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- .. Copyright David Abrahams 2006. 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)
- ::
- using namespace boost;
- int i = 0;
- typedef std::vector< int > element_range_type;
- typedef std::list< int > index_type;
- static const int element_range_size = 10;
- static const int index_size = 4;
- element_range_type elements( element_range_size );
- for(element_range_type::iterator el_it = elements.begin() ; el_it != elements.end() ; ++el_it)
- *el_it = std::distance(elements.begin(), el_it);
- index_type indices( index_size );
- for(index_type::iterator i_it = indices.begin() ; i_it != indices.end() ; ++i_it )
- *i_it = element_range_size - index_size + std::distance(indices.begin(), i_it);
- std::reverse( indices.begin(), indices.end() );
- typedef permutation_iterator< element_range_type::iterator, index_type::iterator > permutation_type;
- permutation_type begin = make_permutation_iterator( elements.begin(), indices.begin() );
- permutation_type it = begin;
- permutation_type end = make_permutation_iterator( elements.begin(), indices.end() );
- std::cout << "The original range is : ";
- std::copy( elements.begin(), elements.end(), std::ostream_iterator< int >( std::cout, " " ) );
- std::cout << "\n";
- std::cout << "The reindexing scheme is : ";
- std::copy( indices.begin(), indices.end(), std::ostream_iterator< int >( std::cout, " " ) );
- std::cout << "\n";
- std::cout << "The permutated range is : ";
- std::copy( begin, end, std::ostream_iterator< int >( std::cout, " " ) );
- std::cout << "\n";
- std::cout << "Elements at even indices in the permutation : ";
- it = begin;
- for(i = 0; i < index_size / 2 ; ++i, it+=2 ) std::cout << *it << " ";
- std::cout << "\n";
- std::cout << "Permutation backwards : ";
- it = begin + (index_size);
- assert( it != begin );
- for( ; it-- != begin ; ) std::cout << *it << " ";
- std::cout << "\n";
- std::cout << "Iterate backward with stride 2 : ";
- it = begin + (index_size - 1);
- for(i = 0 ; i < index_size / 2 ; ++i, it-=2 ) std::cout << *it << " ";
- std::cout << "\n";
- The output is::
- The original range is : 0 1 2 3 4 5 6 7 8 9
- The reindexing scheme is : 9 8 7 6
- The permutated range is : 9 8 7 6
- Elements at even indices in the permutation : 9 7
- Permutation backwards : 6 7 8 9
- Iterate backward with stride 2 : 6 8
- The source code for this example can be found `here`__.
- __ ../example/permutation_iter_example.cpp
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