1 | #ifndef _theplu_yat_utility_sort_index_ |
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2 | #define _theplu_yat_utility_sort_index_ |
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3 | |
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4 | // $Id: sort_index.h 3237 2014-05-24 05:49:24Z peter $ |
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5 | |
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6 | /* |
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7 | Copyright (C) 2008, 2010, 2014 Peter Johansson |
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8 | |
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9 | This file is part of the yat library, http://dev.thep.lu.se/yat |
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10 | |
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11 | The yat library is free software; you can redistribute it and/or |
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12 | modify it under the terms of the GNU General Public License as |
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13 | published by the Free Software Foundation; either version 3 of the |
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14 | License, or (at your option) any later version. |
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15 | |
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16 | The yat library is distributed in the hope that it will be useful, |
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17 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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19 | General Public License for more details. |
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20 | |
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21 | You should have received a copy of the GNU General Public License |
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22 | along with yat. If not, see <http://www.gnu.org/licenses/>. |
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23 | */ |
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24 | |
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25 | #include <boost/concept_check.hpp> |
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26 | |
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27 | #include <algorithm> |
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28 | #include <functional> |
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29 | #include <iterator> |
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30 | #include <vector> |
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31 | |
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32 | namespace theplu { |
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33 | namespace yat { |
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34 | namespace utility { |
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35 | |
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36 | /** |
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37 | Create a vector \a sort_index containing the indeces of elements |
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38 | in a range [first, last). The elements of \a sort_index give the |
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39 | index of the range element which would have been stored in that |
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40 | position if the range had been sorted in place. The first element |
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41 | of \a sort_index gives the index of the least element in the |
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42 | range, and the last element of \a sort_index gives the index of |
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43 | the greatest element in the range. The function will not affect |
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44 | the range, i.e., ForwardIterator can be read-only. |
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45 | |
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46 | Type Requirements: |
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47 | - \c InputIterator is a model of \input_iterator |
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48 | - \c InputIterator::value_type is |
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49 | <a href=http://www.sgi.com/tech/stl/LessThanComparable.html> |
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50 | LessThan Comparable</a> |
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51 | |
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52 | \since New in yat 0.5. In versions prior 0.13 function was restricted to |
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53 | \forward_iterator and \c value_type of \c double. |
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54 | */ |
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55 | template<typename InputIterator> |
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56 | void sort_index(InputIterator first, InputIterator last, |
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57 | std::vector<size_t>& sort_index); |
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58 | |
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59 | /** |
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60 | Same as sort_index(InputIterator, InputIterator,std::vector<size_t>&), |
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61 | but objects are compared with \c comp rather than with \c operator<. |
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62 | |
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63 | Type Requirements: |
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64 | - \c InputIterator is a model of \input_iterator |
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65 | - \c Compare is a model of |
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66 | <a href="http://www.sgi.com/tech/stl/StrictWeakOrdering.html"> |
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67 | Strict Weak Ordering</a> |
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68 | - \c InputIterator::value_type is convertible to \c Compare's |
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69 | argument type |
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70 | |
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71 | \since New in yat 0.13 |
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72 | */ |
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73 | template<typename InputIterator, class Compare> |
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74 | void sort_index(InputIterator first, InputIterator last, |
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75 | std::vector<size_t>& sort_index, Compare comp); |
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76 | |
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77 | |
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78 | /// \cond IGNORE_DOXYGEN |
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79 | |
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80 | // private stuff |
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81 | namespace detail { |
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82 | |
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83 | template<typename InputIterator, class Compare> |
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84 | void sort_index(InputIterator first, InputIterator last, |
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85 | std::vector<size_t>& idx, Compare comp, |
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86 | std::input_iterator_tag); |
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87 | |
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88 | // Specialization for random access iterator |
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89 | template<typename RandomAccessIterator, class Compare> |
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90 | void sort_index(RandomAccessIterator first, RandomAccessIterator last, |
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91 | std::vector<size_t>& idx, Compare comp, |
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92 | std::random_access_iterator_tag); |
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93 | |
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94 | |
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95 | template<typename RandomAccessIterator, class Compare> |
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96 | class sort_index_Compare |
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97 | { |
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98 | public: |
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99 | sort_index_Compare(RandomAccessIterator it, Compare comp) |
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100 | : data_(it), compare_(comp) {} |
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101 | |
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102 | bool operator()(size_t i, size_t j) const |
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103 | { return compare_(data_[i], data_[j]); } |
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104 | |
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105 | private: |
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106 | RandomAccessIterator data_; |
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107 | Compare compare_; |
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108 | }; |
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109 | |
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110 | } // end of namespace detail |
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111 | |
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112 | /// \endcond |
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113 | |
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114 | |
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115 | ////////////// template implementation /////////////////////////// |
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116 | |
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117 | template<typename InputIterator> |
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118 | void sort_index(InputIterator first, InputIterator last, |
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119 | std::vector<size_t>& idx) |
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120 | { |
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121 | BOOST_CONCEPT_ASSERT((boost::InputIterator<InputIterator>)); |
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122 | typedef typename std::iterator_traits<InputIterator>::value_type T; |
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123 | BOOST_CONCEPT_ASSERT((boost::LessThanComparable<T>)); |
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124 | sort_index(first, last, idx, std::less<T>()); |
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125 | } |
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126 | |
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127 | |
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128 | template<typename InputIterator, class Compare> |
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129 | void sort_index(InputIterator first, InputIterator last, |
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130 | std::vector<size_t>& idx, Compare comp) |
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131 | { |
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132 | BOOST_CONCEPT_ASSERT((boost::InputIterator<InputIterator>)); |
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133 | |
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134 | typedef typename std::iterator_traits<InputIterator> traits; |
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135 | typedef typename traits::iterator_category category; |
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136 | detail::sort_index(first, last, idx, comp, category()); |
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137 | } |
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138 | |
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139 | |
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140 | // implementation of private functions |
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141 | namespace detail { |
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142 | |
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143 | // general implementation. copy range to a std::vector and call |
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144 | // random access version. |
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145 | template<typename InputIterator, class Compare> |
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146 | void sort_index(InputIterator first, InputIterator last, |
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147 | std::vector<size_t>& idx, Compare comp, |
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148 | std::input_iterator_tag tag) |
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149 | { |
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150 | typedef typename std::iterator_traits<InputIterator>::value_type T; |
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151 | std::vector<T> vec(first, last); |
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152 | sort_index(vec.begin(), vec.end(), idx, comp, |
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153 | std::random_access_iterator_tag()); |
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154 | } |
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155 | |
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156 | // Specialization for random access iterator |
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157 | template<typename RandomAccessIterator, class Compare> |
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158 | void sort_index(RandomAccessIterator first, RandomAccessIterator last, |
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159 | std::vector<size_t>& idx, Compare comp, |
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160 | std::random_access_iterator_tag tag) |
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161 | { |
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162 | sort_index_Compare<RandomAccessIterator, Compare> compare(first, comp); |
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163 | // Peter would like to use boost::iota here, but that is only |
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164 | // available in boost v1.50 and newer, which is too recent at |
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165 | // time of writing. |
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166 | size_t n = last-first; |
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167 | idx.clear(); |
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168 | idx.reserve(n); |
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169 | for (size_t i=0; i<n; ++i) |
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170 | idx.push_back(i); |
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171 | std::sort(idx.begin(), idx.end(), compare); |
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172 | } |
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173 | |
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174 | } // end of namespace detail |
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175 | |
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176 | }}} // of namespace utility, yat, and theplu |
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177 | |
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178 | #endif |
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