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annotate scripts/statistics/base/mahalanobis.m @ 19867:9fc020886ae9

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maint: Clean up m-files to follow Octave coding conventions. Try to trim long lines to < 80 chars. Use '##' for single line comments. Use '(...)' around tests for if/elseif/switch/while. Abut cell indexing operator '{' next to variable. Abut array indexing operator '(' next to variable. Use space between negation operator '!' and following expression. Use two newlines between endfunction and start of %!test or %!demo code. Remove unnecessary parens grouping between short-circuit operators. Remove stray extra spaces (typos) between variables and assignment operators. Remove stray extra spaces from ends of lines.
author Rik <rik@octave.org>
date Mon, 23 Feb 2015 14:54:39 -0800
parents 4197fc428c7d
children d9341b422488
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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4197fc428c7d maint: Update copyright notices for 2015.
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1 ## Copyright (C) 1996-2015 John W. Eaton
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18
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19 ## -*- texinfo -*-
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20 ## @deftypefn {Function File} {} mahalanobis (@var{x}, @var{y})
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21 ## Return the Mahalanobis' D-square distance between the multivariate
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22 ## samples @var{x} and @var{y}, which must have the same number of
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23 ## components (columns), but may have a different number of observations
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24 ## (rows).
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25 ## @end deftypefn
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27 ## Author: Friedrich Leisch <leisch@ci.tuwien.ac.at>
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28 ## Created: July 1993
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29 ## Adapted-By: jwe
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30
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31 function retval = mahalanobis (x, y)
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33 if (nargin != 2)
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34 print_usage ();
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35 endif
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36
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37 if ( ! (isnumeric (x) || islogical (x))
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38 || ! (isnumeric (y) || islogical (y)))
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39 error ("mahalanobis: X and Y must be numeric matrices or vectors");
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40 endif
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41
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42 if (ndims (x) != 2 || ndims (y) != 2)
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43 error ("mahalanobis: X and Y must be 2-D matrices or vectors");
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44 endif
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45
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46 [xr, xc] = size (x);
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47 [yr, yc] = size (y);
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49 if (xc != yc)
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50 error ("mahalanobis: X and Y must have the same number of columns");
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51 endif
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52
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53 if (isinteger (x))
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54 x = double (x);
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55 endif
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56
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57 xm = mean (x);
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58 ym = mean (y);
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60 ## Center data by subtracting means
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61 x = bsxfun (@minus, x, xm);
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62 y = bsxfun (@minus, y, ym);
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64 w = (x' * x + y' * y) / (xr + yr - 2);
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66 winv = inv (w);
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68 retval = (xm - ym) * winv * (xm - ym)';
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70 endfunction
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73 ## Test input validation
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74 %!error mahalanobis ()
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75 %!error mahalanobis (1, 2, 3)
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76 %!error mahalanobis ('A', 'B')
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77 %!error mahalanobis ([1, 2], ['A', 'B'])
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78 %!error mahalanobis (ones (2,2,2))
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79 %!error mahalanobis (ones (2,2), ones (2,2,2))
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80 %!error mahalanobis (ones (2,2), ones (2,3))
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