Whether a point lies within a rectangle (Fast solution)
31 次查看(过去 30 天)
显示 更早的评论
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
2 个评论
采纳的回答
Star Strider
2014-10-22
编辑:Adam Danz
2020-6-20
3 个评论
Adam Danz
2020-6-20
编辑:Adam Danz
2020-6-20
* 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
更多回答(4 个)
Guillaume
2014-10-22
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.
0 个评论
Matt J
2014-10-22
编辑:Matt J
2014-10-22
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.
Hary
2024-7-15
Using index would much faster than row to row comparison if you have less rectangle in comparison to the points you are checking in. Although loop is still needed. For example
For ii.....
index=the whole matrix >=xmin(ii) &...
end
0 个评论
另请参阅
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!