Mercurial > octave
view scripts/general/rot90.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) 1993-2021 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 {} {} rot90 (@var{A}) ## @deftypefnx {} {} rot90 (@var{A}, @var{k}) ## Rotate array by 90 degree increments. ## ## Return a copy of @var{A} with the elements rotated counterclockwise in ## 90-degree increments. ## ## The second argument is optional, and specifies how many 90-degree rotations ## are to be applied (the default value is 1). Negative values of @var{k} ## rotate the matrix in a clockwise direction. ## For example, ## ## @example ## @group ## rot90 ([1, 2; 3, 4], -1) ## @result{} 3 1 ## 4 2 ## @end group ## @end example ## ## @noindent ## rotates the given matrix clockwise by 90 degrees. The following are all ## equivalent statements: ## ## @example ## @group ## rot90 ([1, 2; 3, 4], -1) ## rot90 ([1, 2; 3, 4], 3) ## rot90 ([1, 2; 3, 4], 7) ## @end group ## @end example ## ## The rotation is always performed on the plane of the first two dimensions, ## i.e., rows and columns. To perform a rotation on any other plane, use ## @code{rotdim}. ## ## @seealso{rotdim, fliplr, flipud, flip} ## @end deftypefn function B = rot90 (A, k = 1) if (nargin < 1) print_usage (); endif if (! (isscalar (k) && isreal (k) && k == fix (k))) error ("rot90: K must be a single real integer"); endif k = mod (k, 4); nd = ndims (A); if (k == 0) B = A; elseif (k == 1) B = flipud (permute (A, [2 1 3:1:nd])); elseif (k == 2) idx(1:nd) = {':'}; idx{1} = rows (A):-1:1; idx{2} = columns (A):-1:1; B = A(idx{:}); elseif (k == 3) B = permute (flipud (A), [2 1 3:1:nd]); else error ("rot90: internal error!"); endif endfunction %!test %! x1 = [1, 2; 3, 4]; %! x2 = [2, 4; 1, 3]; %! x3 = [4, 3; 2, 1]; %! x4 = [3, 1; 4, 2]; %! %! assert (rot90 (x1), x2); %! assert (rot90 (x1, 2), x3); %! assert (rot90 (x1, 3), x4); %! assert (rot90 (x1, 4), x1); %! assert (rot90 (x1, 5), x2); %! assert (rot90 (x1, -1), x4); ## Test NDArrays %!test %! a(1:2,1:2,1) = [1 2; 3 4]; %! a(1:2,1:2,2) = [5 6; 7 8]; %! b(1:2,1:2,1) = [2 4; 1 3]; %! b(1:2,1:2,2) = [6 8; 5 7]; %! assert (rot90 (a, 1), b); %! assert (rot90 (a, 2), rot90 (b, 1)); %! assert (rot90 (a, 3), rot90 (b, 2)); %!test %! a = b = zeros (2, 2, 1, 2); %! a(1:2,1:2,:,1) = [1 2; 3 4]; %! a(1:2,1:2,:,2) = [5 6; 7 8]; %! b(1:2,1:2,:,1) = [2 4; 1 3]; %! b(1:2,1:2,:,2) = [6 8; 5 7]; %! assert (rot90 (a, 1), b); %! assert (rot90 (a, 2), rot90 (b, 1)); %! assert (rot90 (a, 3), rot90 (b, 2)); ## With non-square matrices %!test %! a = zeros (3, 2, 1, 2); %! b = zeros (2, 3, 1, 2); %! a(1:2,1:3,:,1) = [ 1 2 3; 4 5 6]; %! a(1:2,1:3,:,2) = [ 7 8 9; 10 11 12]; %! b(1:3,1:2,:,1) = [ 3 6; 2 5; 1 4]; %! b(1:3,1:2,:,2) = [ 9 12; 8 11; 7 10]; %! assert (rot90 (a, 1), b); %! assert (rot90 (a, 2), rot90 (b, 1)); %! assert (rot90 (a, 3), rot90 (b, 2)); ## Test input validation %!error <Invalid call> rot90 () %!error rot90 (1, ones (2)) %!error rot90 (1, 1.5) %!error rot90 (1, 1+i)