Mercurial > octave
view scripts/geometry/convhull.m @ 31119:df030ac26390
uniquetol.m: improve matlab compatibility and add byrows sorting (bug #59850)
* /scripts/set/uniquetol.m: improve empty and NaN handling, add sorting to
'byrows' output, ensure ia and ic outputs have column orientation for arrays
and cells, verify consistent single class handling, add BISTs for
aforementioned cases, and update docstring to note non-complex input
requirement.
author | Nicholas R. Jankowski <jankowski.nicholas@gmail.com> |
---|---|
date | Tue, 05 Jul 2022 15:22:46 -0400 |
parents | 796f54d4ddbf |
children | 597f3ee61a48 |
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######################################################################## ## ## Copyright (C) 2000-2022 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{H} =} convhull (@var{x}, @var{y}) ## @deftypefnx {} {@var{H} =} convhull (@var{x}, @var{y}, @var{z}) ## @deftypefnx {} {@var{H} =} convhull (@var{x}) ## @deftypefnx {} {@var{H} =} convhull (@dots{}, @var{options}) ## @deftypefnx {} {[@var{H}, @var{V}] =} convhull (@dots{}) ## Compute the convex hull of a 2-D or 3-D set of points. ## ## The hull @var{H} is a linear index vector into the original set of points ## that specifies which points form the enclosing hull. For 2-D inputs only, ## the output is ordered in a counterclockwise manner around the hull. ## ## The input @var{x} may also be a matrix with two or three columns where the ## first column contains x-data, the second y-data, and the optional third ## column contains z-data. ## ## An optional final argument, which must be a string or cell array of strings, ## contains options passed to the underlying qhull command. ## See the documentation for the Qhull library for details ## @url{http://www.qhull.org/html/qh-quick.htm#options}. ## The default option is @code{@{"Qt"@}}. ## ## If @var{options} is not present or @code{[]} then the default arguments are ## used. Otherwise, @var{options} replaces the default argument list. ## To append user options to the defaults it is necessary to repeat the ## default arguments in @var{options}. Use a null string to pass no arguments. ## ## If the second output @var{V} is requested the volume of the enclosing ## convex hull is calculated. ## ## @seealso{convhulln, delaunay, voronoi} ## @end deftypefn function [H, V] = convhull (varargin) if (nargin < 1 || nargin > 4) print_usage (); endif z = []; options = []; switch (nargin) case 1 if (! ismatrix (varargin{1}) || (columns (varargin{1}) != 2 && columns (varargin{1}) != 3)) error ("convhull: X must be a matrix with 2 or 3 columns"); else x = varargin{1}(:,1); y = varargin{1}(:,2); if (columns (varargin{1}) == 3) z = varargin{1}(:,3); endif endif case 2 if (isnumeric (varargin{2})) x = varargin{1}; y = varargin{2}; elseif (! (ischar (varargin{2}) || iscellstr (varargin{2}))) error ("convhull: OPTIONS must be a string or cell array of strings"); else options = varargin{2}; ncols = columns (varargin{1}); if (! ismatrix (varargin{1}) || (ncols != 2 && ncols != 3)) error ("convhull: X must be a matrix with 2 or 3 columns"); else x = varargin{1}(:,1); y = varargin{1}(:,2); if (ncols == 3) z = varargin{1}(:,3); endif endif endif case 3 if (isnumeric (varargin{3})) x = varargin{1}; y = varargin{2}; z = varargin{3}; elseif (! (ischar (varargin{3}) || iscellstr (varargin{3}))) error ("convhull: OPTIONS must be a string or cell array of strings"); else x = varargin{1}; y = varargin{2}; options = varargin{3}; endif case 4 x = varargin{1}; y = varargin{2}; z = varargin{3}; options = varargin{4}; if (! (ischar (options) || iscellstr (options))) error ("convhull: OPTIONS must be a string or cell array of strings"); endif endswitch if (isempty (z)) x = x(:); y = y(:); if (! size_equal (x, y)) error ("convhull: X and Y must be the same size"); endif if (nargout > 1) [Htmp, V] = convhulln ([x, y], options); else Htmp = convhulln ([x, y], options); endif else x = x(:); y = y(:); z = z(:); if (! size_equal (x, y, z)) error ("convhull: X, Y, and Z must be the same size"); endif if (nargout > 1) [H, V] = convhulln ([x, y, z], options); else H = convhulln ([x, y, z], options); endif endif if (isempty (z)) ## Order 2-D convex hull in a counter-clockwise manner. n = rows (Htmp); Htmp = Htmp.'(:); H = zeros (n + 1, 1); H(1) = Htmp(1); next_pt = Htmp(2); Htmp(2) = 0; for k = 2:n next_idx = find (Htmp == next_pt); H(k) = Htmp(next_idx); if (rem (next_idx, 2) == 0) next_pt = Htmp(next_idx - 1); Htmp(next_idx - 1) = 0; else next_pt = Htmp(next_idx + 1); Htmp(next_idx + 1) = 0; endif endfor H(n + 1) = H(1); endif endfunction %!demo %! clf; %! x = -3:0.05:3; %! y = abs (sin (x)); %! k = convhull (x, y); %! plot (x(k),y(k),"r-;convex hull;", x,y,"b+;points;"); %! axis ([-3.05, 3.05, -0.05, 1.05]); %!testif HAVE_QHULL %! x = -3:0.5:3; %! y = abs (sin (x)); %! assert (convhull (x, y), [1;7;13;12;11;10;4;3;2;1]); %!testif HAVE_QHULL %! [~, V] = convhull ([0,2,2,0], [0,0,1,1]); %! assert (V == 2); ## Input validation tests %!error <Invalid call> convhull () %!error <Invalid call> convhull (1,2,3,4,5) %!error <X must be a matrix with 2 or 3 columns> convhull (ones (2,4)) %!error <OPTIONS must be a string or cell array> convhull (ones (2,2), struct ()) %!error <X must be a matrix with 2 or 3 columns> convhull (ones (2,4), "") %!error <OPTIONS must be a string or cell array> convhull (ones (2,2), ones (2,2), struct ()) %!error <OPTIONS must be a string or cell array> convhull (ones (2,2), ones (2,2), ones (2,2), struct ()) %!error <X and Y must be the same size> convhull (1, [1 2]) %!error <X, Y, and Z must be the same size> convhull (1, [1 2], [1 2])