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imported patch sort3.diff
author Jaroslav Hajek <highegg@gmail.com>
date Wed, 11 Feb 2009 15:25:53 +0100
parents fd11a08a9b31
children 3ef774603887
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1 ## Copyright (C) 2000, 2005, 2007 Daniel Calvelo
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2 ## Copyright (C) 2009 Jaroslav Hajek
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3 ##
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4 ## This file is part of Octave.
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5 ##
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6 ## Octave is free software; you can redistribute it and/or modify it
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7 ## under the terms of the GNU General Public License as published by
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8 ## the Free Software Foundation; either version 3 of the License, or (at
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9 ## your option) any later version.
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10 ##
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11 ## Octave is distributed in the hope that it will be useful, but
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12 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 ## General Public License for more details.
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15 ##
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16 ## You should have received a copy of the GNU General Public License
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17 ## along with Octave; see the file COPYING. If not, see
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18 ## <http://www.gnu.org/licenses/>.
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19
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20 ## -*- texinfo -*-
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21 ## @deftypefn {Function File} {} sortrows (@var{a}, @var{c})
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22 ## Sort the rows of the matrix @var{a} according to the order of the
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23 ## columns specified in @var{c}. If @var{c} is omitted, a
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24 ## lexicographical sort is used. By default ascending order is used
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25 ## however if elements of @var{c} are negative then the corresponding
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26 ## column is sorted in descending order.
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27 ## @end deftypefn
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28
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29 ## Author: Daniel Calvelo, Paul Kienzle
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30 ## Adapted-by: jwe
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31
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32 function [s, i] = sortrows (m, c)
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33
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34 default_mode = "ascend";
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35 other_mode = "descend";
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36
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37 if (issparse (m))
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38 error ("sortrows: sparse matrices not yet supported");
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39 endif
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40
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41 ## If the sort is homogeneous, we use the built-in faster algorithm.
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42 if (nargin == 1)
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43 i = __sortrows_idx__ (m, default_mode);
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44 elseif (all (c > 0))
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45 i = __sortrows_idx__ (m(:,c), default_mode);
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46 elseif (all (c < 0))
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47 i = __sortrows_idx__ (m(:,c), other_mode);
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48 else
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49 ## Otherwise, fall back to the old algorithm
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50 for ii = 1:length (c);
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51 if (c(ii) < 0)
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52 mode{ii} = other_mode;
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53 else
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54 mode{ii} = default_mode;
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55 endif
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56 endfor
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57 indices = abs(c(:));
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58
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59 ## Since sort is 'stable' the order of identical elements will be
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60 ## preserved, so by traversing the sort indices in reverse order we
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61 ## will make sure that identical elements in index i are subsorted by
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62 ## index j.
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63 indices = flipud (indices);
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64 mode = flipud (mode');
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65 i = [1:size(m,1)]';
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66 for ii = 1:length (indices);
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67 [trash, idx] = sort (m(i, indices(ii)), mode{ii});
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68 i = i(idx);
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69 endfor
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70 endif
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71
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72 s = m(i,:);
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73
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74 endfunction
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75
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76 %!shared x, idx
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77 %! [x, idx] = sortrows ([1, 1; 1, 2; 3, 6; 2, 7], [1, -2]);
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78 %!assert (x, [1, 2; 1, 1; 2, 7; 3, 6]);
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79 %!assert (idx, [2; 1; 4; 3]);