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update copyright notices
author John W. Eaton <jwe@octave.org>
date Fri, 14 Jan 2011 05:47:45 -0500
parents e151e23f73bc
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11523
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John W. Eaton <jwe@octave.org>
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1 ## Copyright (C) 1995-2011 Kurt Hornik
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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} {} studentize (@var{x})
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21 ## @deftypefnx {Function File} {} studentize (@var{x}, @var{dim})
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22 ## If @var{x} is a vector, subtract its mean and divide by its standard
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23 ## deviation.
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24 ##
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25 ## If @var{x} is a matrix, do the above along the first non-singleton
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26 ## dimension.
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27 ## If the optional argument @var{dim} is given, operate along this dimension.
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28 ## @seealso{center}
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29 ## @end deftypefn
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30
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31 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
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32 ## Description: Subtract mean and divide by standard deviation
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33
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34 function t = studentize (x, dim)
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35
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36 if (nargin != 1 && nargin != 2)
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37 print_usage ();
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38 endif
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39
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40 if (! isnumeric(x))
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41 error ("studentize: X must be a numeric vector or matrix");
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42 endif
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43
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44 if (isinteger (x))
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45 x = double (x);
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46 endif
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47
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48 nd = ndims (x);
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49 sz = size (x);
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50 if (nargin != 2)
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51 ## Find the first non-singleton dimension.
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52 dim = find (sz > 1, 1);
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53 if (isempty (dim))
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54 dim = 1;
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55 endif
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56 else
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57 if (!(isscalar (dim) && dim == fix (dim))
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58 || !(1 <= dim && dim <= nd))
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59 error ("studentize: DIM must be an integer and a valid dimension");
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60 endif
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61 endif
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62
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63 c = sz(dim);
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64 if (c == 0)
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65 t = x;
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66 else
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67 idx = ones (1, nd);
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68 idx(dim) = c;
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69 t = x - repmat (mean (x, dim), idx);
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70 t = t ./ repmat (max (cat (dim, std(t, [], dim), ! any (t, dim)), [], dim), idx);
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71 endif
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72
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73 endfunction
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74
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75 %!assert(studentize ([1,2,3]), [-1,0,1])
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76 %!assert(studentize (int8 ([1,2,3])), [-1,0,1])
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77 #%!assert(studentize (ones (3,2,0,2)), zeros (3,2,0,2))
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78 %!assert(studentize ([2,0,-2;0,2,0;-2,-2,2]), [1,0,-1;0,1,0;-1,-1,1])
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79
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80 %% Test input validation
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81 %!error studentize ()
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82 %!error studentize (1, 2, 3)
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83 %!error studentize ([true true])
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84 %!error studentize (1, ones(2,2))
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85 %!error studentize (1, 1.5)
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86 %!error studentize (1, 0)
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87 %!error studentize (1, 3)
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88