libs/range/doc/reference/algorithm/nth_element.qbk
[/
Copyright 2010 Neil Groves
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
/]
[section:nth_element nth_element]
[heading Prototype]
``
template<class RandomAccessRange>
RandomAccessRange& nth_element(
RandomAccessRange& rng,
typename range_iterator<RandomAccessRange>::type nth);
template<class RandomAccessRange>
const RandomAccessRange& nth_element(
const RandomAccessRange& rng,
typename range_iterator<const RandomAccessRange>::type nth);
template<class RandomAccessRange>
RandomAccessRange& nth_element(
RandomAccessRange& rng,
typename range_iterator<RandomAccessRange>::type nth,
BinaryPredicate sort_pred);
template<class RandomAccessRange>
const RandomAccessRange& nth_element(
const RandomAccessRange& rng,
typename range_iterator<const RandomAccessRange>::type nth,
BinaryPredicate sort_pred);
``
[heading Description]
`nth_element` partially orders a range of elements. `nth_element` arranges the range `rng` such that the element corresponding with the iterator `nth` is the same as the element that would be in that position if `rng` has been sorted.
[heading Definition]
Defined in the header file `boost/range/algorithm/nth_element.hpp`
[heading Requirements]
[*For the non-predicate version:]
* `RandomAccessRange` is a model of the __random_access_range__ Concept.
* `RandomAccessRange` is mutable.
* `RandomAccessRange`'s value type is a model of the `LessThanComparableConcept`.
* The ordering relation on `RandomAccessRange`'s value type is a [*/strict weak ordering/], as defined in the `LessThanComparableConcept` requirements.
[*For the predicate version:]
* `RandomAccessRange` is a model of the __random_access_range__ Concept.
* `RandomAccessRange` is mutable.
* `BinaryPredicate` is a model of the `StrictWeakOrderingConcept`.
* `RandomAccessRange`'s value type is convertible to both of `BinaryPredicate`'s argument types.
[heading Complexity]
On average, linear in `distance(rng)`.
[endsect]
