Whether a point lies within a rectangle (Fast solution)
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I have a large list of points and a large list of rectangles.I want to find the number of points inside each rectangle.I have a working solution which is very TPT heavy.
Is there a faster way of implementing this.
What I am doing now : Assume point P’s coordinate is (xp,yp), and the rectangle’s lower left point is (x1,y1) and upper right point is (x2,y2):if (xp is between x1 and x2) AND (yp is between y1 and y2) then the point(xp,yp) is inside the rectangle.The issue is i have a large set of points (> 20000) and a larger set of rectangles(lets say also > 2000)
Now i can loop over each rectangle to caluclate the the number of points in each
for ii=1:20000
ind = Xcord>Rects(ii,1) & Xcord<Rects(ii,3) & Ycord>Rects(ii,2) & Ycord<Rects(ii,4);
count = sum(ind);
end
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답변 (4개)
Star Strider
2014년 10월 22일
편집: Adam Danz
2020년 6월 20일
댓글 수: 3
Adam Danz
2020년 6월 20일
편집: Adam Danz
2020년 6월 20일
* Just FYI, I edited Star Strider's answer to update the links to the two functions. They were from r2014a documentation which no longer exists.
+1
Guillaume
2014년 10월 22일
I don't think you'll find a faster way to do it in matlab, short of performing the search in a mex file.
In my limited understanding of this domain , a spatially indexed R-tree would be the way to go. Implementing this in matlab is bound to be difficult with the limited data structures available and probably not that efficient in the end.
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Matt J
2014년 10월 22일
편집: Matt J
2014년 10월 22일
You should partition your field into an NxN chequerboard of 2D bins, say with N=10. Use sort or histc to bin your Rect and XY coordinate data into each square of the chequerboard . Then you don't have to compare all XY coordinates with all Rectangles. You can loop over the chequerboard squares and just compare XY data lying in a given square with rectangle data lying in that square.
Leonardo Souto Ferreira
2018년 2월 8일
U can accelerate your search using a quadtree for example.
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