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## Copyright (C) 2017-2022 Philip Nienhuis
##
## This program 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.
##
## This program 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 this program. If not, see
## <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} [@var{Xo}, @var{Yo}, ... ] = closePolygonParts (@var{Xi}, @var{Yi}, ...)
## @deftypefnx {Function File} [@var{Xo}, @var{Yo}, ... ] = closePolygonParts (@var{Xi}, @var{Yi}, ..., @var{angunit})
## Ensure that (each part of a multipart) polygon is a closed ring.
##
## For each (part of a) polygon, closePolygonParts checks if the vertices
## of that part form a closed ring, i.e., if first and last vertices coincide.
## If the polygon or polygon parts (the latter separated separated by NaNs) do
## not form a closed ring, the first vertex coordinates of each open part are
## appended after its last vertex. Input polygons need not be multipart.
##
## @var{Xi} and @var{Yi} (plus optionally, @var{Zi} and/or @var{Mi}) are input
## vectors of X and Y or Longitude and Latitude (plus optionally Z or Height,
## and/or M) vectors of vertex coordinates (and measure values) of an input
## polygon. If a vector of measures is given as argument, it should always be
## the last vector.
##
## Optional last argument @var{angunit} can be one of 'Degrees' or 'Radians'
## (case-insensitive, only the first 3 characters need to match). If this
## argument is given and if the first two input vectors are longitude/latitude
## vectors rather than X/Y vectors, it indicates that the longitudes of those
## first and last vectors need only coincide modulo 360 degrees or 2*pi radians.
##
## The number of output vectors @var{Xo}, @var{Yo}, ... matches the number of
## input vectors.
##
## @seealso{isShapeMultiPart}
## @end deftypefn
## Author: Philip Nienhuis <prnienhuis@users.sf.net>
## Created: 2017-11-08
function [varargout] = closePolygonParts (varargin)
nargs = nargin;
ang = 0;
## Input checks
if (ischar (varargin{end}))
ang = find (ismember ({"rad", "deg"}, lower (varargin{end}(1:3))));
if (isempty (ang))
error ("closePolygonParts: unknown angle unit: '%s'; must be Degrees or Radians", ...
varargin{end});
endif
--nargs;
endif
if (! all (cellfun (@isnumeric, varargin(1:nargs))))
error ("closePolygonParts: numeric input vectors expected");
elseif (nargs != nargout)
error ("closePolygonParts: nr. of input vectors doesn't match nr. of output vectors");
endif
## Check orientation, matching NaN positions and lengths of input vectors
mp = cell (nargs, 1);
for ii=1:nargs
mp(ii) = find (isnan (varargin{ii}));
endfor
for ii=2:nargs
if (numel (varargin{ii-1}) != numel (varargin{ii}))
error ("closePolygonParts: incompatible input vectors #%d and #%d", ii-1, ii);
endif
if (isrow (varargin{ii-1}) != isrow (varargin{ii}))
error ("closePolygonParts: all input vectors should have same dimension");
endif
## Check NaN positions. M vectors may have more NaNs indicating missing values
if (! isempty (mp{ii-1}) && ! isempty (mp{ii}) && ...
numel (mp{ii-1}) == numel (mp{ii}))
## The next loop uses ismember() to cope with M vectors with missing values
if (! all (ismember (mp{ii-1}, mp{ii})))
error ("closePolygonParts: NaN positions of arg# %d and arg #d don't match", ii-1, ii);
endif
endif
endfor
## Input validation done, check for open rings.
## Assess extent of each polygon part.
idn = [ 0 (find (isnan (varargin{1}))) (numel (varargin{1})+1) ];
## Process polygons backwards to avoid stale (multipart) idn indices
for jj=numel (idn)-1 : -1 : 1
isclosed = true;
if (ang == 1)
isclosed = isclosed && ...
abs (wrapTo2Pi (varargin{1}(idn(jj)+1)) - wrapTo2Pi (varargin{1}(idn(jj+1)-1))) < eps;
elseif (ang == 2)
isclosed = isclosed && ...
abs (wrapTo360 (varargin{1}(idn(jj)+1)) - wrapTo360 (varargin{1}(idn(jj+1)-1))) < eps;
else
isclosed = isclosed && ...
abs (varargin{1}(idn(jj)+1) - varargin{1}(idn(jj+1)-1)) < eps;
endif
for ii=2:nargs
isclosed = isclosed && ...
abs (varargin{ii}(idn(jj)+1) - varargin{ii}(idn(jj+1)-1)) < eps;
endfor
if (! isclosed)
for ii=1:nargs
varargin{ii}(idn(jj+1):end+1) = varargin{ii}(idn(jj+1)-1:end);
varargin{ii}(idn(jj+1)) = varargin{ii}(idn(jj)+1);
endfor
endif
endfor
for ii=1:nargs
varargout{ii} = varargin{ii};
endfor
endfunction
%!test
%! xi = [ 1 5 6 2 NaN 11 15 16 12 ];
%! yi = [ 1 2 5 6 NaN 1 2 5 6 ];
%! zi = [ 1 3 5 3 NaN 11 13 15 13 ];
%! mi = [ 8 9 NaN -1 NaN NaN -3 -2 NaN];
%! [a, b, c, d] = closePolygonParts (xi, yi, zi, mi);
%! assert (a, [1 5 6 2 1 NaN 11 15 16 12 11], 1e-10);
%! assert (b, [1 2 5 6 1 NaN 1 2 5 6 1], 1e-10);
%! assert (c, [1 3 5 3 1 NaN 11 13 15 13 11], 1e-10);
%! [d, e, f] = closePolygonParts (a, b, c);
%! assert (a, d, 1e-10);
%! assert (b, e, 1e-10);
%! assert (c, f, 1e-10);
%!test
%! xxi = [ 400 405 406 402 NaN 311 315 316 312 671 ];
%! yyi = [ 1 2 5 6 NaN 1 2 5 6 1 ];
%! zzi = [ 1 3 5 3 NaN 11 13 15 13 11 ];
%! [a, b, c] = closePolygonParts (xxi, yyi, zzi, "deg");
%! assert (a, [400 405 406 402 400 NaN 311 315 316 312 671], 1e-10);
%! assert (b, [ 1 2 5 6 1 NaN 1 2 5 6 1], 1e-10);
%! assert (c, [ 1 3 5 3 1 NaN 11 13 15 13 11], 1e-10);
%!error <unknown angle unit> a = closePolygonParts ([0 1], "ged");
%!error <numeric input vectors expected> [a, b] = closePolygonParts ([0 1], {"c", "d"})
%!error <nr. of input vectors> a = closePolygonParts ([0 1], [2 3])
%!error <nr. of input vectors> a = closePolygonParts ("radians")
%!error <incompatible input vectors> [a, b] = closePolygonParts ([0 NaN 1], [2 NaN 3 4])
%!error <NaN positions of> [a, b] = closePolygonParts ([0 1 NaN 1], [2 NaN 3 4])
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