| Finding pairs of points within a certain distance [message #83822] |
Mon, 08 April 2013 15:56  |
koensayr
Messages: 1
Registered: April 2013
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Junior Member |
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Hello all,
I have a problem that I'm trying to find an efficient way to solve.
I have a large list of points (on the order of 10^8), that I need to match to a second list of points (on the order of 10^5 points), and find all pairs that are within a certain distance from each other.
The points are located on the surface of the Earth, so they are given in lat/lon coordinates. I have looked at functions like map_2points that can calculate the distance, but brute force way of matching them would be way too slow.
I noticed a user written library in the Documents of Exelis called match_sph that seem to do what I need, but I cannot find where to download it, and the website where that library was hosted seems to be down.
I have also thought about maybe dividing the points into small chunks using something like hist_nd, but was hoping that there might be an existing program for something like this already.
Any help is greatly appreciated,
Thanks!
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| Re: Finding pairs of points within a certain distance [message #83904 is a reply to message #83822] |
Tue, 09 April 2013 06:43  |
Kenneth Bowman
Messages: 86
Registered: November 2006
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Member |
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On 2013-04-08 22:56:23 +0000, koensayr@gmail.com said:
> Hello all,
>
> I have a problem that I'm trying to find an efficient way to solve.
>
> I have a large list of points (on the order of 10^8), that I need to
> match to a second list of points (on the order of 10^5 points), and
> find all pairs that are within a certain distance from each other.
>
> The points are located on the surface of the Earth, so they are given
> in lat/lon coordinates. I have looked at functions like map_2points
> that can calculate the distance, but brute force way of matching them
> would be way too slow.
>
> I noticed a user written library in the Documents of Exelis called
> match_sph that seem to do what I need, but I cannot find where to
> download it, and the website where that library was hosted seems to be
> down.
>
> I have also thought about maybe dividing the points into small chunks
> using something like hist_nd, but was hoping that there might be an
> existing program for something like this already.
>
> Any help is greatly appreciated,
>
> Thanks!
There are vectorized version of MAP_2POINTS and LL_ARC_AZIMUTH in my
library that you can download here
http://learnidl.com/downloads/
Ken Bowman
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