Difference between revisions of "cpp/numeric/random/bernoulli distribution"
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{{cpp/title|bernoulli_distribution}} | {{cpp/title|bernoulli_distribution}} | ||
{{cpp/numeric/random/bernoulli_distribution/navbar}} | {{cpp/numeric/random/bernoulli_distribution/navbar}} | ||
| − | {{ddcl | header=random | | + | {{ddcl|header=random|since=c++11|1= |
class bernoulli_distribution; | class bernoulli_distribution; | ||
}} | }} | ||
| − | Produces random boolean values, according to the discrete probability function. The probability of {{ | + | Produces random boolean values, according to the discrete probability function. The probability of {{co|true}} is |
| − | :{{math|P(b{{!}}p) | + | :{{math|1=P(b{{!}}p) =}}{{mparen|{||{{math|p}}, if {{math|b}} is {{co|true}}|{{math|1 − p}}, if {{math|b}} is {{co|false}}|style=text-align:right}} |
| + | |||
| + | {{tt|std::bernoulli_distribution}} satisfies {{named req|RandomNumberDistribution}}. | ||
===Member types=== | ===Member types=== | ||
| − | {{ | + | {{dsc begin}} |
| − | {{ | + | {{dsc hitem|Member type|Definition}} |
| − | {{ | + | {{dsc|{{tt|result_type}} {{mark c++11}}|{{co|bool}}}} |
| − | {{ | + | {{cpp/numeric/random/param_type}} |
| − | {{ | + | {{dsc end}} |
===Member functions=== | ===Member functions=== | ||
| − | {{ | + | {{dsc begin}} |
| − | {{ | + | {{dsc inc|cpp/numeric/random/distribution/dsc constructor|bernoulli_distribution}} |
| − | {{ | + | {{dsc inc|cpp/numeric/random/distribution/dsc reset|bernoulli_distribution}} |
| − | {{ | + | {{dsc h2|Generation}} |
| − | {{ | + | {{dsc inc|cpp/numeric/random/distribution/dsc operator()|bernoulli_distribution}} |
| − | {{ | + | {{dsc h2|Characteristics}} |
| − | {{ | + | {{dsc inc|cpp/numeric/random/bernoulli_distribution/dsc p}} |
| − | {{ | + | {{dsc inc|cpp/numeric/random/distribution/dsc param|bernoulli_distribution}} |
| − | {{ | + | {{dsc inc|cpp/numeric/random/distribution/dsc min|bernoulli_distribution}} |
| − | {{ | + | {{dsc inc|cpp/numeric/random/distribution/dsc max|bernoulli_distribution}} |
| − | {{ | + | {{dsc end}} |
===Non-member functions=== | ===Non-member functions=== | ||
| − | {{ | + | {{dsc begin}} |
| − | {{ | + | {{dsc inc|cpp/numeric/random/distribution/dsc operator_cmp|bernoulli_distribution}} |
| − | {{ | + | {{dsc inc|cpp/numeric/random/distribution/dsc operator_ltltgtgt|bernoulli_distribution}} |
| − | {{ | + | {{dsc end}} |
===Example=== | ===Example=== | ||
{{example | {{example | ||
| − | + | |code= | |
| − | + | ||
#include <iomanip> | #include <iomanip> | ||
| − | #include < | + | #include <iostream> |
#include <map> | #include <map> | ||
#include <random> | #include <random> | ||
| + | #include <string> | ||
int main() | int main() | ||
| Line 55: | Line 57: | ||
std::map<bool, int> hist; | std::map<bool, int> hist; | ||
| − | for(int n=0; n<10000; ++n) | + | for (int n = 0; n < 10000; ++n) |
++hist[d(gen)]; | ++hist[d(gen)]; | ||
| − | + | ||
| − | for(auto | + | std::cout << std::boolalpha; |
| − | std::cout | + | for (auto const& [key, value] : hist) |
| − | + | std::cout << std::setw(5) << key << ' ' | |
| − | + | << std::string(value / 500, '*') << '\n'; | |
} | } | ||
| − | + | |p=true | |
| + | |output= | ||
false *************** | false *************** | ||
true **** | true **** | ||
| Line 69: | Line 72: | ||
===External links=== | ===External links=== | ||
| − | [ | + | {{eli|[https://mathworld.wolfram.com/BernoulliDistribution.html Weisstein, Eric W. "Bernoulli Distribution."] From MathWorld — A Wolfram Web Resource.}} |
| − | + | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | |
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
| − | + | ||
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Latest revision as of 23:26, 16 October 2023
| Defined in header <random>
|
||
| class bernoulli_distribution; |
(since C++11) | |
Produces random boolean values, according to the discrete probability function. The probability of true is
- P(b|p) =⎧
⎨
⎩p, if b is true
1 − p, if b is false
std::bernoulli_distribution satisfies RandomNumberDistribution.
Contents |
[edit] Member types
| Member type | Definition |
result_type (C++11)
|
bool |
param_type (C++11)
|
the type of the parameter set, see RandomNumberDistribution. |
[edit] 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 | |
| (C++11) |
returns the p distribution parameter (probability of generating true) (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) |
[edit] 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) |
[edit] Example
Run this code
#include <iomanip> #include <iostream> #include <map> #include <random> #include <string> int main() { std::random_device rd; std::mt19937 gen(rd()); // give "true" 1/4 of the time // give "false" 3/4 of the time std::bernoulli_distribution d(0.25); std::map<bool, int> hist; for (int n = 0; n < 10000; ++n) ++hist[d(gen)]; std::cout << std::boolalpha; for (auto const& [key, value] : hist) std::cout << std::setw(5) << key << ' ' << std::string(value / 500, '*') << '\n'; }
Possible output:
false *************** true ****
[edit] External links
| Weisstein, Eric W. "Bernoulli Distribution." From MathWorld — A Wolfram Web Resource. |
