--- /dev/null
+## Copyright (C) 2007-2012 David Bateman
+##
+## 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
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} mode (@var{x})
+## @deftypefnx {Function File} {} mode (@var{x}, @var{dim})
+## @deftypefnx {Function File} {[@var{m}, @var{f}, @var{c}] =} mode (@dots{})
+## Compute the most frequently occurring value in a dataset (mode).
+## @code{mode} determines the frequency of values along the first non-singleton
+## dimension and returns the value with the highest frequency. If two, or
+## more, values have the same frequency @code{mode} returns the smallest.
+##
+## If the optional argument @var{dim} is given, operate along this dimension.
+##
+## The return variable @var{f} is the number of occurrences of the mode in
+## in the dataset. The cell array @var{c} contains all of the elements
+## with the maximum frequency.
+## @seealso{mean, median}
+## @end deftypefn
+
+function [m, f, c] = mode (x, dim)
+
+ if (nargin < 1 || nargin > 2)
+ print_usage ();
+ endif
+
+ if (! (isnumeric (x) || islogical (x)))
+ error ("mode: X must be a numeric vector or matrix");
+ endif
+
+ nd = ndims (x);
+ sz = size (x);
+ if (nargin < 2)
+ ## Find the first non-singleton dimension.
+ (dim = find (sz > 1, 1)) || (dim = 1);
+ else
+ if (!(isscalar (dim) && dim == fix (dim))
+ || !(1 <= dim && dim <= nd))
+ error ("mode: DIM must be an integer and a valid dimension");
+ endif
+ endif
+
+ sz2 = sz;
+ sz2(dim) = 1;
+ sz3 = ones (1, nd);
+ sz3(dim) = sz(dim);
+
+ if (issparse (x))
+ t2 = sparse (sz(1), sz(2));
+ else
+ t2 = zeros (sz);
+ endif
+
+ if (dim != 1)
+ perm = [dim, 1:dim-1, dim+1:nd];
+ t2 = permute (t2, perm);
+ endif
+
+ xs = sort (x, dim);
+ t = cat (dim, true (sz2), diff (xs, 1, dim) != 0);
+
+ if (dim != 1)
+ t2(permute (t != 0, perm)) = diff ([find(permute (t, perm))(:); prod(sz)+1]);
+ f = max (ipermute (t2, perm), [], dim);
+ xs = permute (xs, perm);
+ else
+ t2(t) = diff ([find(t)(:); prod(sz)+1]);
+ f = max (t2, [], dim);
+ endif
+
+ c = cell (sz2);
+ if (issparse (x))
+ m = sparse (sz2(1), sz2(2));
+ else
+ m = zeros (sz2, class (x));
+ endif
+ for i = 1 : prod (sz2)
+ c{i} = xs(t2(:, i) == f(i), i);
+ m(i) = c{i}(1);
+ endfor
+endfunction
+
+
+%!test
+%! [m, f, c] = mode (toeplitz (1:5));
+%! assert (m, [1,2,2,2,1]);
+%! assert (f, [1,2,2,2,1]);
+%! assert (c, {[1;2;3;4;5],[2],[2;3],[2],[1;2;3;4;5]});
+%!test
+%! [m, f, c] = mode (toeplitz (1:5), 2);
+%! assert (m, [1;2;2;2;1]);
+%! assert (f, [1;2;2;2;1]);
+%! assert (c, {[1;2;3;4;5];[2];[2;3];[2];[1;2;3;4;5]});
+%!test
+%! a = sprandn (32, 32, 0.05);
+%! [m, f, c] = mode (a);
+%! [m2, f2, c2] = mode (full (a));
+%! assert (m, sparse (m2));
+%! assert (f, sparse (f2));
+%! c_exp(1:length(a)) = { sparse (0) };
+%! assert (c ,c_exp);
+%! assert (c2,c_exp );
+
+%!assert(mode ([2,3,1,2,3,4],1),[2,3,1,2,3,4]);
+%!assert(mode ([2,3,1,2,3,4],2),2);
+%!assert(mode ([2,3,1,2,3,4]),2);
+%!assert(mode (single([2,3,1,2,3,4])), single(2));
+%!assert(mode (int8([2,3,1,2,3,4])), int8(2));
+
+%!assert(mode ([2;3;1;2;3;4],1),2);
+%!assert(mode ([2;3;1;2;3;4],2),[2;3;1;2;3;4]);
+%!assert(mode ([2;3;1;2;3;4]),2);
+
+%!shared x
+%! x(:,:,1) = toeplitz (1:3);
+%! x(:,:,2) = circshift (toeplitz (1:3), 1);
+%! x(:,:,3) = circshift (toeplitz (1:3), 2);
+%!test
+%! [m, f, c] = mode (x, 1);
+%! assert (reshape (m, [3, 3]), [1 1 1; 2 2 2; 1 1 1]);
+%! assert (reshape (f, [3, 3]), [1 1 1; 2 2 2; 1 1 1]);
+%! c = reshape (c, [3, 3]);
+%! assert (c{1}, [1; 2; 3]);
+%! assert (c{2}, 2);
+%! assert (c{3}, [1; 2; 3]);
+%!test
+%! [m, f, c] = mode (x, 2);
+%! assert (reshape (m, [3, 3]), [1 1 2; 2 1 1; 1 2 1]);
+%! assert (reshape (f, [3, 3]), [1 1 2; 2 1 1; 1 2 1]);
+%! c = reshape (c, [3, 3]);
+%! assert (c{1}, [1; 2; 3]);
+%! assert (c{2}, 2);
+%! assert (c{3}, [1; 2; 3]);
+%!test
+%! [m, f, c] = mode (x, 3);
+%! assert (reshape (m, [3, 3]), [1 2 1; 1 2 1; 1 2 1]);
+%! assert (reshape (f, [3, 3]), [1 2 1; 1 2 1; 1 2 1]);
+%! c = reshape (c, [3, 3]);
+%! assert (c{1}, [1; 2; 3]);
+%! assert (c{2}, [1; 2; 3]);
+%! assert (c{3}, [1; 2; 3]);
+
+%% Test input validation
+%!error mode ()
+%!error mode (1, 2, 3)
+%!error mode ({1 2 3})
+%!error mode (['A'; 'B'])
+%!error mode (1, ones(2,2))
+%!error mode (1, 1.5)
+%!error mode (1, 0)
+%!error mode (1, 3)
+
git://git.creatis.insa-lyon.fr / CreaPhase.git / blobdiff