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std::experimental::sample(3)  C++ Standard Libary std::experimental::sample(3)

NAME
       std::experimental::sample - std::experimental::sample

Synopsis
	  Defined in header <experimental/algorithm>
	  template< class PopulationIterator, class
	  SampleIterator,

		    class Distance, class URBG >
	  SampleIterator  sample(  PopulationIterator first,	  (1) (library
       fundamentals TS)
	  PopulationIterator last,
				 SampleIterator	out, Distance
	  n,

				 URBG&&	g );
	  template< class PopulationIterator, class
	  SampleIterator, class	Distance >

	  SampleIterator sample( PopulationIterator first,	 (2)  (library
       fundamentals TS
	  PopulationIterator last,				    v2)

				 SampleIterator	out, Distance n
	  );

	  Selects  n  elements	from the sequence [first, last)	such that each
       possible	sample
	  has equal probability	of appearance, and writes those	selected  ele-
       ments into the
	  output iterator out.

	  If n is greater than the number of elements in the sequence, selects
       last - first
	  elements.

	  The  algorithm  is  stable  only if PopulationIterator meets the re-
       quirements of
	  LegacyForwardIterator.

	  1) Random numbers are	generated using	the random number generator g.
	  2) Random numbers are	generated using	the per-thread engine.

Parameters
	  first, last	     -	     pair of iterators forming the range  from
       which to	make
				     the sampling (the population)
	  out		     -	     the output	iterator where the samples are
       written.	Must
				     not be in the range [first, last)
	  n		     -	     number of samples to make
	  g		      -	       the random number generator used	as the
       source of
				     randomness
	  -
	  PopulationIterator must meet the requirements	 of  LegacyInputItera-
       tor.
	  -
	  SampleIterator must meet the requirements of LegacyOutputIterator.
	  -
	  SampleIterator must also meet	the requirements of LegacyRandomAcces-
       sIterator if
	  PopulationIterator doesn't meet LegacyForwardIterator.
	  -
	  PopulationIterator's value type must be writeable to out.
	  -
	  Distance must	be an integer type.
	  -
	  URBG must meet the requirements of UniformRandomBitGenerator and its
       return type
	  must be convertible to Distance.

Return value
	  Returns  a  copy  of out after the last sample that was output, that
       is, end of the
	  sample range.

Complexity
	  Linear in std::distance(first, last).

Notes
	  This function	may implement selection	 sampling  or  reservoir  sam-
       pling.

Example
       // Run this code

	#include <experimental/algorithm>
	#include <iostream>
	#include <iterator>
	#include <random>
	#include <string>

	int main()
	{
	    std::string	in = "abcdefgh", out;
	    std::experimental::sample(in.begin(),    in.end(),	 std::back_in-
       serter(out),
				      5,	  std::mt19937{std::random_de-
       vice{}()});
	    std::cout  <<  "five random	letters	out of " << in << " : "	<< out
       << '\n';
	}

Possible output:
	five random letters out	of abcdefgh : cdefg

See also
	  random_shuffle
	  shuffle	 randomly re-orders elements in	a range
	  (until C++17)	 (function template)
	  (C++11)

Category:
	    * Noindexed	pages

http://cppreference.com		  2024.06.10	  std::experimental::sample(3)

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