1 | #ifndef theplu_yat_statistics_euclidean_distance_h |
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2 | #define theplu_yat_statistics_euclidean_distance_h |
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3 | |
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4 | // $Id: EuclideanDistance.h 1115 2008-02-21 19:20:59Z markus $ |
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5 | |
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6 | /* |
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7 | Copyright (C) 2007 Peter Johansson, Markus Ringnér |
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8 | Copyright (C) 2008 Peter Johansson |
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9 | |
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10 | This file is part of the yat library, http://trac.thep.lu.se/yat |
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11 | |
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12 | The yat library is free software; you can redistribute it and/or |
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13 | modify it under the terms of the GNU General Public License as |
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14 | published by the Free Software Foundation; either version 2 of the |
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15 | License, or (at your option) any later version. |
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16 | |
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17 | The yat library is distributed in the hope that it will be useful, |
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18 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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19 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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20 | General Public License for more details. |
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21 | |
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22 | You should have received a copy of the GNU General Public License |
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23 | along with this program; if not, write to the Free Software |
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24 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA |
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25 | 02111-1307, USA. |
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26 | */ |
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27 | |
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28 | #include "AveragerPair.h" |
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29 | #include "AveragerPairWeighted.h" |
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30 | #include "yat/utility/iterator_traits.h" |
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31 | |
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32 | #include <cmath> |
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33 | |
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34 | namespace theplu { |
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35 | namespace yat { |
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36 | namespace statistics { |
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37 | |
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38 | /// |
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39 | /// @brief Calculates the Euclidean distance between two points |
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40 | /// given by elements of ranges. |
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41 | /// |
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42 | /// This class is modelling the concept \ref concept_distance. |
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43 | /// |
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44 | /// |
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45 | struct EuclideanDistance |
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46 | { |
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47 | /** |
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48 | \brief Calculates the Euclidean distance between elements of |
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49 | two ranges. |
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50 | |
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51 | If elements of both ranges are unweighted the distance is |
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52 | calculated as \f$ \sqrt{\sum (x_i-y_i)^2 } \f$, where \f$ x_i |
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53 | \f$ and \f$ y_i \f$ are elements of the first and second range, |
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54 | respectively. |
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55 | |
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56 | If elements of one or both of ranges have weights the distance |
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57 | is calculated as \f$ \sqrt{N \sum |
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58 | w_{x,i}w_{y,i}(x_i-y_i)^2/\sum w_{x,i}w_{y,i}} \f$, where \f$ N |
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59 | \f$ is the number of elements in the two ranges and \f$ w_x \f$ |
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60 | and \f$ w_y \f$ are weights for the elements of the first and |
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61 | the second range, respectively. If the elements of one of the |
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62 | two ranges are unweighted, the weights for these elements are |
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63 | set to unity. |
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64 | */ |
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65 | template <typename Iter1, typename Iter2> |
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66 | double operator() |
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67 | (Iter1 beg1,Iter1 end1, Iter2 beg2) const |
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68 | { |
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69 | return this->distance(beg1, end1, beg2, |
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70 | typename utility::weighted_if_any2<Iter1,Iter2>::type()); |
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71 | } |
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72 | |
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73 | private: |
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74 | template <typename Iter1, typename Iter2> |
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75 | double distance (Iter1 beg1,Iter1 end1, Iter2 beg2, |
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76 | utility::unweighted_iterator_tag) const |
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77 | { |
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78 | AveragerPair ap; |
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79 | add(ap,beg1,end1,beg2); |
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80 | return sqrt(ap.sum_squared_deviation()); |
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81 | } |
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82 | |
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83 | template <typename Iter1, typename Iter2> |
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84 | double distance (Iter1 beg1,Iter1 end1, Iter2 beg2, |
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85 | utility::weighted_iterator_tag) const |
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86 | { |
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87 | AveragerPairWeighted ap; |
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88 | add(ap,beg1,end1,beg2); |
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89 | return sqrt(std::distance(beg1,end1)*ap.msd()); |
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90 | } |
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91 | |
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92 | }; |
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93 | |
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94 | }}} // of namespace statistics, yat, and theplu |
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95 | |
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96 | #endif |
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