std::piecewise_constant_distribution
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piecewise_constant_distribution
(C++11)
(C++11)
std::piecewise_constant_distribution
Member functions
Generation
Characteristics
Non-member functions
(C++11)(C++11)(until C++20)
(C++11)(C++11)
Defined in header
<random>
template< class RealType = double >
class piecewise_constant_distribution;
(since C++11)
class piecewise_constant_distribution;
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.
wi
S (bi+1 - bi)
, where S is the sum of all weights.
std::piecewise_constant_distribution satisfies all requirements of RandomNumberDistribution.
Contents
[edit] 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.
[edit] Member types
Member type
Definition
result_type (C++11)
RealType
[edit] Member functions
Generation
Characteristics
[edit] Non-member functions
(C++11)
(function template) [edit]
[edit] 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 *********
[edit] 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)