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780 lines
36 KiB
780 lines
36 KiB
11 years ago
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/*
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* Copyright 2008-2012 NVIDIA Corporation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*! \file reduce.h
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* \brief Functions for reducing a range to a single value
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*/
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#pragma once
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#include <thrust/detail/config.h>
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#include <thrust/detail/execution_policy.h>
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#include <thrust/iterator/iterator_traits.h>
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#include <thrust/pair.h>
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namespace thrust
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{
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/*! \addtogroup reductions
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* \{
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*/
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/*! \p reduce is a generalization of summation: it computes the sum (or some
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* other binary operation) of all the elements in the range <tt>[first,
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* last)</tt>. This version of \p reduce uses \c 0 as the initial value of the
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* reduction. \p reduce is similar to the C++ Standard Template Library's
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* <tt>std::accumulate</tt>. The primary difference between the two functions
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* is that <tt>std::accumulate</tt> guarantees the order of summation, while
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* \p reduce requires associativity of the binary operation to parallelize
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* the reduction.
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*
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* Note that \p reduce also assumes that the binary reduction operator (in this
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* case operator+) is commutative. If the reduction operator is not commutative
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* then \p thrust::reduce should not be used. Instead, one could use
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* \p inclusive_scan (which does not require commutativity) and select the
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* last element of the output array.
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*
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* The algorithm's execution is parallelized as determined by \p exec.
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*
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* \param exec The execution policy to use for parallelization.
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* \param first The beginning of the sequence.
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* \param last The end of the sequence.
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* \return The result of the reduction.
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*
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* \tparam DerivedPolicy The name of the derived execution policy.
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* \tparam InputIterator is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>
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* and if \c x and \c y are objects of \p InputIterator's \c value_type,
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* then <tt>x + y</tt> is defined and is convertible to \p InputIterator's
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* \c value_type. If \c T is \c InputIterator's \c value_type, then
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* <tt>T(0)</tt> is defined.
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*
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* The following code snippet demonstrates how to use \p reduce to compute
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* the sum of a sequence of integers using the \p thrust::host execution policy for parallelization:
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*
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* \code
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* #include <thrust/reduce.h>
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* #include <thrust/execution_policy.h>
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* ...
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* int data[6] = {1, 0, 2, 2, 1, 3};
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* int result = thrust::reduce(thrust::host, data, data + 6);
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*
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* // result == 9
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* \endcode
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*
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* \see http://www.sgi.com/tech/stl/accumulate.html
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*/
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template<typename DerivedPolicy, typename InputIterator>
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typename thrust::iterator_traits<InputIterator>::value_type
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reduce(const thrust::detail::execution_policy_base<DerivedPolicy> &exec, InputIterator first, InputIterator last);
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/*! \p reduce is a generalization of summation: it computes the sum (or some
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* other binary operation) of all the elements in the range <tt>[first,
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* last)</tt>. This version of \p reduce uses \c 0 as the initial value of the
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* reduction. \p reduce is similar to the C++ Standard Template Library's
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* <tt>std::accumulate</tt>. The primary difference between the two functions
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* is that <tt>std::accumulate</tt> guarantees the order of summation, while
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* \p reduce requires associativity of the binary operation to parallelize
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* the reduction.
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*
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* Note that \p reduce also assumes that the binary reduction operator (in this
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* case operator+) is commutative. If the reduction operator is not commutative
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* then \p thrust::reduce should not be used. Instead, one could use
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* \p inclusive_scan (which does not require commutativity) and select the
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* last element of the output array.
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*
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* \param first The beginning of the sequence.
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* \param last The end of the sequence.
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* \return The result of the reduction.
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*
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* \tparam InputIterator is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>
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* and if \c x and \c y are objects of \p InputIterator's \c value_type,
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* then <tt>x + y</tt> is defined and is convertible to \p InputIterator's
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* \c value_type. If \c T is \c InputIterator's \c value_type, then
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* <tt>T(0)</tt> is defined.
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*
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* The following code snippet demonstrates how to use \p reduce to compute
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* the sum of a sequence of integers.
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*
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* \code
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* #include <thrust/reduce.h>
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* ...
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* int data[6] = {1, 0, 2, 2, 1, 3};
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* int result = thrust::reduce(data, data + 6);
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*
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* // result == 9
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* \endcode
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*
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* \see http://www.sgi.com/tech/stl/accumulate.html
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*/
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template<typename InputIterator> typename
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thrust::iterator_traits<InputIterator>::value_type reduce(InputIterator first, InputIterator last);
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/*! \p reduce is a generalization of summation: it computes the sum (or some
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* other binary operation) of all the elements in the range <tt>[first,
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* last)</tt>. This version of \p reduce uses \p init as the initial value of the
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* reduction. \p reduce is similar to the C++ Standard Template Library's
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* <tt>std::accumulate</tt>. The primary difference between the two functions
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* is that <tt>std::accumulate</tt> guarantees the order of summation, while
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* \p reduce requires associativity of the binary operation to parallelize
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* the reduction.
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*
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* Note that \p reduce also assumes that the binary reduction operator (in this
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* case operator+) is commutative. If the reduction operator is not commutative
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* then \p thrust::reduce should not be used. Instead, one could use
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* \p inclusive_scan (which does not require commutativity) and select the
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* last element of the output array.
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*
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* The algorithm's execution is parallelized as determined by \p exec.
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*
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* \param exec The execution policy to use for parallelization.
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* \param first The beginning of the input sequence.
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* \param last The end of the input sequence.
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* \param init The initial value.
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* \return The result of the reduction.
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*
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* \tparam DerivedPolicy The name of the derived execution policy.
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* \tparam InputIterator is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>
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* and if \c x and \c y are objects of \p InputIterator's \c value_type,
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* then <tt>x + y</tt> is defined and is convertible to \p T.
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* \tparam T is convertible to \p InputIterator's \c value_type.
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*
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* The following code snippet demonstrates how to use \p reduce to compute
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* the sum of a sequence of integers including an intialization value using the \p thrust::host
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* execution policy for parallelization:
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*
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* \code
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* #include <thrust/reduce.h>
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* #include <thrust/execution_policy.h>
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* ...
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* int data[6] = {1, 0, 2, 2, 1, 3};
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* int result = thrust::reduce(thrust::host, data, data + 6, 1);
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*
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* // result == 10
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* \endcode
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*
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* \see http://www.sgi.com/tech/stl/accumulate.html
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*/
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template<typename DerivedPolicy, typename InputIterator, typename T>
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T reduce(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
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InputIterator first,
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InputIterator last,
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T init);
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/*! \p reduce is a generalization of summation: it computes the sum (or some
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* other binary operation) of all the elements in the range <tt>[first,
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* last)</tt>. This version of \p reduce uses \p init as the initial value of the
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* reduction. \p reduce is similar to the C++ Standard Template Library's
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* <tt>std::accumulate</tt>. The primary difference between the two functions
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* is that <tt>std::accumulate</tt> guarantees the order of summation, while
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* \p reduce requires associativity of the binary operation to parallelize
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* the reduction.
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*
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* Note that \p reduce also assumes that the binary reduction operator (in this
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* case operator+) is commutative. If the reduction operator is not commutative
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* then \p thrust::reduce should not be used. Instead, one could use
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* \p inclusive_scan (which does not require commutativity) and select the
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* last element of the output array.
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*
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* \param first The beginning of the input sequence.
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* \param last The end of the input sequence.
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* \param init The initial value.
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* \return The result of the reduction.
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*
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* \tparam InputIterator is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>
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* and if \c x and \c y are objects of \p InputIterator's \c value_type,
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* then <tt>x + y</tt> is defined and is convertible to \p T.
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* \tparam T is convertible to \p InputIterator's \c value_type.
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*
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* The following code snippet demonstrates how to use \p reduce to compute
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* the sum of a sequence of integers including an intialization value.
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*
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* \code
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* #include <thrust/reduce.h>
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* ...
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* int data[6] = {1, 0, 2, 2, 1, 3};
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* int result = thrust::reduce(data, data + 6, 1);
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*
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* // result == 10
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* \endcode
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*
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* \see http://www.sgi.com/tech/stl/accumulate.html
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*/
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template<typename InputIterator, typename T>
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T reduce(InputIterator first,
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InputIterator last,
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T init);
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/*! \p reduce is a generalization of summation: it computes the sum (or some
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* other binary operation) of all the elements in the range <tt>[first,
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* last)</tt>. This version of \p reduce uses \p init as the initial value of the
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* reduction and \p binary_op as the binary function used for summation. \p reduce
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* is similar to the C++ Standard Template Library's <tt>std::accumulate</tt>.
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||
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* The primary difference between the two functions is that <tt>std::accumulate</tt>
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* guarantees the order of summation, while \p reduce requires associativity of
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* \p binary_op to parallelize the reduction.
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*
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* Note that \p reduce also assumes that the binary reduction operator (in this
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* case \p binary_op) is commutative. If the reduction operator is not commutative
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* then \p thrust::reduce should not be used. Instead, one could use
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* \p inclusive_scan (which does not require commutativity) and select the
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* last element of the output array.
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*
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* The algorithm's execution is parallelized as determined by \p exec.
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*
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* \param exec The execution policy to use for parallelization.
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* \param first The beginning of the input sequence.
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* \param last The end of the input sequence.
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* \param init The initial value.
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* \param binary_op The binary function used to 'sum' values.
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* \return The result of the reduction.
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*
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* \tparam DerivedPolicy The name of the derived execution policy.
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* \tparam InputIterator is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>
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* and \c InputIterator's \c value_type is convertible to \c T.
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* \tparam T is a model of <a href="http://www.sgi.com/tech/stl/Assignable.html">Assignable</a>,
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* and is convertible to \p BinaryFunction's \c first_argument_type and \c second_argument_type.
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* \tparam BinaryFunction is a model of <a href="http://www.sgi.com/tech/stl/BinaryFunction.html">Binary Function</a>,
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* and \p BinaryFunction's \c result_type is convertible to \p OutputType.
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*
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* The following code snippet demonstrates how to use \p reduce to
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* compute the maximum value of a sequence of integers using the \p thrust::host execution policy
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* for parallelization:
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*
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* \code
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* #include <thrust/reduce.h>
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* #include <thrust/functional.h>
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* #include <thrust/execution_policy.h>
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* ...
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* int data[6] = {1, 0, 2, 2, 1, 3};
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* int result = thrust::reduce(thrust::host,
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* data, data + 6,
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* -1,
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* thrust::maximum<int>());
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* // result == 3
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* \endcode
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*
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* \see http://www.sgi.com/tech/stl/accumulate.html
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* \see transform_reduce
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*/
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template<typename DerivedPolicy,
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typename InputIterator,
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typename T,
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typename BinaryFunction>
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T reduce(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
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InputIterator first,
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InputIterator last,
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T init,
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BinaryFunction binary_op);
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|
|
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||
|
|
|
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/*! \p reduce is a generalization of summation: it computes the sum (or some
|
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|
|
* other binary operation) of all the elements in the range <tt>[first,
|
||
|
|
* last)</tt>. This version of \p reduce uses \p init as the initial value of the
|
||
|
|
* reduction and \p binary_op as the binary function used for summation. \p reduce
|
||
|
|
* is similar to the C++ Standard Template Library's <tt>std::accumulate</tt>.
|
||
|
|
* The primary difference between the two functions is that <tt>std::accumulate</tt>
|
||
|
|
* guarantees the order of summation, while \p reduce requires associativity of
|
||
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* \p binary_op to parallelize the reduction.
|
||
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|
*
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||
|
|
* Note that \p reduce also assumes that the binary reduction operator (in this
|
||
|
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* case \p binary_op) is commutative. If the reduction operator is not commutative
|
||
|
|
* then \p thrust::reduce should not be used. Instead, one could use
|
||
|
|
* \p inclusive_scan (which does not require commutativity) and select the
|
||
|
|
* last element of the output array.
|
||
|
|
*
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||
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* \param first The beginning of the input sequence.
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||
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* \param last The end of the input sequence.
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||
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* \param init The initial value.
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||
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* \param binary_op The binary function used to 'sum' values.
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||
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* \return The result of the reduction.
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||
|
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*
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||
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* \tparam InputIterator is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>
|
||
|
|
* and \c InputIterator's \c value_type is convertible to \c T.
|
||
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* \tparam T is a model of <a href="http://www.sgi.com/tech/stl/Assignable.html">Assignable</a>,
|
||
|
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* and is convertible to \p BinaryFunction's \c first_argument_type and \c second_argument_type.
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||
|
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* \tparam BinaryFunction is a model of <a href="http://www.sgi.com/tech/stl/BinaryFunction.html">Binary Function</a>,
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|
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* and \p BinaryFunction's \c result_type is convertible to \p OutputType.
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||
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*
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* The following code snippet demonstrates how to use \p reduce to
|
||
|
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* compute the maximum value of a sequence of integers.
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||
|
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*
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||
|
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* \code
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||
|
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* #include <thrust/reduce.h>
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||
|
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* #include <thrust/functional.h>
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||
|
|
* ...
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||
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* int data[6] = {1, 0, 2, 2, 1, 3};
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||
|
|
* int result = thrust::reduce(data, data + 6,
|
||
|
|
* -1,
|
||
|
|
* thrust::maximum<int>());
|
||
|
|
* // result == 3
|
||
|
|
* \endcode
|
||
|
|
*
|
||
|
|
* \see http://www.sgi.com/tech/stl/accumulate.html
|
||
|
|
* \see transform_reduce
|
||
|
|
*/
|
||
|
|
template<typename InputIterator,
|
||
|
|
typename T,
|
||
|
|
typename BinaryFunction>
|
||
|
|
T reduce(InputIterator first,
|
||
|
|
InputIterator last,
|
||
|
|
T init,
|
||
|
|
BinaryFunction binary_op);
|
||
|
|
|
||
|
|
|
||
|
|
/*! \p reduce_by_key is a generalization of \p reduce to key-value pairs.
|
||
|
|
* For each group of consecutive keys in the range <tt>[keys_first, keys_last)</tt>
|
||
|
|
* that are equal, \p reduce_by_key copies the first element of the group to the
|
||
|
|
* \c keys_output. The corresponding values in the range are reduced using the
|
||
|
|
* \c plus and the result copied to \c values_output.
|
||
|
|
*
|
||
|
|
* This version of \p reduce_by_key uses the function object \c equal_to
|
||
|
|
* to test for equality and \c plus to reduce values with equal keys.
|
||
|
|
*
|
||
|
|
* The algorithm's execution is parallelized as determined by \p exec.
|
||
|
|
*
|
||
|
|
* \param exec The execution policy to use for parallelization.
|
||
|
|
* \param keys_first The beginning of the input key range.
|
||
|
|
* \param keys_last The end of the input key range.
|
||
|
|
* \param values_first The beginning of the input value range.
|
||
|
|
* \param keys_output The beginning of the output key range.
|
||
|
|
* \param values_output The beginning of the output value range.
|
||
|
|
* \return A pair of iterators at end of the ranges <tt>[keys_output, keys_output_last)</tt> and <tt>[values_output, values_output_last)</tt>.
|
||
|
|
*
|
||
|
|
* \tparam DerivedPolicy The name of the derived execution policy.
|
||
|
|
* \tparam InputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam InputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam OutputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator1's \c value_type is convertible to \c OutputIterator1's \c value_type.
|
||
|
|
* \tparam OutputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator2's \c value_type is convertible to \c OutputIterator2's \c value_type.
|
||
|
|
*
|
||
|
|
* \pre The input ranges shall not overlap either output range.
|
||
|
|
*
|
||
|
|
* The following code snippet demonstrates how to use \p reduce_by_key to
|
||
|
|
* compact a sequence of key/value pairs and sum values with equal keys using the \p thrust::host
|
||
|
|
* execution policy for parallelization:
|
||
|
|
*
|
||
|
|
* \code
|
||
|
|
* #include <thrust/reduce.h>
|
||
|
|
* #include <thrust/execution_policy.h>
|
||
|
|
* ...
|
||
|
|
* const int N = 7;
|
||
|
|
* int A[N] = {1, 3, 3, 3, 2, 2, 1}; // input keys
|
||
|
|
* int B[N] = {9, 8, 7, 6, 5, 4, 3}; // input values
|
||
|
|
* int C[N]; // output keys
|
||
|
|
* int D[N]; // output values
|
||
|
|
*
|
||
|
|
* thrust::pair<int*,int*> new_end;
|
||
|
|
* new_end = thrust::reduce_by_key(thrust::host, A, A + N, B, C, D);
|
||
|
|
*
|
||
|
|
* // The first four keys in C are now {1, 3, 2, 1} and new_end.first - C is 4.
|
||
|
|
* // The first four values in D are now {9, 21, 9, 3} and new_end.second - D is 4.
|
||
|
|
* \endcode
|
||
|
|
*
|
||
|
|
* \see reduce
|
||
|
|
* \see unique_copy
|
||
|
|
* \see unique_by_key
|
||
|
|
* \see unique_by_key_copy
|
||
|
|
*/
|
||
|
|
template<typename DerivedPolicy,
|
||
|
|
typename InputIterator1,
|
||
|
|
typename InputIterator2,
|
||
|
|
typename OutputIterator1,
|
||
|
|
typename OutputIterator2>
|
||
|
|
thrust::pair<OutputIterator1,OutputIterator2>
|
||
|
|
reduce_by_key(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
|
||
|
|
InputIterator1 keys_first,
|
||
|
|
InputIterator1 keys_last,
|
||
|
|
InputIterator2 values_first,
|
||
|
|
OutputIterator1 keys_output,
|
||
|
|
OutputIterator2 values_output);
|
||
|
|
|
||
|
|
|
||
|
|
/*! \p reduce_by_key is a generalization of \p reduce to key-value pairs.
|
||
|
|
* For each group of consecutive keys in the range <tt>[keys_first, keys_last)</tt>
|
||
|
|
* that are equal, \p reduce_by_key copies the first element of the group to the
|
||
|
|
* \c keys_output. The corresponding values in the range are reduced using the
|
||
|
|
* \c plus and the result copied to \c values_output.
|
||
|
|
*
|
||
|
|
* This version of \p reduce_by_key uses the function object \c equal_to
|
||
|
|
* to test for equality and \c plus to reduce values with equal keys.
|
||
|
|
*
|
||
|
|
* \param keys_first The beginning of the input key range.
|
||
|
|
* \param keys_last The end of the input key range.
|
||
|
|
* \param values_first The beginning of the input value range.
|
||
|
|
* \param keys_output The beginning of the output key range.
|
||
|
|
* \param values_output The beginning of the output value range.
|
||
|
|
* \return A pair of iterators at end of the ranges <tt>[keys_output, keys_output_last)</tt> and <tt>[values_output, values_output_last)</tt>.
|
||
|
|
*
|
||
|
|
* \tparam InputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam InputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam OutputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator1's \c value_type is convertible to \c OutputIterator1's \c value_type.
|
||
|
|
* \tparam OutputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator2's \c value_type is convertible to \c OutputIterator2's \c value_type.
|
||
|
|
*
|
||
|
|
* \pre The input ranges shall not overlap either output range.
|
||
|
|
*
|
||
|
|
* The following code snippet demonstrates how to use \p reduce_by_key to
|
||
|
|
* compact a sequence of key/value pairs and sum values with equal keys.
|
||
|
|
*
|
||
|
|
* \code
|
||
|
|
* #include <thrust/reduce.h>
|
||
|
|
* ...
|
||
|
|
* const int N = 7;
|
||
|
|
* int A[N] = {1, 3, 3, 3, 2, 2, 1}; // input keys
|
||
|
|
* int B[N] = {9, 8, 7, 6, 5, 4, 3}; // input values
|
||
|
|
* int C[N]; // output keys
|
||
|
|
* int D[N]; // output values
|
||
|
|
*
|
||
|
|
* thrust::pair<int*,int*> new_end;
|
||
|
|
* new_end = thrust::reduce_by_key(A, A + N, B, C, D);
|
||
|
|
*
|
||
|
|
* // The first four keys in C are now {1, 3, 2, 1} and new_end.first - C is 4.
|
||
|
|
* // The first four values in D are now {9, 21, 9, 3} and new_end.second - D is 4.
|
||
|
|
* \endcode
|
||
|
|
*
|
||
|
|
* \see reduce
|
||
|
|
* \see unique_copy
|
||
|
|
* \see unique_by_key
|
||
|
|
* \see unique_by_key_copy
|
||
|
|
*/
|
||
|
|
template <typename InputIterator1,
|
||
|
|
typename InputIterator2,
|
||
|
|
typename OutputIterator1,
|
||
|
|
typename OutputIterator2>
|
||
|
|
thrust::pair<OutputIterator1,OutputIterator2>
|
||
|
|
reduce_by_key(InputIterator1 keys_first,
|
||
|
|
InputIterator1 keys_last,
|
||
|
|
InputIterator2 values_first,
|
||
|
|
OutputIterator1 keys_output,
|
||
|
|
OutputIterator2 values_output);
|
||
|
|
|
||
|
|
|
||
|
|
/*! \p reduce_by_key is a generalization of \p reduce to key-value pairs.
|
||
|
|
* For each group of consecutive keys in the range <tt>[keys_first, keys_last)</tt>
|
||
|
|
* that are equal, \p reduce_by_key copies the first element of the group to the
|
||
|
|
* \c keys_output. The corresponding values in the range are reduced using the
|
||
|
|
* \c plus and the result copied to \c values_output.
|
||
|
|
*
|
||
|
|
* This version of \p reduce_by_key uses the function object \c binary_pred
|
||
|
|
* to test for equality and \c plus to reduce values with equal keys.
|
||
|
|
*
|
||
|
|
* The algorithm's execution is parallelized as determined by \p exec.
|
||
|
|
*
|
||
|
|
* \param exec The execution policy to use for parallelization.
|
||
|
|
* \param keys_first The beginning of the input key range.
|
||
|
|
* \param keys_last The end of the input key range.
|
||
|
|
* \param values_first The beginning of the input value range.
|
||
|
|
* \param keys_output The beginning of the output key range.
|
||
|
|
* \param values_output The beginning of the output value range.
|
||
|
|
* \param binary_pred The binary predicate used to determine equality.
|
||
|
|
* \return A pair of iterators at end of the ranges <tt>[keys_output, keys_output_last)</tt> and <tt>[values_output, values_output_last)</tt>.
|
||
|
|
*
|
||
|
|
* \tparam DerivedPolicy The name of the derived execution policy.
|
||
|
|
* \tparam InputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam InputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam OutputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator1's \c value_type is convertible to \c OutputIterator1's \c value_type.
|
||
|
|
* \tparam OutputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator2's \c value_type is convertible to \c OutputIterator2's \c value_type.
|
||
|
|
* \tparam BinaryPredicate is a model of <a href="http://www.sgi.com/tech/stl/BinaryPredicate.html">Binary Predicate</a>.
|
||
|
|
*
|
||
|
|
* \pre The input ranges shall not overlap either output range.
|
||
|
|
*
|
||
|
|
* The following code snippet demonstrates how to use \p reduce_by_key to
|
||
|
|
* compact a sequence of key/value pairs and sum values with equal keys using the \p thrust::host
|
||
|
|
* execution policy for parallelization:
|
||
|
|
*
|
||
|
|
* \code
|
||
|
|
* #include <thrust/reduce.h>
|
||
|
|
* #include <thrust/execution_policy.h>
|
||
|
|
* ...
|
||
|
|
* const int N = 7;
|
||
|
|
* int A[N] = {1, 3, 3, 3, 2, 2, 1}; // input keys
|
||
|
|
* int B[N] = {9, 8, 7, 6, 5, 4, 3}; // input values
|
||
|
|
* int C[N]; // output keys
|
||
|
|
* int D[N]; // output values
|
||
|
|
*
|
||
|
|
* thrust::pair<int*,int*> new_end;
|
||
|
|
* thrust::equal_to<int> binary_pred;
|
||
|
|
* new_end = thrust::reduce_by_key(thrust::host, A, A + N, B, C, D, binary_pred);
|
||
|
|
*
|
||
|
|
* // The first four keys in C are now {1, 3, 2, 1} and new_end.first - C is 4.
|
||
|
|
* // The first four values in D are now {9, 21, 9, 3} and new_end.second - D is 4.
|
||
|
|
* \endcode
|
||
|
|
*
|
||
|
|
* \see reduce
|
||
|
|
* \see unique_copy
|
||
|
|
* \see unique_by_key
|
||
|
|
* \see unique_by_key_copy
|
||
|
|
*/
|
||
|
|
template<typename DerivedPolicy,
|
||
|
|
typename InputIterator1,
|
||
|
|
typename InputIterator2,
|
||
|
|
typename OutputIterator1,
|
||
|
|
typename OutputIterator2,
|
||
|
|
typename BinaryPredicate>
|
||
|
|
thrust::pair<OutputIterator1,OutputIterator2>
|
||
|
|
reduce_by_key(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
|
||
|
|
InputIterator1 keys_first,
|
||
|
|
InputIterator1 keys_last,
|
||
|
|
InputIterator2 values_first,
|
||
|
|
OutputIterator1 keys_output,
|
||
|
|
OutputIterator2 values_output,
|
||
|
|
BinaryPredicate binary_pred);
|
||
|
|
|
||
|
|
|
||
|
|
/*! \p reduce_by_key is a generalization of \p reduce to key-value pairs.
|
||
|
|
* For each group of consecutive keys in the range <tt>[keys_first, keys_last)</tt>
|
||
|
|
* that are equal, \p reduce_by_key copies the first element of the group to the
|
||
|
|
* \c keys_output. The corresponding values in the range are reduced using the
|
||
|
|
* \c plus and the result copied to \c values_output.
|
||
|
|
*
|
||
|
|
* This version of \p reduce_by_key uses the function object \c binary_pred
|
||
|
|
* to test for equality and \c plus to reduce values with equal keys.
|
||
|
|
*
|
||
|
|
* \param keys_first The beginning of the input key range.
|
||
|
|
* \param keys_last The end of the input key range.
|
||
|
|
* \param values_first The beginning of the input value range.
|
||
|
|
* \param keys_output The beginning of the output key range.
|
||
|
|
* \param values_output The beginning of the output value range.
|
||
|
|
* \param binary_pred The binary predicate used to determine equality.
|
||
|
|
* \return A pair of iterators at end of the ranges <tt>[keys_output, keys_output_last)</tt> and <tt>[values_output, values_output_last)</tt>.
|
||
|
|
*
|
||
|
|
* \tparam InputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam InputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam OutputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator1's \c value_type is convertible to \c OutputIterator1's \c value_type.
|
||
|
|
* \tparam OutputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator2's \c value_type is convertible to \c OutputIterator2's \c value_type.
|
||
|
|
* \tparam BinaryPredicate is a model of <a href="http://www.sgi.com/tech/stl/BinaryPredicate.html">Binary Predicate</a>.
|
||
|
|
*
|
||
|
|
* \pre The input ranges shall not overlap either output range.
|
||
|
|
*
|
||
|
|
* The following code snippet demonstrates how to use \p reduce_by_key to
|
||
|
|
* compact a sequence of key/value pairs and sum values with equal keys.
|
||
|
|
*
|
||
|
|
* \code
|
||
|
|
* #include <thrust/reduce.h>
|
||
|
|
* ...
|
||
|
|
* const int N = 7;
|
||
|
|
* int A[N] = {1, 3, 3, 3, 2, 2, 1}; // input keys
|
||
|
|
* int B[N] = {9, 8, 7, 6, 5, 4, 3}; // input values
|
||
|
|
* int C[N]; // output keys
|
||
|
|
* int D[N]; // output values
|
||
|
|
*
|
||
|
|
* thrust::pair<int*,int*> new_end;
|
||
|
|
* thrust::equal_to<int> binary_pred;
|
||
|
|
* new_end = thrust::reduce_by_key(A, A + N, B, C, D, binary_pred);
|
||
|
|
*
|
||
|
|
* // The first four keys in C are now {1, 3, 2, 1} and new_end.first - C is 4.
|
||
|
|
* // The first four values in D are now {9, 21, 9, 3} and new_end.second - D is 4.
|
||
|
|
* \endcode
|
||
|
|
*
|
||
|
|
* \see reduce
|
||
|
|
* \see unique_copy
|
||
|
|
* \see unique_by_key
|
||
|
|
* \see unique_by_key_copy
|
||
|
|
*/
|
||
|
|
template <typename InputIterator1,
|
||
|
|
typename InputIterator2,
|
||
|
|
typename OutputIterator1,
|
||
|
|
typename OutputIterator2,
|
||
|
|
typename BinaryPredicate>
|
||
|
|
thrust::pair<OutputIterator1,OutputIterator2>
|
||
|
|
reduce_by_key(InputIterator1 keys_first,
|
||
|
|
InputIterator1 keys_last,
|
||
|
|
InputIterator2 values_first,
|
||
|
|
OutputIterator1 keys_output,
|
||
|
|
OutputIterator2 values_output,
|
||
|
|
BinaryPredicate binary_pred);
|
||
|
|
|
||
|
|
|
||
|
|
/*! \p reduce_by_key is a generalization of \p reduce to key-value pairs.
|
||
|
|
* For each group of consecutive keys in the range <tt>[keys_first, keys_last)</tt>
|
||
|
|
* that are equal, \p reduce_by_key copies the first element of the group to the
|
||
|
|
* \c keys_output. The corresponding values in the range are reduced using the
|
||
|
|
* \c BinaryFunction \c binary_op and the result copied to \c values_output.
|
||
|
|
* Specifically, if consecutive key iterators \c i and \c (i + 1) are
|
||
|
|
* such that <tt>binary_pred(*i, *(i+1))</tt> is \c true, then the corresponding
|
||
|
|
* values are reduced to a single value with \c binary_op.
|
||
|
|
*
|
||
|
|
* This version of \p reduce_by_key uses the function object \c binary_pred
|
||
|
|
* to test for equality and \c binary_op to reduce values with equal keys.
|
||
|
|
*
|
||
|
|
* The algorithm's execution is parallelized as determined by \p exec.
|
||
|
|
*
|
||
|
|
* \param exec The execution policy to use for parallelization.
|
||
|
|
* \param keys_first The beginning of the input key range.
|
||
|
|
* \param keys_last The end of the input key range.
|
||
|
|
* \param values_first The beginning of the input value range.
|
||
|
|
* \param keys_output The beginning of the output key range.
|
||
|
|
* \param values_output The beginning of the output value range.
|
||
|
|
* \param binary_pred The binary predicate used to determine equality.
|
||
|
|
* \param binary_op The binary function used to accumulate values.
|
||
|
|
* \return A pair of iterators at end of the ranges <tt>[keys_output, keys_output_last)</tt> and <tt>[values_output, values_output_last)</tt>.
|
||
|
|
*
|
||
|
|
* \tparam DerivedPolicy The name of the derived execution policy.
|
||
|
|
* \tparam InputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam InputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam OutputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator1's \c value_type is convertible to \c OutputIterator1's \c value_type.
|
||
|
|
* \tparam OutputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator2's \c value_type is convertible to \c OutputIterator2's \c value_type.
|
||
|
|
* \tparam BinaryPredicate is a model of <a href="http://www.sgi.com/tech/stl/BinaryPredicate.html">Binary Predicate</a>.
|
||
|
|
* \tparam BinaryFunction is a model of <a href="http://www.sgi.com/tech/stl/BinaryFunction.html">Binary Function</a>
|
||
|
|
* and \c BinaryFunction's \c result_type is convertible to \c OutputIterator2's \c value_type.
|
||
|
|
*
|
||
|
|
* \pre The input ranges shall not overlap either output range.
|
||
|
|
*
|
||
|
|
* The following code snippet demonstrates how to use \p reduce_by_key to
|
||
|
|
* compact a sequence of key/value pairs and sum values with equal keys using the \p thrust::host
|
||
|
|
* execution policy for parallelization:
|
||
|
|
*
|
||
|
|
* \code
|
||
|
|
* #include <thrust/reduce.h>
|
||
|
|
* #include <thrust/execution_policy.h>
|
||
|
|
* ...
|
||
|
|
* const int N = 7;
|
||
|
|
* int A[N] = {1, 3, 3, 3, 2, 2, 1}; // input keys
|
||
|
|
* int B[N] = {9, 8, 7, 6, 5, 4, 3}; // input values
|
||
|
|
* int C[N]; // output keys
|
||
|
|
* int D[N]; // output values
|
||
|
|
*
|
||
|
|
* thrust::pair<int*,int*> new_end;
|
||
|
|
* thrust::equal_to<int> binary_pred;
|
||
|
|
* thrust::plus<int> binary_op;
|
||
|
|
* new_end = thrust::reduce_by_key(thrust::host, A, A + N, B, C, D, binary_pred, binary_op);
|
||
|
|
*
|
||
|
|
* // The first four keys in C are now {1, 3, 2, 1} and new_end.first - C is 4.
|
||
|
|
* // The first four values in D are now {9, 21, 9, 3} and new_end.second - D is 4.
|
||
|
|
* \endcode
|
||
|
|
*
|
||
|
|
* \see reduce
|
||
|
|
* \see unique_copy
|
||
|
|
* \see unique_by_key
|
||
|
|
* \see unique_by_key_copy
|
||
|
|
*/
|
||
|
|
template<typename DerivedPolicy,
|
||
|
|
typename InputIterator1,
|
||
|
|
typename InputIterator2,
|
||
|
|
typename OutputIterator1,
|
||
|
|
typename OutputIterator2,
|
||
|
|
typename BinaryPredicate,
|
||
|
|
typename BinaryFunction>
|
||
|
|
thrust::pair<OutputIterator1,OutputIterator2>
|
||
|
|
reduce_by_key(const thrust::detail::execution_policy_base<DerivedPolicy> &exec,
|
||
|
|
InputIterator1 keys_first,
|
||
|
|
InputIterator1 keys_last,
|
||
|
|
InputIterator2 values_first,
|
||
|
|
OutputIterator1 keys_output,
|
||
|
|
OutputIterator2 values_output,
|
||
|
|
BinaryPredicate binary_pred,
|
||
|
|
BinaryFunction binary_op);
|
||
|
|
|
||
|
|
|
||
|
|
/*! \p reduce_by_key is a generalization of \p reduce to key-value pairs.
|
||
|
|
* For each group of consecutive keys in the range <tt>[keys_first, keys_last)</tt>
|
||
|
|
* that are equal, \p reduce_by_key copies the first element of the group to the
|
||
|
|
* \c keys_output. The corresponding values in the range are reduced using the
|
||
|
|
* \c BinaryFunction \c binary_op and the result copied to \c values_output.
|
||
|
|
* Specifically, if consecutive key iterators \c i and \c (i + 1) are
|
||
|
|
* such that <tt>binary_pred(*i, *(i+1))</tt> is \c true, then the corresponding
|
||
|
|
* values are reduced to a single value with \c binary_op.
|
||
|
|
*
|
||
|
|
* This version of \p reduce_by_key uses the function object \c binary_pred
|
||
|
|
* to test for equality and \c binary_op to reduce values with equal keys.
|
||
|
|
*
|
||
|
|
* \param keys_first The beginning of the input key range.
|
||
|
|
* \param keys_last The end of the input key range.
|
||
|
|
* \param values_first The beginning of the input value range.
|
||
|
|
* \param keys_output The beginning of the output key range.
|
||
|
|
* \param values_output The beginning of the output value range.
|
||
|
|
* \param binary_pred The binary predicate used to determine equality.
|
||
|
|
* \param binary_op The binary function used to accumulate values.
|
||
|
|
* \return A pair of iterators at end of the ranges <tt>[keys_output, keys_output_last)</tt> and <tt>[values_output, values_output_last)</tt>.
|
||
|
|
*
|
||
|
|
* \tparam InputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam InputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
|
||
|
|
* \tparam OutputIterator1 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator1's \c value_type is convertible to \c OutputIterator1's \c value_type.
|
||
|
|
* \tparam OutputIterator2 is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a> and
|
||
|
|
* and \p InputIterator2's \c value_type is convertible to \c OutputIterator2's \c value_type.
|
||
|
|
* \tparam BinaryPredicate is a model of <a href="http://www.sgi.com/tech/stl/BinaryPredicate.html">Binary Predicate</a>.
|
||
|
|
* \tparam BinaryFunction is a model of <a href="http://www.sgi.com/tech/stl/BinaryFunction.html">Binary Function</a>
|
||
|
|
* and \c BinaryFunction's \c result_type is convertible to \c OutputIterator2's \c value_type.
|
||
|
|
*
|
||
|
|
* \pre The input ranges shall not overlap either output range.
|
||
|
|
*
|
||
|
|
* The following code snippet demonstrates how to use \p reduce_by_key to
|
||
|
|
* compact a sequence of key/value pairs and sum values with equal keys.
|
||
|
|
*
|
||
|
|
* \code
|
||
|
|
* #include <thrust/reduce.h>
|
||
|
|
* ...
|
||
|
|
* const int N = 7;
|
||
|
|
* int A[N] = {1, 3, 3, 3, 2, 2, 1}; // input keys
|
||
|
|
* int B[N] = {9, 8, 7, 6, 5, 4, 3}; // input values
|
||
|
|
* int C[N]; // output keys
|
||
|
|
* int D[N]; // output values
|
||
|
|
*
|
||
|
|
* thrust::pair<int*,int*> new_end;
|
||
|
|
* thrust::equal_to<int> binary_pred;
|
||
|
|
* thrust::plus<int> binary_op;
|
||
|
|
* new_end = thrust::reduce_by_key(A, A + N, B, C, D, binary_pred, binary_op);
|
||
|
|
*
|
||
|
|
* // The first four keys in C are now {1, 3, 2, 1} and new_end.first - C is 4.
|
||
|
|
* // The first four values in D are now {9, 21, 9, 3} and new_end.second - D is 4.
|
||
|
|
* \endcode
|
||
|
|
*
|
||
|
|
* \see reduce
|
||
|
|
* \see unique_copy
|
||
|
|
* \see unique_by_key
|
||
|
|
* \see unique_by_key_copy
|
||
|
|
*/
|
||
|
|
template <typename InputIterator1,
|
||
|
|
typename InputIterator2,
|
||
|
|
typename OutputIterator1,
|
||
|
|
typename OutputIterator2,
|
||
|
|
typename BinaryPredicate,
|
||
|
|
typename BinaryFunction>
|
||
|
|
thrust::pair<OutputIterator1,OutputIterator2>
|
||
|
|
reduce_by_key(InputIterator1 keys_first,
|
||
|
|
InputIterator1 keys_last,
|
||
|
|
InputIterator2 values_first,
|
||
|
|
OutputIterator1 keys_output,
|
||
|
|
OutputIterator2 values_output,
|
||
|
|
BinaryPredicate binary_pred,
|
||
|
|
BinaryFunction binary_op);
|
||
|
|
|
||
|
|
|
||
|
|
/*! \} // end reductions
|
||
|
|
*/
|
||
|
|
|
||
|
|
|
||
|
|
} // end namespace thrust
|
||
|
|
|
||
|
|
#include <thrust/detail/reduce.inl>
|
||
|
|
|