Mercurial > octave
view scripts/statistics/center.m @ 33567:9f0f7a898b73 bytecode-interpreter tip
maint: Merge default to bytecode-interpreter
author | Arun Giridhar <arungiridhar@gmail.com> |
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date | Fri, 10 May 2024 17:57:29 -0400 |
parents | 2e484f9f1f18 |
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######################################################################## ## ## Copyright (C) 1995-2024 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 {} {@var{y} =} center (@var{x}) ## @deftypefnx {} {@var{y} =} center (@var{x}, @var{dim}) ## Center data by subtracting its mean. ## ## 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. ## ## Programming Note: @code{center} has obvious application for normalizing ## statistical data. It is also useful for improving the precision of general ## numerical calculations. Whenever there is a large value that is common ## to a batch of data, the mean can be subtracted off, the calculation ## performed, and then the mean added back to obtain the final answer. ## @seealso{zscore} ## @end deftypefn function y = center (x, dim) if (nargin < 1) 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) && dim > 0)) error ("center: DIM must be an integer and a valid dimension"); endif endif n = size (x, dim); if (n == 0) y = x; else ## FIXME: Use bsxfun, rather than broadcasting, until broadcasting ## supports diagonal and sparse matrices (Bugs #41441, #35787). y = bsxfun (@minus, x, mean (x, dim)); ## y = x - mean (x, dim); # automatic broadcasting 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]) %!assert (center (1, 3), 0) ## Test input validation %!error <Invalid call> center () %!error <DIM must be an integer> center (1, ones (2,2)) %!error <DIM must be an integer> center (1, 1.5) %!error <DIM must be .* a valid dimension> center (1, 0)