how to use inpolygon function

Question

Sososasa 2014-3-30

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/123680-how-to-use-inpolygon-function

评论： Sososasa 2014-3-30

采纳的回答： Jos (10584)

在 MATLAB Online 中打开

Hi,

I have two polygons with different number of vertices:

polygon1= [0.1624   -0.6477;
           0.2247   -0.6477;
           0.2247    0.3874;    
           0.1624    0.5219]
polygon2= [0.1624    0.5219;
           0.2247    0.3874;
           0.2247    0.5651]

Where the first column is X-coordinates and the second column in Y-coordinates. I want to know if a any random point is in the first or second polygon. How can I do that? I read the documentation of this function (inpolygon) but I don't understand it well.

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Answer 1

Jos (10584) 2014-3-30

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/123680-how-to-use-inpolygon-function#answer_131376

在 MATLAB Online 中打开

A polygon is defined by its vertices(corner points), being pairs of (x,y) coordinates. In your case, these coordinates are stored in a single N-by-2 matrix.

polygon1= [0.1624   -0.6477;
         0.2247   -0.6477;
         0.2247    0.3874;    
         0.1624    0.5219]
P = rand(1,2)/2 % we will look at 1 point, but in poly can accept multiple points!
tf = inpolygon(P(:,1), P(:,2),polygon1(:,1), polygon1(:,2))
plot(polygon1([1:end 1],1), polygon1([1:end 1],2),'b.-',P(:,1), P(:,2),'r*') % a plot is often informative
if any(tf==1),
   title('Some point(s) is (are) in or on the edge of polygon 1') ;
else
   title('All points are outside polygon 1') ;
end