How select data just out from a polygon, considering a constraint

Question

Francesco Porretta 2021-9-13

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1452134-how-select-data-just-out-from-a-polygon-considering-a-constraint

编辑： Matt J 2021-9-13

borders % matrix 20x2 with the x and y coordinates of the generic polygon perimeter
datas   % matrix 550x2 containing the x and y coordinates of all my datas

Using the function "inpolygon" I'm able to find all the points of "datas" that are inside the polygon perimeter defined by "borders".

However, I also want to take into account all the points that are outside the polygon and near the perimeter.

More precisely, I want to consider all the points outside the polygon for which the distance in x is lower than 0.3 and the distance in y is lower than 0.1, with respect to the border.

Hoping to be clear, thanks for help!

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Answer 1

Matt J 2021-9-13

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https://ww2.mathworks.cn/matlabcentral/answers/1452134-how-select-data-just-out-from-a-polygon-considering-a-constraint#answer_786364

编辑：Matt J 2021-9-13

在 MATLAB Online 中打开

borders=[0,0;0,1;1 1;1 0];
p=polyshape(borders);
p=blurHull(p,[0.3,0]);
p=blurHull(p,[0, 0.1]);
isinterior(p,datas)
        function ps=blurHull(p,v)
        
              N=100;
              t=linspace(-1,1,N).'*v;
              
              ps=p;
              for i=1:size(t,1)
                 
                  ps=union(ps,translate(p,t(i,:)));
              end
             
              d=2/N;
              ps=polybuffer(ps,d,'JointType','square');
              ps=polybuffer(ps,-d,'JointType','square');
        end

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Answer 2

KSSV 2021-9-13

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1452134-how-select-data-just-out-from-a-polygon-considering-a-constraint#answer_786309

Read about knnsearch. This will give you indices of points lying closer to the given set of points from a set of points along with distances. You can play around with distances obtained from here.