Identifying elements of an array in clockwise order

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Sean 2014-7-7

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https://ww2.mathworks.cn/matlabcentral/answers/140774-identifying-elements-of-an-array-in-clockwise-order

评论： Sean 2014-7-8

If I have an array A such that it contains vertex coordinates of polygons where

and C such that it contains the collection of vertex locations in A of a polygon where C is something like:

C = {[ 2, 5, 8, 9]
           .
           .
           .
     [x,y locations in A]}

C{1} contains the coordinates (2,0), (0,0), (0,2), and (2,2) from A. I want to take say, the first elements of C{1}, and sort C such that the remaining element order in C{1} moves clockwise (or counter-clockwise) in terms of element location with respect to polygon generation. So C{1}(1)=2 (2,0), and the remaining elements would follow as such:

C{1}(2)=9 (2,2)
C{1}(3)=8 (0,2)
C{1}(4)=5 (0,0)

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Sean 2014-7-7

That is clever, cheers.

Sean 2014-7-8

在 MATLAB Online 中打开

For future reference, something like this

v = cell(size(C)); 
for j=1:length(C)
frodo = C{j};
aragorn_x = new_pts(frodo,1);
aragorn_y = new_pts(frodo,2);
DT = delaunayTriangulation(aragorn_x,aragorn_y);
[K,v{j}] = convexHull(DT);
end