update packages

[CreaPhase.git] / octave_packages / m / set / union.m

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+## Copyright (C) 1994-2012 John W. Eaton
+## 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} {} union (@var{a}, @var{b})
+## @deftypefnx {Function File} {} union (@var{a}, @var{b}, "rows")
+## Return the set of elements that are in either of the sets @var{a} and
+## @var{b}.  @var{a}, @var{b} may be cell arrays of string(s).
+## For example:
+##
+## @example
+## @group
+## union ([1, 2, 4], [2, 3, 5])
+##     @result{} [1, 2, 3, 4, 5]
+## @end group
+## @end example
+##
+## If the optional third input argument is the string "rows" each row of
+## the matrices @var{a} and @var{b} will be considered an element of sets.
+## For example:
+##
+## @example
+## @group
+## union ([1, 2; 2, 3], [1, 2; 3, 4], "rows")
+##    @result{}  1   2
+##        2   3
+##        3   4
+## @end group
+## @end example
+##
+## @deftypefnx {Function File} {[@var{c}, @var{ia}, @var{ib}] =} union (@var{a}, @var{b})
+##
+## Return index vectors @var{ia} and @var{ib} such that @code{a(ia)} and
+## @code{b(ib)} are disjoint sets whose union is @var{c}.
+##
+## @seealso{intersect, setdiff, unique}
+## @end deftypefn
+
+## Author: jwe
+
+function [y, ia, ib] = union (a, b, varargin)
+
+  if (nargin < 2 || nargin > 3)
+    print_usage ();
+  endif
+
+  [a, b] = validargs ("union", a, b, varargin{:});
+
+  if (nargin == 2)
+    y = [a(:); b(:)];
+    na = numel (a); nb = numel (b);
+    if (size (a, 1) == 1 || size (b, 1) == 1)
+      y = y.';
+    endif
+  else
+    y = [a; b];
+    na = rows (a); nb = rows (b);
+  endif
+
+  if (nargout == 1)
+    y = unique (y, varargin{:});
+  else
+    [y, i] = unique (y, varargin{:});
+    ia = i(i <= na);
+    ib = i(i > na) - na;
+  endif
+
+endfunction
+
+%!assert(all (all (union ([1, 2, 4], [2, 3, 5]) == [1, 2, 3, 4, 5])));
+
+%!assert(all (all (union ([1; 2; 4], [2, 3, 5]) == [1, 2, 3, 4, 5])));
+
+%!assert(all (all (union ([1, 2, 3], [5; 7; 9]) == [1, 2, 3, 5, 7, 9])));
+
+%!error union (1);
+
+%!error union (1, 2, 3);
+
+%!test
+%! a = [3, 1, 4, 1, 5]; b = [1, 2, 3, 4];
+%! [y, ia, ib] = union (a, b.');
+%! assert(y, [1, 2, 3, 4, 5]);
+%! assert(y, sort([a(ia), b(ib)]));