Mercurial > octave
view scripts/statistics/mean.m @ 28945:6e460773bdda
maint: Use newlines after "function" and before "endfunction" for clarity.
* quad2d.m, rng.m, __ok_cancel_dlg__.m, __unimplemented__.m,
get_first_help_sentence.m, imformats.m, vectorize.m, ordeig.m, inputParser.m,
tar_is_bsd.m, publish.m, axis.m, legend.m, polar.m, __plt__.m, print.m,
__add_default_menu__.m, __gnuplot_draw_axes__.m, struct2hdl.m, movfun.m,
gmres.m, pcg.m, __alltohandles__.m, tfqmr.m, betaincinv.m, gammainc.m,
gammaincinv.m, mean.m, weboptions.m:
Use newlines after "function" and before "endfunction" for clarity.
author | Rik <rik@octave.org> |
---|---|
date | Fri, 16 Oct 2020 09:27:56 -0700 |
parents | 9e43deb9bfc3 |
children | 54509b7fddd3 |
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######################################################################## ## ## Copyright (C) 1995-2020 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## This file is part of Octave. ## ## Octave is free software: you can redistribute it and/or modify it ## under the terms of the GNU General Public License as published by ## the Free Software Foundation, either version 3 of the License, or ## (at your option) any later version. ## ## Octave is distributed in the hope that it will be useful, but ## WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ## GNU General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with Octave; see the file COPYING. If not, see ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {} mean (@var{x}) ## @deftypefnx {} {} mean (@var{x}, @var{dim}) ## @deftypefnx {} {} mean (@var{x}, @var{opt}) ## @deftypefnx {} {} mean (@var{x}, @var{dim}, @var{opt}) ## @deftypefnx {} {} mean (@dots{}, @var{outtype}) ## Compute the mean of the elements of the vector @var{x}. ## ## The mean is defined as ## ## @tex ## $$ {\rm mean}(x) = \bar{x} = {1\over N} \sum_{i=1}^N x_i $$ ## where $N$ is the number of elements of @var{x}. ## ## @end tex ## @ifnottex ## ## @example ## mean (@var{x}) = SUM_i @var{x}(i) / N ## @end example ## ## @noindent ## where @math{N} is the length of the @var{x} vector. ## ## @end ifnottex ## If @var{x} is a matrix, compute the mean for each column and return them ## in a row vector. ## ## If the optional argument @var{dim} is given, operate along this dimension. ## ## The optional argument @var{opt} selects the type of mean to compute. ## The following options are recognized: ## ## @table @asis ## @item @qcode{"a"} ## Compute the (ordinary) arithmetic mean. [default] ## ## @item @qcode{"g"} ## Compute the geometric mean. ## ## @item @qcode{"h"} ## Compute the harmonic mean. ## @end table ## ## The optional argument @var{outtype} selects the data type of the ## output value. The following options are recognized: ## ## @table @asis ## @item @qcode{"default"} ## Output will be of class double unless @var{x} is of class single, ## in which case the output will also be single. ## ## @item @qcode{"double"} ## Output will be of class double. ## ## @item @qcode{"native"} ## Output will be the same class as @var{x} unless @var{x} is of class ## logical in which case it returns of class double. ## ## @end table ## ## Both @var{dim} and @var{opt} are optional. If both are supplied, either ## may appear first. ## @seealso{median, mode} ## @end deftypefn function y = mean (x, varargin) if (nargin < 1 || nargin > 4) print_usage (); endif if (! (isnumeric (x) || islogical (x))) error ("mean: X must be a numeric vector or matrix"); endif nd = ndims (x); sz = size (x); ## We support too many options... ## If OUTTYPE is set, it must be the last option. If DIM and ## MEAN_TYPE exist, they must be the first two options out_type = "default"; if (numel (varargin)) maybe_out_type = tolower (varargin{end}); if (any (strcmpi (maybe_out_type, {"default", "double", "native"}))) out_type = maybe_out_type; varargin(end) = []; endif endif scalars = cellfun (@isscalar, varargin); chars = cellfun (@ischar, varargin); numerics = cellfun (@isnumeric, varargin); dim_mask = numerics & scalars; mean_type_mask = chars & scalars; if (! all (dim_mask | mean_type_mask)) print_usage (); endif switch (nnz (dim_mask)) case 0 # Find the first non-singleton dimension (dim = find (sz > 1, 1)) || (dim = 1); case 1 dim = varargin{dim_mask}; if (dim != fix (dim) || dim < 1) error ("mean: DIM must be an integer and a valid dimension"); endif otherwise print_usage (); endswitch switch (nnz (mean_type_mask)) case 0 mean_type = "a"; case 1 mean_type = varargin{mean_type_mask}; otherwise print_usage (); endswitch ## The actual mean computation n = size (x, dim); switch (mean_type) case "a" y = sum (x, dim) / n; case "g" if (all (x(:) >= 0)) y = exp (sum (log (x), dim) ./ n); else error ("mean: X must not contain any negative values"); endif case "h" y = n ./ sum (1 ./ x, dim); otherwise error ("mean: mean type '%s' not recognized", mean_type); endswitch ## Convert output as requested switch (out_type) case "default" ## do nothing, the operators already do the right thing case "double" y = double (y); case "native" if (islogical (x)) ## ignore it, return double anyway else y = cast (y, class (x)); endif otherwise ## this should have been filtered out during input check, but... error ("mean: OUTTYPE '%s' not recognized", out_type); endswitch endfunction %!test %! x = -10:10; %! y = x'; %! z = [y, y+10]; %! assert (mean (x), 0); %! assert (mean (y), 0); %! assert (mean (z), [0, 10]); ## Test small numbers %!assert (mean (repmat (0.1,1,1000), "g"), 0.1, 20*eps) %!assert (mean (magic (3), 1), [5, 5, 5]) %!assert (mean (magic (3), 2), [5; 5; 5]) %!assert (mean ([2 8], "g"), 4) %!assert (mean ([4 4 2], "h"), 3) %!assert (mean (logical ([1 0 1 1])), 0.75) %!assert (mean (single ([1 0 1 1])), single (0.75)) %!assert (mean ([1 2], 3), [1 2]) ## Test input validation %!error <Invalid call to mean. Correct usage is> mean () %!error <Invalid call to mean. Correct usage is> mean (1, 2, 3, 4) %!error <X must be a numeric> mean ({1:5}) %!error <Invalid call to mean. Correct usage is> mean (1, 2, 3) %!error <Invalid call to mean. Correct usage is> mean (1, ones (2,2)) %!error <DIM must be an integer> mean (1, 1.5) %!error <DIM must be .* a valid dimension> mean (1, 0) %!error <X must not contain any negative values> mean ([1 -1], "g") %!error <mean type 'b' not recognized> mean (1, "b") %!error <Invalid call to mean. Correct usage is> mean (1, 1, "foo") ## Test outtype option %!test %! in = [1 2 3]; %! out = 2; %! assert (mean (in, "default"), mean (in)); %! assert (mean (in, "default"), out); %! %! in = single ([1 2 3]); %! out = 2; %! assert (mean (in, "default"), mean (in)); %! assert (mean (in, "default"), single (out)); %! assert (mean (in, "double"), out); %! assert (mean (in, "native"), single (out)); %! %! in = uint8 ([1 2 3]); %! out = 2; %! assert (mean (in, "default"), mean (in)); %! assert (mean (in, "default"), out); %! assert (mean (in, "double"), out); %! assert (mean (in, "native"), uint8 (out)); %! %! in = logical ([1 0 1]); %! out = 2/3; %! assert (mean (in, "default"), mean (in)); %! assert (mean (in, "default"), out); %! assert (mean (in, "native"), out); # logical ignores native option