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## Copyright (C) 2000-2013 Paul Kienzle
## Copyright (C) 2008-2009 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} {} unique (@var{x})
## @deftypefnx {Function File} {} unique (@var{x}, "rows")
## @deftypefnx {Function File} {} unique (@dots{}, "first")
## @deftypefnx {Function File} {} unique (@dots{}, "last")
## @deftypefnx {Function File} {[@var{y}, @var{i}, @var{j}] =} unique (@dots{})
## Return the unique elements of @var{x}, sorted in ascending order.
## If the input @var{x} is a vector then the output is also a vector with the
## same orientation (row or column) as the input. For a matrix input the
## output is always a column vector. @var{x} may also be a cell array of
## strings.
##
## If the optional argument @qcode{"rows"} is supplied, return the unique
## rows of @var{x}, sorted in ascending order.
##
## If requested, return index vectors @var{i} and @var{j} such that
## @code{x(i)==y} and @code{y(j)==x}.
##
## Additionally, if @var{i} is a requested output then one of @qcode{"first"} or
## @qcode{"last"} may be given as an input. If @qcode{"last"} is specified,
## return the highest possible indices in @var{i}, otherwise, if @qcode{"first"}
## is specified, return the lowest. The default is @qcode{"last"}.
## @seealso{union, intersect, setdiff, setxor, ismember}
## @end deftypefn
function [y, i, j] = unique (x, varargin)
if (nargin < 1)
print_usage ();
endif
if (nargin > 1)
## parse options
if (iscellstr (varargin))
optfirst = strcmp ("first", varargin);
optlast = strcmp ("last", varargin);
optrows = strcmp ("rows", varargin);
if (! all (optfirst | optlast | optrows))
error ("unique: invalid option");
endif
optfirst = any (optfirst);
optlast = any (optlast);
optrows = any (optrows);
if (optfirst && optlast)
error ('unique: cannot specify both "last" and "first"');
endif
else
error ("unique: options must be strings");
endif
if (optrows && iscell (x))
warning ('unique: "rows" is ignored for cell arrays');
optrows = false;
endif
else
optfirst = false;
optrows = false;
endif
## FIXME -- the operations
##
## match = (y(1:n-1) == y(2:n));
## y(idx) = [];
##
## are very slow on sparse matrices. Until they are fixed to be as
## fast as for full matrices, operate on the nonzero elements of the
## sparse array as long as we are not operating on rows.
if (issparse (x) && ! optrows && nargout <= 1)
if (nnz (x) < numel (x))
y = unique ([0; (full (nonzeros (x)))], varargin{:});
else
## Corner case where sparse matrix is actually full
y = unique (full (x), varargin{:});
endif
return;
endif
if (optrows)
n = rows (x);
dim = 1;
else
n = numel (x);
dim = (rows (x) == 1) + 1;
endif
y = x;
## Special cases 0 and 1
if (n == 0)
if (! optrows && isempty (x) && any (size (x)))
if (iscell (y))
y = cell (0, 1);
else
y = zeros (0, 1, class (y));
endif
endif
i = j = [];
return;
elseif (n == 1)
i = j = 1;
return;
endif
if (optrows)
if (nargout > 1)
[y, i] = sortrows (y);
else
y = sortrows (y);
endif
match = all (y(1:n-1,:) == y(2:n,:), 2);
idx = find (match);
y(idx,:) = [];
else
if (! isvector (y))
y = y(:);
endif
if (nargout > 1)
[y, i] = sort (y);
else
y = sort (y);
endif
if (iscell (y))
match = strcmp (y(1:n-1), y(2:n));
else
match = (y(1:n-1) == y(2:n));
endif
idx = find (match);
y(idx) = [];
endif
if (isargout (3))
j = i;
if (dim == 1)
j(i) = cumsum ([1; !match]);
else
j(i) = cumsum ([1, !match]);
endif
endif
if (isargout (2))
if (optfirst)
i(idx+1) = [];
else
i(idx) = [];
endif
endif
endfunction
%!assert (unique ([1 1 2; 1 2 1; 1 1 2]),[1;2])
%!assert (unique ([1 1 2; 1 0 1; 1 1 2],"rows"),[1 0 1; 1 1 2])
%!assert (unique ([]),[])
%!assert (unique ([1]),[1])
%!assert (unique ([1 2]),[1 2])
%!assert (unique ([1;2]),[1;2])
%!assert (unique ([1,NaN,Inf,NaN,Inf]),[1,Inf,NaN,NaN])
%!assert (unique ({"Foo","Bar","Foo"}),{"Bar","Foo"})
%!assert (unique ({"Foo","Bar","FooBar"}'),{"Bar","Foo","FooBar"}')
%!assert (unique (zeros (1,0)), zeros (0,1))
%!assert (unique (zeros (1,0), "rows"), zeros (1,0))
%!assert (unique (cell (1,0)), cell (0,1))
%!assert (unique ({}), {})
%!assert (unique ([1,2,2,3,2,4], "rows"), [1,2,2,3,2,4])
%!assert (unique ([1,2,2,3,2,4]), [1,2,3,4])
%!assert (unique ([1,2,2,3,2,4]', "rows"), [1,2,3,4]')
%!assert (unique (sparse ([2,0;2,0])), [0,2]')
%!assert (unique (sparse ([1,2;2,3])), [1,2,3]')
%!assert (unique ([1,2,2,3,2,4]', "rows"), [1,2,3,4]')
%!assert (unique (single ([1,2,2,3,2,4]), "rows"), single ([1,2,2,3,2,4]))
%!assert (unique (single ([1,2,2,3,2,4])), single ([1,2,3,4]))
%!assert (unique (single ([1,2,2,3,2,4]'), "rows"), single ([1,2,3,4]'))
%!assert (unique (uint8 ([1,2,2,3,2,4]), "rows"), uint8 ([1,2,2,3,2,4]))
%!assert (unique (uint8 ([1,2,2,3,2,4])), uint8 ([1,2,3,4]))
%!assert (unique (uint8 ([1,2,2,3,2,4]'), "rows"), uint8 ([1,2,3,4]'))
%!test
%! [a,i,j] = unique ([1,1,2,3,3,3,4]);
%! assert (a, [1,2,3,4]);
%! assert (i, [2,3,6,7]);
%! assert (j, [1,1,2,3,3,3,4]);
%!
%!test
%! [a,i,j] = unique ([1,1,2,3,3,3,4]', "first");
%! assert (a, [1,2,3,4]');
%! assert (i, [1,3,4,7]');
%! assert (j, [1,1,2,3,3,3,4]');
%!
%!test
%! [a,i,j] = unique ({"z"; "z"; "z"});
%! assert (a, {"z"});
%! assert (i, [3]');
%! assert (j, [1;1;1]);
%!
%!test
%! A = [1,2,3;1,2,3];
%! [a,i,j] = unique (A, "rows");
%! assert (a, [1,2,3]);
%! assert (A(i,:), a);
%! assert (a(j,:), A);
%!error unique({"a", "b", "c"}, "UnknownOption")
%!error unique({"a", "b", "c"}, "UnknownOption1", "UnknownOption2")
%!error unique({"a", "b", "c"}, "rows", "UnknownOption2")
%!error unique({"a", "b", "c"}, "UnknownOption1", "last")
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