std::discrete_distribution
Defined in header <random> | ||
|---|---|---|
template< class IntType = int > class discrete_distribution; | (since C++11) |
std::discrete_distribution produces random integers on the interval [0, n), where the probability of each individual integer i is defined as wi/S, that is the weight of the ith integer divided by the sum of all n weights.
std::discrete_distribution satisfies all requirements of RandomNumberDistribution.
Template parameters
| IntType | - | The result type generated by the generator. The effect is undefined if this is not one of short, int, long, longlong, unsignedshort, unsignedint, unsignedlong, or unsignedlonglong. |
Member types
| Member type | Definition |
|---|---|
result_type (C++11) | IntType |
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 |
|
| obtains the list of probabilities (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
#include <iomanip>
#include <iostream>
#include <map>
#include <random>
int main()
{
std::random_device rd;
std::mt19937 gen(rd());
std::discrete_distribution<> d({40, 10, 10, 40});
std::map<int, int> map;
for (int n = 0; n < 1e4; ++n)
++map[d(gen)];
for (const auto& [num, count] : map)
std::cout << num << " generated " << std::setw(4) << count << " times\n";
}
Possible output:
0 generated 4037 times 1 generated 962 times 2 generated 1030 times 3 generated 3971 times
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