update packages

[CreaPhase.git] / octave_packages / m / statistics / base / center.m

diff --git a/octave_packages/m/statistics/base/center.m b/octave_packages/m/statistics/base/center.m
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+## Copyright (C) 1995-2012 Kurt Hornik
+## Copyright (C) 2009 VZLU Prague
+##
+## 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} {} center (@var{x})
+## @deftypefnx {Function File} {} center (@var{x}, @var{dim})
+## If @var{x} is a vector, subtract its mean.
+## If @var{x} is a matrix, do the above for each column.
+## If the optional argument @var{dim} is given, operate along this dimension.
+## @seealso{zscore}
+## @end deftypefn
+
+## Author: KH <Kurt.Hornik@wu-wien.ac.at>
+## Description: Center by subtracting means
+
+function retval = center (x, dim)
+
+  if (nargin != 1 && nargin != 2)
+    print_usage ();
+  endif
+
+  if (! (isnumeric (x) || islogical (x)))
+    error ("center: X must be a numeric vector or matrix");
+  endif
+
+  if (isinteger (x))
+    x = double (x);
+  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 ("center: DIM must be an integer and a valid dimension");
+    endif
+  endif
+
+  n = sz(dim);
+
+  if (n == 0)
+    retval = x;
+  else
+    retval = bsxfun (@minus, x, mean (x, dim));
+  endif
+
+endfunction
+
+%!assert(center ([1,2,3]), [-1,0,1])
+%!assert(center (single([1,2,3])), single([-1,0,1]))
+%!assert(center (int8 ([1,2,3])), [-1,0,1])
+%!assert(center (logical ([1, 0, 0, 1])), [0.5, -0.5, -0.5, 0.5])
+%!assert(center (ones (3,2,0,2)), zeros (3,2,0,2))
+%!assert(center (ones (3,2,0,2, 'single')), zeros (3,2,0,2, 'single'))
+%!assert(center (magic (3)), [3,-4,1;-2,0,2;-1,4,-3])
+%!assert(center ([1 2 3; 6 5 4], 2), [-1 0 1; 1 0 -1])
+
+%% Test input validation
+%!error center ()
+%!error center (1, 2, 3)
+%!error center (1, ones(2,2))
+%!error center (1, 1.5)
+%!error center (1, 0)
+%!error center (1, 3)