Mercurial > octave
view scripts/general/shift.m @ 29359:7854d5752dd2
maint: merge stable to default.
author | John W. Eaton <jwe@octave.org> |
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date | Wed, 10 Feb 2021 10:10:40 -0500 |
parents | d8318c12d903 0a5b15007766 |
children | 796f54d4ddbf |
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######################################################################## ## ## Copyright (C) 1995-2021 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 {} {} shift (@var{x}, @var{b}) ## @deftypefnx {} {} shift (@var{x}, @var{b}, @var{dim}) ## If @var{x} is a vector, perform a circular shift of length @var{b} of ## the elements of @var{x}. ## ## If @var{x} is a matrix, do the same for each column of @var{x}. ## ## If the optional @var{dim} argument is given, operate along this dimension. ## @end deftypefn function y = shift (x, b, dim) if (nargin < 2) print_usage (); endif if (numel (x) < 1) error ("shift: X must not be empty"); elseif (! (isscalar (b) && b == fix (b))) error ("shift: B must be an integer"); endif nd = ndims (x); sz = size (x); if (nargin == 3) if (!(isscalar (dim) && dim == fix (dim)) || !(1 <= dim && dim <= nd)) error ("shift: DIM must be an integer and a valid dimension"); endif else ## Find the first non-singleton dimension. (dim = find (sz > 1, 1)) || (dim = 1); endif d = sz(dim); idx = repmat ({':'}, nd, 1); if (b > 0) b = rem (b, d); idx{dim} = [d-b+1:d, 1:d-b]; elseif (b < 0) b = rem (abs (b), d); idx{dim} = [b+1:d, 1:b]; endif y = x(idx{:}); endfunction %!test %! a = [1, 2, 3]; %! b = [4, 5, 6]; %! c = [7, 8, 9]; %! %! r = [a, b, c]; %! m = [a; b; c]; %! %! assert (shift (r, 0), r); %! assert (shift (r, 3), [c, a, b]); %! assert (shift (r, -6), [c, a, b]); %! assert (shift (r, -3), [b, c, a]); %! assert (shift (m, 1), [c; a; b]); %! assert (shift (m, -2), [c; a; b]); ## Test input validation %!error <Invalid call> shift () %!error <Invalid call> shift (1) %!error <X must not be empty> shift ([], 1) %!error <B must be an integer> shift (ones (2), ones (2)) %!error <B must be an integer> shift (ones (2), 1.5) %!error <DIM must be an integer> shift (1, 1, 1.5) %!error <DIM must be .* a valid dimension> shift (1, 1, 0) %!error <DIM must be .* a valid dimension> shift (1, 1, 3)