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## Copyright (C) 2000-2013 Daniel Calvelo
## Copyright (C) 2009 Jaroslav Hajek
##
## 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
## <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {[@var{s}, @var{i}] =} sortrows (@var{A})
## @deftypefnx {Function File} {[@var{s}, @var{i}] =} sortrows (@var{A}, @var{c})
## Sort the rows of the matrix @var{A} according to the order of the
## columns specified in @var{c}. If @var{c} is omitted, a
## lexicographical sort is used. By default ascending order is used
## however if elements of @var{c} are negative then the corresponding
## column is sorted in descending order.
## @seealso{sort}
## @end deftypefn
## Author: Daniel Calvelo, Paul Kienzle
## Adapted-by: jwe
function [s, i] = sortrows (A, c)
if (nargin < 1 || nargin > 2)
print_usage ();
endif
if (nargin == 2)
if (! (isnumeric (c) && isvector (c)))
error ("sortrows: C must be a numeric vector");
elseif (any (c == 0) || any (abs (c) > columns (A)))
error ("sortrows: all elements of C must be in the range [1, columns (A)]");
endif
endif
default_mode = "ascend";
reverse_mode = "descend";
if (issparse (A))
## FIXME: Eliminate this case once __sort_rows_idx__ is fixed to
## handle sparse matrices.
if (nargin == 1)
i = sort_rows_idx_generic (default_mode, reverse_mode, A);
else
i = sort_rows_idx_generic (default_mode, reverse_mode, A, c);
endif
elseif (nargin == 1)
i = __sort_rows_idx__ (A, default_mode);
elseif (all (c > 0))
i = __sort_rows_idx__ (A(:,c), default_mode);
elseif (all (c < 0))
i = __sort_rows_idx__ (A(:,-c), reverse_mode);
else
## Otherwise, fall back to the old algorithm.
i = sort_rows_idx_generic (default_mode, reverse_mode, A, c);
endif
## Only bother to compute s if needed.
if (isargout (1))
s = A(i,:);
endif
endfunction
function i = sort_rows_idx_generic (default_mode, reverse_mode, m, c)
if (nargin == 3)
indices = [1:columns(m)]';
mode(1:columns(m)) = {default_mode};
else
for j = 1:length (c);
if (c(j) < 0)
mode{j} = reverse_mode;
else
mode{j} = default_mode;
endif
endfor
indices = abs (c(:));
endif
## Since sort is 'stable' the order of identical elements will be
## preserved, so by traversing the sort indices in reverse order we
## will make sure that identical elements in index i are subsorted by
## index j.
indices = flipud (indices);
mode = flipud (mode');
i = [1:rows(m)]';
for j = 1:length (indices);
[~, idx] = sort (m(i, indices(j)), mode{j});
i = i(idx);
endfor
endfunction
%!test
%! m = [1, 1; 1, 2; 3, 6; 2, 7];
%! c = [1, -2];
%! [x, idx] = sortrows (m, c);
%! [sx, sidx] = sortrows (sparse (m), c);
%! assert (x, [1, 2; 1, 1; 2, 7; 3, 6]);
%! assert (idx, [2; 1; 4; 3]);
%! assert (issparse (sx));
%! assert (x, full (sx));
%! assert (idx, sidx);
%!test
%! m = [1, 0, 0, 4];
%! c = 1;
%! [x, idx] = sortrows (m, c);
%! [sx, sidx] = sortrows (sparse (m), c);
%! assert (x, m);
%! assert (idx, 1);
%! assert (issparse (sx));
%! assert (x, full (sx));
%! assert (idx, sidx);
%% Test input validation
%!error sortrows ()
%!error sortrows (1, 2, 3)
%!error sortrows (1, "ascend")
%!error sortrows (1, ones (2,2))
%!error sortrows (1, 0)
%!error sortrows (1, 2)
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