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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{B} =} rotdim (@var{A})
## @deftypefnx {} {@var{B} =} rotdim (@var{A}, @var{n})
## @deftypefnx {} {@var{B} =} rotdim (@var{A}, @var{n}, @var{plane})
## Return a copy of @var{A} with the elements rotated counterclockwise in
## 90-degree increments.
##
## The second argument @var{n} is optional, and specifies how many 90-degree
## rotations are to be applied (the default value is 1). Negative values of
## @var{n} rotate the matrix in a clockwise direction.
##
## The third argument is also optional and defines the plane of the rotation.
## If present, @var{plane} is a two element vector containing two different
## valid dimensions of the matrix. When @var{plane} is not given the first two
## non-singleton dimensions are used.
##
## For example,
##
## @example
## @group
## rotdim ([1, 2; 3, 4], -1, [1, 2])
## @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
## rotdim ([1, 2; 3, 4], -1, [1, 2])
## rotdim ([1, 2; 3, 4], 3, [1, 2])
## rotdim ([1, 2; 3, 4], 7, [1, 2])
## @end group
## @end example
## @seealso{rot90, fliplr, flipud, flip}
## @end deftypefn
function B = rotdim (A, n, plane)
if (nargin < 1)
print_usage ();
endif
if (nargin > 1 && ! isempty (n))
if (! isscalar (n) || ! isreal (n) || fix (n) != n)
error ("rotdim: N must be a scalar integer");
endif
else
n = 1;
endif
nd = ndims (A);
sz = size (A);
if (nargin < 3)
if (nd > 2)
## Find the first two non-singleton dimension.
plane = [];
dim = 0;
while (dim < nd)
dim += 1;
if (sz (dim) != 1)
plane = [plane, dim];
if (length (plane) == 2)
break;
endif
endif
endwhile
if (length (plane) < 1)
plane = [1, 2];
elseif (length (plane) < 2)
plane = [1, plane];
endif
else
plane = [1, 2];
endif
else
if (! (isvector (plane) && length (plane) == 2
&& all (plane == fix (plane)) && all (plane > 0)
&& all (plane < (nd + 1)) && plane(1) != plane(2)))
error ("rotdim: PLANE must be a 2-element integer vector defining a valid plane");
endif
endif
n = rem (n, 4);
if (n < 0)
n += 4;
endif
if (n == 0)
B = A;
elseif (n == 2)
B = flip (flip (A, plane(1)), plane(2));
elseif (n == 1 || n == 3)
perm = 1:nd;
perm(plane(1)) = plane(2);
perm(plane(2)) = plane(1);
B = permute (A, perm);
if (n == 1)
B = flip (B, min (plane));
else
B = flip (B, max (plane));
endif
endif
endfunction
%!shared r, rr
%! r = [1,2,3]; rr = [3,2,1];
%!assert (rotdim (r, 0), r)
%!assert (rotdim (r, 1), rr')
%!assert (rotdim (r, 2), rr)
%!assert (rotdim (r, 3), r')
%!assert (rotdim (r, 3), rotdim (r, -1))
%!assert (rotdim (r, 1), rotdim (r))
%!shared c, cr
%! c = [1;2;3]; cr = [3;2;1];
%!assert (rotdim (c, 0), c)
%!assert (rotdim (c, 1), c')
%!assert (rotdim (c, 2), cr)
%!assert (rotdim (c, 3), cr')
%!assert (rotdim (c, 3), rotdim (c, -1))
%!assert (rotdim (c, 1), rotdim (c))
%!shared m
%! m = [1,2;3,4];
%!assert (rotdim (m, 0), m)
%!assert (rotdim (m, 1), [2,4;1,3])
%!assert (rotdim (m, 2), [4,3;2,1])
%!assert (rotdim (m, 3), [3,1;4,2])
%!assert (rotdim (m, 3), rotdim (m, -1))
%!assert (rotdim (m, 1), rotdim (m))
## FIXME: We need tests for multidimensional arrays
## and different values of PLANE.
%!error <Invalid call> rotdim ()
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