Mercurial > octave
annotate scripts/statistics/base/mean.m @ 10687:a8ce6bdecce5
Improve documentation strings.
| author | Rik <octave@nomad.inbox5.com> |
|---|---|
| date | Tue, 08 Jun 2010 20:22:38 -0700 |
| parents | f0c3d3fc4903 |
| children | 693e22af08ae |
| rev | line source |
|---|---|
| 7017 | 1 ## Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2005, |
| 8920 | 2 ## 2006, 2007, 2008, 2009 Kurt Hornik |
| 3426 | 3 ## |
| 3922 | 4 ## This file is part of Octave. |
| 5 ## | |
| 6 ## Octave is free software; you can redistribute it and/or modify it | |
| 7 ## under the terms of the GNU General Public License as published by | |
| 7016 | 8 ## the Free Software Foundation; either version 3 of the License, or (at |
| 9 ## your option) any later version. | |
| 3426 | 10 ## |
| 3922 | 11 ## Octave is distributed in the hope that it will be useful, but |
| 3200 | 12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 3426 | 14 ## General Public License for more details. |
| 15 ## | |
| 3200 | 16 ## You should have received a copy of the GNU General Public License |
| 7016 | 17 ## along with Octave; see the file COPYING. If not, see |
| 18 ## <http://www.gnu.org/licenses/>. | |
| 3200 | 19 |
| 3367 | 20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} mean (@var{x}) |
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a8ce6bdecce5
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Rik <octave@nomad.inbox5.com>
parents:
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22 ## @deftypefnx {Function File} {} mean (@var{x}, @var{dim}) |
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a8ce6bdecce5
Improve documentation strings.
Rik <octave@nomad.inbox5.com>
parents:
9211
diff
changeset
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23 ## @deftypefnx {Function File} {} mean (@var{x}, @var{opt}) |
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a8ce6bdecce5
Improve documentation strings.
Rik <octave@nomad.inbox5.com>
parents:
9211
diff
changeset
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24 ## @deftypefnx {Function File} {} mean (@var{x}, @var{dim}, @var{opt}) |
| 3367 | 25 ## If @var{x} is a vector, compute the mean of the elements of @var{x} |
| 26 ## @tex | |
| 27 ## $$ {\rm mean}(x) = \bar{x} = {1\over N} \sum_{i=1}^N x_i $$ | |
| 28 ## @end tex | |
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29 ## @ifnottex |
| 3426 | 30 ## |
| 3367 | 31 ## @example |
| 32 ## mean (x) = SUM_i x(i) / N | |
| 33 ## @end example | |
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34 ## @end ifnottex |
| 3367 | 35 ## If @var{x} is a matrix, compute the mean for each column and return them |
| 36 ## in a row vector. | |
| 3200 | 37 ## |
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Rik <octave@nomad.inbox5.com>
parents:
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38 ## The optional argument @var{opt} selects the type of mean to compute. |
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Rik <octave@nomad.inbox5.com>
parents:
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39 ## The following options are recognized: |
| 3367 | 40 ## |
| 41 ## @table @code | |
| 42 ## @item "a" | |
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Rik <octave@nomad.inbox5.com>
parents:
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diff
changeset
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43 ## Compute the (ordinary) arithmetic mean. [default] |
| 3367 | 44 ## |
| 45 ## @item "g" | |
| 7001 | 46 ## Compute the geometric mean. |
| 3367 | 47 ## |
| 48 ## @item "h" | |
| 49 ## Compute the harmonic mean. | |
| 50 ## @end table | |
| 4022 | 51 ## |
| 52 ## If the optional argument @var{dim} is supplied, work along dimension | |
| 53 ## @var{dim}. | |
| 54 ## | |
| 55 ## Both @var{dim} and @var{opt} are optional. If both are supplied, | |
| 56 ## either may appear first. | |
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57 ## @seealso{median,mode} |
| 3367 | 58 ## @end deftypefn |
| 3426 | 59 |
| 5428 | 60 ## Author: KH <Kurt.Hornik@wu-wien.ac.at> |
| 3456 | 61 ## Description: Compute arithmetic, geometric, and harmonic mean |
| 3200 | 62 |
| 4022 | 63 function y = mean (x, opt1, opt2) |
| 64 | |
| 65 need_dim = 0; | |
| 3200 | 66 |
| 4022 | 67 if (nargin == 1) |
| 68 opt = "a"; | |
| 69 need_dim = 1; | |
| 70 elseif (nargin == 2) | |
| 5443 | 71 if (ischar (opt1)) |
| 4022 | 72 opt = opt1; |
| 73 need_dim = 1; | |
| 74 else | |
| 4525 | 75 dim = opt1; |
| 4022 | 76 opt = "a"; |
| 77 endif | |
| 78 elseif (nargin == 3) | |
| 5443 | 79 if (ischar (opt1)) |
| 4022 | 80 opt = opt1; |
| 81 dim = opt2; | |
| 5443 | 82 elseif (ischar (opt2)) |
| 4022 | 83 opt = opt2; |
| 84 dim = opt1; | |
| 85 else | |
| 6046 | 86 error ("mean: expecting opt to be a string"); |
| 4022 | 87 endif |
| 88 else | |
| 6046 | 89 print_usage (); |
| 3200 | 90 endif |
| 3426 | 91 |
| 4022 | 92 if (need_dim) |
| 93 t = find (size (x) != 1); | |
| 94 if (isempty (t)) | |
| 95 dim = 1; | |
| 96 else | |
| 97 dim = t(1); | |
| 98 endif | |
| 3200 | 99 endif |
| 100 | |
| 5243 | 101 if (dim > ndims (x)) |
| 102 n = 1; | |
| 103 else | |
| 104 sz = size (x); | |
| 105 n = sz (dim); | |
| 106 endif | |
| 3426 | 107 |
| 3200 | 108 if (strcmp (opt, "a")) |
| 4022 | 109 y = sum (x, dim) / n; |
| 3200 | 110 elseif (strcmp (opt, "g")) |
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111 y = prod (x, dim) .^ (1/n); |
| 3200 | 112 elseif (strcmp (opt, "h")) |
| 4022 | 113 y = n ./ sum (1 ./ x, dim); |
| 3200 | 114 else |
| 3456 | 115 error ("mean: option `%s' not recognized", opt); |
| 3200 | 116 endif |
| 3426 | 117 |
| 3200 | 118 endfunction |
| 7411 | 119 |
| 120 %!test | |
| 121 %! x = -10:10; | |
| 122 %! y = x'; | |
| 123 %! z = [y, y+10]; | |
| 124 %! assert(mean (x) == 0 && mean (y) == 0 && mean (z) == [0, 10]); | |
| 125 | |
| 126 %!error mean (); | |
| 127 | |
| 128 %!error mean (1, 2, 3); | |
| 129 |