number generator default_random_engine generator; gamma_distribution<double> distribution(1.0,2.0); // prints first random number cout << distribution(generator) << endl; // use of reset distribution.reset(); // prints the second random number // independent of first cout << distribution(generator) << endl; return 0;} |
Output:
1.14392 2.23359
4. weibull_distribution:It is a random number distribution that produces floating-point values according to a 2-parameter Weibull distribution,given by:
// Illustrating the use of min and max// in weibull_distribution#include <iostream>#include <chrono>#include <random>using namespace std; // Driver programint main (){ // It constructs a trivial random // generator engine from a time-based seed unsigned seed = chrono::system_clock::now().time_since_epoch().count(); default_random_engine generator (seed); weibull_distribution<double> distribution (2.0,1.0); cout << distribution(generator) << " is a random number between "; // use of min and max cout << generator.min() << " and " << generator.max(); return 0;} |
Output:
1.54229 is a random number between 1 and 2147483646
5. extreme_value_distribution:It is a random number distribution that produces floating-point values according to a Type I extreme value distribution,given by:
// Illustrating the use of param in // extreme_value_distribution#include <iostream>#include <random>using namespace std; // Driver programint main(){ default_random_engine generator; extreme_value_distribution<double> d1(2.0,4.0); extreme_value_distribution<double> d2(d1.param()); // prints the first value cout << d1(generator) << endl; // prints the second independent value cout << d2(generator) << endl; return 0;} |
Output:
9.8351 3.95306
V. Related to Normal distribution
| normal_distribution | Normal Distribution |
| lognormal_distribution | Lognormal Distribution |
| chi_squared_distribution | Chi-squared Distribution |
| cauchy_distribution | Cauchy Distribution |
| fisher_f_distribution | Fisher F-Distribution |
| student_t_distribution | Student T-Distribution |
1. normal_distribution: It is a random number distribution that produces floating-point values according to a normal distribution, given by:
where: (µ) :mean sigma :standard deviation
// Illustrating the use of operator()// in normal_distribution #include <iostream>#include <chrono>#include <random>using namespace std; // Driver programint main(){ // It constructs a trivial random // generator engine from a time-based seed unsigned seed = chrono::system_clock::now().time_since_epoch().count(); default_random_engine generator (seed); // Initializes the normal distribution normal_distribution<double> distribution (1.0,2.0); cout << "Normal-distribution(1.0,2.0):" << endl; for (int i=0; i<5; i++) // Use of operator() cout << distribution(generator) << endl; return 0;} |
Output:
Normal-distribution(1.0,2.0): 1.59499 -0.458303 1.34411 0.138838 3.03433
2. lognormal_distribution:It is a random number distribution that produces floating-point values according to a lognormal distribution, given by:
// Illustrating the use of reset in // lognormal_distribution#include <iostream>#include <random>using namespace std; // Driver programint main(){ // the random number generator default_random_engine generator; lognormal_distribution<double> distribution(1.0,2.0); // prints first value: cout << distribution(generator) << endl; // Use of reset distribution.reset(); // prints second value independent of first cout << distribution(generator) << endl; return 0;} |
Output:
2.12989 10.6822
3. chi_squared_distribution:It is a random number distribution that produces floating-point values according to a chi-squared distribution,given by:
where, n : degrees of freedom and n>0, n/2 : shape parameter
// Illustrating the use of operator() in // chi_squared_distribution #include <iostream>#include <chrono>#include <random>using namespace std; // Driver programint main(){ // It constructs a trivial random // generator engine from a time-based seed unsigned seed = chrono::system_clock::now().time_since_epoch().count(); default_random_engine generator (seed); chi_squared_distribution<double> distribution (4.0); cout << "chi-squared-distribution(4.0):" << endl; for (int i=0; i<5; i++) // use of operator() cout << distribution(generator) << endl; return 0;} |
Output:
chi-squared-distribution(4.0): 2.18701 6.86953 1.77983 9.79626 5.04758
4. cauchy_distribution:It is a random number distribution that produces floating-point values according to a Cauchy distribution, given by:
where, a and b are distribution parameters
// Illustrating the use of param// in cauchy_distribution#include <iostream>#include <random>using namespace std; // Driver programint main(){ default_random_engine generator; cauchy_distribution<double> d1(0.0,1.0); cauchy_distribution<double> d2(d1.param()); // prints the first value cout << d1(generator) << endl; // prints the second value cout << d2(generator) << endl; return 0;} |
Output:
0.438486 7.65462
5. fisher_f_distribution:It is a random number distribution that produces floating-point values according to a Fisher F-distribution, given by:
It produces random numbers by dividing two independent Chi-squared distributions of m and n degrees of freedom.
// Illustrating the use of // operator() in fisher_f_distribution #include <iostream>#include <chrono>#include <random>using namespace std; // Driver programint main(){ // It constructs a trivial random generator engine // from a time-based seed unsigned seed = chrono::system_clock::now().time_since_epoch().count(); default_random_engine generator (seed); fisher_f_distribution<double> distribution (1.0,2.0); cout << "fisher-f-distribution(1.0,2.0):" << endl; for (int i=0; i<5; i++) // use of operator() cout << distribution(generator) << endl; return 0;} |
Output:
fisher-f-distribution(1.0,2.0): 0.208066 2.76882 0.0305701 0.96243 0.444256
6. student_t_distribution:It is a random number distribution that produces floating-point values according to a Student T-distribution, given by:
where, n is the distribution parameter
// Illustrating the use of min and max// in student_t_distribution#include <iostream>#include <chrono>#include <random>using namespace std; // Driver programint main (){ // It constructs a trivial random // generator engine from a time-based seed unsigned seed = chrono::system_clock::now().time_since_epoch().count(); default_random_engine generator (seed); student_t_distribution<double> distribution (8.0); cout << distribution(generator) << " is a random number between "; // use of min and max cout << generator.min() << " and " << generator.max(); return 0;} |
Output:
0.00906058 is a random number between 1 and 2147483646
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