Mercurial > octave
view scripts/general/shiftdim.m @ 33577:2506c2d30b32 bytecode-interpreter tip
maint: Merge default to bytecode-interpreter
author | Arun Giridhar <arungiridhar@gmail.com> |
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date | Sat, 11 May 2024 18:49:01 -0400 |
parents | 2e484f9f1f18 |
children |
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######################################################################## ## ## Copyright (C) 2004-2024 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} =} shiftdim (@var{x}, @var{n}) ## @deftypefnx {} {[@var{y}, @var{ns}] =} shiftdim (@var{x}) ## Shift the dimensions of @var{x} by @var{n}, where @var{n} must be ## an integer scalar. ## ## When @var{n} is positive, the dimensions of @var{x} are shifted to the left, ## with the leading dimensions circulated to the end. If @var{n} is negative, ## then the dimensions of @var{x} are shifted to the right, with @var{n} ## leading singleton dimensions added. ## ## Called with a single argument, @code{shiftdim}, removes the leading ## singleton dimensions, returning the number of dimensions removed in the ## second output argument @var{ns}. ## ## For example: ## ## @example ## @group ## x = ones (1, 2, 3); ## size (shiftdim (x, -1)) ## @result{} 1 1 2 3 ## size (shiftdim (x, 1)) ## @result{} 2 3 ## [b, ns] = shiftdim (x) ## @result{} b = ## 1 1 1 ## 1 1 1 ## @result{} ns = 1 ## @end group ## @end example ## @seealso{reshape, permute, ipermute, circshift, squeeze} ## @end deftypefn function [y, ns] = shiftdim (x, n) if (nargin < 1) print_usage (); endif nd = ndims (x); orig_dims = size (x); if (nargin == 1) ## Find the first non-singleton dimension. (n = find (orig_dims != 1, 1) - 1) || (n = nd); elseif (! (isscalar (n) && n == fix (n))) error ("shiftdim: N must be a scalar integer"); endif if (n >= nd) n = rem (n, nd); endif if (n < 0) singleton_dims = ones (1, -n); y = reshape (x, [singleton_dims, orig_dims]); elseif (n > 0) ## We need permute here instead of reshape to shift values in a ## compatible way. y = permute (x, [n+1:nd 1:n]); else y = x; endif ns = n; endfunction %!test %! x = rand (1, 1, 4, 2); %! [y, ns] = shiftdim (x); %! assert (size (y), [4 2]); %! assert (ns, 2); %! assert (shiftdim (y, -2), x); %! assert (size (shiftdim (x, 2)), [4 2]); %!assert (size (shiftdim (rand (0, 1, 2))), [0 1 2]) ## Test input validation %!error <Invalid call> shiftdim () %!error shiftdim (1, ones (2)) %!error shiftdim (1, 1.5)