std::piecewise_constant_distribution - cppreference.com (original) (raw)

std::piecewise_constant_distribution

| | | | | ------------------------------------------------------------------------------ | | ------------- | | 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 , 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
param_type (C++11) the type of the parameter set, see RandomNumberDistribution.

[edit] Member functions

(constructor)(C++11) constructs new distribution (public member function) [edit]
reset(C++11) resets the internal state of the distribution (public member function) [edit]
Generation
operator()(C++11) generates the next random number in the distribution (public member function) [edit]
Characteristics
intervalsdensities returns the distribution parameters (public member function) [edit]
param(C++11) gets or sets the distribution parameter object (public member function) [edit]
min(C++11) returns the minimum potentially generated value (public member function) [edit]
max(C++11) returns the maximum potentially generated value (public member function) [edit]

[edit] Non-member functions

[edit] Example

#include #include #include #include   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 i {0, 1, 10, 15}; std::vector 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