std::piecewise_constant_distribution
From cppreference.com
| Defined in header <random>
|
||
template< class RealType = double >
class piecewise_constant_distribution;
|
(since C++11) | |
std::piecewise_constant_distribution produces random floating-point numbers, which are uniformly distributed within each of the several subintervals [bi, bi+1), each with its own weight wi. The set of interval boundaries and the set of weights are the parameters of this distribution.
The probability density for any bi ≤ x <bi+1 is
| wi |
| S (bi+1 - bi) |
, where S is the sum of all weights.
std::piecewise_constant_distribution satisfies all requirements of RandomNumberDistribution.
Template parameters
| RealType | - | The result type generated by the generator. The effect is undefined if this is not one of float, double, or long double.
|
Member types
| Member type | Definition |
result_type (C++11)
|
RealType
|
param_type (C++11)
|
the type of the parameter set, see RandomNumberDistribution. |
Member functions
(C++11) |
constructs new distribution (public member function) |
(C++11) |
resets the internal state of the distribution (public member function) |
Generation | |
(C++11) |
generates the next random number in the distribution (public member function) |
Characteristics | |
| returns the distribution parameters (public member function) | |
(C++11) |
gets or sets the distribution parameter object (public member function) |
(C++11) |
returns the minimum potentially generated value (public member function) |
(C++11) |
returns the maximum potentially generated value (public member function) |
Non-member functions
(C++11)(C++11)(removed in C++20) |
compares two distribution objects (function) |
(C++11) |
performs stream input and output on pseudo-random number distribution (function template) |
Example
Run this code
#include <iostream>
#include <map>
#include <random>
#include <string>
int main()
{
std::random_device rd;
std::mt19937 gen(rd());
// 50% of the time, generate a random number between 0 and 1
// 50% of the time, generate a random number between 10 and 15
std::vector<double> i {0, 1, 10, 15};
std::vector<double> w {1, 0, 1};
std::piecewise_constant_distribution<> d(i.begin(), i.end(), w.begin());
std::map<int, int> hist;
for (int n {}; n < 1e4; ++n)
++hist[d(gen)];
for (std::cout << std::hex << std::uppercase; auto [x, y] : hist)
std::cout << x << ' ' << std::string(y / 100, '*') << '\n';
}
Possible output:
0 **************************************************
A **********
B *********
C *********
D **********
E *********
References
- C++23 standard (ISO/IEC 14882:2024):
- 28.5.9.6.2 Class template piecewise_constant_distribution [rand.dist.samp.pconst] (p: 1421-1422)
- C++20 standard (ISO/IEC 14882:2020):
- 29.6.9.6.2 Class template piecewise_constant_distribution [rand.dist.samp.pconst] (p: 1207-1208)
- C++17 standard (ISO/IEC 14882:2017):
- 29.6.8.6.2 Class template piecewise_constant_distribution [rand.dist.samp.pconst] (p: 1098-1100)
- C++14 standard (ISO/IEC 14882:2014):
- 26.5.8.6.2 Class template piecewise_constant_distribution [rand.dist.samp.pconst] (p: 962-964)
- C++11 standard (ISO/IEC 14882:2011):
- 26.5.8.6.2 Class template piecewise_constant_distribution [rand.dist.samp.pconst] (p: 955-957)
